Prosthodontics

• Complete Denture
  • Introduction to Complete Dentures Question and Answers
    • Introduction To Complete Denture Notes and Short Essays
    • Complete Dentures Short Question and Answers
  • Diagnosis and Treatment Planning Question and Answers
  • Impression and Mouth Preparation Question and Answers
    • Impression And Mouth Preparation Definition and Short Essays
    • Impression And Mouth Preparation Short Question and Answers
    • Impression And Mouth Preparation Long Essays
  • Maxillomandibular Relations Question and Answers
    • Maxillomandibular Relations Definitions And Notes
    • Maxillomandibular Relations Short Essays
    • Maxillomandibular Relations Long Essays
  • Laboratory Procedures Prior to Try In Question and Answers
    • Laboratory Procedures Prior To Try In Notes And Short Essays
    • Laboratory Procedures Prior To Try In Short Question and Answers
    • Laboratory Procedures Prior To Try In Long Essays
  • Denture Insertion Question and Answers
  • Post Insertion Problems Question and Answers
  • Relining and Rebasing Question and Answers
  • Special Complete Dentures Question and Answers
• Removal Partial Dentures Question and Answers
  • Removable Partial Dentures Notes
  • Removable Partial Dentures Short Essays
  • Removable Partial Dentures Short Answers
  • Removable Partial Dentures Long Essays
• Fixed Partial Denture (FPD) Question and Answers
• Maxillofacial Prosthetics Question and Answers
• Implant Dentistry Question and Answers

Relining And Rebasing

 

Relining And Rebasing Definitions

 Relining: A procedure to resurface the tissue surface of the denture with new base material to make the denture it more accurately

Rebasing: A process of refitting a denture by the replacement of the denture base material

Relining And Rebasing Important Notes

Relining And Rebasing:

Indications of Relining And Rebasing:

• Immediate dentures at 3-6 months after their original construction
• When the residual alveolar ridges have resorbed and adaptation of the denture base to the ridge is poor
• When a patient cannot afford the cost of new dentures
• Geriatric or chronically ill patients
• Centric occlusion should coincide with centric relation

Contra-Indications of Relining And Rebasing:

• An excessive amount of resorption
• Abused soft tissues are present
• The patient complains of TMJ problems
• Dentures have poor esthetics
• Denture creating speech problems
• Severe osseous undercuts exists until surgical removal and healing occurs

Relining And Rebasing Short Essays

Question 1. Tissue conditioner.
Answer:

Tissue conditioners are tissue-lining materials

Functions of Tissue conditioner:

• Permit wider dispersion of forces
• Aid to decrease the force per unit area transmitted to the supporting tissues
• Serve as analog of the mucoperiosteum

Composition of Tissue conditioner:

• Polyethyl methacrylate
• Aromatic ester
• Ethyl alcohol

Uses of Tissue conditioner:

• Tissue treatment
• Temporary obturator
• Baseplate stabilization
• To diagnose the outcome of resilient liners
• Liners in surgical splints
• Trial denture base Functional impression material

Question 2. Uses of resilient liners.
Answer:

Uses of resilient liners:

• Adjuncts for tissue healing
• Preserve the residual ridge
• Heal irritated tissue
• As temporary obturator
• Done directly in the mouth
• Or indirectly after making an impression of the surgical site
• Stabilization of baseplate
• Used in presence of undercuts to stabilize the denture base and prevent its breakage
• Diagnosis of the outcome of resilient liner
• In case of chronic soreness caused by dentures
• For surgical splint
• As it is of stiffer consistency
• As a trial denture base
• As functional impression material
• In the presence of movable tissues

Read And Learn More: Prosthodontics Question And Answers

Question 3. Open mouth relining.
Answer:

Boucher’s Technique:

Question. 4. Relining & rebasing.
Or
Indications for relining the complete denture.
Answer:

Definition:

Relining:  A procedure to resurface the tissue surface of the denture with new base material to make the denture fit more accurately

Rebasing:  A process of refitting a denture by the replacement of the denture base material

Indications of relining the complete denture:

• Immediate dentures after 3–6 months
• Poor adaptation of dentures
• Economic
• Old patients

Contraindications of relining the complete denture:

• Excessive residual ridge resorption
• Abused soft tissues
• TMJ problems
• Dissatisfied patients
• Abnormal jaw relations
• Patient having speech defect
• Presence of severe undercuts

Advantages of relining the complete denture:

• The need of frequent visits
• Economic
• Good fit
• Incorporation of soft liner possible

Disadvantages of relining the complete denture:

• Alters jaw relation
• Impossible to correct jaw relation, aesthetics
• Impossible to correct occlusal arrangements
• Not used in dentures with excessive resorption

Question 5. Remounting procedure.
Answer:

Used to refine the occlusion of prosthesis

Purpose of Remounting :

• Reproduce the relationship of the cast at rest & at function
• Verify the records
• Correct processing errors
• Refine occlusion

Requirements of Remounting :

• Not weaken the cast
• Not create undercut
• Be functional
• Quick & easy to fabricate
• Easy to remove
• Provide 3D fit of the denture

Methods of Remounting :

1. Groove indexing method:

• Two lines are drawn
• One line sagittally & other transversely

2. Notch indexing method:

• Notches are created one anterior & 2 posterior

3. Split remounting plates for indexing:

• Male & female remounting plates are used
• These can be fitted to one another & unlocked with the help of locking pins

Relining And Rebasing Short Question And Answers

Question 1. Conditioning of abused & irritated tissues.
Answer:

• Tissue conditioners are used
• Composition
• Polymer
• Monomer
• Liquid plasticizer

Manipulation of abused:

• Mixing ratio 1.25 parts polymer, 1 part monomer, 0.5cc plasticizer
• Mix the ingredients to form a gel
• Apply sufficient thickness of material to the tissue surface of the denture
• Insert the denture in the patient’s mouth
• Carry out border movements

Maintenance of abused:

• Avoid cleaning with a hard brush
• Use a soft brush under running water

Question 2. Clinical remounting
Answer:

Clinical remounting is done using interocclusal records

Steps of Clinical remounting:

• Occlusal surface of the maxillary denture was lubricated with Vaseline and inserted into mouth
• Two layers of aluwax are placed over posterior teeth in mandibular fixed partial denture
• Wax is sealed to the denture
• A mandibular fixed denture is inserted in the mouth and the mandible is guided into centric relation
• Next patient is asked to close his mouth such that maxillary teeth penetrate about 1-1.5 mm deep into the wax
• Dentures are removed
• They are reinserted and the process is repeated with complete closure
• A maxillary denture is mounted on the articulator using a remount cast
• A mandibular denture is repositioned against the articulated maxillary denture using a centric record and articulated

Question 3. Functional relining technique.
Answer:

Functional relining technique:

• Suggested by Winkler
• The patient is advised to avoid nightwear of the denture
• Occlusal correction is carried out
• Overextension of the denture are corrected
• The tissue surface is reduced
• The tissue conditioning material is placed
• A denture is inserted in patient’s mouth
• Impression is removed
• Trim the excess material
• The denture is inserted
• Recall the patient after 3 to 5 days
• Examine the depressed areas and renew the material
• The impression is next made with ZOE and the cast is poured

Question 4. Instructions for patients in care & maintenance of tissue conditioners.
Answer:

Instructions for patients in care & maintenance of tissue conditioners:

• Tissue conditioners should not be cleaned by scrubbing with a hard brush to prevent tearing of material
• The use of soft brush under running water should be done
• They tend to harden and roughen within 4 to 8 weeks due to the loss of plasticizers
• Hence, periodic visits should be carried out

Relining And Rebasing Viva Voce

1. Elastic stage of the tissue conditioner is reached in 1- 2 weeks

Special Complete Dentures

 

Special Complete Dentures Definitions

Tooth-supported over denture:

“A dental prosthesis that replaces the lost or missing natural dentition & associated structures of the maxilla &/or mandible & receives partial support & stability from one or more modified natural teeth”

Special Complete Dentures Important Notes

Disadvantages of immediate dentures:

• The fit, appearance or comfort is difficult to predict
• There is no try in
• Often require tissue conditioner during the healing phase
• Need a definite reline

Advantages of immediate dentures:

• Patient’s appearance is maintained
• Circumboreal support, muscle tone, the vertical dimension of occlusion, jaw relationship and face height can be maintained
• The tongue will not spread due to the loss of teeth
• Less post-operative pain
• Easier to duplicate the natural tooth shape and position
• The patient is likely to adapt more easily to dentures

The treatment procedure for an immediate denture:

• The posterior teeth are extracted and allowed to heal
• Impression and cast are made
• Anterior teeth on the master cast are broken away and trimmed up to the cervical margin and smoothened.
• The ridge lap (cervical) portion of the artificial teeth are trimmed and arranged on the master cast.
• Artificial teeth are arranged over the area where the teeth are to be extracted.
• The teeth arrangement should be in harmony with the existing teeth as well as the prosthetic teeth.
• The denture is flashed, dew-axed, packed, processed, and finished.
• During the insertion appointment, the remaining anterior teeth are extracted as a traumatically as possible, preserving the soft tissue and bone.
• The finished denture is seated in the patient’s mouth.

Overdentures:

Advantages of Over dentures:

• Maintains the integrity of the residual ridge
• Improves stability and support
• Improved proprioception

If the abutment fails, the over denture can be used as a conventional denture

Types of over dentures:

• Conventional immediate denture
• Interim or transitional immediate denture

Special Complete Dentures Long Essays

Question. 1. Define immediate complete denture. Write in detail steps in making it.
Answer:

Definition of immediate complete denture:

“A complete or removable partial denture constructed for insertion immediately following the removal of natural teeth”

Steps of immediate complete denture:

• Making of alginate impression
• Duplicating it
• Pouring of the cast(master cast) for one of the impression
• It is used for preparing baseplate, rims, jaw relation & teeth arrangement
• In other impressions pour molten wax into the teeth to be extracted
• After it cools pour the duplicating cast
• It is used for processing of dentures
• Fabricate baseplate & occlusal rims over master cast Record jaw relation
• Teeth arrangement done over it Try in verification is done
• Shift the denture to refractory cast Processing of the denture is carried out
• Atraumatic extraction of the tooth to be done
• Insertion of an immediate denture

Read And Learn More: Prosthodontics Question And Answers

Special Complete Dentures Short Essays

Question 1. Single complete dentures.
Answer:

Types of Single complete dentures:

• Maxillary complete denture opposing a mandibular natural denture
• Maxillary complete denture opposing a mandibular partial denture
• Mandibular complete denture opposing a maxillary natural denture
• Mandibular complete denture opposing a maxillary partial denture

Indications of Single complete dentures:

• Inpatient with a jaw discrepancy
• In cleft patients
• Retrognathia mandible

Disadvantages of Single complete dentures:

• Malposed, unerupted teeth interfere with balanced occlusion
• The presence of lower anterior causes difficulty in aesthetics Acrylic opposing natural teeth causes abrasion of acrylic
• Porcelain opposing natural teeth causes abrasion of natural teeth

Complications of Single complete dentures:

• Combination syndrome
• Wear of natural teeth
• Fracture of the

Question 2. Problems in single denture construction.
Answer:

• Malposed, tipped, or supra-erupted teeth in the lower arch will interfere with balanced occlusion
• It produces soreness, mucosal changes, and ridge resorption in the maxilla
• Maxillary denture tends to get displaced
• As lower anterior are present in a fixed position, it is difficult to obtain aesthetic teeth arrangement
• The use of acrylic teeth opposing natural teeth will produce abrasion of acrylic teeth
• Use of porcelain teeth opposing natural teeth will produce abrasion of natural teeth

1. Problems in maxillary complete denture opposing mandibular partial denture:

• Combination syndrome:
  • The patient tends to concentrate the occlusal load on the remaining natural teeth
  • Results in more force acting on anterior portion of the maxillary denture
  • Increased resorption of the anterior part of the maxilla
  • Labial flange will displace and irritate labial vestibule
  • Posteriorly there will be fibrous overgrowth in maxillary tuberosity
• Wear of natural teeth:
  • Porcelain teeth lead to severe abrasion of opposing natural teeth
  • Denture fracture
  • It occurs due to
  • Excessive anterior occlusal load
  • Deep labial frenal notches
  • High occlusal load

2. Mandibular single denture:

• It causes severe ridge resorption of edentulous mandible because of
• Constant movement of the tongue
• Less denture-bearing area

Question 3. Requirements of overdenture.
Answer:

Requirements of overdenture:

• Abutment teeth should be surrounded by healthy periodontium
• Maximum reduction of the coronal portion of tooth Endodontic treatment is required
• Internal attachment should not be present while tooth preparation
• Fluoride application
• Grossly destroyed tooth sleeve coping retainers
• Attachments for additional retention
• The motivation of the patient to maintain oral hygiene
• Recall appointments
• Regular fluoride application

Patient Selection:

• Young patient
• Favourable psychological effect

Abutment Selection:

• Periodontally sound
• Cuspids & bicuspids are frequently selected
• Free of caries
• Sufficient width of attached gingiva
• Ideal crown root ratio

Question 4. Tooth-supported complete denture.
Or
Disadvantages of overdentures
Or
Indications & contraindications of over dentures
Answer:

Definition of Tooth-supported complete denture:

“A dental prosthesis that replaces the lost or missing natural dentition & associated structures of the maxilla & or mandible & receives partial support & stability from one or more modified natural teeth”

Advantages of Tooth-supported complete denture:

• Maintenance of the integrity of the ridge
• Improves stability & retention of denture Improves proprioception
• Avoid psychological effects on patient
• Universal accepted
• Can be relined

Disadvantages of Tooth-supported complete denture:

• Oral hygiene maintenance is required Periodical fluoride application
• Frequent recall visits are required
• Expensive
• Not used in cases with
• Reduced inter arch space
• Bony undercuts
• Periodontal breakdown of the remaining teeth
• Loss of remaining teeth

Indications of Tooth-supported complete denture:

• Aesthetics
• Cleft palate
• Maxillofacial trauma
• Worn-out denture Congenital anomalies
• Abnormal jaw size & position

Contraindications of Tooth-supported complete denture:

• Poor periodontal status Carious tooth Old age
• Improper crown root ratio
• Anterior teeth due to the resorbed alveolar ridge
• Gingival recession
• Pupal calcification

Special Complete Dentures Short Question And Answers

Question 1. Advantages of an immediate denture.
Answer:

Question 2. Advantages of over dentures
Answer:

• Maintains the integrity of the residual ridge
• Improves retention and stability of the denture
• Improves proprioception
• Helps in regulating biting force over the denture
• Has a psychological effect on the patient
• Can be used universally
• Even if there is abutment failure, the abutment can be extracted and the over-denture can be relined

Question 3. Types of bar-retained over dentures
Answer:

Types of bar-retained over dentures:

• This implant treatment involves the placement of 3-4 im- plants and the attachment of a customized bar.
• This bar provides rigid support through and series of clips to the denture that fits over the top of the bar.
• The bar retained overdenture treatment can be used in both the upper and lower jaws.
• It allows the denture to be removed from the mouth for cleaning.
• Patients also have to brush the bar which remains attached to the implants in the mouth.
• In the upper arch the bar over the denture often allows for a “horse-shoe design” to be adopted thereby eliminating the denture covering the palate.
• After the implants have been integrated and the customized bar is fabricated and screw-retained to the lower implants, this bar cannot be removed by the patient and needs to be brushed and cleaned daily just as teeth.
• The bar provides the retention for the denture which will fit over the top of the bar.

Question 4. The disadvantage of an immediate denture.
Answer:

Disadvantage of an immediate denture

• Time-consuming
• Expensive
• Difficult to record centric relation & occlusion
• Try in not possible
• Difficulty in speech & mastication
• Difficult to adapt to new dentures

Special Complete Dentures Viva Voce

1. The canine is best over denture abutment
2. Periodontal disease is the most common cause of loss of abutment in over denture
3. Regular follow-up examination of over denture is needed at intervals of 3–6 months
4. 24 hours are necessary to wear immediate denture just after extraction
5. After 7 days of extraction, an immediate denture can be removed during the night.

 

Implant Dentistry Definitions

Implant: It is an integral component of the oral implant complex which also consists of supportive bone, interposed kerati- nized and mucosal oral soft tissues and prosthetic superstructure

Splint: Splint is an appliance used for maintaining or stabilizing mobile teeth to their functional position

Osseointegration: It can be defined as “The apparent direct attachment or connection of osseous tissue to an inert alloplastic material without intervening connective tissue”.

Implant Dentistry Important Notes

Implant materials:

• Metals
  • Stainless steel
  • Gold
  • Titanium
  • Tantalum
• Zirconium
• Ceramics
• Calcium phosphate
• Bioactive and biodegradable ceramics
• Polymers

Bone healing events after placement of implant:

Implant Dentistry Short Essays

Question 1. Splints.
Answer:

Definition of Splints:

Splint is an appliance used for maintaining or stabilizing mobile teeth to their functional position

Functions of Solints:

• Stabilize mobile teeth to improve patient comfort and provide stability
• Stabilize moderate to advanced tooth mobility
• Stabilize teeth in secondary occlusal trauma
• Stabilize teeth following acute trauma
• Prevent tipping or drifting of teeth
• Create adequate stability

Contraindications of Solints:

• Presence of periodontal inflammation
• Presence of an insufficient number of non-mobile teeth
• Presence of inadequate oral hygiene
• Absence of prior occlusal adjustment

Read And Learn More: Prosthodontics Question And Answers

Question 2. Parts of implants.
Answer:

1. Implant body:
   • It is the component that is placed within the bone during the first stage of surgery
   • It can be threaded or non-threaded
2. Healing screw:
   • During the healing phase, this screw is placed on the superior surface of the body
   • Functions:
     • Facilitates the suturing of soft tissues
     • Prevents the growth of the tissue over the edge of the implant
3. Healing cap:
   • They are dome-shaped screws placed over the sealing screw after the second stage of surgery
   • Length- 2-10 mm
   • Function:
     • Prevents overgrowth of tissues around the implant
4. Abutments:
   • It resembles prepared tooth
   • Provides retention to the prosthesis
5. Impression posts:
   • It facilitates the transfer of the intra-oral location to a similar position on the cast
6.  Laboratory analogs:
   • It represents the body of the implant
   • Placed on the cast to fabricate an implant-supported prosthesis
7. Waxing sleeves:
   • Designed to be attached to the body of the implant
8. Prosthesis retaining screws:
   • Penetrates the fixed restoration and secures it to the abutment

Question 3. Osseointegration/requirements for successful osseointegration.
Answer:

It can be defined as “The apparent direct attachment or connection of osseous tissue to an inert alloplastic material without intervening connective tissue”.

Requirements of osseointegration:

1. Occlusal load:
   • To develop a strong interface the implant should not be overloaded during its organization period During this period, the surgical area undergoes remodelling process
2. Biocompatibility:
   • The material used should be biocompatible for example, pure titanium
3. Implant design:
   • Most conductive design for oseo-integration is cylindrical
4.  Implant surface:
   • A smooth-surfaced implant is less prone to osseointegration than an implant with mild surface roughness.
5. Surgical site:
   • It should be healthy
6. Surgical technique:
   • Site should be subjected to minimal trauma
7. Infection control:
   • Infection especially from the periodontics should be avoided.

Question 4. Types of Implants.
Answer:

1. Depending on the placement within the tissues:

• Epiosteal:
  • It receives its primary bone support by resting on it
• Transosteal:
  • It penetrates both cortical plates
  • It possesses through the entire thickness of the alveolar bone
• Endosteal:
  • It extends into the basal bone
  • It transects only one cortical bone
  • It is sub-classified into

2. Root form:

• Used over a vertical column of bone

3. Plate form:

• Used over a horizontal column of bone

4. Depending on the material used:

• Metallic implants
• Non-metallic implants

5. Depending on their reaction to bone:

• Bio-active (Hydroxyapatite)
• Bio-inert Implants (metal)

6. Depending on the classification of edentulous spaces:

Question 5. Implant materials
Answer:

Implant Dentistry Short Question And Answers

Question 1. Implant
Answer:

It is an integral component of the oral implant complex which also consists of supportive bone, interposed keratinized and mucosal oral soft tissues and prosthetic supra structure

Materials Used of Implant:

• Metals
  • Stainless steel
  • Tantalum
  • Gold
  • Titanium
• Zirconium
• Ceramics
• Calcium phosphate
• Bioactive and biodegradable ceramics
• Polymers

Implant Dentistry Viva Voce

1. The minimum width of ridge needed for a bio-integrated hydroxyapatite-coated dental implant is 5 mm
2. The minimum bone height of the ridge needed for a bio-integrated hydroxyapatite-coated dental implant is 8 mm.
3. 2 mm of space is needed between the implant and the inferior alveolar canal

Fixed Partial Denture (FPD)

 

Fixed Partial Denture Definitions

Fixed partial denture: It is defined as a partial denture that is cemented to natural teeth or roots which furnish the primary support to the prosthesis

Pontic: An artificial tooth on a fixed partial denture that replaces a missing tooth restores itsfunctions and usually fills the space previously filled by a natural crown

Abutment: A tooth, a portion of a tooth or that portion of an implant used for the support of a fixed or removable prosthesis

Retainer: It is defined as the part of a fixed partial denture which united the abutment to the remainder of the restoration

Connector: The portion of a fixed partial denture that unites the retainer and pontic

Ceramic: It is an inorganic compound with nonmetallic properties typically consisting of oxygen and one or more metallic or semi metallic elements that is formulated to produce the whole or part of ceramic based dental prosthesis

Structural durability: The ability of the restoration to withstand destruction due to external forces is known as “structural durability”

Fixed Partial Denture Important Notes

1. Ante’s law:

It states that “The combined pericemental area of all abutment teeth supporting a fixed partial denture should be equal to or greater in pericemental area than the tooth or teeth being replaced”

2. Finish lines:

1. Shoulder finish line:

Indications Shoulder Finish line:

• All ceramic crown
• PFM crown
• Injectable porcelain

Advantages of  Shoulder Finish lines:

• Good crown contours
• Esthetics
• Less distortion
• Provides adequate bulk

Disadvantages of  Shoulder Finish lines:

• Least conservative
• Inferior marginal adaptation

2.  Shoulder with bevel:

Indications of Shoulder with beve:

• Proximal boxes of inlays and onlays Labial finish line of metal ceramics Occlusal shoulder of onlays

Advantages of Shoulder with bevel:

• Superior marginal adaptation
• Resists distortion
• Facilitates removal of unsupported enamel rods

Read And Learn More: Prosthodontics Question And Answers

Disadvantages of Shoulder with bevel:

• Requires subgingival extension
• Detection of post cementation caries is difficult

3. Chamfer:

Indications of Chamfer:

• Cast metal restorations
• Lingual aspect of metal ceramics
• Advantages of Chamfer:
• Conservative
• Good marginal adaptation
• Provides bulk

Disadvantages of Chamfer :

• Improper fabrication may result in an unsupported tip

4. Knife edge:

Indications of Knife edge:

• Young patients
• MOD onlay
• Inaccessible area
• Finish lines in cementum

Advantages of Knife edge:

• Conservative
• Ideal for marginal adaptation

Disadvantages of Knife edge:

• Does not provide a distinct finish line
• Waxing, polishing and casting becomes critical
• Overcontoured restoration

3. Gingival finish lines:

1. Supragingival finish line:
   • Better periodontal health
   • Facilitates accurate impression making
   • Allows accurate assessment of the fit
2. Subgingival finish line:
   • Used when additional is needed
   • Indicated in anterior zone where esthetics is a prime consideration
   • Used in cervical erosion and root hypersensitivity cases

4. Surface areas of different tooth:

5. Structural durability:

• It is the resistance to deformity of a restoration
• It is achieved by
  • Reduction of 1.5 mm on functional cusp and 1mm on the nonfunctional cusp

6. Principles of tooth preparation:

 7. Root forms:

 8. Types of crowns:

9. Indications of laminates:

• Diastema
• Stained restoration
• Fractures
• Malposition
• Attrition, erosion and abrasion
• Discolored teeth

10. Types of abutment:

• Healthy or ideal abutment
• Cantilever abutment
• Tilted abutment
• Extensively damaged abutment
• Implant abutment

11. Disadvantages of the telescopic crown:

• Esthetically not acceptable
• Expensive
• Cannot be used in short crowns

12. Types of resin bonded retainers:

• Rochette bridges
• Maryland bridge

13. Classification of pontics:

1. Based on mucosal contact
   • With mucosal contact
     • Saddle pontic
     • Concave gingival surface overlaps the ridge buccally and lingually
     • Gingival surface will not have continuous contact with the ridge
     • It is least hygienic
   • Ridge lap pontic
     • Evolved from saddle pontic
     • Resembles natural tooth
     • Satisfies esthetics
     • Not hygienic
     • Difficult to maintain
     • Oviate pontic
   • Without mucosal contact
     • Bullet pontic
     • Sanitary pontic
       • Have zero tissue contact
       • Easy to maintain
       • Highly Unesthetic
       • Recommended in mandibular posteriors
2. Based on type of material:
   • Metal and porcelain veneered pontic
   • Metal and resin veneered pontic
   • All metal pontic
   • All ceramic pontic
3. Based on the method of fabrication
   • Custom made pontic
   • Prefabricated pontic

14. Preformed pontics:

15. Classification of retainer:

1. Based on tooth coverage
   • Full veneer crowns
   • Partial veneer crowns
   • Conservative retainer
2. Based on material used
   • Metal ceramic retainer
   • All metal retainer
   • All ceramic retainer
   • All acrylic retainer

Fixed Partial Denture Long Essays

Question 1. Define and classify provisional restorations. Write in detail the various methods of fabricating a custom provisional restoration.
Answer:

Definition of Provisional Restoratio:

It is a restoration that is established for the time being. until a permanent arrangement can be made

Classification of Provisional Restoration:

1. Based on method of fabrication
   • Preformed: Anatomic form is prefabricated and readily available
   • Custom made: Anatomic form and shape of tooth to be restored is fabricated by the dentist
2. Based on duration of use:
   • Short term used up to 2 weeks
   • Long-term may be used for few months
3. Based on material used:
   • Resins
   • Metals
   • Custom made cast metal alloys
4. Based on technique of fabrication:
   • Direct technique – Restorations are fabricated intra orally
   • Indirect technique – Restoration are fabricated ex- traorally
   • Direct/indirect technique

Custom  of Provisional Restoration:

The restoration is fabricated to reproduce the original contours of the tooth

• Technique of Provisional Restoratio:
  • Tooth preparation is carried out
  • An impression of the prepared tooth is made • Cast is poured
  • The prepared tooth over the cast is waxed up
  • It is carved to reproduce the original contours
• Advantagesof Provisional Restoratio:
  • Minimum interference
  • Wide variety of materials can be used
  • Helpful in evaluating the adequacy of tooth reduction
• Disadvantages of Provisional Restoratio :
  • Additional lab procedure is involved
  • Time consuming

Question 2. Define FPD. Mention different types of retainer and criteria for selection of retainer. Add a note on care of prosthesis.
Or
Classify retainers used in fixed partial
Answer:

Fixed Partial Denture:

It is defined as a partial denture that is cemented to natural teeth or roots which furnish the primary support to the prosthesis

Retainer of Fixed Partial Denture:

It is defined as the part of a fixed partial denture that united the abutment to the remainder of the restoration

Classification of Fixed Partial Denture:

1. Based on tooth coverage:
   • Full veneer crowns
   • Partial veneer crowns
   • Conservative retainer
2. Based on material used:
   1. Metal ceramic retainer
   2. All metal retainer
   3. All ceramic retainer
   4. All acrylic retainer

Question 3. Name parts of bridge. Define and classify pontic. Add a note on selection of pontic and its requirements and Pontic design and selection.
Answer:

Parts Of Bridge:

1.  Retainer
2.  Pontic
3. Connectors

Pontic Definition:

“An artificial tooth on a fixed partial denture that replaces a missing tooth restores its functions and usually fills the space previously filled by a natural crown”

Classification of Pontic: Based on mucosal contact:

1. With mucosal contact:
   • Saddle pontic
   • Ridge lap pontic
   • Oviate pontic
2. Without mucosal contact:
   • Bullet pontic
   • Sanitary pontic
3. Based on type of material:
   • Metal and porcelain veneered pontic
   • Metal and resin veneered pontic
   • All metal pontic
   • All ceramic pontic
4. Based on the method of fabrication:
   • Custom made pontic
   • Prefabricated pontic

Requirements of Pontic:

• It should restore the function of the tooth it replaces
• It should provide good aesthetics
• It should be comfortable to the patient
• It should be biocompatible
• It should have color stability
• It should permit effective oral hygiene
• It should preserve underlying mucosa and bone
• It should not overload the abutment

•  Pontic –  (P)
•  Retainer – (R)

Pontic Selection:

Various factors are considered for pontic selection. They are

1.  Cleansibility:
   • All surfaces of pontic should be made as cleansable as possible
   • All surfaces should be smooth and highly polished
   • It should not contain any junction between material The embrasure and connector should be smooth and cleansable
2. Appearance:
   • Where full length of pontic is visible, it should be as natural as possible
3. Strength:
   • All pontic should be designed to withstand occlusal forces
4. Age of the patient:
   • Younger patients need pontic made up of stronger material like nickel-chromium.
5. Edentulous space:
   • The space created due to the loss of a tooth is usually sufficient for the fabrication of good pontic But due to long period of edentulousness teeth tend to be tilted or drifted
   • In such cases the pontic should be modified
6. Other factors:
   • DMFT score of the individual
   • Oral hygiene status
   • Periodontal support present
   • Arch relation
   • Skeletal relation
   • Vitality of abutment

Question 4. Discuss various types of pontics in fixed partial denture.
Answer:

1. Saddle pontic:

It is a pontic that have concave gingival surface overlapping the ridge buccally and lingually

• Disadvantage:
  • It is difficult to maintain
  • It leads to food accumulation

2. Ridge lap pontics:

• It closely adapts to the ridge
• It resembles natural tooth
• It leads to soft tissues inflammation

3. Modified ridge lap pontic:

• In it the tissue contact occurs only over buccal surface of the ridge crest
• It has slight bucco lingual concavity and mesiodis tal convexity
• Tissue surface of the pontic has “T” shaped contact
• Vertical arm contacting crest of ridge and the horizontal arm contacts buccal surface

• Oviate pontic:
  • Indications:
    • Defective ridge
    • Broad and flat ridges
    • The cervical end of the pontic extends into the ridge defect
    • It is more esthetic

• Bullet Shaped: It has convex tissue surface contacting at one single point
  • Advantage: It is easy to clean and maintain
  • Disadvantage: Poor esthetics
  • Indication: Mandibular posteriors

• Spheroidal pontic: It has tissue contact at the ridge
  • Indications: Reduced inter-arch space
  • Advantages: It develops adequate exaggerated occluso-gingival dimension
• Sanitary pontic or Hygienic ponitic:
  • They do not have any mucosal contact
  • It is easy to maintain
  • They are used only for posterior due to poor esthetics
  • It should have adequate tissue clearance by placing it 3 mm high occluso-gingivally
    • Common designs are or types:
      • Bar sanitary pantic:
        • They have a flat gingival surface
        • They have sufficient gingival dearance to allow maintenance of it
      • Conventional sanitary/fish belly pontic
        • It has convex gingival surface, both buccolingually and mesiodistally
        • It resembles the belly of a fish
        • Its decreases the strength of the prosthesis by decreasing the size of the connector
      • Modified sanitary pontic:
        • The gingival surface is concave mesiodistally and convex buccolingually
        • Due to it, the arch shape obtained increases the size of the connector

1. Metal Ceramic pontics:
   • Due to the use of ceramic, it gives an esthetic ap-
     pearance
   • It is biocompatible
   • Its fabrication is technique sensitive
2. Resin veneered pontic:
   • It includes straight forward procedure for fabrication
   • It has poor esthetics
   • Staining at resin metal interface occurs
3. All metal pontic:
   • It has good strength but poor aesthetics
   • Thus it is used for mandibular molars
   • Its use is indicated in bruxers
4. Custom-made pontics:
   • It is customized for each patient
   • They offer superior aesthetics and flexibility
   • A wax pattern is prepared and cast to prepare it
5. Pre-fabricated pontic:
   • They are available as porcelain pontics
   • These are adjusted according to the individual requirement
   • Finally they are reglazed and fit to a metal
   • backing which is a custom fabricated portion of the poetics
   • The metal backing is such designed that it accept the prefabricated facing

Question 5. Define abutment. Explain criteria for selection of teeth for a fixed partial denture abutment.
Answer:

Definition of abutment:

“A tooth, a portion of a tooth or that portion of an implant used for the support of a fixed or removable prosthesis”

Selection Criteria:

• Location of the tooth:
  • Teeth adjacent to the edentulous spaces are selected
• Condition of the tooth:
  • Teeth should ideally be caries free
  • However, if the teeth are grossly decayed, it should be such that it can be restored with a full veneer crown
  • Vital teeth are preferred
•  Root configuration/shape:
  • The root shape determines the ability of the abutment to withstand the masticatory load
  • Some configurations are preferred for the abutment. They are
  • Wide labiolingual roots
  • Irregular curvature of roots
  • Longer roots
  • Conical roots

• Crown root shape:
  1. Length of the crown
     • It is the length of the tooth structure above the alveolar crest
  2. Length of the root
     • It is the total length of the root
     • The ratio of the above two gives the crown root ratio
     • It is one of the important criteria for abutment selection

Ratio:

• 1:1 – Acceptable
• >1 – Unacceptable
• 2:3 – Ideal

1. Root support:

• The tooth is supported if there is sufficient sur- rounding alveolar bone
• The alveolar should be
• Healthy
• Have normal trabecular pattern
• Have normal architecture
• If there is presence of bone loss or bony defect, the abutment selected will lead to failure of the prosthesis

2. Periodontal ligament area:

• An increased in the bone support results in increase in the periodontal ligament area
• It is used to determine the potency of an abutment Periodontal diseased teeth are unsuitable to be used as abutment

Ante’s Law:

• It states that “The combined pericemental area of all abutment teeth supporting a fixed partial denture should be equal to or greater in pericentral area than the tooth or teeth being replaced”
• The pericemental area is calculated
• If it is inadequate, then there is the addition of a secondary abutment

Assessment Of Pulpal Health:

• Unrestored abutments are preferred
• However, if the abutment tooth has a carious lesion with pulpal involvement then root canal treatment is advised.

Question 6. Enumerate steps in preparation of full ceramic crown for 21. Add a note on the advantages and disadvantages of the same.
Answer:

Tooth Preparation:

1. Step 1: Labial reduction
   • Depth orientation grooves are prepared us- ing a flat end tapered diamond
   • The grooves should be 1.2 – 1.4 mm deep on the labial surface and 2 mm on the incisal surface
   • Two sets of grooves are made
   • First is parallel to gingival third
   • Second is parallel to incisal 2/3rd
   • This provides better aesthetic
   • Next the tooth structure between the grooves is removed
   • The facial reduction should extend around the facio-proximal line angles
2. Step 2: Incisal Reduction
   • Depth orientation grooves are made across the incisal edge
   • They are about 2.0 mm deep
   • The tooth structure between the grooves is removed
     The incisal reduction should be perpendicular to the plane of the incisal half of the labial
     reduction
3. Step 3: Lingual reduction
   • Cingulum should be reduced
   • The reduction of lingual axial surface is carried out with a flat-end tapered diamond
   • The lingual wall should be parallel to the gingival portion of the labial wall.
4. Step 4: Proximal reduction
   • A radial shoulder of atleast 1.0 mm wide is made
     It should be in uniform contour along the line angles of the restoration
   • The axial walls are smoothened with a radial fissure bur
   • Biangle chisel is used to smoothen the shoulder

Advantages of Tooth Preparation:

• Superior esthetics
• Good translucency
• Good biocompatibility
• Good selection of shade

Disadvantages of Tooth Preparation:

• Reduces strength of the restoration
• Less conservative
• An extensively damaged tooth cannot be restored
• Cannot be used as retainers
• Can lead to periodontal failure
• Wear on the functional surfaces of opposing natural teeth

Question 7. Describe advantage, disadvantages, indications and contraindications of FPD.
Answer:

Advantages of Fixed partial denture:

• Movements for a fixed partial denture are less compared to a removable partial denture
• Psychologically better accepted than a removable partial denture
• Acts as a splint
• Less lateral forces are transmitted to abutment
• Can use weak abutment
• Aesthetically better
• Better functioning of the prosthesis
• Causes less bone resorption

Disadvantages of Fixed partial denture:

• It can weaken, a strong abutment
• It is an irreversible treatment
• Patient may not agree to carry out procedure over sound teeth
• Technique sensitive
• It can cause periodontal problems, if over contoured

Indications of Fixed partial denture:

• Length of the edentulous arch:
  • Short span edentulous arches are preferred for FPD
  • This is due to the reason that a long span FPD transfers excessive load to the abutment and also tends to flex to a greater extent
  • To avoid it,short span edentulous arches is preferred

• Condition of the Abutment Tooth:
  • FPD is used if there is the presence of a posterior tooth for support
  • Such a tooth should have
  • Ideal crown root ratio for support
  • Adequate thickness of enamel and dentin for re- duction
  • Adequate bone support
  • Absence of periodontal disease
  • Proper gingival contour

• Condition of the residual ridge:
  • The contour of the ridge and texture of the soft tis- sues should be observed
  • A smooth rounded ridge is best for the placement of FPD
•  Patient’s preference:
  • The patient may not desire to frequently remove and insert the denture
  • If in these patients removable partial denture is given, they may not maintain it
  • This may further lead to post insertion problems To avoid this, FPD is preferred
• Mentally compromised and physically handi- capped patients:
  • Such patients fail to maintain the removable prosthesis
  • This may lead to soft tissue irritation
  • To avoid it, FPD are preferred

Contraindications:

• Excessive bone loss:
  • When there is trauma or excessive residual ridge resorption, there is absence of required support for the prosthesis.
  • In such cases, it is difficult to place the artificial teeth of a fixed partial denture in an ideal buccolingual position
•  Age of the patient:
  • In patients under the age of 17 years, have large dental pulps
  • They lack sufficient clinical crown height for tooth reduction
  • Thus, fixed partial denture is contraindicated
• Long span edentulous space:
  • In such cases the entire occlusal load is directed to the abutment which in turn leads to damage to the abutment
• Periodontally weak teeth:
  • The periodontal membrane is the structure which transfers all the load from the teeth to the underlying bone
  • A periodontally weak tooth will not successfully transmit the forces to the alveolar bone

 

• Bilateral edentulous spaces, which require cross arch stabilization:
  • When the remaining teeth have to be stabilized against lateral and anterior-posterior forces.
  • A fixed partial denture is contraindicated as it will provide only anteroposterior stabilization and limited lateral or buccolingual stabilization.

• Congenitally malformed teeth:
  • Such teeth do not have adequate tooth structure to offer support
• Mentally sensitive patients:
  • Such patients are uncooperative
  • They does not allow tedious procedures to be car- ried out
• Medically compromised patients:
  • Such patients may lead to certain post treatment complications
• Very old patients:
  • Such patients are contra-indicated due to
  • Presence of generalized attrition leading to reduction in clinical crown height
  • Presence of large edentulous spaces results in decreased/limited support
  • Cannot tolerate operative procedures
  • Presence of generalized periodontal weak teeth

Question 8. Discuss mouth preparation for fixed partial denture.
Answer:

Mouth preparation is part of the treatment planning phase carried out to enhance the success of the fixed partial denture

Mouth preparation helps to

• Relieve symptoms
• Removes the etiologic factors
• Repairs the damages
• Maintains dental health

Procedures of Mouth preparation:

1. Diagnosis and treatment planning
2. Treatment to relieve the presenting symptoms
3. Surgical procedures
4. It involves
   • Extraction of:
     • Hopeless abutment
     • Residual root tips
     • Impacted/unerupted supernumerary teeth
     • Malposed teeth, grossly extruded or drifted
   • Cyst and tumors:
     • Enucleation of cyst
     • Excision of tumors
     • Hyperplastic tissue – Surgical excision
     • Bony spines and knife edge ridges
     • Al-veoloplasty to smoothen them
     • Dentofacial deformity – Surgical correction
     • Implant supported fixed prosthesis
     • These are placed under controlled oral surgical procedures
5. Endodontic procedures:
   • Endodontically treated teeth are restored with
     crowns
   • Caries tooth can be restored by amalgam, composite, GIC, pin retained restoration or post and core
6. Periodontal procedures:
   • They are carried out for
   • Removal of plaque and plaque retentive factors Elimination of pockets
   • Crown lengthening procedures carried out when clinical crown height is less and when retention will decrease due to it.
7.  Orthodontic treatment:
   • Minor orthodontic tooth movement can be done to upright a malpositioned abutment tooth
   • It can improve axial alignment
   • It will create pontic space and will improve embrasure form in the fixed prosthesis
   • It can direct occlusal forces along the long axis of the teeth
   •  Definitive occlusal treatment
   • It is done to make intercuspal position to coincide with centric relation and to remove eccentric interferences

Contraindications of Mouth preparation:

• Bruxers
• Angle class II and skeletal class III
• Excessive wear
• Temporomandibular pain
• Prosthetic rehabilitation and follow up The patient needs to be recalled after prosthetic rehabilitation

Question 9. Discuss principles of bio-mechanical preparation in fixed partial denture.
Answer:

1. Biological considerations:

 Prevention of damage during tooth preparation to:

• Adjacent teeth:
  • Protect it by placing a matrix band while tooth preparation
  • A thin taper diamond is used to break the
    contact
  • If, however, the tooth gets damaged it has to be reshaped
• Soft tissues:
  • The tedious procedures can cause abrasion of soft tissues like lip, cheek etc..
  • It can be prevented by retracting it with the help of various types of retractors
  • Pulpal protection
  • Avoid excessive apical preparation
  • Avoid excess removal of dentin
  • Pulp may get damage by the excessive heat generated, chemical irritants used.

2. Conservation of tooth structure:

• The tooth structure can be conserved by
  • Use of partial veneer crowns
  • Use of minimal taper of opposite axial walls
  • Repositioning of tilted teeth before tooth preparation
  • Use of conservative finish line
  • Occlusal surface reduction should be such that
    it follows the anatomical form

3. Margin Placement:

• Margin should be such that
• It is easy to prepare
• It is easy to identify in the impression and on the die
• It is easy to finish
• It should allow sufficient bulk of material
• It should preserve tooth structure

Types of fixed partial dentur:

• At the crest of the gingival:

• Occlusal consideration:
  • Tooth preparation leads to weakening of the tooth Thus, occlusal reduction should be such that it maintains the anatomic form
  • To obtain proper and conservative reduction, the tilted/supra erupted teeth should be aligned prior to the preparation
•  Mechanical considerations:
• Providing retention form:
  • Retention is the quality of a preparation that prevents the restoration from becoming dislodged by forces acting parallel to the path of withdrawal

Factors Affecting Retention:

1. The magnitude of the dislodging forces:
   • It depends on the stickiness of the food, surface area and texture of the restoration
2. Geometry of the tooth preparation:
   • Taper Smaller degrees of taper have more reten- tion
   • The optimum taper is 6 degrees
   • Surface area Crowns with long axial walls are more retentive
   • Stress concentration – Round margins may reduce stress concentration and hence increase the retention
   • Type of preparation – Addition of retentive grooves and boxes
3. Roughness of the surfaces:
   • It increases retention
4. Materials being cemented:
   • Base metal alloys – Better retained ‘
   • Cement – Adheres better to amalgam
   • Crowns – Adheres better to composite
5.  Type of luting agent: Adhesive resin cements are the more retentive
6. Providing resistance Form:
   • It is the form that resist the lateral forces acting on the restoration and prevent its displacement

Factors of fixed partial dentur:

• Magnitude and direction of the dislodging forces
• Geometry of the tooth preparation
  • Increased taper-Decreases resistance
  • Rounded axial angles
  • Decreases resistance Short tooth preparation
• Physical properties of the luting agent zinc phos phate cements have a higher modulus of elasticity

1. Preventing Deformation of the Restoration Factors:

• Alloy selection:
  • Type III or Type IV gold alloys
  • High noble metal content ceramic alloys Nickel chromium alloys
  • All these are harder alloys
  • They resist the deformation, hence preferred
• Adequate tooth reduction:
  • Tooth reduction should be 1.5 mm over functional cusps and 1 mm over non-functional cusps
• Margin design:
  • It depends of the type of the restoration be- ing used
  • Example. Ceramic requires more reduction to obtain space for bulk of material

2. Aesthetic considerations:

• It depends on the patient’s esthetic requirement

3. Partial coverage restoration:

• Proximal margin Place it buccal to the maximal contact area.
• Facial margin – It should be extended just beyond the occluso-facial line angle

4. Metal ceramic restoration:

• Facial reduction – A minimal reduction of 1.5 mm is required
• Labial margin placement margins should be placed after observing the patient’s smiles

Fixed Partial Denture Short Essays

Question 1. Ridge lap and modified ridge lap pontic.
Answer:

1.  Ridge lap pontic:
   • Evolved from saddle pontic
   • It resembles a natural tooth
   • It is designed to adapt closely to the ridge
   • Satisfies esthetics
   • Difficult to maintain
   • Often leads to inflammation of the tissues in contact
2. Modified ridge lap pontic:
   • They are designed to reduce the tissue contact
   • Satisfies both esthetics and hygiene
   • Tissue contact is limited to the buccal surface of the ridge crest
   • It has T shaped contact
   • The vertical arm of the T ends at the crest of the ridge
   • The horizontal arms form the contact along the buccal surface of the ridge
   • Recommended in maxillary anterior-posterior regions
   • Modified ridge lap with no embrasure is recommended in mandibular anterior areas with extensive ridge resorption

Question 2. Sanitary pontic.
Answer:

Pontic Definition:

“An artificial tooth on a fixed partial denture that re- places a missing tooth restores its functions and usu- ally fills the space previously filled by a natural crown”

Sanitary Pontic:

These pontics have zero tissue contact

• Easy to maintain
• Highly unesthetic
• Atleast 3 mm of vertical gap should be present between pontic and the ridge
• Recommended in mandibular posterior area

Question 3. Types of connectors in fixed partial denture.
Answer:

Connector:

Connector is the  portion of a fixed partial denture that unites the retainer and pontic

Types of connector:

1. Rigid connectors: They are used to unite retainers and pontics in fixed partial denture

• Fabrication:
  • The design of the connector is incorporated into wax pattern
  • The part of the connector to be soldered are sectioned
  • The whole assembly is then cast

2. Non rigid connectors:

• These connectors are used in case of parallel abutments
• They allow limited movement between the retainer and pontics
  • Tenon Mortise pontic:
    • It consists of Mortise as the female component and Tenon component as the male component
    • The female component is prepared in the wax pattern within the contours of the retainer
    • The male component is fabricated with auto polymerizing resin and attached to the pontic

• • Loop connectors:
    • It is used in diastema cases
    • It consist of a loop on the lingual aspects of the prosthesis that connects adjacent pontic and retainer
  • Split pontic connectors:
    • It is used with pier abutment
    • The pontic is split into mesial and distal segment
    • Each segment is attached to retainer
    • The mesial segment is fabricated with a key while distal segment with a key way to fit over the key.

3. Cross pin and wing connectors:

• It is used for tilted abutments
• A wing is attached to the distal retainer called retainer wing component
• The pontic is attached to the mesial retainer called retainer pontic component
• These are fabricated and aligned on the working cast
• 0.7 mm pin hole is drilled across the wing The components are cemented
• Next the pin is seated into the hole using a punch and mallet

Question 4. Veneering materials.
Answer:

Veneer is a layer of tooth-colored material that is applied to a tooth to restore localized/generalized defects and intrinsic discoloration

Materials of Veneering:

 1. Ceramic: It is most ideal veneering material when used with metal substructure or in all ceramic restoration

Procedure of Ceramic:

• Metal preparation:
• Clearing of casting defects
• Cleaning of casting by sandblasting and ultrasonic cleaning
• Gingival surface of the pontic is reduced

Porcelain application of Ceramic:

• Opaque layer of porcelain should be applied over metal surface
• Gingival surface of porcealin is coated with cervical porcelain
• Next other parts are build up
• Next porcelain is fired

2. Acrylic:

• After firing the core porcelain, glaze porcelain is added and fired as usual
• It can be used with metallic restoration
• Has poor wear resistance
• So not used as permanent restoration

Procedure of Acrylic:

• Mechanical undercut are made over the entire metal surface
• Surface of cast metal can be roughened using aluminium oxide
• Small quantity opaque resin is added onto metal surface
• Body surface resin is added over opaque resin
• Resin is polymerized
• Excess material is carved out Incisal shade resin is added
• Finally restoration is finished and polished

Question 5. Ceramics.
Answer:

Definition of Ceramics:

It is an inorganic compound with non metallic properties typically consisting of oxygen and one or more metallic or semi-metallic elements that is formulated to produce the whole or part of ceramic-based dental prosthesis

Classification of Ceramics:

• According to firing temperature
  • High fusing
  • Medium fusing
  • Low fusing
  • Ultra low fusing
• According to the type
  • Feldspathic porcelain
  • Leucite reinforced glass ceramic
  • Alumina reinforced porcelain
  • Zirconia reinforced ceramics
• According to the function within the restoration
  • Core ceramics
  • Opaque ceramic
  • Veneering ceramic
• According to microstructure
  • Glass ceramic
  • Crystalline ceramic
  • Crystal containing ceramic
• According to the fabrication process
  • Condensable ceramics
  • Heat pressed ceramic Castable ceramic
  • Machinable ceramics

Composition:

Uses of Ceramics:

• Single unit crown
• Porcelain veneer for crown and bridges
• Artificial teeth
• Inlays and onlays
• Ceramic brackets used in orthodontics
• Implants, bioglasses

Question 6. Blockout procedure.
Answer:

• It is defined as the elimination of undesirable undercut areas on the cast to be used in the fabrication of the removable partial denture
• It is the process by which the undesirable undercuts on the master cast are eliminated using wax
• Since the undercuts are filled with wax, the refractory cast duplicated from the master cast will not have these undercuts
• Before block out, the master cast is coated with a sealer so that it forms a protective film over the cast

Types of Blockout procedure:

1. Parallel blockout:
   • This is the procedure by which undercuts below the height of contour of the existing teeth are eliminated in relation to that path of insertion
   • Blockout wax is filled into the infra-bulge area of the tooth and trimmed such that its surface is par- allel to the path of insertion
2. Arbitary blockout:
   • It involves filling the soft tissues and other unwanted undercuts in the cast with blockout wax
3. Formed or shaped blockout:
   • It is done in the undercut of the primary abutment along the lower border of the proposed retentive arm

Question 7. RPI system.
Asnwer:

• Rest, Proximal Plate and I-bar
• It is a modified I-bar retainer system

1. Mesial Rest modification:

• Mesial rest extends into triangular fossa in molar preparation
• Canine rests are circular, concave depressions pre- pared on the mesial marginal ridge

2. Proximal plate modification:

• Design modification 1: Proximal plate is designed to extend from the marginal ridge to the junction between the middle and cervical third of the tooth
• Design modification 2: Proximal plate is designed to extend along the entire length of the proximal surface of the abutment with a minimum tissue relief
• Design modification 3: Proximal plate is designed to contact just about 1 mm of the gingival third of the guld- ing plane of the abutment tooth

3. I-bar modification:

• The tip of 1-bar is modified to have a podshaped in order to allow more tooth contact
• It is placed more mesially

Question 8. Rubber base impression materials.
(or)
Impression materials in FPD.
Answer:

Properties of Rubber base impression materials:

• They are accurate impression material they excellently reproduce the surface details
• They are dimensionally stable
• Available in various viscocity
• The low viscocity is capable of reproducing even very fine details
• They are generally hydrophobic
• Resilience
• They are flexible with near complete elastic recovery Its coefficient of thermal expansion is high
• It cannot melt, before melting they pass into gaseous state
• They swell in the presence of certain solvents
• They are insoluble
• They have lower creep resistance
• Tear strength is excellent
• They can be electroplated

Uses of Rubber base impression materials:

• In FPD for impressions of prepared teeth
• In RPD for impression of dentulous mouths
• In CD impression of edentulous mouth
• Polyether is used for border moulding
• For bite registration
• Silicon is used for making refractory casts

Materials of Rubber base impression materials:

• Polysulphide
• Condensation silicone
• Addition silicone
• Polyether

Question 9. Soldering-implication and procedures.
Answer:

Soldering involves joining two components of metal with an intermediate metal whose melting tempera-ture is lower than the parent material

Implications of Soldering :

• To cast multiple smaller units
• To rectify casting defects

Proedures of Soldering:

1. Soldering for metal ceramic restoration:
   • It is done prior to ceramic application
   • Done at a temperature of 1075 to 1120 degree C
   • Advantages:
     • Metal framework can be soldered and tried in prior to ceramic build up
     • Minor casting errors can be corrected
   • Disadvantages:
     • Difficult to build ceramic
2. Oven soldering:
   • Performed under vaccuum or in air
3. Torch soldering:
   • It is done uner direct flame
4. Infrared soldering:
   • Used for low-fusing connectors
   • Good accuracy is possible
   • Laser welding:
   • It is done to join titanium components of dental crowns, bridges and partial denture frameworks
   • The maximum penetration depth of the laser welding unit is 2.5 mm

Question 10. Double impression technique.
Answer:

It is one of the method of impression-making for fixed partial dentures

• Technique of Double impression:
  • A suitable stock tray is selected
  • Tray adhesive is applied uniformly into the tray
  • Putty impression material is mixed and made into a rope and loaded onto the tray
  • A spacer for light body material should be placed over the loaded putty material
  • The laoded tray alongwith the spacer is used to make a full mouth impression
  • After making and removing the impression the poly- thene spacer is carefully peeled away
  • The impression is additionally relieved by scraping the areas which recorded the tooth preparation
  • The light body material is then syringed over the putty impression and also over the tooth preparation
  • The final impression will contain the accurate details recorded by the light body impression material

Question 11. Full veneer crown.
Answer:

Full veneer crown covers all the tooth surfaces

Indications of Full veneer crown:

• It is indicated when the Abutment tooth is small
  The edentulous span is long
• When the partial veneer crown lacks in retention, resistance, coverage or esthetics
• When the abutment is extensively decayed or decalcified or previously restored
• For endodontically treated teeth

Contraindications of Full veneer crown:

It is not given for patients with uncontrolled caries

Procedure of Full veneer crown:

• Occlusal reduction
• Axial reduction
  • Buccal reduction
  • Lingual reduction
  • Proximal reduction
• Establishing the finish lines

Commonly Used Full Veneer Crowns:

• Full metal crowns
• Metal ceramic crowns
• All ceramic crowns

Question 12. Diagnostic aids in fixed partial denture.
(or)
Radiographs in fixed partial denture.
Answer:

It includes:

1. Diagnostic cast:

• The impression for the diagnostic cast is made with alginate in a perforated stock tray and poured in dental stone
• The diagnostic cast should be an accurate repro-duction of the teeth and adjacent tissues
• It is a life size reproduction of a part or parts of the oral cavity or facial structures for the purpose of study and treatment planning

Importance of fixed partial denture:

• It permits viewing the occlusion from both lingual and buccal aspect
• It helps to analyze the existing occlusion
• It helps to survey the dental arch
• It helps to survey the cast
• It aids in mouth preparation
• It aids in patient’s education
• It aids in selection of trays
• It may be used as a constant reference
• It helps in mock surgery

Advantages of fixed partial denture:

• It allows changing of the interocclusal relations
• It helps to prepare and assess the tooth preparation
• The path of withdrawal can be determined

2. Radiographs: Types:

• Periapical:
  • It determines the extent of bone support, quality of supporting bone
  • It determines the root morphology of each abutment tooth
  • It evaluates the width of periodontal ligament space
  • It evaluates bone resorption
  • It determines
  • Inclination of teeth
  • Continuity of lamina dura
  • Pulpal morphology Any periapical pathology
  • Crown root ratio
  • Root length, shape
  • Periodontal status of abutment
• Bitewing:
  • Evaluation of proximal caries
  • Evaluates secondary caries on previous restoration
• Panoramic files: Aid in
  • Evaluation of bone resorption, pattern of bone resorption, and quality of bone support
  • To check for presence of retained root tips, impacted tooth
  • To determine the thickness of soft tissue on the ridge in area of pontic placement
• In case of TMJ disorders:
  • Transcranial exposure
  • Serial tomography Arthrography
  • CT scanning
  • Magnetic resonance imaging

Question 13. Recording of jaw relation for crown and bridge.
Answer:

Types of Jaw Relation:

1. Centric registration:
   • Centric occlusion
   • Centric relation
2. Eccentric registration:
   • Lateral excursive records
   • Protrusive records

Centric Occlusion:

1. Direct intercuspation:
   • An interocclusal record is placed over the prepared tooth
   • Patient is asked to close to normal interocclusal position
   • After it sets, the record is trimmed and articulate
2.  Centric Relation:
   • Bite wafer technique
   • A bite wafer is made from base plate wax
     It is used to record the relation
   • The indentations in the wax are brushed with zinc oxide eugenol, repeat the record
3. Anterior stop technique:
   • A wax wafer is pressed to the occlusal surface of the maxillary teeth with the anterior jig
   • The wafer is refined and shaped to the patients arch form
   • Patient is asked to close on posterior teeth until lower teeth touch the anterior jig
   • After recording it, a thin layer of ZOE is applied to the lower cusp indentation of the wafer, and the record is repeated

Eccentric Relation:

• Lateral Relation:
  • Canine guided occlusion: In lateral movement, canine causes the separation of all the other teeth
  • Group function: In lateral movement contact is maintained between a group of teeth

Method of Jaw Relation:

• Mount the patient’s cast on articulator
• Manipulate the mandibular member such that the left mandibular canine is edge to edge with the left maxillary canine
• A wax wafer is placed on lower cast
• The record is checked in patient’s mouth
• It is followed by ZOE record

Protrusive relation:

• Articulate the patient’s cast
• The upper cast is brought with the incisors in an end-to-end relation
• A warm wax is placed in patients mouth
• Reline the indentation of wax with registration paste
• The resultant refined bite is placed on the mandibular cast and the maxillary cast is placed over it

Question 20. Questionable Abutment.
Answer:

They are abutment teeth that can be retained after periodontal and endodontal treatment which otherwise is a hopeless tooth

Selection Of Questionable Abutment

1. Periodontally weak tooth:
   • Tooth with slight mobility
   • Tooth with recession
   • Tooth with furcation involvement
   • Tooth with gingival and periodontal pathology
   • Corrected by:
     • Scaling and root planning
     • Splinting of mobile teeth
     • Flap surgeries for recession
     • Ridge augmentation for osseous defects
2. Abutment tooth requiring Endodontic treatment:
   • If pulpal vitality is doubtful endodontic treatment is carried out
   • It is then treated with post and core
3. Abutment with large restoration:
   • Subgingival margin is used in it
4. Abutments that are malaligned, tilted:
   • Mesially drifted tooth leads to insufficient space for pontic
5. Abutments that cannot withstand forces:
   • Certain modifications are carried out
   • Implant supported prosthesis need to be used
   • Pontics and connectors should be of adequate thickness
   • A single incisor present is best removed
   • Multiple edentulous spaces are best restored with a combination of fixed and removable partial dentures
6. Abutments that are grossly attrited:
   • Crown lengthening procedures or a sub-gingival finish line should be done
   • If chances of pulp exposure are present it should be endodontically treated
   • Proximal boxes and additional grooves are added to the preparation
7. Abutments with reduced bone support:
   • After periodontal disease root surface area is reduced
   • Short conical roots give less support
   • Divergent multiple roots give good support
   • Single rooted tooth with an elliptical cross section gives better support

Question 21. Post and Core/radicular retainer.
Answer:

• When an endodontically treated teeth is used as abutment, post and core is used
• The post/dowel is the screw component that is inserted into the root canal
• The core is the retentive component, that acts as prepared crown for the placement of a retainer

Types of Post and Core:

1. Prefabricated
2. Custom made

Factors To Be Considered:

• The canal should be obturated only with gutta percha
• For proper retention the length of the dowel core inside the root should be atleast 2/3rd of root length
• The coronal portion of the dowel should be encircled at least by 1-2 mm of tooth structure to obtain a ferrule effect.

Tooth Preparation:

• Unsupported enamel is removed
• Any weak enamel wall or restoration should be removed
• Remove the gutta-percha and enlarge the canal using peesoreamer
• There should be atleast 1 mm of tooth structure at the apical end
• The diameter of the canal should be atleast 1/3rd the width of the tooth
• A contrabevel is placed around the occluso-axial line angle
• The canal and plastic sprue are coated with petrolatum jelly
• Impression is made with resin
• The pattern is cast and finished

Question 22. Bridge Retainer.
Answer:

Retainer:

“The part of a fixed partial denture which unites the abutment to the remainder of the restoration”.

Types Bridge Retainer:

1. Based on tooth coverage:

• Full veneer crown:
  • It covers all the surfaces of abutment
  • These are indicated for extensively damaged teeth
  • They are the most retentive

• Partial veneer:
  • They require less tooth reduction
  • They are less retentive

Conservative:

• They require less tooth reduction
• They are indicated for anterior teeth
• They have small metallic extensions luted onto the lingual surface of the abutment using resin cement

2. Based on the material used:

• All metal:
  • They can be partial/full veneer
  • They require minimal tooth reduction
  • They are strong enough

• Metal ceramic retainers:
  • They require more tooth reduction
  • They can be fabricated over an entire full veneer crown or over labial/buccal surface of full veneer or over partial veneer

• All ceramic retainers:
  • They require maximum tooth reduction be- cause porcelain requires sufficient bulk for adequate strength
• All acrylic retainers:
  • They are used for long term temporary fixed partial dentures

Question 23. Structural Durability.
Answer:

• The ability of the restoration to withstand destruction due to external forces is known as “structural durability”
• Adequate reduction during tooth preparation is necessary to obtain adequate thickness of restoration
• The amount of reduction required depends on the type of the restoration and the design of restoration

Question 24. Supragingival Finish lines.
Answer:

Requirements of Supragingival Finish lines:

• Shallow bevels nearly parallel to the cavosurface should be avoided
• The bevel should not produce a very acute margin
• The tooth should not be reduced more than half of the width of the diamond.

Types of Supragingival Finish lines:

1. Chamfer of Supragingival Finish lines:

• This possess a curved slope from the axial wall till the margin

Indications of Supragingival Finish lines:

• Cast metal restorations
• Metal collars
• Lingual margins of metal ceramic restoration

Contraindications of Supragingival Finish lines:

• Restoration where finish line will be obvious

Disadvantages of Supragingival Finish lines:

• Marginal distortion
• Provide less room cervically

2.  Shoulder:

It has a gingival finish wall perpendicular to the axial surfaces of teeth

Indications of Shoulder:

• All anterior restoration
• All ceramic restoration
• Facial margins of metal-ceramic

Advantages of Shoulder:

• Less marginal distortion
• Good marginal adaptation
• Esthetic
• Increased retention
• Better resistance to occlusal forces
• It accommodates bulk of porcelain

Disadvantages of Shoulder:

• Requires more tooth reduction
• Leads to adverse pulpal involvement 90°

3. Shoulder With A Bevel:

An external bevel is created on the gingival margin of the finish line

Indications of Shoulder With A Bevel:

• Facial finish line of metal ceramic
• Presence of ledge

Advantages of Shoulder With A Bevel:

• Aids in contouring the restoration
• Improves burnish ability
• Minimizes the marginal discrepancy
• It prevents unsupported margins from chipping

4. Feather Edge And Knife Edge:

• Difficult to wax up and cast
• Difficult to produce smooth margin
• Susceptible to distortion
• Overcontoured restoration

Indications of Knife Edge:

• Lingual surface of mandibular posteriors
• Very convex axial surface
• For the undercut of tipped teeth

Question 25. Merits of complete veneer and partial veneer
Answer:

Question 23. All ceramic restoration/metal-free ceramics.
Answer:

It was introduced by Land in 1903

They are defined as man made solid objects formed by baking raw materials at high temperatures

Classification of ceramic restoration :

• Conventional powder- Slurry ceramics
• Castable ceramics – Dicor plus
• Machinable ceramics – Dicor MGC
• Pressable ceramics – IPS Empress
• Infiltrated ceramics – In ceram

Advantages of ceramic restoration:

• Superior aesthetics
• Excellent translucency
• Requires slightly more preparation of the facial surface ‘The appearance can be influenced and modified by selecting different colors of luting agent

Disadvantages of ceramic restoration:

• Reduced strength
• It is very difficult to obtain a well-finished margin
• They cannot be used on extensively damaged teeth
• Due to porcelain’s brittle nature, large connectors have to be used
• This usually leads to impingement of the interdental papilla
• Wear of opposing natural teeth

Question 26. Cantilever Fixed Partial Denture/Bridge.
Answer:

It is a fixed partial denture in which the pontic is re- tained and supported only on one end by one or more abutments

Selection Of Cantilever Abutment:

• Good bone support should be present more than the average
• Adequate clinical crown height should be present
• Should be able to develop a harmonious occlusion
• Should have good clinical crown height

Indications Of Cantilever Abutment:

• Replacement of lateral incisor
• Replacement of first premolar

Contraindications Of Cantilever Abutment:

• Extensively damaged teeth Maligned teeth.
• Mobile teeth
• Endodontically treated teeth

Advantages Of Cantilever Abutment:

• Conservative design with preservation of tooth structure
• Secondary abutments used can be prepared easily with parallelism
• Easy to fabricate

Disadvantages Of Cantilever Abutment:

• Produces torquing and lateral forces Cannot restore long span edentulous space
• Lateral forces can tip, rotate or drift the abutment tooth

Question 27. Gingival Retraction Techniques.
(or)
Gingival Retraction
Answer:

1. Mechanical methods:

• Rubber Dam:
  • Punch holes are made in the area of preparation site of the rubber dam and clamped in position.
• Cotton rolls:
  • In maxillary arch, a single cotton roll is used in the buccal vestibule.
  • While in mandibular arch, cotton rolls are placed both in the buccal vestibule and lingual sulcus
• High Vaccum:
  • It can be used as a retractor as well as for clear-ing saliva and water during preparation
  • It is also useful to remove small operatory debris

• Saliva ejector:
  • It is placed in the corner of the mouth opposite the quadrant being operated
  • It is used for the evacuation of the maxillary arch

• Svedopter:
  • It consist of a metal saliva ejector with a tongue deflector
  • Effectively used in the mandibular arch
  • Effective fluid control

Disadvantages of Gingival Retraction :

• Access to the lingual surface of mandibular teeth is limited
• It may cause injury to the floor of the mouth due to metallic nature
• Presence of tori, makes its use difficult

1. Tongue deflector
2. Suction tip

• Cellulose Wafers:
  • It is used along with cotton rolls to control saliva and retract cheek laterally
• Oversized Copper bands:
  • They are placed on the prepared tooth and elastomeric impression material is used to make an impression of the prepared tooth which retracts the gingival

2. Chemical methods:

• Agents:
  • Anti-Sialogogues:
    • These are group of drugs that can be effectively used to control salivary flow
    • They inhibit the action of myoepithelial cells in the salivary glands
    • Examples:
      1. Methantheline bromide 50 mg: 1 hour be- fore procedure
      2. Propantheline bromide 15 mg: 1 hour before procedure
      3. Clonidine hydrochloride 0.2 mg: 1 hour procedure
  • Local Anaesthetic:
    • Contraindications:
      • Hypersensitive patients
      • Patients with glaucoma
      • Asthamatic patients
      • Obstructive conditions of congestive heart failure

3. Mechanico-Chemical methods:

It is a method of combining a chemical with pres- sure packing which leads to enlargement of the gingival sulcus

• Chemical used:
  • 8% Racemic epinephrine
  • Aluminium chloride
  • Alum
  • Ferrous sulphate
• Technique:
  • Operating area should be dry
  • The retraction cord is drawn from the dispenser bottle
  • The cord is dipped in 25% AIC13 solution in a da- pen dish
  • The retraction cord is looped around the tooth and packed into the gingival sulcus
  • After 10 minutes, the cord should be removed slowly

4. Surgical methods:

• Rotary Curettage: It is a troughing technique, where in a por- tion of the epithelium within the sulcus is removed to expose the finish line
  • Technique:
    • The torpedo diamond point is extended into the gingival sulcus to remove a portion of sulcular epithelium
    • Abundant water should be sprayed

• Electrosurgery:
  • An electrosurgery unit is a high frequency oscillator or radio transmitter which uses either a vacuum tube,or a transmitter for delivering a high frequency electric current of atleast 1 MHz.
  • It denotes surgical reduction of sulcular epithelium using an electrode to produce gingival retraction.

Question 28. Impression Procedures for fixed partial denture
Answer:

1. Stock tray/Putty wash impression:
   • Double Mix
   • Single Mix
2. Custom tray impression – Single Mix:
3. Closed bite double arch method/triple tray technique.
4. Copper tube impressions
5. Post space impressions

1. Putty Wash Impression:

• Double Mix Technique:
  • An appropriate stock tray is selected
  • Tray adhesive is applied over it
  • Putty material is mixed and formed in the shape of rope and loaded onto the tray
  • A spacer (polythene sheet) is placed over it • Impression is made
  • Remove the impression Next, take out the spacer
  • Light body material is syringed over the tray as well as the prepared tooth
  • Repeat the impression

• Single Mix Technique:
  • Putty material is loaded into the tray while light body material is syringed over the prepared tooth
  • A full mouth impression is made

2. Custom Tray Impression:

• Two sheets of tin foil spacer is applied over the primary cast
• An acrylic special tray is fabricated over it
• Tray adhesive is applied over it
• Medium body elastomer is loaded into the tray and light body material is syringed over the prepared tooth
• Full mouth impression is made

3. Triple Tray Impression:

• The tray consists of a plastic framework with a plastic sleeve and handle
• Light body material is injected into the prepared
  tooth
• High viscosity material is placed in excess on both the arches
• The tray is placed in between the arches
• The patient is asked to bite slowly
• After the material sets, the patient is asked to open the mouth due to which the tray adheres to one arch
• Bilateral pressure should be applied to remove it

4. Copper Band Impression Technique:

• A softened impression compound is filled upto 1/3rd of the copper band
• It is placed onto the prepared tooth
• Light body material is syringed over the prepared
  tooth

5. Post Space Impression:

• A separating medium is applied on the post space
• Light body material is syringed into it
• A lentulo spiral, coated with tray adhesive is used to push the material into the post space
  Before it sets, medium/heavy bodied impression.
• material is loaded over the tray and placed over it
• Both are removed together

Question 29. Temporization/Provisional Restoration.
Answer:

It is a restoration that is established for the time being, until a permanent arrangement can be made

Requirements of Temporization:

1. Biological requirement:
   • It should provide pulpal protection
   • It should maintain periodontal health
   • It should maintain occlusal harmony
2.  Mechanical Requirements:
   • The restoration should be able to transmit the occlusal forces
   • It should closely adapt
   • It should not be damaged during removal
3.  Material Requirements:
   • It should be bio-compatible
   • It should have sufficient working time
   • It should be easy to fabricate
   • It should be dimensionally stable
   • It should have adequate strength
   • It should be esthetic
   • It should be compatible with the luting agents

Types of Temporization:

1. Based on method of fabrication:
   • Custom made
   • Preformed
2. Based on the type of material used:
   • Resin based
   • Metal
3. Based on duration of use:
   • Short term
   • Long term
4. Based on technique for fabrication:
   • Direct technique Indirect technique
   • Direct-indirect technique

Disadvantages of Temporization:

• Provisional restoration tends to fracture They poorly adapt to the margins
• They wear off easily
• They have unpleasant odour
• They may cause tissue irritation
• It is difficult to remove it
• They have poor colour stability

Question 30. Die Materials.
Answer:

Question 31. Luting Cements for fixed Partial Denture.
Or
Properties of polycarboxylate and GIC
Or
Cements in FPD
Answer:

Question 32. Porosities.
Answer:

1. Solidification defects:

• Solidification shrinkage:
  • Mainly occurs near sprue-cast junction
  • Causes:
    • Incomplete feeding of molten metal
    • Premature solidification of the sprue
• Suck back porosities:
  • Occurs near sprue
  • Cause:
    • This occurs when a hot metal, impinging from sprue channel onto a point on the mould wall, causes a hot spot
    • This causes local region to freeze last result- ing in shrinkage
  • Prevention: Lowering casting temperature

2. Microporosities:

• Cause: Too rapid solidification
• Prevention: Lowering the temperature

3. Pinhole porosity:

• It is spherical in shape
• During solidification absorbed gases are expelled leading to pinhole porosity

4. Sub-surface porosity:

• Cause:
  • Simultaneous nucleation of solid grains and gas bubbles as the metal freezes at the mould walls
  • Can be decreased by controlling the rate of molten metal entry

5. Residual air in the mould:

• Causes back pressure porosity
• It occurs as a large concave depression due to the inability of air in the mold to escape
• Causes:
  • Dense investments
  • Low mold temperature
• Prevention:
  • Adequate mold temperature
  • Ideal casting pressure

Question 31. Failures in fixed Partial Dentures
Answer:

Question 33. Abrasive and Polishing agents.
Answer:

1. Diamond:
2. Emery: Mixture of aluminium oxide and iron oxide bound to paper discs with glue or resins
3. Aluminium Oxide:
4. Garmet: For metal and porcelain
5.  Sandpaper discs:
   • They are made from a dense crystalline form of quartz
6. Tripoli:
   • A fine silicaous polishing powder combined with a wax binder to form light brown cakes used with a cloth buff wheel or a soft bristle bursh
7. Rouge:
   • Composed of Iron Oxide
   • Used for gold restorations applied with a soft bristle brush
8.  Electrochemical finishing:
   • One part nitric acid and three parts hydrochloric acid
9.  Electrochemical milling:
   • The casting is placed in cyanide solution which etches the casting by removing a layer of 40 micron from Type III alloy in one minute

Question 34. Nonprecious alloys used in fixed partial denture
Answer:

 1. Nickel-Chromium alloys:

• Composition:
  • Nickel-70-80%
  • Chromium-13-20%
  • Beryllium – Small quantities
• Advantages:
  • Good strength
  • Have superior physical properties
• Disadvantages:
  • High casting shrinkage
  • Questionable biocompatible
  • Requires modified casting techniques

2. Cobalt Chromium alloys:

• Composition:
  • Cobalt-55-68%
  • Chromium-25-27%

3. Cobalt-Chromium Nickel alloys:

• Advantages:
  • Cheaper
  • Good strength
  • Can be used along with metal ceramics
• Disadvantages:
  • High fusion temperature
  • Poor marginal fit
  • Cannot be burnished
  • Nickel-containing alloy can cause allergy

Question 35. Recent Advances in Fixed Partial Dentures.
Answer:

Recent Advances In Metal Ceramics:

• Pure titanium can be used as a coping and framework metal for metal-ceramic restoration.
• Copy milling is used to prepare duplicate dies of graph- ite and to machine the outer form of a titanium crown
• Titanium based products are melted in a specialized casting machine and cast using the conventional lost wax technology

Recent Advances In Veneering Materials:

• Reinforced composites:

1. Encore Bridge:
   • The composite super structure is bonded with porcelain veneers
   • It is composed of 81% filled composite with a glass fiber reinforcement
   • The frame work has sufficient flexure to attain a class 1 mobility
     • Advantage:
       • It requires minimal tooth preparation
2. Castable hydroxyapatite: Hydroxyapatite mixed with composite fibers is slip cast by vibration
3.  Injectable ceramics/castable ceramics:
   • Dicor – It was used for FPD’s, in lays and on lays
   • Indication – Laminates for periodontally compromised patients
   • Contraindication – Short clinical crowns
     • Advantages:
       • Good strength
       • Good marginal adaptation
       • Bio-compatible
       • Highly aesthetic
       • Low thermal conductivity
     • Disadvantage:
       • Technique sensitive
4. Shrink free ceramic system:
   • Indication: For periodontally compromised patients
   • Advantages:
     • Good flexural strength
     • Highly aesthetic
     • Good marginal fit

Question 36. Splinting of abutment teeth
Answer:

A fixed partial denture usually requires the splinting of additional abutments to overcome the loss of bone support of an abutment

Purpose of abutment teeth:

• To distribute and direct the functional forces
• To eliminate any mobility present Stabilizes and reorient the forces
• Improves the function and form of teeth
• Modifies occlusal pattern

Classification of abutment teeth:

1. Based on the Extent of the Prosthesis Across the Midline:
   • Unilateral splint:
     • It is joining of two or more teeth in one plane of an arch segment
     • They are very resistant to the mesiodistal forces
   • Bilateral or cross arch splints:
     • They cross midline
     • Resists forces that comes from all the direction
2.  Based on Duration of use:
   • Temporary splints
   • Used for a shorter span of time
   • Permanent splints
   • Help in prevention of further progress of periodontal diseases

Question 37. Temporary crowns.
Answer:

1. Polycarbonate crown:
   • These are performed crowns used for provisional restoration
   • These are available in various sizes
   • The operator can choose the size and material that would best suit the patient and place it as a provisional restoration
   • Before cementing they are slightly altered and modified to fit the tooth
2. Cast metal Restorations:
   • Indications:
     • Patients with gross maxilla-mandibular discrepan- cies
     • Medically compromised patients
     • For maintenance of vertical dimension
3. Aluminium Shell Crowns: Used for premolars and molars
4. Nickel Chromium metal crowns:
   • Used in children with extensively damaged primary teeth
   • Used for long term provisional restoration
   • It is very hard
5. Cellulose Acetate crown: It is a thin, soft, and transparent material
6. Heat-polymerised resin:
   • A wax pattern with the desired shape is made on the mounted casts
   • Wax patterns are flasked, dewaxed and packed with heat cure acrylic resin and cured

Question 38. Marginal integrity
Answer:

• Marginal adaptation and seating of restoration affects marginal integrity
• Poor marginal adaptation leads to percolation of oral fluids and secondary caries
• Margin of a restoration should be preferably placed supragingivally

Advantages of supragingival finish line:

• Easy to maintain
• Fit can be evaluated
• Easy to make an impression
• Easily finish
• Compatible to surrounding tissue

Indications of subgingival finish line:

• Contact point located below the gingival crest
• Short clinical crown
• To conceal metal ceramic margin
• Presence of secondary caries

Question 39. Anterior three-quarter crown.
Answer:

Advantages of Anterior three-quarter crown:

• Conservative tooth reduction Esthetics
• Electric pulp testing can be done
• Favourable periodontal response
• Ensures complete seating

Disadvantages of Anterior three-quarter crown:

• Poor retention and resistance Critical preparation
• May cause discoloration of anterior teeth

Indications of Anterior three-quarter crown:

• Intact or minimally restored teeth
• Teeth with adequate crown length
• Teeth with adequate labiolingual thickness
• Teeth having normal anatomic configuration

Contraindications of Anterior three-quarter crown:

• High caries rate
• Short teeth
• Bell shaped teeth
• Thin teeth

Tooth Preparation Sequence:

• Occlusal reduction
• Lingual reduction
• Placing proximal grooves
• Placing occlusal grooves
• Placement of facial bevel
• Chamfer finish is preferred

Question 40. Partial crowns.
Answer:

1. Three quarter crown:  Restores occlusal surface and three of the four axial surfaces not including the facial surface
2. Reverse three quarter crowns:
   • Restores all surfaces except lingual surface
   • Indicated on mandibular molars with severe lingual inclination
3. Seven-eights crown: Extension of the three-quarter crown to include major portion of the facial surface
4. One half crown:
   • It is a three quarter crown rotated at 90 degrees preserving the distal surface
   • Indicated on a tilted mandibular molar abutment

Question 41. Direct technique of provisionalization
Answer:

Bis-acryl composites exhibit less heat and shrinkage during polymerization and hence can be used to fabricate provisional restoration via direct technique

Technique of Direct :

• Overimpression is made using additional silicon Tooth preparation is carried out
• The prepared tooth is coated with petrolatum
• Base and catalyst of the composite are mixed and loaded into overexpression
• Before composite polymerises the over impression is reseated in the patient’s mouth
• The composite is allowed to be polymerized intraorally for 10 min
• The over impression is removed and the polymerized composite is teased out carefully
• Restoration is finally finished, polished, and cemented

Question 42. Mutually protected occlusion.
Answer:

• Proposed by Stalled and Staurt
• It states that the balancing contents during eccentric jaw movements were eliminated by making the canines on the working side disocclude the posterior teeth
• During lateral or protrusive excursions there is no pos- terior occlusal contacts

Rationale of Mutually protected:

• Anterior teeth have an advantage over posterior teeth when it comes to mechanical properties
• Forces generated by muscles of mastication is comparatively lesser when the tooth contact occurs more anteriorly
• The class 3 lever arm at the anterior teeth exerts lesser pressure

Features of Mutually protected:

• When condyles are in their most superior position uniform contact of all the teeth happens
• With functional jaw movement, the anterior tooth contact is harmonised
• At the lateral or protrusive movement, there is no contact of the posterior teeth

Question 43. Gingival finish lines.
Answer:

Requirements of Gingival finish lines:

• Shallow bevels nearly parallel to the cavosurface should be avoided
• The bevel should not produce a very acute margin
• The tooth should not be reduced more than half of the width of the diamond.

Question 44. Indications of fixed partial dentures
Answer:

Indications:

1. Length of the edentulous arch:

• Short span edentulous arches are preferred for FPD
• This is due to the reason that a long span FPD transfers excessive load to the abutment and also tends to flex to a greater extent
• To avoid it short span edentulous arches is preferred

2. Condition of the Abutment Tooth:

• FPD is used if there is presence of posterior tooth for support
• Such a tooth should have
• Provides primary tion of gingival sulcus retention
• Axial contour can be Difficult to maintain modified
• Aid in resistance and finish
• Ideal crown root ratio for support
• Adequate thickness of enamel and dentin for re- duction
• Adequate bone support
• Absence of periodontal disease
• Proper gingival contour

3. Condition of the residual ridge:

The contour of the ridge and texture of the soft tis- sues should be observed

• A smooth rounded ridge is best for the placement of FPD

4. Patient’s preference:

• The patient may not desire to frequently remove and insert the denture
• If in these patients removable partial denture is given, they may not maintain it
• This may further lead to post insertion problems
• To avoid this, FPD is preferred

Question 45. Virginia bridge.
Answer:

• Proposed by Moon and Hudgins
• These are resin bonded fixed partial denture that use particle roughed retainers

Method of fabrication:

• 150-250 μm salt crystals are sprinkled over the cast
• Retainer wax pattern are fabricated using resin
• The salt particles gets incorporated onto the tissue surface of resin pattern
• Salt particles gets dissolved – Lost salt technique
• Resin pattern is invested and cast
• Dissolve crystals produces voids in the resin pattern
• These voids are reproduced in the cast metal retainer which help in mechanical retention

Advantages of Virginia bridg:

• Even noble metal alloys can be used
• Surface treatment of retainer is not required
• Air abrasion with aluminium oxide is sufficient

Fixed Partial Denture Short Question And Answers

Question 1. Suck back porosity.
Answer:

• It is external void seen inside of a crown opposite the sprue
• A hot spot is created by the hot metal impinging on the mold wall near the sprue
• The hot spot causes this region to freeze last
• Since the sprue has already solidified no more molten material is available and the resulting shrinkage causes a peculiar type of shrinkage called suck back porosity

Question 2. Maryland bridges.
Answer:

• Livaditis and Thompson from university of
• Maryland School of dentistry used Dunn’s study and developed Maryland bridges
• In it mechanical retention was developed by the micro-porosities present on the tissue surface of the retainer
• Micro-porosities are created by etching the tissue sur- face of the retainer

Question 3. Solders.
Answer:

Requirements of Solders:

• It should fuse safely below the sag or creep temperature of the parent alloy
• It should resist tarnish and corrosion
• It should be non-pitting
• It should be free-flowing
• It should match the color of parent metal
• The joint should be strong

Composition of Solders:

• Gold
• Silver
• Copper
• Tin
• Zinc

Question 4. Types of occlusion in FPD.
Answer:

1.  Centric occlusion: It is occlusion of opposing teeth when the mandible is at centric relation
2. Eccentric occlusion: It is an occlusion other than centric occlusion
3. Myocentric occlusion:
   1. Proposed by Bernard Jankelson
   2. It produces relaxation of the mandibular muscles and then initiates controlled isotonic muscle contraction
4. Pathologic occlusion: It is defined as one in which sufficient disharmony exists between the teeth and the temporomandibular joint to result in symptoms that require intervention

Question 5. Casting defects.
Answer:

• Distortion
• Surface roughness Porosity
• Caused by solidification shrinkage
  • Localized shrinkage porosity
  • Suck back porosity
  • Microporosity
• Caused by gas
  • Pinhole porosity
  • Gas inclusion
  • Subsurface porosity
• Caused by air entrapment
  • Back pressure porosity Incomplete casting
• Contamination of casting due to oxidation

Question 6. Disadvantages of partial veneer crown.
Answer:

• Less retentive than complete cast crown
• Limited adjustment of path of withdrawal
• Some display of metal

Question 7. Partial veneer crown.
Answer:

Indications of Partial veneer crown:

• Clinical crown of average length or longer
• Intact buccal surface that is not in need of contour or modification and that is well-supported
• No conflict between axial relationship of tooth and proposed path of withdrawal of the FPD

Contra-Indications of Partial veneer crown:

• Short teeth
• High caries index of tooth
• Extensive destruction
• Bulbous teeth
• Thin teeth
• Poor alignment

Question 8. Dicor.
Answer:

• Dicor is the first commercially available castable ceramic material for dental use
• It was developed by Dentsply international
• It is a castable glass that is formed into an inlay, facial veneer or full crown restoration by a lost wax casting process
• It is not used nowadays because of
  • Very low tensile strength
  • Tends to fracture easily
  • More amount of tooth preparation is required

Question 9. Cerestore.
Answer:

• It is a shrink free ceramic system
• It offsets conventional ceramic shrinkage by a combination of
  • Chemical transformation- By oxidation of silicone
  • Crystalline transformation- By formation of MgAl₂O₄

Question 10. Reversible hydrocolloid.
Answer:

Agar is reversible hydrocolloid

Composition of Reversible hydrocolloid:

Question 11. Shade selection.
Answer:

• If natural teeth are present, the shade of the teeth adjacent to the edentulous space is taken as index
• The artificial tooth should be moistened before matching it with a shade guide
• Natural light is better than artificial light for shade selection
• When operator stares at tooth for a long time his/her eyes will undergo fatigue leading to misinter pretation of shades
• Fatigue can be avoided by providing intermittent rest to the eyes

Question 12. Retraction cord.
Answer:

• Pressure packing the retraction cord into the gingival sulcus provides sufficient gingival retraction
• It should be made of absorbent material like cotton

Technique of Retraction cord:

• Dry out the area
• Cut desired length of cord from the dispenser bottle
• Twist the cord
• Dipped in 25% aluminium chloride solution Loop it around the tooth
• Cord is packed into gingival sulcus
  Excess cord is cut off
• Atleast 2-3 mm of cord is left protruding outside the sulcus
• After 10 minutes the cord is removed slowly to avoid bleeding

Question 13. Pain control in tooth preparation.
Answer:

Anaesthesia is given to tooth to be operated and of adjacent soft tissues prior to tooth preparation

• Result:
  • Pain elimination
  • Reduces salivation
  • Results in more pleasant procedure for patient and operator

Question 14. Axio-proximal grooves.
Answer:

• Axio-proximal grooves are indicated when the prepared tooth is short
• When properly positioned, grooves are in sound dentin close to DEJ
• Long axis of bur must be held parallel to the line of draw

Question 15. Disadvantages of ridge lap pontic.
Answer:

• It is difficult to maintain
• It often leads to inflammation of the tissues in contact

Question 16. Disadvantages of subgingival finish lines.
Answer:

• Leads to inflammation of gingival sulcus
• Difficult to maintain and finish

Question 17. Importance of full mouth intra oral radiographs.
Answer:

• Aids in:
  • Evaluation of bone resorption, pattern of bone resorption, and quality of bone support
  • To check for presence of retained root tips, impacted tooth
  • To determine the thickness of soft tissue on the ridge in area of pontic placement

Question 18. Indications of fixed partial denture.
Answer:

• Short span edentulous arches
• Presence of posterior tooth for support
• Presence of smooth rounded ridge Patient’s preference
• Mentally compromised and physically handicapped patients

Question 19. Articulating Paper.
Answer:

• It is available in blue and red strips
• It is used to check the occlusion

Method Of Use:

• Articulating paper is placed over occlusal surface of mandibular teeth
• Patient is asked to bite over it
• The paper is gently pulled out
• The markings over the high points are observed and reduced accordingly

Question 20. Pier Abutment.
Answer:

It is a natural tooth located between terminal abutments that serve to support a fixed or removable prosthesis

Disadvantages of placing a rigid connector in pier abutment:

• Intrusion of abutment teeth
• Tooth moves in buccolingual direction
• Weakening of terminal retainers
• Microleakage and caries
• Trauma to the periodontum

Prevention: To avoid the adverse effects, stress breaker should be provided

Question 21. Relationship between pontic and soft tissue.
Answer:

• The contour of the soft tissue is surveyed on the diagnostic cast during treatment plan
• A smooth rounded ridge is best for pontic placement
• Siebert grouped residual ridges into 3 categories
• Class 1 : It is a ridge with loss of faciolingual width with normal apicocoronal height
  • It is corrected by ridge augmentation
• Class 2: It is the ridge with loss of ridge height with normal ridge width
  • It is corrected by grafting
• Class 3: It is the ridge with loss of both height and width

Question 22. Depth orientation Grooves.
Answer:

• These are made during tooth preparation Three depth orientation grooves, 1.0 mm deep are placed.
• One in the middle of the facial wall and one each in the mesio-facial and distofacial line angles in the incisal edge.
• Two more depth orientation grooves of 2.0 mm depth are placed on the incisal half/occlusal half – 2 mm deep grooves are placed on the incisal edge for incisal reduction.

Question 23. Mesial Half crown/Proximal Half crown.
Answer:

Mesial half crown restores the occlusal and mesial surfaces as well as portions of the facial and lingual surfaces.

Indications of Mesial Half crown:

• In mesially tilted molars
• Patients with good oral hygienc status and low incidence of caries

Contraindications of Mesial Half crown:

• Distal caries present
• In caries prone mouth
• In poor oral hygiene maintenance
• If there is severe marginal ridge height difference between the distal of the second molar and the mesial of the third molar.

Question 24. All ceramic systems/ Metal free ceramics.
Answer:

They are man made solid objects formed by baking raw materials at high temperatures

Classification of ceramic systems:

• Conventional powder-slurry ceramics
• Castable ceramics
• Machinable ceramics
• Pressable ceramics
• Infiltrated ceramics

Question 25. Dowel Pin.
Answer:

• Used when an endodonticaaly treated teeth is used as abutment
• It is the screw component that is inserted into the root canal

Types of Dowel Pin:

• Pre fabricated
• Custom made

Factors To Be Considered:

• The canal should be obturated only with gutta-percha
• For proper retention the length of the dowel inside the root should be atleast 2/3rd of root length
• The coronal portion of the dowel should be encircled atleast by 1-2 mm of tooth structure to obtain a ferrule effect

Question 26. Disadvantages of Porcelain veneer.
Answer:

• Reduced strength
• Technique sensitive
• Least conservative
• Brittle in nature
• Can be used as single restoration only

Question 27. Advantages of Porcelain fused to metal crowns/Metal ceramic crowns.
Answer:

• Good strength
• Good marginal fit
• Good aesthetic
• Can be used as a fixed partial denture retainer

Its tooth preparation provides:

• Structural durability
• Preservation of periodontal health
• Provide retention
• Resistance
• Preservation of tooth structure

Question 28. Indications for Jacket Crown.
Answer:

• High esthetic requirement
• Considerable proximal caries
• Incisal edge reasonably intact
• Endodontically treated teeth
• Favorable occlusal distribution

Question 29. Advantages of Partial veneer.
Answer:

Advantages of Partial veneer:

• Conservation of tooth structure
• Improved access for finishing by the dentist and cleaning by the patient
• Improved periodontal health as there is limited contact between the margins of the restoration and gingiva
• It can be completely seated during cementation
• The marginal fit can be easily verified

Question 30. Types Finish lines.
Answer:

Types of fish lines:

1. Supragingival
2. Subgingival
3. Chamfer
4. Shoulder
5. Shoulder with bevel
6. Feather edge
7. Knife edge

Question 31. The angle of Cervical Convergence.
Answer:

The angle of Cervical Convergence:

• The degree of taper is inversely proportional to the retention form
• Zero degree taper is the most retentive
• The sum of the degree of taper is called as angle of cervical convergence
• 4-100 optimum retention
• Mandibular premolars No reduction as they are lingually tilted 60 needed for tooth preparation
• Bur used – tapering fissure diamond with 3⁰

Question 32. Laminate Veneers.
Answer:

Synonym: Facial veneer

Features of Laminate Veneers:

• They are prosthesis which are used of ceramic
• They are used as a thin layer over the facial surface of the tooth
• Its inner surface is etched with hydrofluoric acid and bonded to tooth with composite resin cement

Advantages of Laminate Veneers:

• Good translucency
• Reduced plaque adherence
• Reduced chair time
• Wear resistant
• Bio-compatible
• Good bond strength

Disadvantages of Laminate Veneers:

• Fragile
• Loss of glaze while finishing
• Expensive
• Technique sensitive

Question 33. Polycarbonate Crown.
Answer:

• These are performed crowns used for provisional restoration
• These are available in various sizes
• The operator can choose the size and material that would best suit the patient and place it as a provisional restoration
• Before cementing they are slightly altered and modified to fit the tooth

Advantage of Polycarbonate Crown:

• Less time consuming
• Its shade can be altered by the shade of the luting agent
• Esthetic

Disadvantage of Polycarbonate Crown:

• Limited to single tooth preparation

Indication of Polycarbonate Crown:

• For anterior teeth restoration

Question 34. Relationship of finish line and restoration.
Answer:

Question 35. Rochette Bridges-Design by Rochette in 1973.
Answer:

• It is a wing like retainer with six perforations to provide mechanical undercut for resin cement
• Etched retainers are coated with pyrolized silane and bonded with resin cements
• It is funnel shaped with base towards the tooth surface

Disadvantage of Rochette Bridges:

• The resin is exposed through the perforation to oral fluids and external stress, which leads to abrasive and marginal leakage

Variation of Rochette Bridges:

• Non-perforated retainers

Question 36. Spring Cantilever Bridge.
Answer:

It is special cantilever bridge designed for replacement of maxillary incisors

Design Considerations:

• A long resilient bar connector is used to connect the posterior retainer to the anterior pontic
• The bar adapts closely and extend over the soft tissues of the palate
• The bar should be thin and resilient enough to resist permanent deformation under masticatory load

Advantages of Spring Cantilever Bridge:

• Can be used for diastema cases
• Requires minimal tooth preparation

Disadvantages of Spring Cantilever Bridge:

• The bar may interefere with speech and mastication
• Its deformation may produce coronal displacement of the pontic
• May lead to tissue hyperplasia due to food entrapment

Question 37. Fixed fixed-partial denture.
Answer:

• It consists of fixed partial dentures with rigid connectors
• Thus, there can be no movement between the connected components

Advantages of Fixed fixed-partial denture:

• Easy to fabricate
• Easy to maintain
• Economical
• Strong
• Helps to splint mobile abutments
• Can be used along with periodontally weak abutments

Disadvantages of Fixed fixed-partial denture:

• Unwanted forces are directed to the abutment Requires excessive tooth preparation
• Difficult to cement
• Cannot be used for pier abutments

Question 38. Impression materials.
Answer:

Ideal Requirements:

• It should be dimensionally stable
• It should be accurate
• It should be sufficiently elastic
• It should be able to wet the oral tissues
• It should be compatible with the model and materials
• It should be possible to electroplate them

Question 39. Removable Dies.
Answer:

In this system a special type of working cast is pre pared and the dies are carefully sectioned so that the individual dies can be removed and replaced in their original position in the cast

Question 40. Soldering Flux.
Answer:

It is a substance applied to surfaces to be soldered by joining, to increase fluidity and reduce oxidation of a molten metal

Significance of Soldering Flux:

• Removes oxides and prevents oxidation
• Allows solder to wet the metal surface
• Helps solder to adhere to metal surface

Composition of Soldering Flux:

• Borax glass 55 parts
• Boric acid-35 parts
• Silica – 10 parts

 Question 41. Pressure Indicating Paste (PIP).
Answer:

Any substance applied to a prosthesis that when seated on a structure, demonstrates the adaptation of the prosthesis to the structure it opposes

Composition of Indicating Paste:

Equal parts of vegetable additives with Zinc Oxide or a mixture of Calcium Carbonate and Chloroform

Method Of Use:

• The two paste are mix to a homogenous mix
• It is applied over the occlusal and denture bearing area
• Pressure is applied by the patient/dentist

Pressure Areas:

• In Maxilla:
  • Palate
  • Lateral sides of tuberosity
• In Mandible:
  • Mylohyoid ridge
  • Area buccal to the bicuspid
  • Distolingual border of denture
  • Retromylohyoid space

Question 42. Die spacer.
Answer:

To produce space for luting cement, die spacer is used over die

Materials Used of Die spacer: 

• Commonly resins
• Colored nail polish
• Thermoplastic polymers dissolved in volatile solvents

Technique of Die spacer:

• Such spacer are applied in several coats to within 0.5 mm of the preparation finish line

Purpose of Die spacer:

• Provide relief space for luting cement
• Ensures proper seating of the otherwise precisely fit- ting casting or coping

Question 43. Night Guards.
Answer:

It acts as an occlusal protective device

Uses of Night Guard:

• In bruxer
• In acute TMJ disorders cases
• To prevent abnormal mandibular closure
• In sports like boxing

Materials Used of Night Guard:

• Acrylic
• Latex rubber
• KVA Copolymer
• Polyurethane
• PVC

Advantages of Night Guard:

• It supports the edentulous spaces
• Reduces chances of jaw fracture and dislocation
• Protects occurrence of tooth fracture and dislocation

Question 44. The function of functional cusp bevel in fixed partial denture.
Answer:

• Functional cusp bevel is prepared on palatal cusps of maxillary molars and buccal cusps of mandibular posteriors
• The angulation of the functional cusp bevel should be at 45 degrees angle to the long axis of the tooth for partial veneer crown
• For complete veneer crown the angulation should be parallel to the inner inclines of the cusps of opposing tooth
• Provides adequate bulk in the areas of heavy occlusal contacts
• Lack of functional cusp bevel can cause a thin areas of perforation in the casting
• It provides structural durability of restoration

Question 45. Classify fixed partial dentures.
Answer:

1. Class – Identifies location of edentulous space
   • Class 1- Posterior edentulous space
   • Class 2 – Anterior edentulous space
   • Class 3-anteroposterior edentulous space
2. Division indicates teeth present adjacent to the edentulous space that are capable of taking support
   • Division 1 –  Cantilever FPD abutment present on one side of edentulous space
   • Division 2 –  Conventional FPD abutment present on both sides of edentulous space
   • Division 3 –  Pier abutment single tooth sur rounded by edentulous space on either side
3. Subdivision – denotes status of the tooth
   • Sub-division 1- Ideal abutment
   • Sub-division 2 -Tilted abutment
   • Sub-division 3 – Periodontally weak abutment
   • Sub-division 4 -Extensively damaged abutment
   • Sub-division 5 -Implant abutment

Question 46. Di-lock system
Answer:

• It is special tray used to pour the cast
• It has orientation grooves on the inner aspect
• In di lock system, impression is poured using two pour technique
• First pour is poured up to the level of the impression
• Next the rim of the di-lock tray is positioned over the impression
• Second pour is poured over it
• Cast is allowed to set
• Di-lock tray is then dismantled
• Grooves formed on the base of the cast by the di-lock
• Tray is used as guide for die sectioning

Advantage of Di-lock system:

• Simple and easy to prepare

Disadvantage of Di-lock system:

• Requires special equipment

Question 47. Pickling
Answer:

• Pickling is the process of cleaning the casting by 50% warm HCI
• Used to remove surface oxides from casting
• It is not a routine procedure
• Used only when indicated

Question 48. Flux and anti-flux
Answer:

Flux: Flux means flow

• Uses of Flux:
  • Removal of oxide coating of solder
  • Dissolves impurities
  • Prevents oxidation
  • Reduces melting point
• Composition of Flux:
  •  Borax glass- 55%
  • Boric acid-35%
  • Silica – 10%

Antiflux: It confines flow of molten solder

• Example:
  • Lead pencil markings
  • Graphite lines
  • Iron rouge

Question 49. Non-rigid connectors in fixed partial dentures
Answer:

• Used in case of non-parallel abutments. They are
• Tenon mortise connector
• Loop connector
• Split connector
• Cross pin and wing connector

Question 50. Indications and contraindications of porcelain jacket crown.
Answer:

Indications:

• Fractured incisal angles
• Hypoplastic, discolored, and malformed teeth
• Facial/ proximal caries that cannot be restored by composites

Contra-Indications:

• Young patients
• Short clinical crowns
• Sports persons
• Excessive overbite
• Least overjet
• High DMF rate

Question 51. Differences between direct and indirect spruing.
Answer:

Question 52. Classification of posts
Answer:

Types Of Posts:

1. Prefabricated
   • Available with either amalgam or resin core
   • Materials used are
   • Stainless steel
   • Titanium
   • Nickel and chromium
   • Molybdenum
   • They can be parallel sided or tapering
   • Further classified into
   • Passive/cemented type
   • Active/threaded type
2. Custom made:
   • They are cast from wax pattern fabricated in the canal
   • A brass wire or a paper clip may be used to make the wax pattern within the canal
   • Further classified into
   • Prefabricated noble metal
   • Resin pattern fabrication
   • Wax pattern fabrication
3. Fabrication Steps:
   • Tooth preparation
   • Canal preparation
   • Canal pattern fabrication
   • Casting
   • Finishing and cementation

Question 53. Advantages of a fibre post.
Answer:

Advantages of a fibre post:

• Biocompatibility
• More rapid treatment
• Esthetics
• Corrosion resistance
• Safe
• Easily removed
• Conserves tooth structure
• Tend to absorb and dissipate stress like natural dentin
• Prevents root fracture

Question 54. Tube impression
Answer:

Indications of Tube impression:

• Single tooth preparation

Advantages of Tube impression:

• Saves time
• An accurate finish line can be obtained

Disadvantages of Tube impression:

• Requires additional impressions
• Proper orientation of the die with the dies of adjacent/ opposing teeth is difficult

Method of Tube Impression:

• Copper tube is selected and customized according to the patient
• Fingers are coated with petroleum jelly
• Green stick compound is softened and filled up to one third of the tube
• This tube is then placed onto tooth preparation
• Light body material is then syringed over the prepared tooth

Question 55. Bull’s law.
Answer:

• For correction of occlusal errors selective grinding is done
• All contact areas are made visible by the markings of articulating paper
• On the non-working side, contacts occurs between maxillary buccal and mandibular lingual cusps
• Selective grinding on the working side is done following Bull law which is grinding of Buccal cusps of Up- per molar and Lingual cusps of Lower molar
• Selective grinding is verified and repeated is required

1. B-buccal
2. P-palatal

Fixed Partial Denture Viva Voce

1. After removing from mouth, alginate impression should be poured within 15 minutes
2. Average root surface area of maxillary permanent 1st molar is 433 mm3
3. A molar with divergent roots provides better support in FPD
4. Long span fixed partial denture should be fabricated by material having high strength and rigidity
5. Shoulder gingival margin is less conservative
6. Chisel edge gingival margin is indicated in tilted teeth
7. Shoulder gingival margin is indicated on facial margins of metal-ceramic crowns
8. Chamfer gingival margin is indicated for lingual margin of metal ceramic crown
9. The functional cusp bevel is placed at 45 degrees to long axis of the tooth
10. Incisal reduction for metal-ceramic crown 1.5-2mm
11. Incisal reduction for porcelain crown – 1.5 mm
12. Optimal cavosurface angle in all ceramic crown is 90 degrees
13. The facial surface is more reduced in metal ceramic crown as compared to complete ceramic crown
14. Hydrofluoric acid is etchant used in bonding of porcelain to tooth
15. Polysulfide and hydrocolloid are not compatible with resin dies
16. Bullet shaped pontic has only one point contact
17. Modified ridge lap pontic is recommended in maxillary anterior region
18. Sanitary pontic is the most hygienic
19. All metal pontic is needed in situations of high stress
20. Sprue is attached to the thickest part of the wax pattern
21. Recommended soldering gap is 0.25 mm
22. Loop connector is used to maintain a diastema in a planned fixed prosthesis
23. Graphite is used as antireflux
24. Rouge contains iron oxide
25. Reducing zone of flame is used in torch soldering
26. Modified zinc oxide eugenol cement is used as luting agent for provisional restoration
27. RPI stands for – Rest, Plate, I bar clasp
28. Cyanoacrylate is used as die hardener
29. Modified ridge lap pontic is sued to replace missing canine

Denture Insertion

 

Denture Insertion Important Notes

1. Denture adhesives:
   • Vegetable gums – possess very little cohesive strength
   • Gum-based adhesives – highly water-soluble and washed out easily
   • Synthetic salts of Gontrez  display good ionic adherence
2.  Soft liners:
   • They are denture-lining materials
   • Help in conditioning the traumatized tissues
   • It acts as a cushion between the hard plastic base of the denture and the oral tissues
   • Commonly used soft liners are
     • Poly ethyl methacrylate
     • Silicon soft liners
     • Heat activated silicones
3. Denture cleansers:
   • The most commonly used denture cleansers are alkaline peroxides and hypochlorites
   • Alkaline peroxides
     • Provided in powder and tablet forms
     • It contains alkaline compounds.
     • Detergents, sodium perborate, and flavoring agents
     • When mixed with water, sodium perborate decomposes releasing peroxides which in turn decompose releasing oxygen
     •  Hypochlorite solutions are available only in solution form
4. Problems in denture wearers:

Denture Insertion Long Essays

Question 1. Discuss in detail about insertion, instructions, and aftercare of complete denture.
Or
Instructions to complete denture patient.
(or)
Post-insertion instructions are to be given to a complete denture patient
Answer:

Instruction For Insertion & Removal:

• The patient is taught to insert & remove the denture along the path of insertion
• In the presence of a unilateral undercut, the Denture should be inserted into the undercut first then rotate the prosthesis into the final position
• If a denture is more retentive the patient is asked to blow with lips closed to break the peripheral seal

Maintenance of Prothesis:

• Patients are taught to clean the dentures regularly
• Cleansers used are:
  • Chemicals: Chlorhexidine
  • Ultrasonic cleaner
• Soaking & brushing the denture
• Avoid hard brushing
• Avoid excessive flossing

Read And Learn More: Prosthodontics Question And Answers

Night Wear of Prosthesis:

• Avoid nightwear of dentures
• Allowed to wear only in brutes
• Store the denture in water or any dilute medicinal solution at night
• Report to the dentist if the denture causes any irrita- tion even after 24 hours
• The patient is asked to read newspapers or novels loudly during 1st 24 hours to get adapt to the denture
• Recall the patient after a week to check for tissue reaction Recall after every 3–6 months to determine the amount of residual ridge resorption

Denture Insertion Short Essays

Question 1. Write Recall Visit
Answer:

Recall Visit:

• Explain the patient the sequences of denture insertion like increased salivation, and difficulty in speech.
• If it continues for more than 1 week, ask him to visit the dentist.
• If an ulcer or any irritation is experienced by the patient, ask him to visit the dentist.

Denture Insertion Short Question And Answers

Question 1. Factors in denture design affecting speech.
Answer:

• Denture wearers have shallow pronunciation
• In dentulous patient, rugae enhance speech
• In a denture wearer speech is affected due to absence of rugae
• The use of metal dentures improves speech
• Injury to the external laryngeal nerve
• Presence of tongue tie
• Production of various sounds
  1. Bilabial – b, p, m
  2. Labiodental-f, v
  3. Linguodental-th
  4. Linguoalveolar- t, d, s, z, v, 1
  5. ‘s’ sound is controlled by the anterior part of the palatal plate of the denture base

Question 2. Torus palatinus.
Answer:

It is exostosis/ overgrowth of cortical corticocancellous bone

Technique for excision of palatal torus:

Denture Insertion Viva Voce

1. Poor denture retention and excessive vertical dimension are the two common causes of clicking of complete dentures.

Maxillofacial Prosthetics

 

Maxillofacial Prosthetics Definition

Obturator: “A prosthesis used to close a congenital or acquired tissue opening, primarily of the hard palate and/or contiguous alveolar structures”.

Surgical obturator: It is defined as “A temporary prosthesis used to restore the continuity of the hard palate immediately after sur- gery or traumatic loss of a portion or all of the hard palate and/or contiguous alveolar structures”.

Interim obturator: It is defined as “A prosthesis that is made several weeks or months following the surgical resection of a portion of one or both maxillae. It frequently includes replacement of teeth in the defect area.’

Definitive obturator: It is defined as “A prosthesis that artificially replaces part or all of the maxilla and the associated teeth lost due to surgery or trauma”.

Maxillofacial Prosthetics Important Notes

1. Types of obturator

• Types:
  • Based on the phase of treatment
    1. Surgical Obturators -Types:
       • Immediate surgical obturator – Inserted at the time of surgery
       • Delayed surgical obturator – Inserted 7–10 days after surgery
    2. Definitive obturators
    3. Interim Obturators
  • Based on the Material used
    • Metal obturators
    • Resin obturators
    • Silicone obturators
  • Based on the area of restoration
    • Palatal obturator
    • Metal obturator

2. Materials used in maxillofacial prosthesis:

• Heat cure acrylic resin
• Polyvinyl chloride and copolymers
• Polyurethane elastomers
• Silicones
• Polyphosphates
• Chlorinated polyethylene

Maxillofacial Prosthetics Short Essays

Question 1. Treatment Planning for a maxillary prosthesis.
Answer:

1. First Phase – Initial Stabilization
   • It lasts for 2 weeks
   • The physician determines the prognosis
2. Second Phase – Early management
   • It extends for 2–8 weeks
   • Treatments like inter maxillary Fixation, Splinting, and RCT are done
3. Third Phase – Intermediate management
   • It extends for 3–8 months
   • A treatment prosthesis is provided and defects are evaluated
4. Fourth Phase – Definitive management
   • It extends from 6 months – 3 years
   • A permanent prosthesis is fabricated

Read And Learn More: Prosthodontics Question And Answers

Question 2. Obturators.
Answer:

Definition: “A prosthesis used to close a congenital or acquired tissue opening, primarily of the hard palate and/or contiguous alveolar structures”.

Types of Obturators:

1. Based on the phase of treatment:

• Surgical Obturators: It is defined as “A temporary prosthesis used to restore the continuity of the hard palate immediately after surgery or traumatic loss of a portion or all of the hard palate and/or contiguous alveolar structures”.
  • Types:
    1. Immediate surgical obturator:
       • Inserted at the time of surgery
    2. Delayed surgical obturator: Inserted 7 -10 days after surgery
       • Interim Obturators: It is defined as “A prosthesis that is made several weeks or months following the surgical resection of a portion of one or both maxillae. It frequently includes the replacement of teeth in the defect area.
         • This prosthesis when used, replaces the surgical obturator that is placed immediately following the resection and may be subsequently replaced with a definitive obturator”.
       • Definitive obturators: It is defined as “A prosthesis that artificially replaces part or all of the maxilla and the associated teeth lost due to surgery or trauma”.

2. Based on the Material used:

• Metal obturators
• Resin obturators
• Silicone obturators

3. Based on the area of restoration:

• Palatal obturator
• Metal obturator

Fabrication of Obturators:

• Plan the design and extent of the obturator
• Primary impression is made
• Fabricate the custom tray
• Carry out border molding by asking the patient to swallow
• The final impression is made using alginate or elastomeric impression materials
• Record the jaw relation and arrange the teeth. Insert the prosthesis

Uses of Obturators:

• Provides stable matrix for surgical packing
• Reduces oral contamination
• Effective speech obtained post-operatively
• Permits deglutition
• Reduces the psychological impact of surgery
• Reduce the period of hospitalization

Question 3. Materials for a maxillofacial prosthesis.
Answer:

1. Acrylic resin: Preferred for restoring defects that require minimal movement

Advantages of Acrylic resin:

• Easily available
• Commonly used material
• Intrinsic and extrinsic colouration can be used
• Has better colour stability

Disadvantages of Acrylic resin:

• Rigid
• Difficulty in duplicating

2. Acrylic copolymers: They are plasticized methyl meth acrylate polymers that are not commonly used

Disadvantages of Acrylic copolymers:

• Tacky so leads to a collection of dust and stains
• Poor edge strength
• Poor durability
• Degrades under sunlight

3. Polyvinyl chloride and copolymers: It is a hard, clear, tasteless, and odorless resin

Disadvantages of Polyvinyl chloride and copolymers:

• Excessive shrinkage
• Long processing time
• Discoloration
• Hardening of the margins

4. Chlorinated polyethylene:

• It requires metal molds for processing

5. Polyurethane elastomers:

• Have excellent elasticity
• Used to restore defects
• Has moisture sensitivity during processing
• Poor colour stability

6. Silicones: The most commonly used material

• Types:
  • Implant grade
  • Medical grade
  • Clean grade
  • Industrial grade

7. Polyphosphates:

8. Adhesives:

• Used to retain a maxillofacial prosthesis

9. Metal:

• Used to obtain bone anchorage for a prosthesis

Maxillofacial Prosthetics Viva Voce

1. The interim obturator can serve up to 6 months
2. The goal of the interim obturator is to restore deglutition and speech
3. The surgical obturator is used for approximately 5 days

Removable Partial Dentures Definitions

1. Removable partial denture: Any prosthesis that replaces some teeth in a partially dentate arch is called a removable partial denture It can be removed from the mouth and replaced at will
2. Direct retainer: It is defined as “A clasp or attachment placed on an abutment tooth for the purpose of holding a removable denture in position
3. Indirect retainer: It is defined as “a part of a removable partial denture which assists the direct retainers in preventing displacement of distal extension denture bases by functioning through lever action on the opposite side of the fulcrum”.
4. Major connector: It is defined as “A part of a removable partial denture which connects the components on one side of the arch to the components on the opposite side of the arch”
5. Minor connector: It is defined as “The connecting link between the major connector or base of a removable partial denture and other units of the prosthesis, such as clasps, indirect retainers, and occlusal rests”.
6. Rest: “It is defined as “A rigid extension of a fixed or removable partial denture which contacts a remaining tooth or teeth to dissipate vertical or horizontal forces.”
7. Denture base: It is defined as “that part of a complete or removable partial denture which rests upon the basal seat and to which teeth are attached”.
8. Surveyor: An instrument used in the construction of removable partial dentures to locate and delineate contours and relative positions of abutment teeth and associated structures
9. Retentive arm: “A flexible segment of a removable partial denture which engages an undercut on an abutment and which is designed to retain the denture”
10. Reciprocal arm: “A clasp arm or other extension used on a removable partial denture to oppose the action of some other part or parts of the prosthesis”
11. Reciprocation: It is defined as the means by which one part of a prosthesis is made to counter the effect created by another part
12. Stress breaker: A device that relieves the abutment teeth of all or part of the occlusal forces
13. Interim removable denture: “A transitional denture may become an interim denture when all of the natural teeth have been removed from the dental arch”.
14. Immediate partial denture:  “A complete removable partial denture constructed for insertion immediately following the removal of natural teeth”
15. Guiding planes: “Two or more vertically parallel surfaces of abutment teeth so oriented as to direct the path of placement and removal of removable partial denture”
16. Survey line: “A line drawn on a tooth or teeth of a cast by means of a surveyor for the purpose of determining the positions of the various parts of a clasp or clasps”.
17. Height of contour: A line encircling a tooth designating its greatest circumference at a selected position.
18. Internal attachment: “A retainer, used in removable partial denture construction, consisting of a metal receptacle and a closely fitting part: the former is usually contained with the normal or expanded contours of the crown of the abutment tooth and the latter is attached to a pontic or the denture framework”.
19. Fulcrum line: “An imaginary line around which a partial denture tends to rotate”

Removable Partial Dentures Important Notes

1. Kennedy’s classification:

• Class 1:
  • Bilateral edentulous areas located posterior to the remaining natural teeth
  • There are two edentulous spaces located in the posterior region without any teeth posterior to it.
• Class 2:
  • The unilateral edentulous area located posterior to the remaining natural teeth
  • There is a single edentulous space located in the posterior region without any teeth posterior to it.
• Class 3:
  • Unilateral edentulous area with natural teeth anterior and posterior to it.
  • It indicates a single edentulous area that does not cross the mid line of the arch
• Class 4:
  • Single Bilateral Edentulous area located anteriuor to the remaining natural teeth
  • It crosses the midline of the arch
  • Teeth are present only posterior to the edentulous arch
• Class 5:
  • The edentulous area is bounded anterior and posteriorly by natural teeth
• Class 6:
  • Edentulous area in which the teeth adjacent to the space are capable of total support of the required prosthesis

Read And Learn More: Prosthodontics Question And Answers

2. Applegate’s rules:

• Rule one – Classification should follow rather than precede extractions that might alter the original classification
• Rule two – If the third molar is missing and not to be replaced, it is not considered in the classification
• Rule three – If the third molar is present and is used as an abutment, it is considered in the classification
• Rule Four – If the second molar is missing and not to be replaced, it is not considered in the classification
• Rule Five – The most posterior edentulous area or areas always determine the classification
• Rule Six –  Edentulous areas other than those, which determine the classification, are referred to as modification spaces and are designated by their number
• Rule Seven – The extent of the modification is not considered, only the number of additional edentulous spaces are considered
• Rule Eight – There can be no modification areas in class 4.

3. Surveying tools:

• Analysing rod
• Carbon marker
• Undercut gauge
• Wax knife

4. Indications for removable partial dentures:

• Distal extension
• After recent extractions
• Long span edentulous arches
• Need for bilateral cross-arch stabilization
• Excessive loss of alveolar bone

5. Components of removable partial denture:

• Major connector
• Minor connector
• Direct retainer
• Indirect retainer
• Denture base
• Artificial teeth

6. Parts of surveyor:

• Surveying platform
• Cast holder/surveying table
• Vertical arm
• Horizontal arm
• Surveying arm
• Surveying tools

7. Types of major connectors:

8. Functions of minor connector:

• Joins other units of the prosthesis to major connector
• Transfers functional stress to the abutment teeth
• Transfers the effect of the retainers, rests, and stabilizing components to the rest of the denture

9. Types of minor connectors:

• The minor connector that connect the direct retainer to the major connector
• The minor connector that connect auxiliary rests to major connector
• The minor connector that connect the denture base to the major connector
• The minor connector that extends as the approach arm of a bar clasp

10. Parts of direct retainer:

• Retentive arm
• Shoulder
• Rest
• Reciprocal arm
• Body
• Minor connector

11. Functions of direct retainer:

12. Functions of reciprocal arm:

• Acts as an indirect retainer
• It can resist the rocking of the denture base
• It provides stability and reciprocation against the retentive arm
• The denture is stabilized against horizontal movement

13. Functions of indirect retainer:

• It counteracts the lifting forces and stabilizes the denture
• It counteracts horizontal forces and provide stability and support to the denture
• It can splint and protect the anterior teeth
• It may act as an auxillary rest
• The dislodgement of indirect retainer suggest the need of relining

14. Types of indirect retainers:

• Auxillary occlusal rest
• Canine rest
• Modification areas
• Direct indirect retention
• Canine extension
• Continuous bar retainer
• Rugae support
• Indirect retention from major connectors

15. Factors affecting stability of the RPD:

• Design of the framework
• Harmonious occlusion
• Relationship of the teeth to the residual ridge

Viva Voce

1. Distal extension partial denture derives support from both the teeth and residual ridge
2. The anteroposterior palatal bar and strap are the most rigid palatal major connector
3. The U-shaped palatal connector is least rigid palatal major connector
4. A partial denture is supported by dual support- soft tissue and tooth support
5. In Kennedy’s classification, the deciding factor is missing of most posterior tooth
6. In Kennedy’s classification, the most common arch is class 1
7. Totally tooth supported denture is class 3
8. In the palatal major connector, relief should always be given for the palatal torus
9. Elastomers are best material for taking impressions in RPD
10. Guiding planes prepared on enamel surfaces should be flat
11. The seat for occlusal rest on the abutment should be on the marginal ridge at 90 degrees to the long axis of the abutment
12. The main function of the reciprocal arm is to counteract the forces transmitted by the retentive arm
13. The indirect retainer should be placed on the opposite side of the fulcrum line
14. The main function of an indirect retainer is to minimize the movement of the denture away from supporting tissue
15. The major connector should be rigid enough to connect the Bilateral components of the removable denture
16. The flexibility of major connector causes greatest damage to a partial denture
17. The major connector should not terminate on gingival tissue
18. In case of large palatal torus, an anteroposterior palatal bar major connector is used
19. The outline form of occlusal rest is triangular
20. The rest seat for lingual rest is V-shaped
21. Incisal rests are frequently seen on mandibular canine
22. Lingual rests are commonly used on maxillary canines 23.
23. The terminal end of the retentive arm should be placed at a cervical third of the crown
24. The realeff effect is described by Hanau
25. The path of insertion of RPD is preferred to be perpendicular to the occlusal plane
26. The encirclement of each clasp is more than 180 degrees 27.
27. The easiest clasp to design and construct is a cast circumferential clasp
28. Ring clasp is most often indicated in tipped molars

Question 1. Internal attachments.
Answer:

Definition of Internal attachments:

“A retainer, used in removable partial denture construction, consisting of a metal receptacle and a closely fitting part:

• The former is usually contained with the normal or expanded contours of
• The crown of the abutment tooth and the latter is attached to a pontic or the denture framework”.

Types of Internal attachments:

• Ney-Chayes attachment
• Stern Goldsmith attachment
• Baker attachment

Advantages of Internal attachments:

• It eliminates the visible retentive component
• It eliminates the visible vertical support
• It provides horizontal stabilization
• It stimulates the underlying tissues

Disadvantages of Internal attachments:

• It requires the preparation of abutments
• It requires tedious lab procedures
• It leads to tooth wear
• It is least effective in teeth with small crowns It is difficult to place

Read And Learn More: Prosthodontics Question And Answers

Contraindications of Internal attachments::

• Teeth with large pulp
• Cost efficient

Question 2. Canine rests.
Answer:

It is a form of indirect retainer

1. Indication: If the mesial marginal ridge of the first premolar is close to the fulcrum line
2. Modification: The minor connector can be placed anterior to the canine
3. Advantage: It increases the efficacy of the indirect retainer

Question 3. Purposes of a surveyor.
Answer:

• To survey the diagnostic and primary casts
• For tripoding the cast
• To transfer the tripod marks to another cast
• To contour crowns and cast restorations
• To perform mouth preparation directly on the cast to determine the outcome of treatment
• To survey the master cast
• To survey ceramic veneers before final glazing

Question 4. Gingivally approaching clasps
Answer:

It is infrabulge clasp

Gingivally approaching clasps Advantages:

• Easy to seat
• Esthetic
• Does not increases the occlusal load
• No decalcification of teeth

Gingivally approaching clasps Disadvantages:

• It tends to collect food debris
• It needs additional stabilizing units

Question 5. Survey Lines

Survey Line: “A line drawn on a tooth or teeth of a cast by means of a surveyor for the purpose of determining the positions of the various parts of a clasp or clasps”.

1. High Survey Line:
   • This line passes from the occlusal third in the near zone and to the occlusal third in the far zone
   • If the survey line lies higher in position, the undercut will be deep
     In this wrought wire clasp with more flexibility is used It is usually common in inclined teeth and in teeth with greater occlusal diameter than its cementoenamel junction
2. Medium Survey Line:
   • It passes from the occlusal third in the near zone to the middle third in the far zone
   • In it Aker’s clasp is used
3. Low Survey Line:
   • This survey line is closer to the cervical third of the tooth in both near and far zone
   • A modified T clasp is used for teeth with low survey line

CLASP used: A modified T – Clasp is used

Question 6. U-shaped major connector.
Answer:

• It has a thin metal band running along lingual surface of posterior teeth
• Anteriorly it covers cingula of the teeth

U-shaped major connector Indications:

• Used in Kennedy’s class IV
• Used in presence of tori
• Used in excessive over bite

U-shaped major connector Advantages:

• Reasonably strong
• Has moderate indirect retention and support

U-shaped major connector Disadvantages:

• When vertical forces are applied on either one or both ends it tends to straighten
• Greater bulk is required to avoid flexing of the major , connector
• Increased thickness may cause patient discomfort

Question 7. Indications for removable partial dentures (RPD).
Answer:

• Length of Edentulous span – RPD are preferred for longer edentulous arches as it helps to distribute forces around the ridge evenly
• Age – RPD are preferred in young patients due to presence of large dental pulps
• Abutment – When there is no tooth posterior to the edentulous space to act as abutment, RPD is preferred
• Periodontal support – Tooth with weakened periodontal support are preferred for RPD as it requires less support from the abutment

• Cross- Arch stabilization –  To stabilize the remaining teeth against lateral and anteroposterior forces, RPD is indicated

• Excessive Bone Loss –  In case of ridge resorption, RPD can be fabricated as it can provide the required support and esthetics
• Immediate Teeth Replacement – RPD is preferred as relining can be done
• Esthetic requirement – If required
• Emotional problems –  RPD is indicated as it requires shorter appointments
• Patient desires –
  • If the patient wants RPD due to
  • Avoidance of operative procedure
  • Economic reasons
  • Severe loss of tissue
  • Teeth with short clinical crown
  • When more than two posterior teeth or four anterior teeth are missing
  • If the canine and two of its adjacent teeth are missing
  • When there is no distal abutment
  • Presence of multiple edentulous spaces
  • In case of tilted abutment

Question 8. Factors determining path of insertion.
Answer:

• Aesthetics: The cast should be tilted so that the height of contour is shifted to a lower level This conceal the clasp arm as well as alters the path of insertion
• Guiding Planes: Two or more vertically parallel surfaces of abutment teeth so oriented as to direct the path of placement and removal of removable partial denture”
  • The path of insertion will always be parallel to the guide plane
  • The proximal plates on the partial denture will contact the guide planes during insertion

• • Location of the vertical minor connector
  • This minor connector will be parallel to the guide plane on the abutment which in turn determines the path of insertion

• Interference:
  • Certain areas can cause interference to insertion
  • If these cannot be surgically removed, the path of insertion should be altered
  • Examples:
    1. In Mandible:
       • Lingual tori
       • Lingually placed teeth
       • Bony exostoses
    2. In Maxilla:
       • Tori palatinus
       • Buccaly tipped teeth
       • Bony exostoses
•  Retentive undercuts:
  • Favourable undercuts should be evaluated to ob- tain good retention
  • The cast can be tilted until the height of contour lies between the gingival and middle third of the crown to obtain a good undercut
  • This tilting of the cast will alter the path of insertion

•  Point of origin of the approach arm of a bar clasp:
  • The Approach arm forms a loop that produces terference during insertion
  • if the approach arm cannot be modified the path of insertion is to be altered
  • When the path of insertuion is altered the resulting bar clasp will not provide retention rather it will provide resistance to removal

• Denture base:
  • Shape and extent of it determines the path of insertion
  • If the denture base extends anteriorly on both sides, it embraces abutment limiting multiple paths of insertion

Question 9. Single Palatal Bar.
Answer:

It is a bar running oval cross-section.

• Design:
  • It has a narrow half across the palate
  • It is thickest at the centre
• Fabrication:
  • Mark the extent of the bar on a cast
  • The wax pattern is fabricated and adapted over the area
• Indication:
  • For interim partial denture
• Disadvantages:
  • Poor bony support
  • Cannot be used anterior to the premolar
  • It has poor vertical support
  • It can be used only in Kennedy’s Class 3 cases

Question 10. Factors determining clasp retention/flexibility.
Answer:

•  Depth of the undercut: The deeper the undercut the greater is the retention
• Buccolingual width of the undercut:
• Clasp alloys are selected based on it
  • For 0.010″ undercut – Cast chrome alloy
  • For 0.015″ undercut – Gold alloy
  • For 0.020″ undercut – Wrought wire
• The distance between the survey line and the tip of the retentive clasp:

• The mesiodistal length of the clasp arm below the height of contour:
  • Longer clasp arms offer more flexibility
  • Increased flexibility decreases the magnitude of the horizontal stresses acting on the abutment

• Taper of the clasp arm:
  • The clasp arm should taper uniformly from its origin to the tip

• Cross-sectional form:
  • A half round clasp arm is flexible only in one plane
  • While round clasp is flexible in all planes
  • A cast retentive clasp arm is used mainly in tooth-supported partial dentures because they need to flex only during placement and removal of the denture

Question 11. Occlusal Rest Seat Preparation.
Answer:

The location and extent of the rest seat is determined during the surveying of a diagnostic cast

1. On Enamel:

• A depth orientation groove is drawn along the desired outline
• Next the enamel is removed between these grooves using the same bur
• The design is then verified with that marked on the primary cast
• Occlusal clearance is checked with the help of beading/utility
• Rounding of internal line angles is carried out
• Any unsupported enamel if remaining are removed
• Finally, polishing of the rest seat is carried out

2. Gold Restoration:

• Tooth reduction/preparation is carried out for gold restoration
• Depression is made on the tooth surface at the place of rest seat
• Initially, the rest seat is prepared on a wax pattern using No. 4 round bur in slow speed hand piece or with discoid or cleoid excavator
• It is polished using a finishing bur
• Finally the wax pattern is cast

1. On Amalgam Restoration:
   • Rest seat preparation over amalgam restoration is usually avoided as it would weaken the restoration
2.  For Embrasure Clasp:
   1. Two occlusal reset seats are to be prepared over the involved teeth
   2. Both the marginal ridges are reduced equally, but the contact point should not be removed
   3. The outline must be verified
   4. Finally, finishing and polishing is done using No. 4 round steel bur

Question 12. Methods for obtaining functional support for distal extension base.
Answer:

Support for distal extension base is obtained by following methods

• Functional Impression Technique:
  • The tissues get compressed during function leading to the vertical displacement of the denture
  • This type of tissue ward movement of the denture will produce rotation of the prosthesis around its terminal abutment axis
  • This is prevented if the tissues are recorded in a compressed form
  • The denture fabricated from it will seat and compress the tissues even during rest and there will be no additional tissue ward movement during function

• Providing minimal occlusal contact
  • The occlusal load can affect the support of the denture
  • The occlusal table of the artificial teeth should be narrowed to reduce the occlusal load
• Identification of stress-bearing area
  • The distal extension base derive support from the stress bearing area
  • These areas are identified in maxillary and mandibular arch
  • Maxillary:
    • Buccal slopes of the ridge
    • Hard palate Crest of the ridge
  • Mandibular:
    • Buccal shelf area
    • Slopes of the ridge
• Minimizing the movement of the denture base:
  • The denture base should be designed such that the forces acting on the edentulous ridge can be minimized
  • Minor connectors are added to avoid the rotation of the denture
•  Increasing the tissue coverage of the denture base:
  • Increasing the tissue coverage leads to wider distribution of the occlusal load
  • Thus, it provides support

Question 13. Distal extension denture base.
Answer:

Distal extension denture base are fabricated in case of Kennedy’s class 1 and class 2 cases

• Support for such bases is necessary as the occlusal load may rotate the denture
• Support for a distal extension denture is obtained from both the teeth and the tissues
• Among it the teeth are less compressible and intrude little to the occlusal load compared to the supporting soft tissues.

Factors Effecting It:

• Quality of soft tissues
• Quality of underlying bone Tissue coverage of denture base
• Amount of forces acting on denture Stress bearing area
• Fit of the denture
• Type of Impression

Question 14. Methods of establishing occlusal relationship in removable partial denture.
(or)
Occlusal relation in removable partial denture.
Answer:

1. Noncontact relation:
   1. Protursion
   2. Lateral movement
   3. Rest position and freeway space
2. Contact relation:
   1. Protursive
   2. Retrusion
   3. Lateral
   4. Canine guided
   5. Group function
   6. Intercuspal

Methods:

• Direct apposition of cast:
  • Cast are fabricated
  • These cast are articulated
  • Occlusal is established over the cast on the articulator itself
• Interocclusal record on remaining posterior:
  • The upper and lower trial dentures are inserted into patients mouth
  • Wax or impression paste is loaded onto the occlusal surface of teeth in the mandibular occlusal rim
  • The patient is asked to slowly retrude the mandible and close on the wax till tooth contact occurs
  • The trial dentures are removed and the wax is allowed to cool
  • Both the maxillary and mandibular trial dentures are placed on their articulated casts.
•  Occlusal relation with record base and rims:
  • Rims made from wax or modeling plastic are fabricated over record base
  • These are inserted into patient’s mouth and various mandibular movements are recorded
•  Entirely with rims:
  • The occlusal relation is recorded with the help of extraoral tracing
  • The record bases attached to the recording devices are inserted in the patient’s mouth
  • The pointer is coated with precipitated chalk and denatured alcohol
  • The patient is asked to perform protrusive, lateral, and anteroposterior movements

•  Registration of occlusal pathways:
  • Record base is fabricated using metal/resin
  • A layer of sticky wax is placed over it
  • Next, occlusal rim by hard inlay wax is fabricated It is inserted into patient’s mouth
  • Mandibular movements are recorded

Question 15. Direct v/s Indirect Retention.
Answer:

Direct Retention:

• Retention obtained in a removable partial denture by the use of clasps or attachments that resist removal from the abutment teeth.
• Component of a removable partial denture used to re- tain and prevent dislodgement consisting of a clasp assembly called direct retainer

1. Retentive terminal
2. Retentive clasp arm
3. Reciprocal arm
4. Occlusal rest
5. shoulder
6. Body
7. Minor Connector

• It is the ability of the component to prevent the distion and provide indirect retention placement of the denture

Indirect Retention:

• It is the effect achieved by one or more indirect retainers of removable partial denture that reduce the tendency for a denture base to move in an occlusal direction or rotate about the fulcrum line.
• The component of a removable partial denture that assists the direct retainer in preventing displacement of the distal extension denture base by functioning through lever action on the opposite side of the ful- crum line called indirect retainer

• It is the ability of the component to retain denture in place

Question 16. Immediate partial denture.
Answer:

“A complete removable partial denture constructed for insertion immediately following the removal of natural teeth”

Types of Immediate partial denture:

1. Temporary Immediate Partial denture
   • Indicated when the permanent immediate partial denture is likely to become ill-fitting due to more than normal bone resorption
2. Permanent Immediate Partial denture
   • Indicated when bone resorption is expected to be less and denture prognosis is good

Advantages of Immediate partial denture:

• It is more esthetics
• Prevents supra-eruption and drifting of the opposing and adjacent teeth
• It acts like a splint over the surgical site thus controls hemorrhage and swelling

Question 17. Swing Lock.
Answer:

• Described by Dr. Joe J.Simmons
• It has a labial bar in addition to lingual major connector
• The labial bar extends labially all along the arch
• It is attached to the remaining parts of the denture by a hinge on one side and a lock on the other

Swing Lock Method Of Use:

• It is unlocked during insertion and locked after insertion
• As the labial bar moves around a hinge joint these dentures are called “Swing lock dentures”

Swing Lock Function:

• To support periodontally weak teeth

Swing Lock Indications:

• If the functional abutment teeth are missing
• In case of abutment teeth that has questionable prognosis
• Presence of few remaining teeth
• Presence of unfavorable tooth contours
• When the position of the remaining teeth does not facilitates conventional design
• Presence of unfavorable soft tissue contours
• For retention and stability of a maxillofacial prosthesis.

Swing Lock Contraindications:

• Poor oral hygiene
• Shallow vestibule
• High frenal attachment

Swing Lock Advantages:

• Inexpensive
• Provide stability and retention
• It is possible to add additional teeth to it

Swing Lock Disadvantages:

• Poor esthetics
• Leads to lingual tipping of the teeth

Swing Lock Fabrication:

Metal selection chrome alloy
↓
Surveying of cast
↓
Designing of various components
↓
Making the impression
↓
Fabrication of framework
↓
Trying of the framework
↓
Jaw relation and teeth arrangement
↓
Insertion of the prosthesis

Question 1. Contra-indication for removable partial dentures
Answer:

• Patients with macroglossia having a tendency to push the denture away
• Cannot be used in mentally retarded patients
• Should be avoided in patients with poor oral hygiene

Question 2. Linguoplate major connector
Answer:

• Superior border extends up to the cingulum
• It is scalloped in between the teeth
• In presence of large embrasures, it is made to dip down step back design
• Anteriorly, it should be supported by rest

Linguoplate major connector Advantages:

• Rigid, stable
• Provide indirect retention

Linguoplate major connector Disadvantages:

• Food accumulation
• Decalcification of teeth
• Soft tissue irritation

Question 3. Ring clasp.
Answer:

It is example of cast circumferential clasp

• Indication:
  • Distal extension denture
• Contraindication:
  • Soft tissue undercut
  • Buccinator’s attachment if present close to lower molar
• Disadvantages:
  • Alters food flow
  • Increased tooth surface coverage
  • Cannot retain its physical qualities
  • Difficult to repair or adjust

Question 4. Objectives of surveying
Answer:

• To achieve good retention and bracing by designing the rigid and flexible components of a removable prosthesis
• Aids in marking the survey lines by determining the height of contour of hard and soft tissues areas above the undercut
• Decides the path of insertion
• Helps in deciding the areas into which the prosthesis should not extend by determining the undesirable undercuts

Question 5. Cingulum rest
Answer:

• Also known as lingual rest
• It is placed on the lingual surface of a tooth
• It is specially placed over maxillary canine

Question 6. Enameloplasty/ Dimpling.
Answer:

• Enameloplasty is defined as the intentional alteration of the occlusal surface of the teeth to change their form
• It is done to produce a retentive undercut
• It is a gentle depression created on the enamel surface of the abutment teeth to provide a retentive undercut It is done when abutment teeth does not provide any surface undercut
• It can also be done to modify the existing undercut

Read And Learn More: Prosthodontics Question And Answers

Question 7. Limitations of Kennedy’s classification.
Answer:

• Did not explain the length of the edentulous span or number of missing teeth only provide number of modification spaces.
• Not enough consideration about the condition of teeth and the remaining supporting structures.
• No distinction between modification spaces which occur in the anterior segment to those of posterior segment

Question 8. Uses of surveyor.
Answer:

• Surveying the diagnostic and primary casts
• Tripoding the cast
• Transferring the tripod marks to another cast
• Contouring wax pattern
• Contouring crowns and cast restoration Placing internal attachments and rests
• Performing mouth preparation on casts
• Surveying master cast
• Surveying ceramic veneer

Question 9. Cingulum bar
Answer:

• It is located on or slightly above the cingula of the anterior teeth
• Indications:
• Large embrasures
• Large diastema cases

Question 10. Merits of occlusally approaching clasp.
Answer:

It is easy to fabricate and repair

• It leads to less food retention
• It can be best applied in a tooth-supported partial denture
• Provides excellent support and retention

Question 11. Define  Interim Removable Denture.
Answer:

“A transitional denture may become an interim denture when all of the natural teeth have been removed from the dental arch”.

Question 12. Support for RPD
Answer:

• Support for RPD depends on
• Quality of the residual ridge
• Total occlusal load applied
• Accuracy of the denture base
• Accuracy and type of impression registration

Question 13. Height of Contour.
Answer:

Height of Contour Definition: A line encircling a tooth designating its greatest circumference at a selected position.

Height of Contour Significance:

• It is used as a guideline that helps in the placement of the components of the clasp
• The retentive clasp arm of the retentive arm is located above the height of contour while the retentive terminal lies below the height of the contour
• Reciprocal arm is located above the height of contour

Question 14. Guiding Planes.
Answer:

Guiding Planes Definition: “Two or more vertically parallel surfaces of abutment teeth so oriented as to direct the path of placement and removal of removable partial denture”.

Types of Guiding Planes:

• Guide planes on abutment teeth supporting a tooth supported partial denture
• Guide planes on abutment teeth that supports a secondary distal extension denture base
• Guide planes prepared on lingual surfaces of abutment teeth
• Guide planes on anterior abutments

Functions of Guiding Planes:

• Minimizes the wedging stresses on the abutments
• Makes insertion and removal easier
• Aids to stabilize the prosthesis against horizontal stresses
• Aids to stabilize individual teeth
• It improves oral hygiene
• It contributes to indirect retention and frictional retention

Question 15.  Internal Rests.
Answer:

• These are large box shaped metallic extensions that function as intracoronary retainers
• They differ from internal attachments
• These are not pre-fabricated instead the rest seat is formed by the sound tooth structure

Question 16. Prothero’s cone theory.
Answer:

• Prothero described cone theory in 1916 to explain the basis for clasp retention
• He described the shape of the crown of premolars and molars to be equivalent to two cones sharing a common base
• The upper cone resembles the occlusal half of the tooth and the lower cone resembles the cervical half of the tooth
• A clasp tip that ends below the junction of the two cones will resist movement in the upward direction
• The degree of resistance to deformation determines the amount of clasp retention

Question 17. Combination clasp.
Answer:

It is a combination of wrought wire and rigid cast alloy

1. Indication: Maxillary canines and premolars
2. Contraindications: Undercut adjacent to edentulous space
3. Advantages: It has thin line contact It can flex in all planes
4. Disadvantages:
   • Tedious lab procedures
   • Easily breaks or distorts
   • Poor stability

Question 18. Half and Half clasp.
Answer:

• It has a retentive arm arising from one direction and a reciprocal arm arising from another
• Thus it needs two minor connector
  1. First attaches the occlusal rest and the retentive arm to the major connector
  2. Second, connects the reciprocal arm with or without an auxiliary rest
• Modification:  The reciprocal arm is converted into short bar to reduce the tooth coverage
• Advantage: It provides dual retention

Question 19. Fulcrum Line.
Answer:

• Definition: “An imaginary line around which a partial denture tends to rotate”
• Location: It is usually formed at the terminal abutment axis

Types of Fulcrum line:

• Retentive Fulcrum line: “An imaginary line connecting the retentive points of clasp arms, around which the denture tends to rotate when subjected to forces, such as the pull of sticky foods”.
• Stabilizing Fulcrum line: “An imaginary line, connecting occlusal rests, around which the denture tends to rotate under masticatory forces”.

Question 20. Displacing forces.
Answer:

Question 21. Group Function.
Answer:

Group Function Definition:

It is multiple contract relations between the maxillary and mandibular teeth in lateral movements on the working side whereby simultaneous contact of several teeth acts as a group to distribute occlusal forces

Group Function Indications:

• End-on-end bite
• Anterior open bite
• Class 2 and Class 3 molar relation

Group Function Types:

1. Partial group function:
   • In this occlusion, some of the posterior teeth are al- lowed to shear the load in excursion whereas others contact only in centric relation.
2.  Anterior group function:
   • Most practical method of disoccluding
3. Advantages:
   • Efficient and comfortable
   • Distributes wear over more teeth
   • Distributes stresses over more teeth
   • Distributes stresses to teeth farther from condylar axis
4. Limitations:
   • Not possible in all cases
   • Some arch relations does not permit it
   • Concave anterior guidance permit it whereas