Prosthodontics

Question 1. Define rests and rest seats. Discuss the various types of rests, their functions, and their design considerations.
Answer:

Definitions:

1. 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.”

2.  Rest Seat: The prepared recess in a tooth or restoration created to receive the occlusal, incisal, cingulum or lingual rest

• Types Of Rest Seat:
  1. Based on the relation of rest to the direct retainer
     • Primary rest-placed along the clasp assembly
     • Secondary rest placed away from the clasp
  2. Based on the position of the rest
     • Occlusal rest placed on occlusal surface of posterior
     • Cingulum rest placed on lingual surface of the tooth
     • Incisal rest-placed on the incisal edge of the tooth

Question 2. Define indirect retainer. What are the functions of an indirect retainer?
Or
Write about various forms of indirect retainers in detail.
Or
Define indirect retainers and discuss in detail about various types of it.
Answer:

Indirect retainers:

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 line.

Functions of Indirect retainers:

• It counteract the lifting forces and stabilizes the denture It counteract 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.

Read And Learn More: Prosthodontics Question And Answers

Types of Indirect retainers:

1. Auxillary Occlusal rest:

• It is located on the occlusal surfaces away from the distal extension base
• It is placed perpendicular to the midpoint of the fulcrum line.
  • Location:
    • Bilaterally over 1st premolars in Kennedy’s class 1
    • Over 1st premolar of opposite side in Kennedy’s class 2

2. Canine extension from the occlusal rest:

• It is a finger like extension from a premolar rest is placed on the lingual slope of the adjacent canine
• It is used when the first premolar must also acts as a primary abutment

3. Canine rest:

• If the mesial marginal ridge of the first premolar is close to the fulcrum line, canine rest is used.

4. Continuous bar retainers and lingual plates:

• In Kennedy’s class I and class II, these retainers are placed just above the middle third of the anterior teeth to act as indirect retainers.

5. Modification areas:

• In class 2 modification I, the fulcrum line runs from the left second premolar to the right second molar
• In such cases, the direct retainer resting on right first premolar act as an indirect retainer

6. Rugae support:

• As the rugae area is firm and well placed it can be used for indirect retention for a palatal horseshoe major connector.
• Horde shoe Connector lacks Posterior retention
• In this case ruge acts as indirect retainer

7. Direct Indirect retention:

The reciprocal arm of a direct retainer located anterior to the fulcrum line may act as an indirect retainer.

8. Indirect retention from major connector:

The major connector provides indirect rerention due to its rigidity

Question 3. Define direct retainers. Enumerate the requirements of direct retainers with a note on the circumferential clasp.
Answer:

Definition:

It is defined as “A clasp or attachment placed on a abutment tooth for the purpose of holding a removable denture in position

Requirements:

1. Passivity:
   • The quality or condition of inactivity or rest assumed by the teeth, tissues, and denture when a removable partial denture is in place but not under masticatory pressure
   • The retentive function should act only when dis- lodging forces are present
2. Retention:
   • It is that quality inherent in the prosthesis which resists the force of gravity, the adhesiveness of foods, and the forces associated with the opening of the jaws
   • It is provided by the retentive arm of the clasp
3. Reciprocation:
   • It is defined as the means by which one part of a prosthesis is made to counter the effect created by another part
   • It is provided by a rigid reciprocal arm
   • It resists the stresses generated by the retentive arm
4. Encirclement:
   • It is the property of the clasp assembly to encompass more than 180 degrees of the abutment tooth either by continuous or broken contact to prevent dislodgement during the function
   • Each clasp much encircle more than 180 degree of the abutment tooth
   • There can be continuous contact or broken contact
5. Stability:
   • It is defined as the quality of a denture to be firm, steady, or constant to resist displacement by functional stresses and not to be subject to change of position when forces are applied
   • Provided by shoulder and vertical arm of minor connector
6. Support:
   • It is defined as holding up or serving as a foundation or prop for
   • It is resistance to the movement of the denture in a gingival direction provided by rest
   • Path of escapement should never coincide with the path of removal
   • Primary abutment should never exert tipping forces on the abutment
   • Place reciprocal elements at the height of the contour and retentive element below the height of contour

Circumferential clasp/aker’s clasp

• These clasps embrace more than half of the abutment tooth
• It prevents the rotation of the denture
• They approach the undercut from an occlusal direction

Advantages:

• 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

Disadvantages:

• It covers a large tooth surface area
• Alters buccolingual width of the crown
• Interferes with the normal food flow
• This leads to food accumulation and decalcification of the tooth structure
• Deprives periodontal stimulation
• It cannot be used for cases with an undercut away from edentulous space

Question 4. Classify partial edentulous areas according to Applegate-Kennedy’s classification and mention Applegate’s rules for Kennedy’s classification.
Answer:

Applegate Kennedy’s classification:

• Proposed by Dr. Edward Kennedy in 1923
• Kennedy classified partially edentulous arches and not the denture
• This classification is anatomical
• In Kennedy’s classification, he included 4 classes Further, 2 additional classes were included by Apple-gate

The classification is as follows:

• 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:
  • 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 midline of the arch
• Class 4:
  • The single, bilateral edentulous area located anterior 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 bounded anterior and posteriorly by natural teeth
  • But the anterior abutment is not suitable for support

• Class 6:
  • Edentulous area in which the teeth adjacent to the space are capable of total support of the required prosthesis

Applegate’s Rules:

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

Question 5. Define surveyor. Mention its parts. Explain in detail step by step procedure in surveying and Functions.
Or
Define dental cast surveyor. Enumerate their function and Parts of surveyors.
Or
Describe the surveying procedure and Functions and Parts of surveyors.
Answer:

Definition of 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

Parts of surveyor:

• Surveying platform:
  • It is metal plate parallel to the floor
  • It forms base of surveyor
  • Cast holder is placed over it
• Cast holder/Surveying table:
  • It has a base and table to place a cast
  • It should not be tilted more than 10 degrees
•  Vertical arm:
  • It arises vertically from the surveying platform
• Horizontal arm:
  • It extends from top of the vertical arm
  • It supports the surveying arm at its free end
  • Variations:
    • Fixed- in Ney surveyor
    • Revolving- in Jelenko surveyor

• Surveying arm:
  • It extends from free end of horizontal arm
  • It is parallel to the vertical arm
  • It can move upward and downward
  • Its lower end has mandrel for attachment of surveying tools
• Surveying tools:
  • Analyzing rod:
    • It is solid cylindrical metal rod
    • It helps to analyze the location of height of contours, presence and absence of undercut
    • It helps to determine path of insertion

• • Carbon markers:
    • They resemble the lead points
    • They are used to draw height of contour of the object
  • Undercut gauges:
    • It is used to measure the depth and location of the undercuts
    • Sizes:
      • According to Stewart-0.010″, 0.015″, 0.020″ According to McCracken- 0.010″, 0.020″, 0.030″
    • Shape:
      • Ney surveyor circular beaded
      • Jelenko- Fan shpaed bead

• • Wax knife:
    • Used to trim the excess wax and to eliminate undesirable undercut

Surveying Procedure:

• The primary cast is mounted on the surveying table It is locked in the position with a zero-degree tilt with the help of clamps on the surveying table
• It is mounted such that the occlusal surfaces of the remaining teeth are parallel to the base
• After this the surveying arm is positioned in relation to the cast
• It is positioned as follows:
  • First the horizontal arm is adjusted vertically such that the surveying arm can contact at least three different spaced-out points on the cast
  • It is locked to the vertical arm with the help of a thumb screw
    Next the cast is analyzed by using different analyzing tools

Analyzing Tools:

• Analyzing rod:
  • It is first surveying tool used
  • It is attached to the mandrel of the surveying arm
  • The cast is rotated against it to analyze the presence of undercuts whether favourable or unfavorable
•  Carbon markers:
  • These resemble the lead points
  • After analyzing the teeth with anallysing rod, it is replaced by carbon markers
  • These are used to draw survey line, which denote the height of contour of the teeth

• Undercut gauges:
  • These are used to measure the depth and location of the undercuts in three dimensions

Tripoding:

• It is done next to maintain the records of the primary cast in the master cast
• A carbon marker is fixed to the mandrel of the surveying arm along with a locked horizontal arm
• The surveying arm is moved freely
• Due to this three points are marked that lie in the same plane
• Additional reference points are marked
• They are
  • A distal marginal ridge of 1st premolar Incisal edge of lateral incisor
  • Lingual cusp tip of 1st premolar of opposite side
• After marking the primary cast is removed and the master cast is placed on the surveying table
• The master cast is adjusted in the surveying table such that the carbon marker contacts in the same manner as that with the primary cast

Functions of Surveyor:

• 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

Uses Of Tripoding:

• Helps in positioning the master cast
• Helps to remount the diagnostic casts on the surveying table

Question 6. Define major connector. Mention different types and discuss criteria for the selection of major connectors.
Answer:

Definition of Major Connectors:

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”

Types of Major Connectors:

1. Maxillary:
   • Single posterior palatal bar
   • Palatal strap
   • Palatal plate
   • Antero posterior palatal bar
   • Horseshoe connector Closed horseshoe
   • Complete palate
2. Mandibular:
   • Lingual bar Lingual plate
   • Kennedy bar
   • Sublingual bar
   • Cingulum bar
   • Labial bar

Criteria For Selection Of Major Connectors:

Major connector should fulfill the following criteria

1.  Functional requirement: It should distribute forces among all the teeth
2. Anatomical restraints: In case of mandibular connector less space is present, hence connector is designed accordingly
3. Relief: Adequate amount of releif should be provided
4. Hygiene: It should be enable to clean the connector
5. Patient’s compliance:
   • It should be accepted by the patient
   • It should be comfortable

Question 7. Define removable partial denture. How do you choose a direct retainer for RPD.
Answer:

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

Selection Of Direct Retainer For Rpd:

Type of direct retainer is selected according to the following condition

Question 8. What is direct retainer. Describe its parts
Answer:

Definition of Direct retainer:

It is defined as “A clasp or attachment placed on a abutment tooth for the ppurpose of holding a removable denture in position

Parts of Direct retainer:

1. 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”

Parts:

1. Retentive clasp arm:
   • It is not flexible
   • It is located above the height of contour
2. Retentive terminal:
   • It is flexible
   • It is located below the height of contour

2. 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”
• It is located on opposite side of retentive arm
• It is placed above the height of contour
  • Functions:
    • 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

3. Shoulder:

• It is part of the clasp that connects the body to the clasp terminals
• It lies above the height of the contour and provides stabilization against horizontal displacement

4. Body:

• It is part of the clasp that connects the rests and shoulders of the clasp to the minor connector.
• It is rigidly above the height of the contour
• It is designed such that it contacts the guide plane of the abutment during insertion and removal

5. Rest:

• It is rigid extension of the removable partial denture which contacts a remaining tooth or teeth to dissipate vertical or horizontal forces
• It is the part of the clasp that lies on the occlusal or lingual or incisal edge or surfaces of the tooth
• It resists tissue-ward movement of the clasp by acting like a vertical stop

6. Minor connector:

• It is 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
• It joins the clasp with the remaining part of the metal framework

Question 9. Discuss how to achieve stress equalization in Kennedy’s class 1 and 2 situations.
Answer:

Stress Equalization Or Stress Breaker:

This is used for stress equalization in Kennedy’s class I and II situation

Definition of Stress Breaker:

A device that relieves the abutment teeth of all or part of the occlusal forces

Significance of Stress Breaker:

• In a tooth tissue-supported partial denture when an occlusal load is applied, the denture tends to rock due to the difference in the compressibility of the abutment teeth and the soft tissues
• This can produce harmful effects on the abutment teeth In order to protect the abutment from such conditions, stress breakers are incorporated into a denture

Advantages of Stress Breaker :

• It preserves the alveolar support of the abutment
• It helps to create balanced stress on the residual ridge and the abutment
• It requires minimal direct retention
• This avoids the frequent need for relining and rebasing Weak teeth are well splinted
• It produces massaging effect over soft tissues

Disadvantages of Stress Breaker:

• It is expensive
• It is difficult to repair
• It gets easily distorted
• It tends to food accumulation
• It reduces the stability of the denture It reduces indirect retention

Types of Stress Breakers:

1. Type 1:

• • Here a movable joint is placed between the direct retainer and a denture base
  • It decreases the amount of force acting on the abutment
  • A Movable joint is placed between the direct retainer and denture base
  • Thisjoint may either be a Hinge or a ball and socket or a sleeve and cylinder
  • Example: DALBO

2. Type 2:

• • It has flexible connection between the direct retainer and the denture base
  • It can be a wrought wire connector divided or split major connector or a movable joint between two major connectors

Question 10. Classify direct retainers in the removable partial prosthesis. Explain about occlusal approaching clasps.
Answer:

Direct Retainer:

“A clasp or attachment applied to an abutment tooth for the purpose of holding a removable denture in position.”

Classification of Direct Retainer::

By Herman:

1. Extracoronal Direct Retainer: “A part of a removable partial denture which acts as a direct retainer for the denture by partially encircling or contacting an abutment tooth”
   • It includes:
     • Suprabulge clasps
     • Infrabulge clasps
2. Intracoronary Direct Retainer:
3. In it a part or the whole of the retentive components are located within the anatomic contour of the abutment teeth
   • It includes:
     • Precision attachment
     • External attachment
     • Stud attachment
     • Bar attachment

Occlusally Approaching Clasps:

• Circumferential clasp/Aker’s clasp:
  • These clasps embrace more than half of the abutment tooth
  • It prevents the rotation of the denture
  • They approach the undercut from an occlusal direction
• Advantages:
  • 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
• Disadvantages:
  • It covers a large tooth surface area
  • Alters buccolingual width of the crown
  • Interferes with the normal food flow
  • Leads to food accumulation and decalcification of the tooth structure
  • Deprives periodontal stimulation
  • It cannot be used for cases with an undercut away from edentulous space

Question 11. Give in detail the impression methods for providing adequate support in extension base removable partial denture.
Or
Physiologic impression in RPD
or
Functional relining methods
or
Fluid wax functional impression
or
Impression procedures for distal extension RPD
Answer:

• Dual impression techniques are used for extension base removable partial dentures.
• Such techniques records a part in the functional form and the remaining areas in the anatomical form

 Dual impressions are classified as:

• Physiological or functional dual impression:
  • McLean’s technique
  • Hindle’s modification
  • Functional relining method
  • Fluid wax method
• Selective pressure technique:
  • McLean’s technique
  • A custom-made impression tray is fabricated over the edentulous areas of the primary cast
  • Occlusal rims are made on the custom tray
  • The tray is loaded with impression material
  • It is inserted into the patient’s mouth
  • Ask the patient to close on the rims
  • Due to it, the tissues under the tray are compressed and the impression is recorded in this relation
  • An alginate impression is made over the existing impression using a large stock tray
  • Finger pressure is applied on the stock tray
  • The impression is removed
  • This leads the alginate over the impression to carry the functional impression along with it
  • A cast is poured into the impression

• Hindle’s modification:
  • A special tray with stoppers and occlusal rims is fabricated using primary cast
  • It is loaded with impression material
  • It is inserted in the patient’s mouth
  • A special stock tray with large holes loaded with alginate is used for over impression
    • The finger is placed into the holes to apply pressure on the occlusal rim
    • Pressure is held till the alginate sets
    • This pressure pushes the tray against the edentulous ridge

• Functional Relining Method:
  • The single anatomic master impression is made
  • The master cast is made from it
  • It is then duplicated and a refractory cast is made • Soft metal spacer is adapted on the cast
  • A framework is fabricated using a refractory cast and tried in the patient’s mouth
  • Spacer is removed
  • A functional impression is made on the tissue sur- face of a framework using low-fusing modeling plastic
  • It is tempered and placed within the mouth
  • Sufficient pressure is applied
  • The modeling plastic at the borders of the framework are re-softened
  • Border molding is carried out
  • Modelling plastic is reduced by 1 mm
  • Final impression is made with zinc oxide eugenol impression paste.

• Fluid wax Functional Impression:
  • The metal framework is fabricated using a refractory cast
  • It is tried in patient’s mouth
  • The framework is positioned on the master cast
  • The outline of the tray is drawn on the master cast
  • The cast is coated with separating media
  • A spacer is adapted over the crest of the edentulous ridge
  • The framework is placed over the spacer
  • Auto-polymerizing resin is adapted over the framework
• Excess material is trimmed:
  • Relief holes are made along the crest of the ridge
  • Impression wax is softened and painted over the tissue surface of framework
  • It is seated in the patient’s mouth with half-open for at least 5 minutes
  • The framework is removed and the impression is examined for glossy and dull areas
  • Finally place it for 12 minutes

•  Selective Pressure Technique:
  • The special tray is fabricated on the master cast
  • The tissue surface of the tray is trimmed
  • It is loaded with impression material
  • It is inserted in the patient’s mouth
  • Pressure is applied over the stress-bearing area.

Question 12. Discuss various components of removable partial denture and the functional role of each.
Answer:

Components Of Removable Partial Denture:

1. 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”.
• It is the largest and most important component of the removable partial denture
• It forms the basic framework.

2. Ideal Requirements:

• It should be rigid enough to uniformly distribute occlusal forces
• It should provide vertical support
• It should protect soft tissues
• It should provide indirect retention when needed It should be comfortable for the patient
• It should not allow food accumulation
• It should be self cleansable

3. Classification:

• Maxillary:
  • Single posterior palatal bar
  • Palatal strap
  • Palatal plate
  • Antero posterior palatal bar
  • Horseshoe connector
  • Closed horseshoe
  • Complete palate
• Mandibular:
  • Lingual bar
  • Lingual plate
  • Kennedy bar
  • Sublingual bar
  • Cingulum bar
  • Labial bar

4. Location:

• It should be placed free of movable tissue
• It should avoid impingement of gingival tissue
• Bony and soft tissue prominence should be avoided
• Relief should be provided
• The border of the major connector should be 6 mm away from gingival margins in the maxillary arch and 3 mm in case of the mandibular arch

5. Functions:

• It connects all the components of RPD
• It provide indirect retention

6. 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”.

7. Types:

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

Form And Location:

• It should have sufficient bulk for rigidity
• Its thickest portion should lie on lingual surface
• It should taper in contact area to avoid sharp edges
• It should not rest in convex area rather present within embrasure

1. Functions:

• It connects the major connector to other parts
• It transmits stresses evenly to all components
• It transmits the force acting on the prosthesis to the edentulous ridge and the remaining natural teeth

2. Rest:

• “It is defined as “A rigid extension of a fixed or re- movable partial denture which contacts a remaining tooth or teeth to dissipate vertical or horizontal forces.”
• Rests are metallic extensions in the denture frame. work that extend over the occlusal/lingual surface of the supporting teeth

Function Of Rest:

To transmit the occlusal forces acting on the denture along the long axis of the abutment teeth

Classification Of Rest:

• Based on the relation of the rest to the direct retainer
  • Primary rest –  They are placed along with the clasp assembly
  • Secondary/Auxillary rest – These are the one placed for in direct
    retention

• Based on the location of the rest:
  
  • Occlusal Rest
  • Cingulum/ Lingual Rest
  • Incisal Rest

• Based on the shape and structure of the rest:
  • Triangular
  • Boomerang shaped
  • Conservative circular

3. 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”.

The function of Direct retainer:

• It prevents the displacement of the denture
• It provides retention through the retentive arm of the clasp
• All components of the clasp except the retentive arm provide stability
• It resist the movement of denture against the path of insertion
• It stabilizes the denture against horizontal movement
• The encirclement of the clasp confines it to the tooth during function

Classification of Direct retainer:

1. Intracoronary:
   • Precision attachment
   • Semiprecision attachment
2. Extracoronal:
   • Attachment
   • Clasp assemblies
   • Suprabulge
   • Infrabulge

4. Indirect retainers:

It is defined as “a part of a removable partial denture which assists the direct retainers in prevent- ing displacement of distal extension denture bases by functioning through lever action on the opposite side of the fulcrum”.’

Functions of Indirect retainers:

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

Types of Indirect retainers:

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

5. 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”.

Requirements of Denture Base:

• Accurate tissue adaptation Thermal conductivity
• Sufficient strength
• Cleanability
• Cost-effective

Types of Denture Base:

• Acrylic
• Metal
• Combination

Functions Denture Base:

• Provide framework for tooth adaptation
• Restores the contour of the edentulous ridge

6. Artificial teeth:

• Teeth are attached to the denture base by the following methods
• Acrylic teeth fused with the denture base acrylic resin
  Porcelain or acrylic tube teeth are usually cemented to the metal base
  Resin teeth processed directly over the metal base
• Metal teeth are cast along with the framework
• Chemical bonding of acrylic with the metal base

Question 13. Enumerate various components of RPD and discuss in detail about the maxillary major connector.
Answer:

Components Of RPD:

• Major connector
• Minor connector
• Direct retainer
• Indirect retainer
• Rest
• Denture base
• Artificial tooth

Maxillary Major Connector Requirements:

Beading should be given to the posterior margin of the maxillary major connector to provide a seal with the soft tissue in their margin

• It should be rigid enough to distribute occlusal forces
• The border of the connector should be 6 mm away from the gingival margins
• The borders should be parallel to the gingival margins
• The borders should be rounded to avoid interference to the tongue

• The Anterior border should end in the  valley of the rugae and not on the crest

Types and Features and Indications:

• Type 1: Single Posterior palatal bar
• Feature And Indication:  It is a bar running across the palate
  • Used in:
    • Interim partial denture

• Type 2: Palatal strap
  
• Feature And Indication:  Thin Band of Metal plate runs across the palate
  • Used in:
    • Unilateral distal extension partial denture

• Type 3: Palatal plate
  
• Feature And Indication:  Broader than the palatal strap 
  
  • Used in:
    • Class 1
    •  ‘V’ Or ‘U’ shaped palate
    • Strong abutment
    • More than six remaining anterior teeth

• Type 4: Anterior Posterior bar
• Feature And Indication: It is a combination of an anterior palatal strap and a posterior palatal bar
  • Used in:
    • When anterior and posterior abutments are widely separated
    • Large inoperable tori

Design Procedure:

• Step 1-Outline the stress-bearing area
• Step 2- Outline the non-stress-bearing area
• Step 3 – Outline the extend of connector
• Step 4- Select the connector based on
  • Patient’s comfort
  • Rigidity required
  • Denture base
  • Amount of indirect retention required

Step 5-Connect all the markings:

Question 14. Add a note on various types of clasp.
Answer:

Types of Clasp:

1. Circumferential clasp/Aker’s clasp:

• These clasps embrace more than half of the abutment tooth
• It prevents the rotation of the denture
• They approach the undercut from an occlusal direction

Advantages:

• 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

Disadvantages:

• It covers a large tooth surface area
• Alters buccolingual width of the crown Interferes with the normal food flow
• Leads to food accumulation and decalcification of the tooth structure
  Deprives periodontal stimulation
• It cannot be used for cases with an undercut away from edentulous space

2. Bar Clasp:

• It is infrabulge clasp
• It approaches the undercut gingivally
• It has a push type of retention

Parts:

• Retentive arm
  • Gingival approach arm
  • Retentive terminal
• Rest
• Shoulder
• Body
• Proximal plate
• Reciprocal arm

Advantages:

• It Is easy to Insert
• It is more esthetic

Disadvantages:

• It tends to collect food debris
• It has reduced bracing and stabilization
• It needs additional stabilizing units

Types of Claps:

• T clasp
• Modified T clasp
• Y clasp
• I clasp
• Mirror view clasp
• I bar

 

Question 15. Discuss diagnosis and treatment planning for Kennedy’s Class 1 patient.
Answer:

Diagnosis:

1. Clinical Diagnosis:

• Periodontal Health:
  • The periodontal condition of the existing teeth should be examined
  • Clinical signs of periodontal health should be evaluated
  • Oral hygiene is evaluated
  • Mobility of teeth, if present is measured
• Occlusion of Existing teeth:
  • The teeth should have a good cusp-to-fossa relationship
  • Evaluate the alignment of teeth
  • Trauma from occlusion is evaluated
• Conservative and Endodontic status
  • The existing teeth should be examined to rule out the presence of carious lesions, vitality of the pulp
  • The teeth should be examined for cracks, chipped corners, and fractures
• Radiological examination
  • The bone loss should be evaluated
  • The structure of the basal bone in the denture-bearing area should be evaluated
  • Presence of periapical bone loss and furcation involvement should be examined
  • Presence of impacted teeth and submerged root stumps should be examined

2. Derived Diagnosis:

It is obtained from diagnostic cast that is obtained from a diagnostic impression.

Preparation:

• A stock tray of a suitable size should be selected Alginate is mixed in motion and loaded into the tray
• ray is inserted in the patient’s mouth
• After the material gets set, it is removed by a single stroke
• Inspect for any void
• Disinfect the impression
• Pour the cast within 12 minutes
• Trimming of the cast is carried out
• Survey the cast

Purpose:

• To locate the favorable and unfavorable undercuts
• To determine the need for pre-prosthetic mouth preparation
• To determine the path of insertion of the denture

Treatment Planning:

• Treatment should be properly planned before starting the treatment
• It can be divided into six different stages

Question 16. Types of mandibular major connectors.
Answer:

Mandibular Major connector:

1. Lingual Bar Design:

• It is half pear-shaped
• Its thickest portion is placed inferiorly
• There must be 8 mm vertical clearance from the floor of the mouth
  The upper border should have 3 mm clearance from the marginal gingiva
• The minimum height should be 5 mm
• It should be as inferior as possible

Advantages:

• It is easy to fabricate
• It has mild soft tissue contact

Disadvantages:

• Contraindicated in the presence of Tori
• Contraindicated in short vestibule

2. Lingual Plate Design:

• The superior border extends upto cingulum It is scalloped in between the teeth
• In the presence of large embrasures, it is made to dip down-step back design
• Anteriorly, it should be supported by rests

Indications:

• In the absence of posterior teeth
• In the presence of periodontally weakened teeth
• In the case of a short vestibule
• In the case of resorbed ridge
• In bilateral distal extension conditions
• When additional teeth are to be added
• In the case of retrognathic jaw

Advantages:

• Rigid, stable
• Provide indirect retention
• Provide the addition of teeth

Disadvantages:

• Food accumulation Decalcification of teeth
• Soft tissue irritation

3. Double Lingual/Kennedy Bar Design:

• The middle portion is cut off
• The lower part is pear-shaped
• The upper part is half oval 2-3 mm high and 1 mm thick
• The upper bar should dip into the embrasure
• Two bars are connected by a minor connector

Indications:

• Large embrasures cases
• Large diastema cases

Advantages:

• Provide indirect retention
• Horizontal stabilization
• Allow free flow of saliva

Disadvantages:

• Tongue interference
• Food entrapment

4. Sublingual Bar:

• Similar to lingual bar
• It is placed more inferiorly and posteriorly

Indications:

• Short vestibular depth
• Along with the lingual plate
• Presence of anterior lingual undercut

Contraindications:

• Lingual tori
• High frenal attachments

5. Cingulum Bar:

• It is located on or slightly above the cingula of the anterior teeth

Indications:

• Large embrasures cases
• Large diastema cases

6. Labial Bar:

• Placed on the labial surface
• It is similar to the lingual bar but broader and thicker

Indications:

• Lingually inclined teeth
• Presence of tori

Disadvantages:

• Poor esthetics
• Distort lower lip
• Patient discomfort

Question 17. Classify clasps. Give the difference between gingivally and occlusally approaching clasps.
Answer:

Classification:

1. Circumferential/Aker’s clasp/Occlusally approaching:

“A clasp that encircles a tooth by more than 180° including opposite angles, and which usually has total contact with the tooth with atleast one terminal being in the infra bulge area”.

Sub-Types:

• Simple circlet clasp
• Reverse clasp
• Multiple circle clasp
• Embrasure clasp
• Ring clasp
• Fishhook or hairpin clasp
• Onlay clasp
• Combination clasp
• Back action
• Half and Half clasp
• Grasso’s clasp

2. Vertical projection/Bar/Roach clasp:

“A clasp having arms which are bar-type extensions from major connectors or from within the denture base the arms pass adjacent to the soft tissues and approach the point or area of contact on the tooth in a gingival-occlusal direction”

3. Continuous clasp:

“A metal bar usually resting on the lingual surface of teeth to aid in their stabilization and to act as an indirect retainer”.

Difference between occlusally approaching and gingival approaching clasp:

Post Insertion Problems Long Essays

Question 1. Discuss post-insertion problems & their management.
(or)
Discuss post-insertion problems in edentulous patients using complete dentures. Enumerate the reason for it & their management
Or
Post-insertion instructions and problems encountered in complete dentures.
Answer:

Instruction for Insertion & Removal:

The patient is taught to insert & remove the denture along the path of insertion

Maintenance of Prosthesis:

• 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

Night Wear of Prosthesis:

• Avoid nightwear of dentures
• Allowed to wear only in bruxers
• Report to the dentist if the denture causes any irritation even after 24 hours.
• The patient is asked to read newspapers or novels loudly during the 1st 24 hours to get adapt to the denture.

Post insertion problems:

Post insertion are

• Direct Sequelae
• Indirect Sequelae

Direct Sequelae:

1. Denture stomatitis:

It is the pathological reaction of the palatal portion of the denture-bearing mucosa

• Types:
  • Type 1: Localized simple infection
  • Type 2: Erythematous type
  • Type 3: Granular type

Read And Learn More: Prosthodontics Question And Answers

• Etiology:
  • Candida albicans
• Predisposing Factors:
  • Local factors:
    • Dentures
    • Xerostomia
    • High carbohydrate diet
    • Use of broad-spectrum antibiotics
    • Smoking
  • Systemic factors:
    • Old age
    • Diabetes mellitus
    • Nutritional deficiency
    • Immune defect
    • Malignancy
• Management:
  • 0.2-2% chlorhexidine
  • Removal & cleaning of dentures after every meal
  • Avoid night wearing of dentures
  • Polishing of denture
  • Administration of antifungal drugs
  • Surgically: Elimination of crypts, by cryosurgery

2. Flabby ridge:

Replacement of bone by fibrous tissue

• Site: Anterior part of maxilla
• Effect: Poor support to the denture
• Causes:
  • Excessive load overdenture
  • Unstable occlusal conditions
• Management:
  • Surgical removal

3. Denture irritation hyperplasia:

• The hyperplastic reaction of mucosa over the borders of the denture
• Cause: Trauma due to unstable dentures
• Features:
  • Deep ulceration
  • Fissuring
  • Inflammation
• Management:
  • Surgical excision
  • Correction of dentures

4. Burning mouth syndrome:

Burning sensation in the structures in contact with the dentures without any visible change in the mucosa

• Features:
  • Pain in the morning
  • Dry mouth
  • Persistent altered taste
  • Generalized symptoms
• Etiology:
  • Irritation by ill-fitting dentures
  • Constant masticatory activity Excessive friction on the mucosa
  • Candidal infection
  • Nutritional deficiency
  • Xerostomia
  • Medication
• Management:
  • Counseling
  • Repair of ill-fitted dentures

5. Gagging:

The gag reflex is a normal, healthy defense mechanism to prevent foreign bodies from entering the trachea

• Causes:
  • Over extended denture borders
  • Unstable occlusal conditions
  • Systemic conditions
  • Alcoholism, smoking
• Features:
  • Causes displacement of denture
  • Triggered by tactile stimulation of the soft palate, posterior part of tongue & fauces
• Site:
  • Posterior part of the maxillary denture
  • Distolingual part of mandibular denture

• Treatment: Limiting the posterior extension of the dentures

6. Residual ridge resorption:

• It is alveolar remodeling that occurs due to a change in the functional stimulus of bone tissue
• It is a chronic progressive change in the bone structure, which results in severe impairment in the fit & function of prosthesis
• Cause: Excessive forces over nonstress bearing areas causing activation of osteoclasts
• Clinical Features:
  • Decreased depth & width of the sulcus
  • Decreased vertical dimension at occlusion
  • Reduced lower facial height
  • Anterior rotation of mandible
  • Increase in relative prognathism
  • Increased mandibular arch
  • Decreased maxillary arch
  • Effects support, stability & retention of dentures

• Treatment:
  • Ridge augmentation to increase the height of the ridge
  • Vestibuloplasty to increase the depth of the sulcus

Indirect Sequele:

1. Atrophy of masticatory muscles:

• Masticatory efficiency depends on the skeletal forces
• This force decreases with age
• Besides, denture wearers donot use their muscles to their maximum function
• Due to poor usage, atrophy of muscle occurs
• Common Muscles Effected: Medial pterygoid & masseter
• Management:
  • Use of overdenture
  • Use of implants

2. Nutritional deficiencies:

• Causes of Malnutrition:
  • Poor general health
  • Poor absorption
  • Catabolic disturbance
  • Anorexia
  • Reduced salivary secretion

Management:

• Intake of protein-rich diet
• Encouraging patients to have good nutritious food
• It helps in the initial retention of the denture increasing the psychological comfort of the patient

Post Insertion Problems Short Essays

Question 1. Denture adhesive.
Answer:

Composition:

1. Basic ingredients:
   • Carbonyl methyl cellulose
   • Vegetable gum
     • Example: Tragacanth
   • Vinyl methyl ether
   • Polyethylene oxide
   • Polyvinyl pyrrolidone
   • Gantrez salts
     • Cationic polyacrylic amide polymers
     • Coloring agents-red dye
     • Flavouring agents-menthol
     • Wetting agents
     • Preservatives-sodium borate
     • Plasticizers- mineral oil
     • Dispersion agents-magnesium oxide
2. Indications:
   • Improve retention and stability of the dentures
   • To stabilize trial dentures
   • For handicapped patients
   • To provide a psychological sense of security
   • To simplify the insertion for patients
   • As an adjunct to the maxillary prosthesis
3. Contraindications:
   • Patients with ill-fitting dentures
   • In medication-induced xerostomia
   • In worn-out dentures
   • As a substitute for recliner
   • In patients with an inability to clean dentures
   • In immediate dentures
   • In case of allergy to components of the adhesive

Laboratory Procedures Prior To Try In Short Answers

Question 1. Pre-extraction guides in selection of teeth.
Answer:

• The diagnostic cast prepared before extraction of teeth
  • It provides 3 dimensional view.
• Photographs – Showing frontal & lateral view
  • Limitation: Anterior teeth should be seen in the photograph.
• Radiographs Accurate measurements are not obtained
  • They provide only 2-dimensional view
• Close relatives- If other methods fail
• Extracted teeth- Best method
  • But all the extracted teeth are not preserved.

Question 2. Compensatory curves.
Answer:

The anteroposterior & lateral curvatures in the alignment of the occluding surfaces & incisal edges of artificial teeth which are used to develop balanced occlusion

• Steep compensatory curves for steep condylar path
• Shallow curves for loss of balancing molar contacts

• Thus balance must be present between all the five factors
• The effect of incisal & condylar guidance must counteract by the effect of other three factors
• If the balance is lost, balanced occlusion cannot be achieved

Question 3. Color selection of teeth.
Answer:

Color For Anterior Teeth:

Age:

• Young people-lighter teeth
• Old people Dark teeth
• More shiny
• Brownish tinge
• Habits smokers porcelain teeth
• Complexion teeth selected in harmony with

Question 4. 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 denture improves speech
  • Injury to the external laryngeal nerve
  • Presence of tongue tie

Read And Learn More: Prosthodontics Question And Answers

• • 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 5. Neutral zone.
Answer:

• It is the potential space between the lips & cheeks on one side & the tongue on other side
• An area or position where the forces between the tongue & cheek or lips are equal
• If the teeth are placed buccally, it leads to cheek biting

If the teeth are placed lingually, it leads to encroachment into tongue space

Question 6. Shortcomings of plane line articulator.
Answer:

• It is single hinge joint
• No lateral or sliding movement is possible
• No guide for mounting the cast
• Single-use
• Difficult for prosthetic work as metallic frame must be hold together with the cast
• Removal of cast is by breaking which leads to loss of integrity of cast & loss of strength of articulator

Question 7. Incisal guidance.
Answer:

The influence of the contacting surfaces of the mandibular & maxillary anterior teeth on mandibular movements

• Second factor of occlusion
• Customized
• If overjet increases, it decreases If overbite increases, it increases
• If incisal guidance is steep, steep cusps, steep occlusal plane & steep compensatory curves are required
• It must be as flat as possible

Question 8. Condylar guidance.
Answer:

• It is the first factor of occlusion to be considered
• Measured using protrusive registration
• Increased in condylar guidance increases jaw separation
• It cannot be modified

Question 9. Hinge axis
Answer:

• It is also known as the transverse axis
• Hinge axis is the axis that runs horizontally from the right side of the mandible to the left
• Rotation around it is seen during protrusive movement It varies during different phases of protrusive movements
  • During the initial mouth opening, the hinge axis passes through the head of the condyle
  • During later stages, the axis passes through the mandibular foramen

Question 10. Posterior teeth form.
Answer:

Factors Effecting Posterior Teeth Form:

• Condylar inclination
• Height of the residual ridge
• Patient’s age
• Ridge relationship
• Hanau’s quint

1. Cusp teeth:

• They have cusps and fossae-like natural teeth
  • Anatomic teeth
    1. Resemble normal newly-erupted teeth
    2. Have the best esthetics
    3. Have 30-degree cuspal angulation
  • Semi-anatomic teeth
    1. Have 20 or 10-degree cuspal angulation
    2. They are more flexible than anatomic teeth

2. Cuspless teeth:

• Have no cuspal angulation
• Very flexible to set

Question 11. Anatomic teeth.
Answer:

Teeth that have prominent pointed or rounded cusps on the masticatory surfaces & which are designed to occlude with the teeth of the opposing denture or natural dentition

Advantages of Anatomic teeth.:

• Efficient cutting
• Balanced occlusion is obtained
• Guide the mandible in centric occlusion
• Aesthetic
• More resemble to natural dentition

The disadvantage of Anatomic teeth.:

Difficulty In Teeth Arrangement

• (a) Incisoe
• (b) Canine
• (c) Premolar
• (d) Molar

Question 12. Advantages of an adjustable articulator.
Answer:

• Capable of adjustability in all directions
• Have numerous adjustable readings
• Customized for each patient
• Have receptacles in which acrylic dough is contoured to form customized condylar & incisal guidance

Question 13. Buccolingual width of posterior teeth in the complete denture.
Answer:

• The buccolingual width of posterior teeth should be decreased to provide a proper path of escapement of food
• It should be such that the forces from the tongue neutralizes the forces from cheek
• If the buccolingual width increases the rate of ridge resorption also increases
• Teeth with broader dimensions interfere with the tongue leading to instability of the denture
• Of the teeth are broader buccally, it may lead to cheek biting.

Question 14. Bilabial sounds.
Answer:

• Bilabial sounds are b, p, and m
• These are controlled by the lip support
• These become defective in the absence of lip support or with alteration in the vertical dimension at occlusion

Question 15. Hanau articulator.
Answer:

• It is an semi-adjustable articulator
• It accepts face bow transfer
• It is capable of the hinge and lateral movements

Parts:

1. Upper member:
   • It is T shaped
   • The vertical arm runs anteroposteriorly and the horizontal arm runs transversely
2. Lower member:
   • It is L shaped structure
   • The horizontal arm is a rectangular strip
   • It has a dowel for attachment of the mounting ring
   • The incisal guide table is located at the anterior end of the horizontal arm
   • The vertical arm is sloping
   • It contains roll pin
3. Condylar guidance:
   • It is attached to the upper member of the articulator
   • It represents the glenoid fossa of the TMJ
4.  Incisal guide table:
   • It is customized
5.  Incisal pin:
   • It is double sided pin’
   • One end is sharp but chisel-like with a flat edge
   • The other end tapers to a pointed tip

Question 16. Beyron’s point.
Answer:

• The first step in placing a face bow is to locate hinge axis on the skin on each side of the face
• One frequently recommended method is to position condylar rods on a line extending from the outer canthus of the eye to the tragus approximately 13 mm in front of the eternal auditory meatus
• This is called Beyron’s point
• The placement generally locates the rods within 5 mm of the true of center of the opening axis of the jaw
• The imaginary line joining two Beyron’s points is approx. hinge axis
• The posterior reference point is 10 mm in front of the external auditory meatus.
• 7 mm below Frankfort horizontal plane
• The anterior reference point is
• 7 mm from orbitale
• 25 mm from nasion
• 18 mm from inner canthus of eye
• 43 mm superior from tip of central incisors

Laboratory Procedures Prior To Try In Definitions

1.  Articulator: A mechanical device that represents the temporomandibular joints & the jaw members to which maxillary & mandibular casts may be attached to stimulate jaw movements
2.  Neutral zone: It is the potential space between the lips & cheeks on one side & the tongue on other side

Laboratory Procedures Prior To Try In Important Notes

1. Classification of articulators:

• Based on theories:
  • Bonwill theory articulator
  • Conical theory articulator
  • Spherical theory articulator
• Based on the type of occlusal record used:
  • Interocclusal record adjustment
  • Graphic record adjustment
• Based on ability to stimulate jaw movements:
  
  
• Based on adjustability
  • Nonadjustable- can open and close in fixed horizontal axis
  • Semi-adjustable – have adjustable horizontal condyla paths, adjustable lateral condylar paths, and adjustable intercondylar distances
  • Fully adjustable – capable of being adjusted to follow the mandibular movements in all directions

2. Functions of articulators:

• Holds maxillary and mandibular casts in a determined fixed relationship
• Stimulates jaw movements like opening and closing
• Produces border and intraborder movements of the teeth similar to those in the mouth

3. Arcon and non-arcon articulators:

4. Dentogenic concept – SPA concept

1. Sex:
   • Females: rounded incisal edges
     1. Less angular teeth
     2. Incisal edges follow the plane the curve of the lower lip
     3. Rotated distal surfaces of centrals
     4. A visible mesial third of canines
     5. Exposure of more anterior while smiling
   • Males: More angular teeth
     1. Incisal edges are above the plane of occlusion
     2. The mesial end of laterals are hidden by centrals
     3. Middle 2/3rd of canine are visible
     4. Prominent cervical regions
2. Personality:
   • Squarish – Vigorous people
   • Flat: Executives
3. Age:
   • Increased horizontal overlapping of posteriors
   • Reduced inter arch distance
   • Reproduce-abrasion, gingival recession in teeth as present in old individual

5. Types of teeth

6. Indications of non-anatomic teeth:

• Flat ridges
• Knife edge ridges
• Large interridge space
• Milling type of chewing pattern
• In bruxers
• Patients with neuromuscular disorders In
• highly resorbed ridges

Read And Learn More: Prosthodontics Question And Answers

7. Separating media:

Separating media Types:

• Tinfoil
• Cellulose lacquers
• Solution of alginate compound
• Calcium oleate
• Soft soaps
• Sodium silicate
• Starches
• Evaporated milk

8. Sodium alginate solution:

• Commonly known as cold mold seal
• It is widely used because of its effective and easy manipulation
• Sodium alginate Composition:
  • Sodium alginate 2% in water
  • Sodium phosphate
  • Glycerine
  • Alcohol
  • Preservatives
• When applied overcast the sodium alginate in the solution reacts with calcium on the cast producing insoluble calcium alginate that forms a membrane and serves as separating medium

Laboratory Procedures Prior To Try In Short Essays

Question 1. The age factor in dentogenic concept
Answer:

Dentogenic Concept Integration detail:

1. Young people have lighter teeth due to translucent enamel
2. Old people have dark & opaque teeth due to secondary dentin formation
3. Shiny teeth in old people
4. Teeth with a brownish tinge in older people
5. Certain diseases are limited to certain ages Thus age can be used to rule out certain systemic conditions
6. Age also determines the prognosis

Question 2. Nonanatomic teeth.
Answer:

Nonanatomic teeth Definition:

Artificial teeth with occlusal surfaces which are not anatomically formed but are designed to improve the function of teeth.

Advantages of Non anatomic teeth.:

• Useful in bruxers
• Greater range of movement possible
• Useful in patients with neuromuscular disorders
• Useful in patients with highly resorbed ridge

Disadvantages of Non anatomic teeth.:

• Unaesthetic appearance
• Less masticatory efficiency
• Balanced occlusion is not possible

Question 3. Trial dentures.
Answer:

A trial denture is the arrangement of teeth in wax, for trial, prior to completion of the denture.

• On receipt of the articulated trial dentures, the first stage is to ensure that the maxillary and mandibular trial dentures are well adapted to the respective master casts and that both bases are stable.
• The next stage is to remove the mandibular trial denture from the articulator and to assess the relationship of the maxillary posterior teeth to the mandibular ridge.
• When both trial dentures have been removed from the articulator, the clinician should inspect the intermaxillary space to ensure no unplanned increase or decrease in dimension has occurred.
• The clinician should also examine the casts to ensure that no laboratory-induced defects have been induced on the denture-bearing areas.
• If both dentures are replaced on their respective casts, the clinician may then examine the occlusal relationships of both dentures, to establish the balanced occlusion
• Next denture are inserted in the mouth and checked for extension, retention and stability of dentures
• When both trial dentures are in the mouth, the follow- ing four aspects of the dentures may be assessed in turn:
  1. Occlusal relations: Vertical, anteroposterior and coronal intermaxillary relation are checked for
  2. Occlusal planes: For evaluate incisal plane, left and right posterior occlusal planes, and plane of posterior mandibular teeth.
  3. Appearance of teeth and gingival: Tooth position, selection, and color of teeth are evaluated
  4.  Speech: Should not be adversely affected by dentures.

Question 4. Try in procedure.
Answer:

Try In:

It is defined as a preliminary insertion of a removable denture wax up or a partial denture casting or a finished restoration to determine the fit, aesthetics, maxillomandibular relation

Features:

It includes following procedures

1. Primary evaluation:
   • Check for adaptation of denture base
   • Evaluation complete occlusion of denture teeth in centric relation
   • Verify vertical height at rest and occlusion
   • Evaluate polished surface
2.  Preliminary evaluation in articulator:
   • Evaluate impression surface for adaptation
   • Evaluate polished surface for absence of voids
   • Evaluate occlusal surface for any wax residues present
   • Carve out gingival margins of the teeth
3. Evaluation in the mouth:
   • Check for denture coverage and borders
4. Evaluation of individual trial dentures:
   • Evaluate denture extension, retention, stability, support and esthetics
5. Evaluate lip and cheek support:
6. Evaluate occlusal plane, vertical height:
   • Intraorally by the position of the parotid papilla and extraoral by interpupillary line and Camper’s line
   • Evaluate centric and eccentric relation

Question 5. Semi-adjustable articulator.
Or
Arcon and non arcon articulator
Or
Define Arcon articulator
Answer:

They have adjustable horizontal condylar paths, adjustable lateral condylar paths, adjustable incisal guide tables & adjustable intercondylar distances

Semi-adjustable articulator Types:

1. Arcon Articulator:
   • In this type condylar element is attached to the lower member of the articulator & the condylar guidance is attached to the upper member
   • This resembles the TMJ.
     • Advantages:  All relations are preserved even when the articular is open or closed
     • Examples: Whip mix articulator:
2. Non-Arcon Articulator:
   • This articulator have a condylar element attach to the upper member
   • The condylar guidance is attached to the lower member
   • It is the reverse of TMJ
     • Examples: Hanau H series:

Question 6. Principles in teeth arrangement.
Answer:

1. Maxillary central incisor:

• Long axis of the tooth is parallel to the vertical axis
• Sloping labially
• Incisal edge contacts evenly

• M-Mesial
• D-Distal
• L-Labial
• P-Palatal

2. Maxillary lateral incisor:

• Long axis parallel to vertical axis, sloping labially
• Incisal edge 2 mm above the occlusal plane

• L-Labial
• P-Palatal
• M-Mesial
• D-Distal

3. Maxillary canine:

• Long axis parallel to vertical axis
• Mild mesial tilt
• Cervical prominence
• The cusp tip touches the plane of occlusion

• L-Labial
• P-Palatal
• M-Mesial
• D-Distal

4. Maxillary first premolar:

• Long axis parallel to the vertical axis
• Buccal cusp touches occlusal plane
• Palatal cusp 0.5 mm above the occlusal plane

• P-Palatal
• B-Buccal
• M-Mesial
• D-Distal

5. Maxillary second premolar:

• Long axis parallel to vertical axis
• Both cusps touches occlusal plane

• P-Palatal
• B-Buccal
• M-Mesial
• D-Distal

6. Maxillary first molar:

• Long axis tilted buccally
• Mesio palatal cusp touches the occlusal plane

• P-Palatal
• B-Buccal
• M-Mesial
• D-Distal

7. Maxillary second molar:

• Similar to first molar but at a higher level

8. Mandibular central & lateral ncisor:

• Long axis parallel to the vertical axis & sloping labially
• Incisal edge 2 mm above occlusal plane

• M-Mesial
• D-Distal
• F-Facial
• L-Lingual

9. Mandibular canine:

• Long axis parallel to vertical axis & sloping lingually
• Cusp tip more than 2 mm of occlusal plane

• M- Mesial
• D-Distal
• F-Facial
• L-Lingual

10. Mandibular first premolar:

• Long axis parallel to vertical axis & sloping lin- gually
• Lingual cusp below occlusal plane
• Buccal cusp 2 mm above occlusal plane

• P-Palatal
• B-Buccal
• M-Mesial
• D-Distal

11. Mandibular second premolar:

• Long axis parallel to vertical axis & sloping lingually
• Both cusps 2 mm above occlusal plane

• M- Mesial
• D-Distal
• F-Facial
• L-Lingual

12. Mandibular first & second molar:

• Long axis parallel to the vertical axis & sloping lingually
• All cusps above occlusal plane
• Mesial & lingual cusps at a lower level

• L-Lingual
• F-Facial
• M-Mesial
• D – Distal

Laboratory Procedures Prior To Try In Viva Voce

1. While setting condylar guidance, the incisal guide pin should be raised out of contact with the incisal table.
2. Alveolar sounds such as ‘s’, ‘n’, ‘d’, ‘t’, and ‘z’ are produced by contact of the tip of the tongue with anterior part of the palate or the lingual side of the anterior teeth.
3. If the teeth are too far anteriorly, the’d’ will sound like ‘t’. If the teeth are too far lingually, then that will sound like ‘d’.
4. The labiodental sounds ‘f’ and ‘v’ are made between the incisal edges of upper incisors and the posterior 3rd of the lower lip.
5. Labial sounds are b, p, and m
6. The dentogenic concept is given by Frush and Fischer
7. Artificial teeth must be arranged on a neutral zone

Laboratory Procedures Prior To Try In Long Essays

Question 1. Define articulator. Give classification, and uses & discuss semi adjustable articulators.
Answer:

Articulator Definition:

“A mechanical device which, represents the temporomandibular joints & the jaw members to which maxillary & mandibular casts may be attached to stimulate jaw movements”.

Articulator Classification:

1. Based on theories:

• Bonwill theory articulator
• Conical theory articulator
• Spherical theory articulator

Read And Learn More: Prosthodontics Question And Answers

2. Based on the type of occlusal record used:

• Interocclusal record adjustment
• Graphic record adjustment

3. Based on the ability to stimulate jaw movements:

• Class 1
• Class 2
• Class 3
• Class 4

4. Based on adjustability:

• Nonadjustable
• Semi adjustable
• Fully adjustable

Uses:

• Diagnose the state of occlusion
• Planning of dental procedures
• Fabrication of restoration
• Correction of restoration
• Arrangement of artificial teeth

Semi-Adjustable Articulator:

They have adjustable horizontal condylar paths, adjustable lateral condylar paths, adjustable incisal guide tables & adjustable intercondylar distances

Types of Articulators:

•  Arcon Articulator:
  • In this type condylar element is attached to the lower member of the articulator & the condylar guidance is attached to the upper member
  • This resembles the TMJ.
• Advantages of Articulator: All relations are preserved even when the articular is open or closed
• Examples: Whip mix articulator:

• Non- Arcon Articulator:
  • This articulator have condylar element attach to the upper member
  • The condylar guidance is attach to the lower member
  • It is reverse of TMJ
• Examples: Hanau H series

Question 2. Discuss in detail about anterior teeth selection for edentulous patients. Add a note dentogenic concept.
Answer:

Anterior Teeth Selection:

Size: Methods:

• Pre-extraction records:
  • Diagnostic cast- prepared before extraction of teeth
  • Photographs- showing frontal & lateral view
  • Radiographs-Accurate measurements not obtained
  • Close relatives- If other methods fail
  • Extracted teeth- Best method
•  Anthropological measurements:
  • Cephalic index: Total width of upper anteriors= Bizygomatic width/3.36
  • Total width of lower anterior: 4/5 the width of upper anterior By H. Pound

• • By Sears: Width of upper central incisor Circumference of head/13

Anatomical Landmarks:

1. Size of maxillary arch:

• Distance between incisive papilla & hamular notch on one side.
• Distance between two hamular notch.
• Total width of all anterior & posteriors

• Canine eminence: Distance between two canine eminence combined width of anterior teeth

2. Buccal frenal attachments: Distance between two frena= total widths of maxillary anterior

 

3. Corners of the mouth: Distance between them = total width of anterior

4. Theoretical concepts:

• Winkler’s concept:
  • Physiological: Evaluate perioral tissues & arrange the teeth
  • Psychological: Camper’s line is used for it
    1. Raised in happy people
    2. Depressed downward in depressed people
  • Biomechanical: Placement of teeth in neutral zone
    
• Typal form theory (Leon Williams): Shape of teeth inverse the shape of the face

• Temperamental theory:
  • People based on mental, functional & physical characteristics contain teeth
• Concept of harmony:
  • Size of teeth corresponds to size of head

5. Others:

• Size of face
• Interarch distance
• Lip length

6. Color:

• Age
• Young people-lighter teeth
• Old people – dark teeth
• More shiny
• Brownish tinge
• Habits – smokers porcelain teeth
• Complexion- teeth selected in harmony with the complexion
• Colour of eyes color of iris is considered

7. Form:

• Patient’s face (Leon William’s concept)
• Facial form can be ovoid, tapering or square Teeth are selected according to it
• Example: Oviod teeth for oval face
  1. (a) Square
  2. (b) Oval
  3. (c) Tapering
  4. (d) combination

• Patient’s profile
• It can be convex, concave, or straight
• Labial form of anterior are selected according to it
• Example: Straight labial form for straight profile

8. Dentogenic concept (SPA concept):

• Sex:
  • Females: Rounded incisal edges
    1. Less angular teeth
    2. Incisal edges follow plane the curve of lower lip
    3. Rotated distal surfaces of central
    4. A visible mesial third of canines
    5. Exposure of more interiors while smiling
  • Males: More angular teeth
    1. Incisal edges are above the plane of occlusion
    2. Mesial end of laterals are hidden by centrals
    3. Middle 2/3rd of canine are visible
    4. Prominent cervical regions

• Personality:
  • Squarish-vigorous people
  • Flat: Executives

• Age:
  • Increased horizontal overlapping of posteriors
  • Reduced inter arch distance
  • Reproduce abrasion, and gingival recession in teeth as present in old individual

Question 3.Given Its functions and requirements of an articulator.
Or
Requirements of articulator
Answer:

Functions of articulator :

• Holds maxillary and mandibular casts in a determined fixed relationship
• Stimulates jaw movements like opening and closing
• Produces border and intraborder movements of the teeth similar to those in the mouth

Requirements of articulator : Requirements of articulator

1. Minimal requirements:
   • It should hold casts in the correct horizontal relationship
   • It should hold casts in the correct vertical relationship
   • The casts should be easily removable and reattachable
   • It should provide positive anterior vertical stop
   • It should accept face bow transfer record using an anterior reference point
   • It should open and close in a hinge movement
   • It should be made of non-corrosive and rigid materials that resist wear and tear
   • It should not be bulky or heavy
   • There should be adequate space present between upper and lower members
   • The moving parts should move freely without any friction
   • The non moving parts should be of a rigid construction
2. Additional requirements:
   1. Condylar guides should allow protursive and lat- eral jaw motion
   2. The condylar guide should be adjustable in a horizontal direction
   3. The articulator should be adjustable to accept and alter
   4. Bennett movement
   5. The incisal guide table should be customized

Question 4. Selection of posterior teeth in complete denture
Or
Criteria For Posterior Teeth Selection
Or
Posterior Teeth Selection
Answer:

Posterior teeth Size:

• Buccolingual Width: Such that it
• Provide escape of food
• Neutralizes forces from cheeks
• Prevent cheek biting

• Mesiodistal length: Such that
• The combined length of all posteriors doesn’t exceed the distance between canine & retromolar pad

• Occlusogingival height
• The occlusal plane should be at the midpoint of the interocclusal distance

2. Form:

• High cuspal height for steep condylar guidance
• Shallow cusps for shallow ridge
• Monoplane teeth for posterior crossbite

Maxillomandibular Relations Long Essays

Question 1. Define vertical jaw relation. Enumerate the different methods to register vertical jaw relation. Describe any one method in detail.
(or)
Question 1. Define jaw relation and explain various methods involved in recording vertical jaw relation.
(or)
Question 1. Discuss various methods of determining vertical dimension in edentulous patients. Describe anyone.
(or)
Question 1. Define vertical jaw relation. Explain in detail various techniques of recording it.
Or
Methods of recording vertical dimension.
Answer:

Maxillomandibular Relations Definition:

1. Jaw relation: Any relation of the mandible to the maxilla
2. Vertical jaw relation:
   1. The length of the face as determined by the amount of separation of the jaws
   2. Methods for recording vertical jaw relation

Methods Of Recording Of Vertical Jaw Relations:

1. Methods to measure vertical jaw relation at rest:

• Facial measurements:
  • Two reference points are marked
  • One on the nose & other over chin
  • The patient is asked to perform various functions Distance between the two reference points are measured
  • This gives a measurement of the physiological rest position of the mandible.

•  Facial expression:
  • The patient is asked to relax
  • Various expressions are viewed
• Anatomical landmarks:
  • Distance between:
  • Pupil of eye & corners of the mouth
  • Anterior nasal spine & lower border of the mandible
  • Is measured
  • If they are equal, jaws are at rest

Read And Learn More: Prosthodontics Question And Answers

• Tactile sensation:
  • The patient is asked to open the mouth wide
  • Then close his mouth slowly till muscles are relaxed
  • Distance between two reference points are measured
• Speech:
  • Patient is asked to repeat the letter ‘m’
  • Distance between two reference points is measured as soon as the patient stops repeating

2. Vertical jaw relations at occlusion:

 Mechanical methods:

• Ridge relation:
  • Distance between incisive papilla to mandibular incisors is measured distance be-tween incisive papilla & maxillary incisors is 6 mm
    1. Overbite is 2 mm
    2. Thus, the distance between the incisive papilla & mandibular incisors is 4 mm
  • Ridge parallelism: Mandible is parallel to maxilla only at occlusion

• Pre-extraction records:
  1. Profile photographs
  2. Profile silhouettes
  3. Radiography
  4. Articulated cast
  5. Facial measurements
• Measurements from former dentures:

3. Physiological methods:

• PowerPoint: by Boos:
  1. A metal central bearing plate is attached to the upper base
  2. Bimeter attached to lower base
  3. Inserted in patient’s mouth & asked to bite
  4. Pressure reading in bimeter is recorded

• Using wax occlusal rims:
  1. Measure vertical relation at rest
  2. Estimate vertical relation to be 2-5 mm less of it
  3. Coat occlusal surface of maxillary rim with petrolatum
  4. Place triangular sectioned occlusal rim over mandibular rim
  5. Soften the wax
  6. Ask the patient to bite over it
  7. Remove it & articulate

• Physiological rest position (Niswonger & Thomson): 
  1. Seat the patient
  2. Ask him to swallow & relax
  3. Part the lips slightly
  4. Space exist between the upper & lower rims
  5. This space is called “Freeway space”
  6. It should be 2-4 mm
  7. By it vertical dimensions at occlusion is calculated from the formula
  8. VD at rest =VD at occlusion + freeway space

Then a= b+c The verticle dimension at rest is equal to the sum of the verticle dimension at occur and free way space

• Phonetics:
  • Silverman’s closest speaking space:
  • Sounds like ch, s, j results in the closest relation of upper & lower rim without contacting each other
  • This indicates the vertical dimension of patient

• Aesthetics:
  • Size of teeth assessed from the residual ridge resorption
• Swallowing threshold:
  • Conical rim is placed over the lower rim
  • Insert both the record bases
  • Ask the patient to swallow
  • By this height of the lower rim is reduced
• Tactile sensation:
  • Occlusal rims with a central bearing plate & screw are inserted in the patient’s mouth,
  • Tighten the screw till the patient feels discomfort

• • A –  Tactile sense method of determining vertical jaw relation vertical jaw relation
  • B –  Central bearing point
  • C – Central bearibearing plate
• Patient’s perception:
  • Occlusal rims with excessive height is inserted in the patient’s mouth
  • Stepwise reduction is carried out till the patient feels comfort

Question. 2. Define balanced occlusion. Discuss in detail the factors effecting balanced occlusion in complete dentures.
Or
Define balanced occlusion. Write in detail about various factors effecting it.
(or)
Define balanced occlusion. Explain its significance. Write in detail about various factors effecting it.
Or
Factors effecting balanced occlusion.
Answer:

Balanced Occlusion Definition:

“The simultaneous contacting of the maxillary & mandibular teeth on the right & left & in the anterior & posterior occlusal areas in centric & eccentric positions, developed to lessen or limit tipping or rotating of the denture bases in relation to the supporting structures

” Factors Affecting Balanced Occlusion:

1. Condylar guidance:

• First factor of occlusion to be considered
• Measured using protrusive registration
• Increased in condylar guidance increases jaw separation
• It cannot be modified

2. Incisal guidance:

• “The influence of the contacting surfaces of the mandibular & maxillary anterior teeth on mandibualr movements”
• The second factor of occlusion
• Customized
• If overjet increases, it decreases
• If overbite increases, it increases
• If incisal guidance is steep, steep cusps, steep occlusal plane & steep compensatory curves are required
• It must be as flat as possible

3. Occlusal plane:

• “An imaginary surface which is related anatomically to the cranium & which theoretically touches the incisal edges of the incisors & the tips of occluding surfaces of posteriors”
• Height of lower canine should coincide with  measure of mouth
• It should not be altered beyond 10°
• A posterior plane parallel to Camper’s line 10°

4. Cuspal angulation:

• “The angle made by the average slope of a cusp with the cusp plane measured mesiodistally or buccolingually”
• Reduced cuspal height in shallow overbite High cuspal angle in deepbite

5. Compensatory curves:

• “The anteroposterior & lateral curvatures in the alignment of the occluding surfaces & incisal edges of artificial teeth which are used to develop balanced occlusion
• Steep compensatory curves for steep condylar path
• Shallow curves for loss of balancing molar contacts
  
• Thus balance must be present between all the five factors
• Effect of incisal & condylar guidance must counter-act by the effect of other three factors
• If the balance is lost, balanced occlusion cannot be achieved

Question 3. Define Centric relation. Classify jaw relation. Write in detail on any one technique of determining jaw relation.
Or
Define centric jaw relation. Classify different methods & explain any one method for recording jaw relation.
Or
Methods of centric jaw relation.
Answer:

Centric Jaw Relation:

The maxilla mandibular relation in which the condyles articulate with the thinnest avascular portion of their respective disc with the complex in the anterior- superior position against the slopes of the articular eminence

Jaw Relations & Methods To Record Them:

Orientation jaw relation: by face bow: Vertical jaw relation:

1. Vertical jaw relation at rest:
   • Facial measurement
   • Tactile sense
   • Measurement of anatomical landmarks
   • Speech
   • Facial expression
2.  Vertical jaw relation at occlusion:
   • Mechanical methods:
     • • Ridge relation
         1. Ridge parallelism
         2. Distance of incisive papilla to mandibular Incisors
   • Pre-extraction records
3. Physiological methods: [PATUS]:
   • Powerpoint
   • Physiological rest
   • Phonetics
   • Patient’s perception
   • Aesthetics
   • Tactile sense
   • Using wax records Swallowing threshold
4.  Horizontal jaw relation: 
   • Physiological methods –
     1. Tactile method
     2. Pressureless method
     3. Pressure method
   • Functional method:
     1. Needlehouse method
     2. Patterson method
   • Graphic method:
     1. Intraoral
     2. Extraoral
   • Radiographic method

Pressureless Method [Nick & Notch]:

Seat the patient in an upright position
↓
Retrude his mandible
↓
Remove up to 3 mm of wax from either side of the mandibular rim
↓
Cut 1-2 notch on the corresponding area of the maxillary rim
↓
Make a nick anterior to it [notch-prevent anterioposterior movement Nick-lateral movement]
↓
Add aluwax upto 4.5 mm in mandibular rim & insert in patient’s mouth Teach the patient to close mouth in centric relation
↓
Remove the rims & place it in cold water
↓
Check for any errors
↓
Articulate it.

Question 4. Classify Jaw and Centric relation. Explain its significance. What are the methods for recording it.
Or
Classification Of Jaw Relation
Answer:

Jaw Relations:

Any relation of the mandible to the maxilla

Jaw Relation Classification:

1. Orientation jaw relation:
   • The jaw relation when the mandible is kept in its most posterior position, it can rotate in the sagittal plane around an imaginary transverse axis passing through or near the condyles’
2. Verticle Jaw Relations: The length of the face as determined by the amount of separation of the jaws
   • Vertical relation at rest:
     • The length of the face when the mandible is in rest position
   • Vertical relation at occlusion:
     • The length of the face when the teeth are in contact & the mandible is in centric relation or the teeth are in centric relation
3. Horizontal jaw relation: It is the relationship of the mandible to the maxilla in the horizontal plane

Centric Jaw Relation:

The maxillomandibular relation in which the condyles articulate wit the thinnest avascular portion of their respective disc with the complex in the anterior-superior position against the slopes of the articular eminence

Centric Jaw Relation Significance:

• Proprioceptive impulses guide the mandible during various movements
• In dentulous patient, it is possible from the impulses of PDL
• But in edentulous patient, it is not possible
• In such cases, impulses are received from our transferred to TMJ
• Centric relation acts as center for such impulses
• It guides the mandible during such movements

Centric Jaw Relation Methods Of Recording It:

1. Physiological methods:

• Tactile method:
  • Ask the patient to retrude the mandible
  • Tentative jaw relation is recorded
  • Based on it casts are articulated
  • Teeth arrangement is done
• Pressureless method:
  • Occlusal rims are fabricated
  • Denture base along with occlusal rim is inserted in the patient’s mouth
  • Ask the patient to close in centric relation
  • Occlusal rims are sealed in this position
• Pressure method:
  • Upper occlusal rim is inserted in the patient’s mouth
  • The lower rim is fabricated with excess material
  • It is thoroughly softened and inserted in the mouth
  • Ask the patient to close in centric relation over softened wax

2. Centric Jaw Relation Functional method:

• It utilizes the functional movements of the jaw to record centric relation
  • Needlehouse method
  • Patterson method

3. Centric Jaw Relation Graphic method:

• It involves tracing to record centric jaw relation
• Intraoral
• Extraoral

4. Centric Jaw Relation  Radiographic method:

Question 5. Define balanced occlusion. Give in detail its various functional objectives in complete dentures.
Answer:

Balanced Occlusion Definition:

The simultaneous contacting of the maxillary & mandibular teeth on the right & left & in the anterior &posterior occlusal areas in centric & eccentric positions, developed to lessen or limit tipping or rotating of the denture bases in relation to the supporting structures

Balanced Occlusion Functional Objectives:

• Smaller the area of the occlusal surface, the lesser transmission of forces to the supporting structures
• Tilted occlusal surface causes, nonvertical forces on the denture
• Tilted tissue support causes nonvertical forces on denture
• Vertical forces on resilient tissues cause lever forces on the denture
• Vertical forces outside the ridge cause tipping of the denture
• Stability of the denture must be present in both centric & eccentric relation
• Balanced occlusal contacts during eccentric movements Unlocking of cusps to settle the denture
• Reduced cuspal height to resist horizontal forces Efficient mastication efficiency
• Minimal tooth contact during mastication
• Absence of sharp ridges & cusps
• Wide & large ridges
• Teeth arranged close to ridge Narrow ridge rest on ridge
• Arrangement of teeth slight lingually Forces of occlusion should be centered

Question 6. Discuss the importance & validity of centric relation.
Or
Significance of centric relation.
Answer:

Centric Relation Importance:

• Proprioceptive impulses guide the mandible during various movements In edentulous patients it is possible from the impulses of PDL
• But in edentulous patient it is not possible In such cases, impulses are received from ridge are transferred to TMJ
• Centric relation acts as center for such impulses
• It guide the mandible during such movements

Centric Relation Validity:

• Learnable
• Repeatable
• All functional movements are possible from this position
• The arrangement of muscles are such that they move the mandible from a centric position
• Helps in the mounting of casts
• Adjustment of condylar guidance in articulator is done according to it
• Definite
• Recordable
• During any movement of the mandible, it has pass from this position first

Question 7.  Mention the significance of physiologic rest position
Or
Physiologic rest position and Discuss effects of increased & decreased vertical jaw relations.
Answer:

1. Significance of Physiological Rest Position:

• “The mandibular position assumed when the head is in an upright position & the involved muscles, particularly the elevator & depressor groups, are in equilibrium in tonic contraction, & the condyles are in a neutral, unstrained position”
• During rest position, space exists between the upper & lower rims
• This is called freeway space
• It should be 2-4 mm
• If it increases, the vertical dimension at occlusion re- duces & becomes inefficient
• If this space decreases, then the vertical dimension at occlusion increases to a greater extent
• Thus increases lower facial height of the patient

2. Effects of Increased Vertical Dimensions:

• Increased trauma to the denture-bearing area
• Increased lower facial height
• Cheek biting
• Difficulty in swallowing & speech
• Pain & clicking in TMJ
• Stretching of facial muscles
• Increased space of oral cavity

3. Effects of Decreased Vertical Dimensions:

• Decreased trauma to the denture-bearing area
• Decreased lower facial height
• Angular cheilitis
• Difficulty in swallowing
• Pain, clicking & discomfort in TMJ
• Loss of lip fullness
• Loss of muscle tone
• Dropping down of corner of the mouth
• Thinning of vermillion borders of lip
• Decreased space of the oral cavity

Maxillomandibular Relations Short Essays

Question 1. Define face bow. Explain the parts of face bow
Answer:
Definition:

A caliper like a device is used to record the relationship of the jaws to the temporomandibular joints & to orient the casts on the articulator to the relationship of the opening axis of the temporomandibular joint

Parts of Face Bow:

1. U-shaped frame:

• It is a U-shaped metallic bar that forms the main frame of the face bow
• All other components are attached to it
• It records the plane of the cranium

2. Condylar rods:

• These re two small metallic rods on either side of the free end of the U-shaped frame
• Helps to locate the hinge axis
• Transfer the hinge axis of the TMJ by attaching to the condylar shaft in the articulator

3. Bite fork:

It is U shaped plate that is attached to the occlusal rims while recording the orientation relation It is attached to the frame with the help of stem

It should be inserted about 3 mm below the occlusal surface within the occlusal rim

4. Locking device:

• It helps to attach the bite fork to the U-shaped frame
• It supports the face bow, and occlusal rim, and is cast during articulation
• It consists of a transfer rod and a transverse rod The U-shaped frame is attached to the vertical transfer rod
• A transverse rod connects the transfer rod with the stem of the bite fork

5. Orbital pointer:

• It marks the anterior reference point
• Present only in the arbitrary face bow

Question 2. Balanced Occlusion.
Answer:

Balanced Occlusion Definition:

“The simultaneous compacting of the maxillary & mandibular teeth on the right & left & in the anterior & posterior occlusal areas in centric & eccentric positions, developed to lessen or limit tipping or rotating of the denture bases in relation to the supporting structures”.

Types of Balanced Occlusion:

• Unilateral balanced occlusion
• Bilateral balanced occlusion
• Protrusive balanced occlusion
• Lateral balanced occlusion

Read And Learn More: Prosthodontics Question And Answers

Laws Of Balanced Articulation:

• Condylar guidance
• Incisal guidance
• Compensatory curves
• Relative cusp height
• Plane of the orientation of the occlusal plane

Factors Influencing Balanced Occlusion:

• Condylar guidance
• Incisal guidance
• Orientation of occlusal plane
• Cuspal angulation
• Compensatory curves

How Balance Is Achieved:

• The incisal & condylar guidance produce an increase in posterior separation
  While other three factors i.e., occlusal plane, caspal angulation & compensatory curves cause a decrease in posterior separation.
• The effect of incisal & condylar guidance should coun- teract the other three factors to obtain a balanced occlusion

Question 3. Nonbalanced occlusion.
Answer:’

It is arrangement Of teeth With Form or purpose

Nonbalanced occlusion General Considerations:

• Opposing artificial teeth should not contact in eccentric relation
• Tooth contact should occur only when the mandible is in centric occlusion
• Repeat the mandibular movements till the comfort of the patient in centric relation

Nonbalanced occlusion Concepts:

1. Pound’s concept:

• Proposed importance of phonetics & aesthetics for anterior teeth
• While posterior teeth should have sharp upper lin- gual cusp & wide lower central fossa
• Lingualized occlusion
• Triangle formed between the mesial end of the ca- nine & the two sides of the retromolar pad

2. Hardy’s concept: Proposed flat occlusal plane with nonanatomical teeth for complete denture

3. Kurth’s concept: Flat posterior teeth in a horizontal plane without any balancing ramps It is an arrangement of teeth with form or purpose

Question 4. Orientation relation in the complete denture And Write Face bow
Answer:

Orientation Jaw Relation:

• “The jaw relation when the mandible is kept in its most posterior position, it can rotate in the sagittal plane around an imaginary transverse axis passing through or near the condyles”.
• It can be recorded with the help of a face bow

Face Bow:

A caliper-like device that is used to record the relationship of the jaws to the temporomandibular joints & to orient the casts on the articulator to the relationship of the opening axis of the temporomandibular joint

Parts:

• U shaped frame
• Condylar rods
• Bite fork
• Locking device
• Orbital pointer

Types:

1. Arbitrary face bow:
   • Facia type
   • Earpiece type
   • Hanau face bow
   • Systematic
   • Twirl bow
   • Whipmix
2. Kinematic face bow:

• Aluwax is softened
• The bite fork is embedded into this wax A thin layer of petroleum jelly is applied over both the rims
• Both the rims are inserted into the patient’s mouth
• The bite fork is also inserted into the patient’s mouth Ask the patient to close the mouth
• The stem of the bite fork is locked to the transverse rod
• The orbital pointer is made to touch the infraorbital notch
• The entire face bow along with the rims is removed and articulated

Question 4. Occlusal rims.
Answer:

Occlusal rims Definition:

Occluding surfaces built on temporary or permanent denture bases for the purpose of making maxillo- mandibular relation records & arranging teeth

Factors Controlling It:

1. Relationship of natural teeth to the bone:

• Rims should be parallel to the long axis of teeth to be replaced
• Maxillary anterior labially inclined, & posteriors are vertically placed

2. Relationship of occlusal rims to edentulous ridge:

• Midline of the occlusal plane should pass through the apex of the edentulous ridge

3. Standard dimensions:

• Maxillary rims
• Height: 22 mm
• Width: 4-6 mm in the anterior region
• Width: 8-12 mm in the posterior region

• Mandibular rims
• Height: 6-8 mm
• Width: 4-6 mm in the anterior region
• Width: 8-12 mm in the posterior region

4. Clinical guidelines:

• Maxillary anterior edge 0-2 mm below the upper lip
• Maxillary posterior occlusal plane 1/4th inch below the opening of Stenson’s duct
• Mandibular incisal edge at the level of the lower lip
• Canine eminence at the corner of the mouth

5. Techniques for fabrications:

• Rolled Wax technique
• Metal occlusal rim former
• Pre-formed Occlusal rim

Maxillomandibular Relations Definitions

1.  Jaw relation: Any relation of the mandible to the maxilla
2. Orientation jaw relation: The jaw relation when the mandible is kept in its most posterior position, it can rotate in the sagittal plane around an imaginary transverse axis passing through or near the condyles
3. Vertical jaw relation: The length of the face as determined by the amount ofseparation of the jaws
4. Horizontal jaw relation: It is the relationship of the mandible to the maxilla in horizontal plane
5. Centric jaw relation: The maxillomandibular relation in which the condyles articulate with the thinnest avascular portion of their re- spective disc with the complex in the anterior-superior position against the slopes of the articular eminence 6.
6. Face bow: A calliper like device which is used to record the relationship of the jaws to the temporomandibular joints & to orient the casts on the articulator to the relationship of the opening axis of the temporomandibular joint
7. Occlusal rim: Occluding surfaces built on temporary or permanent denture bases for the purpose of making maxillomandibular relation records & arranging teeth
8. Physiological rest position: The mandibular position assumed when the head is in an upright position & the involved muscles, particularly the elevator & depressor groups, are in equilibrium in tonic contraction, & the condyles are in a neutral, un- strained position”
9. Balanced occlusion: The simultaneous contacting of the maxillary & mandibular teeth on the right & left & in the anterior & posterior occlusal areas in centric & eccentric positions, developed to lessen or limit tipping or rotating of the denture bases in relation to the supporting structures

Maxillomandibular Relations Important Notes

1. Types of jaw relations:

• Orientation jaw relation
• Vertical jaw relation
• Horizontal jaw relation

2. Dimensions of maxillary occlusal rim

• 22 mm – at canine eminence
• Anterior edge of occlusal rim at midline – 8 mm away from incisive papilla
• Width
  • In anterior region – 4-6 mm
  • In posterior region – 8-12 mm
• Occlusal table
  • Above crest of alveolar ridge in anterior region – 10-12 mm
  • From crest of alveolar ridge in posterior region – 5-7 mm
  • From depth of sulcus in posterior region – 18 mm
  • The anterior part of the maxillary occlusal plane should be 2mm below the upper lip line or smile line.
  • The posterior part of the maxillary plane should be parallel to Campers line of Ala-tragus line.

3. Tracing:

• Jaw movements can be recorded by the simple tracer assembly method. Tracing may be extraoral or intraoral.
• Intraoral tracing is less complicated. Extraoral tracers are less widely used
  • Extra-oral tracers:
    • High extraoral tracer assembly
    • Sears extraoral tracer assembly
  • Intraoral tracers:
    • Microtracer

Read And Learn More: Prosthodontics Question And Answers

4. Freeway space:

• The distance between to arbitrary points on maxilla and mandible when the patient is relaxing is called vertical dimension at rest.
• The same distance when the patient is occluding on rims is called vertical dimension in occlusion.
• The difference between VDR and VDO is called interocclusal distance or “Free-way space”.
• It is usually 2-4 mm when observed at the position of 1 premolars.
• Free way space less than normal means increased vertical dimension of occlusion which results in :-
  • Reversible soft tissue changes and irreversible ridge resorption.
  • Difficulty in swallowing.
  • Diffuse pain of ridge area.
  • Clicking of dentures during speaking.
  • Trauma to TMJ.

5. Gothic arch tracing:

• Gothic arch tracing (also known as arrow point or needle point tracing) is an extra oral method recording centric relation in horizontal jaw relations.
• It indicates the relative position of upper and lower jaws in horizontal plane.

6. Immediate side shift or Bennett movement:

• Here the mandible shifts before the forward movement of the non-working condyle occurs.
• This movement occurs in 86% of the condyles.
• This shift ranges 1 to 4 mm in dimension.

7. Progressive side shift or Bennett side shift:

• Lateral translation that continues linearly after 2-3mm of forward movement of the non working condyle.

8. Beyron point:

• It is a line extending from the counter canthus of the eye to the top of the tragus of the ear and approximately 13mm in front of the external auditory meatus’
• This placement generally locates the rods within 5mm of the true center of the opening axis of the jaws.
• The imaginary line joining the two Beyron points is an approximate hinge axis.

9. Face bow:

• Face bow is a calliper like instrument used to orient maxillary cast on the articulator so that it has the same relation- ship to the opening axis of the jaws.
• There are two types, the kinematic and the arbitrary.
• The kinematic is used to locate the true terminal hinge axis and transfer this record to the articulator when mounting the maxillary cast.
• The arbitrary face bow is the one generally used in the construction of complete dentures is based on average computation of an axis opening of the jaw.
• It is simple to use and relatively accurate

10. Effects of change in vertical dimension:

11. Methods used to record centric relation:

1. Physiological methods
   • Tactile method
   • Pressureless method
   • Pressure method
2. Functional method
   • Needle house
   • Petterson method
3. Graphic method
   • Intraoral
   • Extra oral
   • Radiographic method

12. Materials used for interocclusal check records:

• Waxes
• Zinc oxide eugenol
• Decreased vertical dimension
• Increased freeway space

Maxillomandibular Relations Short Answers

Question 1. Effects of increased vertical dimension.
Answer:

• Increased trauma to the denture-bearing area Increased lower facial height
• Cheek biting
• Difficulty in swallowing & speech
• Pain & clicking in TMJ
• Stretching of facial muscles
• Increased space of oral cavity

Question 2. Interocclusal recording media
Answer:

Commonly used materials for inter-occlusal recording are:

Question 3. Christenson phenomenon.
Answer:

• Mandible is guided by the anterior teeth during protrusive movement
• This is followed by complete disocclusion of the posterior teeth
• This characteristic posterior separation seen during anterior protrusion is called Christenson’s phenomenon

Question 4. Lingualized occlusion
Answer:

• Proposed by Alfred Gysi in 1927 It involves the use of a large upper palatal cusp against wide lower central fossa
• The buccal cusps of upper and lower teeth do not contact each other It is preferred due to its superior chewing efficiency
• Payne proposed the use of 30-degree anatomical teeth which are then reshaped to obtain lingual occlusion

Question 5. Interpupillary line.
Answer:

• It is used for evaluation of occlusal plane extra orally
• It is the distance between the two pupils
• The anterior part of the maxillary occlusal plane should be parallel to the interpapillary line It should be 2 mm below the upper lip line or smile line

Question 6. Arbitrary face bow.
Answer:

It is commonly used for complete denture construction The condylar rods are positioned approximately 13 mm anterior to the auditory meatus on a line running from the outer canthus of the eye to the top of the tragus called cantho-tragal line This locates the rods within 5 mm of the true hinge axis of the jaws

Types:

• Facia type
• Earpiece type
• Hanau face bow
• Slidematictype Twirl bow
• Whipmix facebow

Question 7. Atmospheric pressure.
Answer:

• The peripheral seal prevents air entry between the denture & soft tissue
• Hence a low pressure is maintained within the space between the denture and the soft tissues
• To obtain it denture borders should rest on soft & resilient tissues
• On application of forces, a vacuum is created that aid in retention This is a natural suction of denture
• Hence atmospheric pressure is referred as emergency-retentive force or temporary restraining force
• Retention produced by atmospheric pressure is directly proportional to the denture base area

Question 8. Gothic arch tracing.
Answer:

• It is used for recording centric relation
• It is usually recorded in the horizontal plane
• It is done using an arrow point tracer
• A pen-like pointer is attached to one occlusal rim Recording plate is placed on the other rim
• When the mandible moves the pointer draws characteristic patterns on the recording plate
• The pointer is known as the central bearing point and the recording plate is known as the central bearing plate
• They act at the center of the arch and evenly distribute forces across the supporting structures
• The shape of the tracing pattern resembles arrowhead The apex of the arrow gives the centric relation It should be sharp enough

Maxillomandibular Relations Viva Voce

1. A kinematic face bow is usually used for fixed partial dentures
2. The arbitrary face bow is the one most commonly used in complete denture patients.
3. Wax, plaster, ZOE paste, and self-cure resins are commonly used for interocclusal records
4. Lateral movement produces an anterior translation of condyle on the working side and rotation about the center on
   the nonworking side (balancing side)
   Bennett angle is formed by the sagittal plane and the path of the advancing condyle during lateral mandibular movements as viewed in the horizontal plane.
5. Petterson and Needlehouse are functional methods of recording centric relation
6. Intraoral tracing contains a central bearing plate and a central bearing point tracer
7. The graphic method is accurate method of recording centric relation
8. Orientation jaw relation is related to the cranium
9. Vertical jaw relation is related to jaw separation Face bow is used to record hinge axis

Impression And Mouth Preparation Short Answers

Question 1. Buccal shelf area
Answer:

Area of Buccal shelf :

Between buccal frenum & anterior border of the masseter

Boundaries of Buccal shelf :

• Medial crest of the ridge
• Distal Retromolar pad
• Lateral external oblique ridge

Significance of Buccal shelf :

• Primary stress-bearing area of the mandible
• The width of it increases as resorption continues

Question 2. Ridge Augmentation
Answer:

Definition:

Any procedure designed to enlarge or increase the size, extent, or quality of a deformed residual ridge is referred to be ridge augmentation procedures

Methods of Ridge Augmentation:

1. Mandibular augmentation
   • Superior border augmentation Inferior border augmentation Interpositional augmentation
   • Visor osteotomy
   • Onlay grafting
2. Maxillary augmentation
   • Onlay bone grafting Interpositional grafting Sinus lift procedure
   • Combination procedures

Question 3. “Cohesion” in complete dentures.
Answer:

• It is the physical attraction of like molecules to each other
• Acts within the film of saliva
• Normal quality and adequate quantity of saliva is cohesive
• When the quantity of saliva is excessive and the quality is watery, cohesion is decreased
• When the quantity of saliva is decreased and its viscosity is increased, cohesion is decreased due to increase in the thickness of saliva

Question 4. Mylohyoid ridge  importance
Answer:

• It is a rough bony crest extending from the third molar to second bicuspid region
• The mylohyoid muscle is attached to the mylohyoid ridge
• In the anterior region, the mylohyoid ridge with attached mylohyoid muscle lies close to the inferior border of the mandible
• Posteriorly, it is superior in position and the lingual flange of the denture may extend below the mylohyoid ridge if it drops vertically or slopes at 45 degrees to wards the tongue

Read And Learn More: Prosthodontics Question And Answers

Question 5. Stress-bearing areas of edentulous foundations
Answer:

These are those areas where stresses are directed are right angle

Significance:

• These are important while impression-making especially in the selective pressure technique
• Stresses are applied only over the stress-bearing areas
• These areas are different in the maxilla as well as the mandible

Primary Stress-Bearing Areas In Maxilla:

• Hard palate
• The postero-lateral slopes of the residual alveolar ridge

Primary Stress Bearing Areas In Mandible:

• The postero-lateral slopes of the residual alveolar ridge

Secondary stress-bearing area:

• Maxilla
• Mandible
• Rugae
• Maxillary tuberosity
• Anterior lingual border

Question 6. Retromolar papilla
Answer:

• It is described as a pear-shaped papilla It is a small elevation
• It is a residual scar formed after the extraction of the third molar
• It lies along the line of the ridge
• The denture should terminate at the distal end of the pear-shaped papilla
• Beading this area improves retention

Question 7. Objectives of complete denture impressions
Answer:

• Retention: It is the resistance to displacement away from the tissue surface. It is a mucosa-borne phenomenon.
• Support: It is the resistance to the occlusal forces in the vertical direction. It is a bone-borne phenomenon.
• Stability: It is resistant to lateral shifting.
• Preservation of remaining structures.

Question 8. Diagnostic casts.
Answer:

Requirements:

• Should be:
  • Free of voids
  • Smooth surface
  • Provide good denture support
  • Walls should be tapering outward
  • Smooth tongue space
  • Free of moisture
  • Occlusal table parallel to the floor.

Uses:

• Measure the undercuts Determine the path of insertion
• Treatment planning
• Perform mock surgery Evaluate the arch
• Assess retention & stability
• Determine secondary retentive forms

Question 9. Saliva’s influence on denture retention & stability.
Answer:

• Thick & ropy saliva loss of retention
• Thin & watery saliva compromised retention
• Watery serous saliva is more retentive
• In xerostomia there is no adhesion
• Ptyalism leads to gagging
• Xerostomia Soreness & irritation

Question 10. Retention in maxilla
Answer:

Retention factors present in maxilla are

1. Large denture-bearing area
2. Thick and ropy saliva
3. Interfacial surface tension

Question 11. Maxillary anatomical structures
Answer:

Limiting structures:

• Labial frenum
• Labial vestibule
• Buccal frenum
• Buccal vestibule
• Hamular notch
• Posterior palatal seal area

Supporting structures:

1. Primary stress-bearing areas
   • Hard palate
   • Postero-lateral slopes of the residual alveolar ridge
2. Secondary stress-bearing areas
   • Rugae
   • Maxillary tuberosity
   • Alveolar tubercle
3. Relief areas:
   • Incisive papilla
   • Cuspid eminence
   • Mid-palatine raphe
   • Fovea palatine

Question 13. Final impression methods in complete denture
Answer:

1. Dry gauze is placed in floor of the mouth to remove the saliva
2. It is removed just before making an impression
3. Impression material is manipulated and loaded onto the tray
4. The tray is rotated in the horizontal plane and inserted into mouth using the anterior handle
5. Tray is seated completely by applying alternating pressure over the posterior handles
6. Patient is asked to touch his upper lip with his tongue
7. Passive movements are performed
8. After material gets set and examine for any defects

Question 14. Realeff effect
Answer:

Complete dentures rest on the basal seat area which is primarily oral mucosa and residual alveolar ridge

• The oral mucosa is displaceable and compressible Hanau described this factor as “resiliency and like effect”- Realeff effect
• It helps an important role in all steps of complete denture fabrication as in
• Primary impression
• Border moulding
• Final impression
• Jaw relation
• Try in
• Remount
• Follow up
• Mechanical or pathological reasons cause fibrous changes in the residual ridge, making it resilient
• It is more commonly seen in Mandibular residual ridges
• Maxillary anterior ridges

Factors Affecting Realeff Effect

• Consistency of mucosa
• Excess bone loss during extraction
• Person’s general health
• Elderly tissues
• Smaller forces produce distinct compression
• Parafunctional habits
• Single complete denture

Question 15. Materials used for master impression.
Answer:

Requirements:

• Low viscosity
• Form a thin layer of impression.
• Should be uniform

Materials Used:

• Zinc oxide eugenol paste impression
• Medium-bodied elastomeric impression materials

Question 16. Anterior & posterior vibrating lines.
Answer:

1. Anterior Vibrating Lines:

• It is an imaginary line lying at the junction between the immovable tissues over the hard palate & the slightly movable tissues of the soft palate.
• Shape: Cupid bow shape

Method to Measure:

• By Valsalva maneuver: The patient is asked to close his nostrils firmly & gently blow through his nose
• By asking the patient to say “ah”

2. Posterior Vibrating Line:

• It is an imaginary line located at the junction of the soft palate that shows limited movement & the soft palate that shows marked movement

Method to Measure:

• Conventional method
• Fluid wax technique
• Arbitrary scraping of the master cast Extended palatal technique

Question 17. Modiolus.
Answer:

It is a point where 8 muscles meet at the angle of mouth

They are:

• Depressor anguli oris
• Levator anguli oris
• Risorius
• Orbicularis oris
• Buccinator
• Zygomatic major
• Quadralus labii superioris
• Quadralus labii inferioris

Question 18. Hamular notch.
Answer:

• It is the depression situated between the maxillary tuberosity and the hamulus of the medial pterygoid plate It is soft area of loose connective tissue
• The tissues in this area can be safely displaced to achieve the posterior palatal seal
• The distolateral border of the denture base rests in the hamular notch

Significance:

• The denture border should extend till the hamular notch
• If the border is located anteriorly near the maxillary tuberosity, the denture will not have retentive properties as the denture will lie on non-resilient tissues in such cases

Question 19. Retromylohyoid fossa.
Answer:

• It belongs to the posterior part of the alveolilingual sulcus
• It lies posterior to the mylohyoid muscle

Boundaries:

• Anteriorly retro mylohyoid curtain
• Posterolaterally superior constrictor of the pharynx
• Posteromedially palatoglossus and lateral surface of the tongue
• Inferiorly sub mandibular gland

Question 20. Syneresis & imbibition.
Answer:

• Process of water sorption by hydrocolloids is known as imbibition
• Syneresis is a process where the gel may loose water by exudation of fluid
• Syneresis & imbibition can result in dimensional changes & therefore inaccurate casts
• To avoid this hydrocolloids should be poured immediately

Question 21. Advantages of the perforated stock tray.
Answer:

• It is used for impression materials like alginate
• Holes present in it are advantageous
• It helps in retaining the material while impression making
• It retains the material by mechanical interlocking

Impression And Mouth Preparation Definitions

1. Impression: A complete denture impression is a negative registration of the entire denture bearing, stabilizing & border seal areas present in the edentulous mouth.
2. Retention: That quality inherent in the prosthesis which resists the force of gravity, adhesiveness of foods, and the forces associated with the opening of the jaws
3. Stability: The quality of the denture to be firm, steady & constant, to resist displacement by functional stresses & not to be sub-subject to change of position when forces are applied
4. Support: Resistance to vertical forces of mastication, occlusal forces & other forces applied in a direction toward the denture-bearing area
5. Posterior palatal seal: The soft tissues at or along the junction of the hard & soft palates on which pressure within the physiological limits of the tissues can be applied by a denture to aid in the retention of the denture
6. Anterior vibrating line: It is an imaginary line lying at the junction between the immovable tissues over the hard palate & the slightly movable tissues of the soft palate.
7. Posterior vibrating line: It is an imaginary line located at the junction of the soft palate that shows limited movement & the soft palate that shows marked movement

Impression And Mouth Preparation Important Notes

1. Types of impression:

1. Muco compressive – records tissue in functional and displaced form
2. Mucostatic records tissue in a relaxed form
3. Selective pressure – records tissue without interfering with the limiting structures at function and rest

2. Objectives of impression:

• Retention: It is the resistance to displacement away from the tissue surface. It is a mucosa-borne phenomenon.
• Support: It is the resistance to the occlusal forces in the vertical direction. It is a bone borne phenomenon.
• Stability: It is resistant to lateral shifting.
• Preservation of remaining structures.

3. Factors affecting retention:

• Anatomical factors- Size of denture bearing area, quality of denture bearing area
• Physiological factor – Saliva Physical factor-adhesion, cohesion, capillary attraction, interfacial surface tension, atmospheric pressure
• Mechanical factors- Undercuts, retentive springs, magnetic forces, denture adhesives
• Muscular factors

4. Primary stress-bearing areas:

5. Secondary stress-bearing areas:

 

Read And Learn More: Prosthodontics Question And Answers

6. Relief areas:


7. Anterior vibrating line:

• It is an imaginary line at the junction of the attached tissues overlying the hard palate and movable tissues of the soft palate
• It is always on soft palatal tissue
• It is visualized by asking the patient to say “ah” with a short vigorous burst

8. Posterior vibrating line:

• It is an imaginary line at the junction of the aponeurosis of the tensor veli palatine and muscular portion of the soft palate
• It represents the demarcation between the parts of the soft palate showing limited movements and those with marked movements
• It is the most distal extension of the denture

9. Alveolar lingual sulcus:

• Extends from the lingual frenum to the retro mylohyoid curtain
• It is divided into three parts

10. Posterior palatal seal:

• Lies between anterior and posterior vibrating line
• Functions
  • Retention of the maxillary denture
  • Maintain contact with the anterior portion of the soft palate during functional movements
  • Slightly displaces the soft tissue at the distal end of denture to ensure a complete seal that helps in retention of denture.
  • Prevents ingress of food and saliva beneath denture base.
  • Prevents excess impression material from running down the patient’s throat.

11. Buccal frenum:

• The buccal frenum of maxilla contains Caninus or levator anguli oris.
• The buccal frenum of mandible contains Triangularis or depressor anguli oris.

12. Pterygomandibular raphe:

• It is the tendinous insertion of superior constrictors and buccinators
• It arises from the hamular process of the medial pterygoid
• Gets attached to the mylohyoid ridge

13. Fovea palatine:

• The fovea palatine are indentations near the midline of the palate formed by the coalescence of several mucous gland ducts.
• They are always on the soft palate 2mm behind the vibrating line.

14. Retromylohyoid fossa is bounded by:

• Anterior – Retro mylohyoid curtain
• Posterolateral – Superior constrictor of the pharynx
• Posteromedial – Palatoglossus and lateral surface of the tongue
• Inferior- Submandibular gland

15. Buccal frenum has the following muscle attachments:

• Levator anguli oris
• Orbicularis oris
• Buccinator

16. Buccal shelf area is bounded by:

• Medially crest of the ridge
• Distally-retromolar pad
• Laterally external oblique ridge

17. Retromolar pad:

• Contains glandular tissue and fibers of temporalis, buccinators, superior constrictor, and pterygomandibular raphe
• All these prevent the placement of extra pressure
• Functions
  • Provides peripheral seal to mandibular denture
  • Marks distal extension
  • Provides retention, stability, and support to the denture

18. Frena present:

19. Border molding:

• It is the procedure by which the entire periphery of the tray is refined
• Polyether impression material is the material of choice
• Ideal requisites
  • Should have sufficient viscosity
  • Should not be sticky
  • Should have setting time 3-5 min
  • Should not displace tissues
  • Should be easily trimmed
  • Should retain its flow properties

20. Advantages of ZOE paste include:

• Accurate borders are formed since the material is more plastic in nature.
• Does not absorb the mucous secretion produced in the palate and thus accurately records the palatal part of the impression.
• Does not require a separating medium.

21. Modiolus is a point where eight muscles meet at the Angle Mouth:

• Depressor anguli oris (or) tringularis
• Levator anguli oris or canines
• Risorius
• Orbicularis oris
• Buccinators
• Zygomaticus major
• Quadratus labii superioris
• Quadratus labii inferioris

22. Snow shoe effect:

• The denture base should cover as much denture-bearing area as possible
• It results in the distribution of forces over a wider area
• Leading to the reduction of force per unit area
• Called snowshoe effect

Impression And Mouth Preparation Short Essays

Question 1. Pre-prosthetic surgical management in complete denture
(or)
Pre-prosthetic surgery
Answer:

1. Bony Surgeries:

1. Excision of the torus:
   • Tori are small bony projections of unknown etiology
   • They gradually increase in size
   • It should be excised because mucosa over tori is more prone to irritation
2. Alveoloplasty:
   • It is done to reduce severe undercuts or bilat- eral moderate undercuts
3. Reduction of genial tubercle or Reduction of mylohyoid ridge:
   • Sometimes these become very prominent due to ridge resorption
   • They should be removed if there occurs re- peated ulceration, loss of peripheral seal
4. Maxillary tuberosity reduction:
   • It is easy to correct wide tuberosity compared to the large tuberosity
   • It should be evaluated radiographically before surgical correction

2. Soft Tissue Surgeries:

1. Removal of redundant crystal soft tissue:
   • Crystal soft tissue may interfere with the stability of the denture so it should be removed
2. Frenectomy
   • It is indicated in case of
     • High frenal attachment which cannot be relived by large labial notch
     • Hypertrophic lingual frenum
3. Excision of epulis
   • Epulis is the hyperplastic reaction of the mucosa occurring along the borders of the denture
   • Treated with excision of the tissues and shortening and smoothening of dentures

Question 2. Mucostatic impression.
Answer:

Mucostatic Impression:

• It is an impression technique used in complete denture patients based on theory of impression-making.
• By Richardson
• The impression is made with the oral mucous membrane & the jaws in a normal relaxed condition
• The material Of Choice is impression plaster
• Border moulding is not done here
•  Tray Used: Oversized tray
•  Retention: Due to interfacial surface tension

Significance of Mucostatic impression:

• Closely adapted denture
• Good stability of the denture

Disadvantages of Mucostatic impression:

• Poor peripheral seal
• Poor retention
  • Synonym: Passive impression as the impression is made in rest position of oral tissues

Question 3. Posterior palatal seal area
Or
Definition & functions of the posterior palatal seal.
Answer:

Posterior palatal seal Definition:

The soft tissues at or along the junction of the hard & soft palates on which pressure within the physiological limits of the tissues can be applied by a denture to aid in retention of the denture

• Functions of Posterior Palatal Seal:
  • Aids in retention
  • Maintain constant contact with soft palate during functions
  • Reduces gag reflex
  • Prevents formation of gap between denture & pal- ate during function
  • Prevents food accumulation
  • Compensate for polymerization shrinkage
• Parts of Posterior Palatal Seal:
  • Pterygomaxillary seal
  • Postpalatal seal

Methods To Record It:

• Conventional approach
• Fluid wax technique
• Arbitrary scraping of the master cast
• Extended palatal technique

Question 4. Methods of recording posterior palatal seal
Answer:

1. Conventional method

Fabricate trial base using shellac base plate or self-cure resin

• The posterior palatal area is wiped with gauze
• T burnisher is used to locate the hamular notch by palpating posteriorly to the maxillary tuberosity on both sides
• The full extent of the hamular notch is marked with in- delible pencil
• The posterior vibrating line is marked
• Line marked in the hamular notch is connected with a posterior vibrating line
• The trial base is inserted into the patient’s mouth
• Markings are transferred to the trial base is seated on the master cast
• This transfers the markings to cast
• The trial base is trimmed to the posterior border Anterior vibrating line is marked in the patient’s mouth
• These markings are transferred to the cast The area between the anterior and posterior vibrating line is scrapped

2. Fluid wax technique:

• Wash impression is made
• Anterior and posterior vibratory lines are marked in the patient’s mouth
• The impression is re-inserted in the patient’s mouth
• Markings are transferred into impression The impression is painted with wax in the area of markings
• The impression tray is inserted in the patient’s mouth and the patient is asked to make rotational movements
• The impression is removed after 4-6 minutes and examined
• In contrast to green stick compound, glossy areas show tissue contact
• The procedure is repeated till even tissue contact is achieved
• Wax in the region of the anterior vibrating line should have a knife-edge margin

3. Arbitrary scrapping of master cast:

• In this technique, anterior and posterior vibratory lines are visualized in patient’s mouth and ap- proximately marked overcast
• Technician scrapes 0.5-1 mm of stone in posterior palatal seal area and fabricates the denture

Impression And Mouth Preparation Viva Voce

1. The anterior portion of the lingual flange is called Dublin- goal crescent area
2. The hamular notch determines the distolateral termination of the denture base
3. Posterior vibrating line marks most distal extension of the denture
4. The mid-palatine raphe is the most sensitive part of the palate
5. Retromolar pad aids in the stability of the denture
6. The mandibular denture border should not interfere with the opening of Wharton’s duct
7. The anterior lingual border is the secondary peripheral seal area for the mandibular denture
8. Primary impression can be made using impression compound, impression plaster, or alginate
9. Secondary impression can be made using ZOE im- impression paste, medium-bodied elastomeric impression material
10. Underextension of the peripheral border of mandible- lar denture affects the stability
11. Flabby tissue will interfere with the stability of the denture
12. Passive impression or mucositis or pressure-less impression technique records the tissues with minimal distortion and causes the least possible displacement of tissues.
13. Silicone or metallic oxide paste or rubber base materials are used in a custom tray during the final impression.
14. A wax spacer is used to provide space in the tray for the final impression material
15. The selective pressure technique is the most widely respected and accepted theory by transferring load to acceptable areas.