Prosthodontics

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

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.”

Removable Partial Dentures Long Essay

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

Read And Learn More: Prosthodontics Question And Answers

1. 1. 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:

Indirect Retainers 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:

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

Types Of Indirect Retainers:

1. Auxillary Occlusal Rest:

• Auxillary Occlusal Rest is located on the occlusal surfaces away from the distal extension base
• Auxillary Occlusal Rest 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:

• Occlusal Rest is a finger-like extension from a premolar rest is placed on the lingual slope of the adjacent canine
• Occlusal Rest 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

Removable Partial Denture Prosthodontics Notes

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:

Direct Retainers Definition:

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

Direct Retainers 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 dislodging forces are present
2. Retention:
   • It is that quality inherent in the prosthesis that 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/Maker’s Clasp

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

Maker’s Clasp Advantages:

• Maker’s Clasp is easy to fabricate and repair
• Maker’s Clasp leads to less food retention
• Maker’s Clasp can be best applied in a tooth-supported partial denture
• Provides excellent support and retention

Maker’s Clasp Disadvantages:

• Maker’s Clasp 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
• Maker’s Clasp 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 dentures
• This classification is anatomical
• In Kennedy’s classification, he included 4 classes Further, 2 additional classes were included by Apple-gate

Applegate Kennedy’s 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:
  • The unilateral edentulous area located posterior to the remaining natural teeth
  • There is a single edentulous space located in the posterior region without any teeth posterior to it.
• Class 3:
  • Unilateral edentulous area with natural teeth anterior and posterior to it.
  • It indicates a single edentulous area that does not cross the 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 Kennedy’s Applegate’s Rules:

1. Rule One: Classification should follow rather than preceed 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.

RPD Prosthodontics Long Questions

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

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

• • Carbon Markers:
    • Carbon Markers resemble the lead points
    • Carbon Markers are used to draw height of contour of the object
  • Undercut Gauges:
    • Undercut Gauges 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
• Surveying 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
• Surveying 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
  • Surveying is locked to the vertical arm with the help of a thumb screw Next, the cast is analyzed by using different analyzing tools

Components of Removable Partial Dentures Essay

Analyzing Tools:

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

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

Tripoding:

• Tripoding 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 the 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:

Major Connectors 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

Classification of RPDs in Prosthodontics

Selection Of Direct Retainer For RPD:

Type of direct retainer is selected according to the following condition

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

Definition of Direct Retainer:

Direct Retainer is defined as “A clasp or attachment placed on an abutment tooth for the purpose 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”

Retentive Arm Parts:

1. Retentive Clasp Arm:
   • It is not flexible
   • It is located above the height of the contour
2. Retentive Terminal:
   • It is flexible
   • It is located below the height of the 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”
• Reciprocal Arm is located on the opposite side of retentive arm
• Reciprocal Arm is placed above the height of the contour
  • Reciprocal Arm Functions:
    • Acts as an indirect retainer
    • Reciprocal Arm can resist the rocking of the denture base
    • Reciprocal Arm provides stability and reciprocation against the retentive arm
    • The denture is stabilized against horizontal movement

3. Retentive Arm Shoulder:

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

4. Retentive Arm Body:

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

5.Retentive Arm Rest:

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

6. Minor connector:

• Minor Connector 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
• Minor Connectror 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 :

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

Disadvantages of Stress Breaker:

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

Types of Stress Breakers:

1. Stress Breakers 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
• This joint may either be a Hinge or a ball and socket or a sleeve and cylinder
• Example: DALBO

2. Stress Breakers Type 2:

• Stress Breakers has flexible connections between the direct retainer and the denture base
• Stress Breakers 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. Extracorporeal 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”
   • Extracorporeal Direct Retainer includes:
     • Suprabulge clasps
     • Infrabulge clasps
2. Intracoronary Direct Retainer:
   1. In it, a part or the whole of the retentive components are located within the anatomic contour of the abutment teeth
      • 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
  • Clasps prevents the rotation of the denture
  • They approach the undercut from an occlusal direction
• Occlusally Approaching Clasps Advantages:
  • Clasps is easy to fabricate and repair
  • Clasps leads to less food retention
  • Clasps can be best applied in a tooth-supported partial denture
  • Provides excellent support and retention
• Occlusally Approaching Clasps Disadvantages:
  • Clasps 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 record 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 this, 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
  • Hindle’s is loaded with impression material
  • Hindle’s 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 to 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 surface of a framework using low-fusing modeling plastic
  • It is tempered and placed in the mouth
  • Sufficient pressure is applied
  • The modeling plastic at the borders of the framework is re-softened
  • Border molding is carried out
  • Modelling plastic is reduced by 1 mm
  • The final impression is made with zinc oxide eugenol impression paste.

• Fluid Wax Functional Impression:
  • The metal framework is fabricated using a refractory cast
  • Fluid Wax is tried in the 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 the 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
  • Selective Pressure is loaded with impression material
  • Selective Pressure is inserted in the patient’s mouth
  • Pressure is applied over the stress-bearing area.

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

Components Of Removable Partial Denture:

1. Removable Partial Denture Major Connector:

• A removable Partial Denture 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”.
• Removable Partial Denture is the largest and most important component of the removable partial denture
• Removable Partial Denture forms the basic framework.

2. Removable Partial Denture Ideal Requirements:

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

3. Removable Partial Denture 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. Removable Partial Denture Location:

• Removable Partial Denture should be placed free of movable tissue
• Removable Partial Denture 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 the case of the mandibular arch

5. Removable Partial Denture Functions:

• Removable Partial Denture connects all the components of RPD
• Removable Partial Denture provide indirect retention

6. Removable Partial Denture Minor connector:

• Removable Partial Denture 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. Removable Partial Denture 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.

Removable Partial Denture 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 rRest –  They are placed along with the clasp assembly
  • Secondary/Auxillary rest – These are the one placed for indirect 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:

• Direct Retainer 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:

• Direct Retainer prevents the displacement of the denture
• Direct Retainer provides retention through the retentive arm of the clasp
• All components of the clasp except the retentive arm provide stability
• Direct Retainer resist the movement of the denture against the path of insertion
• Direct Retainer 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:

Indirect Retainer 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”.’

Functions Of Indirect Retainers:

• Indirect Retainers counteract the lifting forces and stabilize the denture
• Indirect Retainers counteract horizontal forces and provide stability and support to the denture
• Indirect Retainers can splint and protect the anterior teeth
• Indirect Retainers 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:

Denture Base 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 a framework for tooth adaptation
• Restores the contour of the edentulous ridge

6. Artificial Teeth 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

Maxillary Major Connector Types Features and Indications:

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

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

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

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

Anterior Posterior bar Design Procedure:

• Step 1-Outline the stress-bearing area
• Step 2- Outline the non-stress-bearing area
• Step 3 – Outline the extend of the 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
• Circumferential Clasp prevents the rotation of the denture
• They approach the undercut from an occlusal direction

Circumferential Clasp Advantages:

• Circumferential Clasp is easy to fabricate and repair
• Circumferential Clasp leads to less food retention
• Circumferential Clasp can be best applied in a tooth-supported partial denture
• Provides excellent support and retention

Circumferential Clasp Disadvantages:

• Circumferential Clasp 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
• Circumferential Clasp cannot be used for cases with an undercut away from edentulous space

2. Bar Clasp:

• Bar Clasp is an infra bulge clasp
• Bar Clasp approaches the undercut gingivally
• Bar Clasp has a push type of retention

Bar Clasp Parts:

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

Bar Clasp Advantages:

• Bar Clasp Is easy to Insert
• It is more esthetic

Bar Clasp Disadvantages:

• Bar Clasp tends to collect food debris
• Bar Clasp has reduced bracing and stabilization
• Bar Clasp 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
  • The presence of impacted teeth and submerged root stumps should be examined

2. Derived Diagnosis:

Derived Diagnosis is obtained from a diagnostic cast that is obtained from a diagnostic impression.

Derived Diagnosis 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

Derived Diagnosis 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

Derived Diagnosis 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

Lingual Bar Design Advantages:

• Lingual Bar Design is easy to fabricate
• Lingual Bar Design has mild soft tissue contact

Lingual Bar Design Disadvantages:

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

2. Lingual Plate Design:

• The superior border extends up to the 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

Lingual Plate Design 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

Lingual Plate Design Advantages:

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

Lingual Plate Design 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

Double Lingual/Kennedy Bar Design Indications:

• Large embrasures cases
• Large diastema cases

Double Lingual/Kennedy Bar Design Advantages:

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

Double Lingual/Kennedy Bar Design Disadvantages:

• Tongue interference
• Food entrapment

4. Sublingual Bar:

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

Sublingual Bar Indications:

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

Sublingual Bar Contraindications:

• Lingual tori
• High frenal attachments

5. Cingulum Bar:

• The Cingulum Bar is located on or slightly above the cingula of the anterior teeth

Cingulum Bar Indications:

• Large embrasures cases
• Large diastema cases

6. Labial Bar:

• Placed on the labial surface
• Labial Bar is similar to the lingual bar, but broader and thicker

Labial Bar Indications:

• Lingually inclined teeth
• Presence of tori

Labial Bar Disadvantages:

• Poor esthetics
• Distort the lower lip
• Patient discomfort

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

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 at least 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 Occlusal Approaching And Gingival Approaching Clasp:

Post-Insertion Problems Long Essays

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

Instructions for Insertion And Removal:

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

Maintenance Of Prosthesis:

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

Read And Learn More: Prosthodontics Questions And Answers

Night Wear Of Prosthesis:

• Avoid nightwear or dentures
• Allowed to wear only in Brussels
• 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 adapt to the denture.

Post Insertion Problems in Complete Dentures

Post Insertion Problems: Post insertion is

• Direct Sequelae
• Indirect Sequelae

Direct Sequelae:

1. Denture Stomatitis:

Denture Stomatitis is the pathological reaction of the palatal portion of the denture-bearing mucosa

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

• Denture Stomatitis Etiology:
  • Candida albicans
• Denture Stomatitis 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
• Denture Stomatitis Management:
  • 0.2-2% chlorhexidine
  • Removal and cleaning of dentures after every meal
  • Avoid wearing dentures
  • Polishing of denture
  • Administration of antifungal drugs
  • Surgically: Elimination of crypts, by cryosurgery

Complete Denture Complications After Insertion

2. Flabby Ridge: Replacement of bone by fibrous tissue

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

3. Denture Irritation Hyperplasia:

• The hyperplastic reaction of the mucosa over the borders of the denture
• Denture Irritation Hyperplasia Cause: Trauma due to unstable dentures
• Denture Irritation Hyperplasia Features:
  • Deep ulceration
  • Fissuring
  • Inflammation
• Denture Irritation Hyperplasia 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

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

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

• Gagging Treatment: Limiting the posterior extension of the dentures

Denture Insertion Follow-Up Guide

6. Residual Ridge Resorption:

• Residual ridge resorption is alveolar remodeling that occurs due to a change in the functional stimulus of bone tissue
• Residual ridge resorption is a chronic progressive change in the bone structure, which results in severe impairment in the fit & function of the prosthesis
• Residual Ridge Resorption Cause: Excessive forces over non-stress bearing areas, causing activation of osteoclasts
• Residual Ridge Resorption Clinical Features:
  • Decreased depth and 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

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

Common Denture Problems and Solutions

Indirect Sequel:

1. Atrophy Of Masticatory Muscles:

• Masticatory efficiency depends on the skeletal forces
• This force decreases with age
• Besides, denture wearers do not use their muscles to their maximum function
• Due to poor usage, atrophy of the muscle occurs
• Common Muscles Affected: Medial pterygoid and masseter
• Muscle Management:
  • Use of an overdenture
  • Use of implants

2. Nutritional Deficiencies:

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

Nutritional Deficiencies Management:

• Intake of a 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

Prosthodontics Notes on Denture Adjustment

Post Insertion Problems Short Essays

Question 1. Denture adhesive.
Answer:

Denture Adhesive Composition:

1. Basic Ingredients:
   • Carbonyl methylcellulose
   • 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. Denture Adhesive  Indications:
   • Improve the 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. Denture Adhesive  Contraindications:
   • Patients with ill-fitting dentures
   • In medication-induced xerostomia
   • In worn-out dentures
   • As a substitute for a recliner
   • In patients with an inability to clean dentures
   • In immediate dentures
   • In case of allergy to components of the adhesive

Introduction to Laboratory Procedures

Laboratory procedures before try-in are critical for ensuring successful outcomes in dental prosthetics. This guide provides essential questions and answers regarding these procedures.

Complete Denture Wax Try-In Procedure

Laboratory Procedures Before Try In Short Answers

Question 1. Pre-Extraction Guides In The Selection Of Teeth.
Answer:

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

Read And Learn More: Prosthodontics Question And Answers

Question 2. Compensatory curves.
Answer:

The anteroposterior and lateral curvatures in the alignment of the occluding surfaces and incisal edges of artificial teeth 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 five factors
• The effect of incisal and condylar guidance must counteract the effect of the other three factors
• If the balance is lost, balanced occlusion cannot be achieved

Pre-Try-In Lab Procedures in Prosthodontics

Question 3. Color selection of teeth.
Answer:

Color For Anterior Teeth:

Age:

• Young people have lighter teeth
• Old people have Dark teeth
• More shiny
• Brownish tinge
• Habits Smoker’s porcelain teeth
• Complexion teeth selected in harmony with

Question 4. Factors in denture design affecting speech.
Answer:

• Denture wearers have shallow pronunciation In dentulous patients, rugae enhance speech
  • In a denture wearer speech is affected due to the absence of rugae
  • The use of metal dentures improves speech
  • Injury to the external laryngeal nerve
  • Presence of tongue tie

Production Of Various Sounds:

1. Bilabial-b, p, m
2. Labiodental-f, v
3. Linguodental- th
4. Linguoalveolar-t, d, s, z, v, 1
5. ‘s’ sound is controlled by the anterior part of the palatal plate of the denture base

Question 5. Neutral zone.
Answer:

• Neutral Zone is the potential space between the lips and cheeks on one side and the tongue on the other side
• An area or position where the forces between the tongue and 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 the tongue space

Essential Lab Steps Before Denture Try-In

Question 6. Shortcomings of the plane line articulator.
Answer:

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

Question 7. Incisal guidance.
Answer:

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

• The second factor of occlusion
• Customized
• If overjet increases, it decreases. If overbite increases, it increases
• If incisal guidance is steep, steep cusps, a steep occlusal plane, and steep compensatory curves are required
• Incisal Guidance must be as flat as possible

Question 8. Condylar guidance.
Answer:

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

Question 9. Hinge axis
Answer:

• The Hinge Axis is also known as the transverse axis
• The 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 Affecting Posterior Teeth Form:

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

Wax Try-In in Complete Dentures – FAQ

1. Cusp Teeth:

• They have cusps and fossae-like natural teeth
  • Anatomic teeth
    1. Resemble normal, newly erupted teeth
    2. Have the best aesthetics
    3. Havea  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 and 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 resembles 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 and incisal guidance

Record Base and Wax Rim Preparation

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 neutralize the forces from the 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
• If 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:

• Hanau Articulator is a semi-adjustable articulator
• Hanau Articulator accepts face bow transfer
• Hanau Articulator is capable of hinge and lateral movements

Hanau Articulator 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 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 a 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 a 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 the 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 external auditory meatus
• This is called Beyron’s point
• The placement generally locates the rods within 5 mm of the true 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’s horizontal plane
• The anterior reference point is
• 7 mm from orbitale
• 25 mm from nasion
• 18 mm from the inner canthus of the eye
• 43 mm superior to the tip of the central incisors

Essential Laboratory Procedures Before Try-In Conclusion

Understanding laboratory procedures before try-in is vital for dental professionals. This question and format provides quick insights into best practices in the field.

Laboratory Procedures Before 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 the other side

Read And Learn More: Prosthodontics Question And Answers

Laboratory Procedures Before 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 the fixed horizontal axis
  • Semi-adjustable – have adjustable horizontal condylar paths, adjustable lateral condylar paths, and adjustable intercondylar distances
  • Fully adjustable – capable of being adjusted to follow the mandibular movements in all directions

Laboratory Procedures Before Wax Try-In

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 of the curve of the lower lip
     3. Rotated distal surfaces of central
     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 is hidden by central
     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 interarch 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

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
• Sodium Alginate 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 ketogenic 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 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 dentures are inserted in the mouth and checked for extension, retention, and stability of dentures
• When both trial dentures are in the mouth, the following four aspects of the dentures may be assessed in turn:
  1. Occlusal relations: Vertical, anteroposterior, and coronal intermaxillary relations are checked for
  2. Occlusal planes: For evaluating the incisal plane, left and right posterior occlusal planes, and the 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.

Complete Denture Wax Try-In Preparation

Question 4. Try the procedure.
Answer:

Try In:

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

Try In Features: It includes following procedures

1. Primary Evaluation:
   • Check for adaptation of denture base
   • Evaluation of 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 surfaces for the absence of voids
   • Evaluate the 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 extraorally by interpupillary line and Camper’s line
   • Evaluate centric and eccentric relation

Custom Tray Fabrication in Complete Dentures

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

Arcon articulators have adjustable horizontal condylar paths, adjustable lateral condylar paths, adjustable incisal guide tables and 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
     • Arcon Articulator Examples: Whip mix articulator:
2. Non-Arcon Articulator:
   • This articulator has a condylar element attached to the upper member
   • The condylar guidance is attached to the lower member
   • Non-Arcon Articulato is the reverse of TMJ
     • Non-Arcon Articulato Examples: Hanau H series:

Question 6. Principles in teeth arrangement.

Answer:

1. Maxillary Central Incisor:

• The 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 the 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:

• The 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

Record Base and Wax Rims in Complete Dentures

5. Maxillary Second Premolar:

• Long axis parallel to the vertical axis
• Both cusps touch occlusal plane

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

6. Maxillary First Molar:

• The 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 the first molar but at a higher level

8. Mandibular Central And Lateral Molar:

• The long axis is parallel to the vertical axis and sloping labially
• Incisal edge 2 mm above occlusal plane

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

9. Mandibular Canine:

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

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

10. Mandibular First Premolar:

• Long axis parallel to vertical axis and sloping lingually
• Lingual cusp below the 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 and sloping lingually
• Both cusps are 2 mm above the occlusal plane

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

12. Mandibular First And Second Molar:

• The long axis parallel to the vertical axis and slopes lingually
• All cusps above the occlusal plane
• Mesial and lingual cusps at a lower level

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

Pre-Try-In Lab Steps in Prosthodontics

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 the 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 ketogenic concept is given by Frush and Fischer
7. Artificial teeth must be arranged on a neutral zone

Laboratory Procedures Before Trying Long Essays

Question 1. Define articulator. Give classification, uses, and 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”.

Laboratory Procedures Before Wax Try-In

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

Articulator Uses:

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

Complete Denture Wax Try-In Preparation

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 articulator is open or closed
• Examples: Whip mix articulator:

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

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

Anterior Teeth Selection:

Size: Methods:

• Pre-Extraction Records:
  • Diagnostic cast- prepared before the extraction of teeth
  • Photographs- showing frontal and lateral views
  • 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
  • The total width of the lower anterior: 4/5 of the width of the upper anterior. By H. Pound

Record Base and Wax Rims in Complete Dentures

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

Anatomical Landmarks:

1. Size Of Maxillary Arch:

• Distance between the incisive papilla and the hamular notch on one side.
• Distance between the two hamuli notches.
• Total width of all anterior and posterior

• Canine Eminence: Distance between two canine eminences combined width ofthe  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 the perioral tissues and arrange the teeth
  • Psychological: Camper’s line is used for it
    1. Raised by happy people
    2. Depressed downward in depressed people
  • Biomechanical: Placement of teeth in the neutral zone
    
• Typal Form Theory (Leon Williams): The shape of teeth inverse the shape of the face

• Temperamental Theory:
  • People based on mental, functional, and physical characteristics contain teeth
• Concept Of Harmony:
  • The size of the  teeth corresponds to the size of the head

5. Others:

• Size of face
• Interarch distance
• Lip length

6. Color:

• Age
• Young people have lighter teeth
• Old people – dark teeth
• More shiny
• Brownish tinge
• Habits – smokers’ porcelain teeth
• Complexion- teeth selected in harmony with the complexion
• The colour of the 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
• Form Example: Oval teeth for oval face
  1. (a) Square
  2. (b) Oval
  3. (c) Tapering
  4. (d) combination

Custom Tray Fabrication in Complete Dentures

• Patient’s profile
• It can be convex, concave, or straight
• The labial form of the anterior is 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 the plane of the curve of the lower lip
    3. Rotated distal surfaces of central
    4. The visible mesial third of canines
    5. Exposure to more interiors while smiling
  • Males: More angular teeth
    1. Incisal edges are above the plane of occlusion
    2. The mesial end of the laterals is hidden by the central
    3. The middle 2/3rd of the canine is visible
    4. Prominent cervical regions

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

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

Question 3.Given its functions and requirements of an articulator.
Or
Requirements of the 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:
   • The articulator should hold casts in the correct horizontal relationship
   • The articulatorshould hold casts in the correct vertical relationship
   • The casts should be easily removable and re-attachable
   • The articulator should provide a positive anterior vertical stop
   • The articulator should accept the face bow transfer record using an anterior reference point
   • Articulator should open and close in a hinge movement
   • Articulator should be made of non-corrosive and rigid materials that resist wear and tear
   • Articulator 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 nonmoving parts should be of a rigid construction
2. Additional Requirements:
   1. Condylar guides should allow protrusive and lateral 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 and retromolar pad

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

Steps Before Wax Try-In in Prosthodontics

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 the 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 the various techniques of recording it.
Or
Methods of recording vertical dimension.
Answer:

Maxillomandibular Relations Long Essays

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

Read And Learn More: Prosthodontics Question And Answers

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 and other over the chin
  • The patient is asked to perform various functions Distance between the two reference points is 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 the eye and corners of the mouth
  • Anterior nasal spine and lower border of the mandible
  • Anatomical Landmarks is measured
  • If they are equal, jaws are at rest

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

Centric Relation in Complete Dentures Essay

2. Vertical Jaw Relations At Occlusion:

• 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 the mandibular rim
  5. Soften the wax
  6. Ask the patient to bite over it
  7. Remove it and articulate

• Physiological Rest Position (Niswonger And Thomson): 
  1. Seat the patient
  2. Ask him to swallow and relax
  3. Part the lips slightly
  4. Space exists between the upper and 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

Vertical Dimension of Occlusion in Prosthodontics

Then a+b+c. The vertical dimension at rest is equal to the sum of the vertical dimension at occurrence and free way space

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

• Aesthetics:
  • The size of teeth assessed from the residual ridge resorption
• Swallowing Threshold:
  • The 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 bearing 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 comfortable

Long Essay on Jaw Relations in Complete Dentures

Question 2. Define balanced occlusion. Discuss in detail the factors affecting balanced occlusion in complete dentures.
Or
Define balanced occlusion. Write in detail about various factors affecting it.
(or)
Define balanced occlusion. Explain its significance. Write in detail about various factors affecting it.
Or
Factors affecting 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 concerning the supporting structures

Factors Affecting Balanced Occlusion:

1. Condylar Guidance:

• The first factor of occlusion to be considered
• Measured using protrusive registration
• Increased 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 mandibular 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 the lower canine should coincide with a measure of the mouth
• It should not be altered beyond 10°
• A posterior plane parallel to the 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 deep bite

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 And 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 And 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

Prosthodontics Essay on Maxillomandibular Relations

Centric Jaw Relation:

The maxillomandibular 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

Centric Jaw Relation Significance:

• Proprioceptive impulses guide the mandible during various movements
• In edentulous patients, it is possible from the impulses of PDL
• But in edentulous patients, it is not possible
• In such cases, impulses are received from our transferred to TMJ
• Centric relation acts as a 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 a centric relation
  • Occlusal rims are sealed in this position
• Pressure Method:
  • Upper occlusal rim is inserted into 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:

• Centric Jaw Relation utilizes the functional movements of the jaw to record centric relation
  • Needlehouse method
  • Patterson method

3. Centric Jaw Relation Graphic method:

• Centric Jaw Relation 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:

• The smaller the area of the occlusal surface, the lesser the transmission of forces to the supporting structures
• A tilted occlusal surface causes, nonvertical forces on the denture
• Tilted tissue support causes nonvertical forces on the denture
• Vertical forces on resilient tissues cause lever forces on the denture
• Vertical forces outside the ridge cause tipping of the denture
• The 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 patients, it is not possible In such cases, impulses received from the ridge are transferred to TMJ
• Centric relation acts as a center for such impulses
• Centric Relation guides the mandible during such movements

Centric Relation Validity:

• Learnable
• Repeatable
• All functional movements are possible from this position
• The arrangement of muscles is 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 passed 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, and 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
• This 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 the 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 the face bow
Answer:

Definition Of Face Bow:

A caliper-like 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:

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

Read And Learn More: Prosthodontics Questions And Answers

2. Condylar Rods:

• Condylar rods are 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 it to the condylar shaft in the articulator

3. Bite Fork:

Bite Fork is U 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 a stem

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

Prosthodontics Notes on Jaw Relations

4. Locking Device:

• The locking Device helps to attach the bite fork to the U-shaped frame
• The locking Device supports the face bow and occlusal rim, and is cast during articulation
• The locking Device 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:

• Orbital Pointer 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 concerning the supporting structures”.

Types Of Balanced Occlusion:

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

Laws Of Balanced Articulation:

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

Factors Influencing Balanced Occlusion:

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

Complete Denture Maxillomandibular Relations

How Balance Is Achieved:

• The incisal and condylar guidance produces an increase in posterior separation
  While other three factors i.e., occlusal plane, cervical angulation, and compensatory curves, cause a decrease in posterior separation.
• The effect of incisal and condylar guidance should counteract the other three factors to obtain a balanced occlusion

Question 3. Unbalanced occlusion.
Answer:

Unbalanced Occlusion is an arrangement of teeth with a Form or purpose

Unbalanced 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

Unbalanced Occlusion Concepts:

1. Pound’s Concept:

• Proposed importance of phonetics & aesthetics for anterior teeth
• While posterior teeth should have a sharp upper lingual cusp & wide lower central fossa
• Lingualized occlusion
• A triangle is formed between the mesial end of the canine & the two sides of the retromolar pad

2. Hardy’s Concept: Proposed a flat occlusal plane with non-anatomical 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

Centric Relation in Complete Dentures

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

Face Bow Parts:

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

Face Bow 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 their 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

Vertical Dimension of Occlusion Essays

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

Occlusal Rims Factors Controlling It:

1. Relationship Of Natural Teeth To The Bone:

• Rims should be parallel to the long axis of the teeth to be replaced
• The maxillary anterior is labially inclined, and the posteriors are vertically placed

2. Relationship Of Occlusal Rims To Edentulous Ridge:

• The 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, 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 is determined by the amount of separation of the jaws
4. Horizontal Jaw Relation: It is the relationship of the mandible to the maxilla in the horizontal plane
5. Centric Jaw Relation: The maxillomandibular 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 6.
6. Face Bow: A calliper-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
7. Occlusal Rim: Occluding surfaces built on temporary or permanent denture bases to make maxillomandibular relation records & arrange 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 and 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 concerning the supporting structures

Read And Learn More: Prosthodontics Question And Answers

Maxillomandibular Relations Important Notes

1. Types Of Jaw Relations:

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

Maxillomandibular Relations Notes

2. Dimensions  Of Maxillary Occlusal Rim

• 22 mm – at canine eminence
• Anterior edge of the occlusal rim at midline – 8 mm away from incisive papilla
• Width
  • In anterior region – 4-6 mm
  • In the posterior region, 8-12 mm
• Occlusal table
  • Above the crest of the alveolar ridge in the anterior region, 10-12 mm
  • From the crest of the alveolar ridge in posterior region – 5-7 mm
  • From the depth of the sulcus in the 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 the 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

4. Freeway Space:

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

5. Gothic Arch Tracing:

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

Complete Denture Maxillomandibular Relations

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 from 1 to 4 mm in dimension.

7. Progressive Side Shift Or Bennett Side Shift:

• The lateral translation continues linearly after 2-3mm of forward movement of the nonworking condyle.

8. Beyron Point:

• Beyron Point 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:

• A face bow is a caliper-like instrument used to orient the maxillary cast on the articulator so that it has the same relationship 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 the average computation of an axis opening of the jaw.
• FaceBow 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
   • Extraoral
   • 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 and speech
• Pain & clicking in TMJ
• Stretching of facial muscles
• Increased space of the oral cavity

Question 2. Interocclusal recording media
Answer:

Commonly Used Materials For Inter-Occlusal Recording Are:

Question 3. Christenson phenomenon.
Answer:

• The 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

Prosthodontics Notes on Jaw Relations

Question 4. Lingualized occlusion
Answer:

• Proposed by Alfred Gysi in 1927, it involves the use of a large upper palatal cusp against a wide lower central fossa
• The buccal cusps of the 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:

• The Interpupillary Line is used for evaluation of the occlusal plane extra orally
• The Interpupillary Line 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:

An Arbitrary Face Bow 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

Arbitrary Face Bow Types:

• Facia type
• Earpiece type
• Hanau face bow
• Slidematic-type 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:

• Gothic Arch Tracing is used for recording centric relation
• Gothic Arch Tracing is usually recorded in the horizontal plane
• Gothic Arch Tracing 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.

Vertical Dimension of Occlusion PDF

1. Petterson and Needlehouse are functional methods of recording centric relation
2. Intraoral tracing contains a central bearing plate and a central bearing point tracer
3. The graphic method is an accurate method of recording centric relation
4. Orientation jaw relation is related to the cranium
5. 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 the buccal frenum and the 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

Read And Learn More: Prosthodontics Question And Answers

Impression and Mouth Preparation in Complete Dentures

Question 2. Ridge Augmentation
Answer:

Ridge Augmentation 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

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

• Cohesion is the physical attraction of like molecules to each other
• Acts within the film of saliva
• Normal quality and adequate quantity of saliva are 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 an increase in the thickness of saliva

Question 4. Mylohyoid ridge  importance
Answer:

• The mylohyoid Ridge is a rough bony crest extending from the third molar to the 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 towards the tongue

Short Questions on Mouth Preparation and Impressions

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

These are those areas where stresses are directed at are right angle

Question 6. Retromolar papilla
Answer:

• Retromolar Papilla is described as a pear-shaped papilla. It is a small elevation
• Retromolar Papilla is a residual scar formed after the extraction of the third molar
• Retromolar Papilla  lies along the line of the ridge
• The denture should terminate at the distal end of the pear-shaped papilla
• Being in 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.

BDS Prosthodontics Viva on Impressions

Question 8. Diagnostic casts.
Answer:

Diagnostic Casts Requirements:

• Diagnostic Casts Should Be:
  • Free of voids
  • Smooth surface
  • Provide good denture support
  • Walls should be tapering outward
  • Smooth tongue space
  • Free of moisture
  • The occlusal table is parallel to the floor.

Diagnostic Casts 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 and ropy saliva, loss of retention
• Thin and watery saliva compromised retention
• Watery serous saliva is more retentive
• In xerostomia there is no adhesion
• Ptyalism leads to gagging
• Xerostomia: Soreness and irritation

Question 10. Retention in the  maxilla
Answer:

Retention factors present in the maxilla are

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

Impression Techniques in Complete Dentures

Question 11. Maxillary anatomical structures
Answer:

Question 13. Final impression methods in complete denture
Answer:

1. Dry gauze is placed on the 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 the mouth using the anterior handle
5. The tray is seated completely by applying alternating pressure over the posterior handles
6. The patient is asked to touch his upper lip with his tongue
7. Passive movements are performed
8. After the material gets set and examined for any defects

Question 14. Realeff effect
Answer:

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

• The oral mucosa is displaceable and compressibl.e Hanau described this factor as “resiliency and like effect”- Realeff effect
• It plays an important role in all steps of complete denture fabricate,on 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 the Real Effect

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

Question 15. Materials used for the master impression.
Answer:

Master Impression Requirements:

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

Master Impression Materials Used:

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

Question 16. Anterior and posterior vibrating lines.
Answer:

Question 17. Modiolus.
Answer:

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

Modiolus Are:

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

Question 18. Hamular notch.
Answer:

• The Hamular Notch is the depression situated between the maxillary tuberosity and the hamulus of the medial pterygoid plate. It is a 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

Hamular Notch Significance:

• The denture border should extend to 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

Complete Denture Pre-Prosthetic Steps

Question 19. Retromylohyoid fossa.
Answer:

• The Retromylohyoid Fossa belongs to the posterior part of the alveolar lingual sulcus
• Retromy lohyoid Fossa lies posterior to the mylohyoid muscle

Retromylohyoid Fossa Boundaries:

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

Question 20. Syneresis and imbibition.
Answer:

• The process of water sorption by hydrocolloids is known as imbibition
• Syneresis is a process where the gel may lose 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:

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

Impression And Mouth Preparation Definitions

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

Read And Learn More: Prosthodontics Question And Answers

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.

Mouth Preparation in Complete Dentures

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:

6. Relief Areas:


7. Anterior Vibrating Line:

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

Pre-Prosthetic Surgery for Complete Dentures

8. Posterior Vibrating Line:

• Posterior Vibrating Line is an imaginary line at the junction of the aponeurosis of the tensor veli palatini and a muscular portion of the soft palate
• Posterior Vibrating Line represents the demarcation between the parts of the soft palate showing limited movements and those with marked movements
• Posterior Vibrating Line 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 the 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 the denture to ensure a complete seal that helps in the retention of the denture.
  • Prevents the ingress of food and saliva beneath the 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:

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

13. Fovea Palatine:

• The fovea palatine is are indentations near the midline of the palate formed by the coalescence of several mucous gland ducts.
• The fovea palatine is 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:

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

Complete Denture Mouth Preparation Steps

17. Retromolar Pad:

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

18. Frena Present:

19. Border Molding:

• Border molding 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 a setting time of 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 the snowshoe effect

Prosthodontics Mouth Preparation Guide

Impression And Mouth Preparation Short Essays

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

Question 2. Mucostatic impression.
Answer:

Mucostatic Impression:

• Mucostatic impression is an impression technique used in complete denture patients based on the 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 molding 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
  • Mucostatic Synonym: Passive impression, as the impression is made in the rest position of oral tissues

Question 3. Posterior palatal seal area
Or
Definition and 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 the retention of the denture

• Functions Of Posterior Palatal Seal:
  • Aids in retention
  • Maintain constant contact with the soft palate during functions
  • Reduces gag reflex
  • Prevents the formation of a gap between the denture and palate during the 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 the posterior palatal seal
Answer:

1. Conventional Method

Fabricate a trial base using a 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 posterior to the maxillary tuberosity on both sides
• The full extent of the hamular notch is marked with a delible pencil
• The posterior vibrating line is marked
• The 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 the 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 scraped

Oral Preparation Before Complete Dentures

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 the 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 the 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 the patient’s mouth and ap- approximately marked overcast
• The technician scrapes 0.5-1 mm of stone in the posterior palatal seal area and fabricates the denture