Sainavle

Laboratory Procedures Prior To Try In Short Answers

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

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

Question 2. Compensatory curves.
Answer:

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

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

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

Question 3. Color selection of teeth.
Answer:

Color For Anterior Teeth:

Age:

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

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

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

Read And Learn More: Prosthodontics Question And Answers

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

Question 5. Neutral zone.
Answer:

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

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

Question 6. Shortcomings of plane line articulator.
Answer:

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

Question 7. Incisal guidance.
Answer:

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

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

Question 8. Condylar guidance.
Answer:

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

Question 9. Hinge axis
Answer:

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

Question 10. Posterior teeth form.
Answer:

Factors Effecting Posterior Teeth Form:

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

1. Cusp teeth:

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

2. Cuspless teeth:

• Have no cuspal angulation
• Very flexible to set

Question 11. Anatomic teeth.
Answer:

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

Advantages of Anatomic teeth.:

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

The disadvantage of Anatomic teeth.:

Difficulty In Teeth Arrangement

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

Question 12. Advantages of an adjustable articulator.
Answer:

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

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

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

Question 14. Bilabial sounds.
Answer:

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

Question 15. Hanau articulator.
Answer:

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

Parts:

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

Question 16. Beyron’s point.
Answer:

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

Laboratory Procedures Prior To Try In Long Essays

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

Articulator Definition:

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

Articulator Classification:

1. Based on theories:

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

Read And Learn More: Prosthodontics Question And Answers

2. Based on the type of occlusal record used:

• Interocclusal record adjustment
• Graphic record adjustment

3. Based on the ability to stimulate jaw movements:

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

4. Based on adjustability:

• Nonadjustable
• Semi adjustable
• Fully adjustable

Uses:

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

Semi-Adjustable Articulator:

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

Types of Articulators:

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

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

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

Anterior Teeth Selection:

Size: Methods:

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

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

Anatomical Landmarks:

1. Size of maxillary arch:

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

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

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

 

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

4. Theoretical concepts:

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

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

5. Others:

• Size of face
• Interarch distance
• Lip length

6. Color:

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

7. Form:

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

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

8. Dentogenic concept (SPA concept):

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

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

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

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

Functions of articulator :

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

Requirements of articulator : Requirements of articulator

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

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

Posterior teeth Size:

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

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

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

2. Form:

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

Maxillomandibular Relations Long Essays

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

Maxillomandibular Relations Definition:

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

Methods Of Recording Of Vertical Jaw Relations:

1. Methods to measure vertical jaw relation at rest:

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

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

Read And Learn More: Prosthodontics Question And Answers

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

2. Vertical jaw relations at occlusion:

 Mechanical methods:

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

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

3. Physiological methods:

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

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

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

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

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

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

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

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

Balanced Occlusion Definition:

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

” Factors Affecting Balanced Occlusion:

1. Condylar guidance:

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

2. Incisal guidance:

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

3. Occlusal plane:

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

4. Cuspal angulation:

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

5. Compensatory curves:

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

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

Centric Jaw Relation:

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

Jaw Relations & Methods To Record Them:

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

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

Pressureless Method [Nick & Notch]:

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

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

Jaw Relations:

Any relation of the mandible to the maxilla

Jaw Relation Classification:

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

Centric Jaw Relation:

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

Centric Jaw Relation Significance:

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

Centric Jaw Relation Methods Of Recording It:

1. Physiological methods:

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

2. Centric Jaw Relation Functional method:

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

3. Centric Jaw Relation Graphic method:

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

4. Centric Jaw Relation  Radiographic method:

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

Balanced Occlusion Definition:

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

Balanced Occlusion Functional Objectives:

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

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

Centric Relation Importance:

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

Centric Relation Validity:

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

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

1. Significance of Physiological Rest Position:

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

2. Effects of Increased Vertical Dimensions:

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

3. Effects of Decreased Vertical Dimensions:

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

Maxillomandibular Relations Short Essays

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

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

Parts of Face Bow:

1. U-shaped frame:

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

2. Condylar rods:

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

3. Bite fork:

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

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

4. Locking device:

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

5. Orbital pointer:

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

Question 2. Balanced Occlusion.
Answer:

Balanced Occlusion Definition:

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

Types of Balanced Occlusion:

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

Read And Learn More: Prosthodontics Question And Answers

Laws Of Balanced Articulation:

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

Factors Influencing Balanced Occlusion:

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

How Balance Is Achieved:

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

Question 3. Nonbalanced occlusion.
Answer:’

It is arrangement Of teeth With Form or purpose

Nonbalanced occlusion General Considerations:

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

Nonbalanced occlusion Concepts:

1. Pound’s concept:

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

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

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

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

Orientation Jaw Relation:

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

Face Bow:

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

Parts:

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

Types:

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

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

Question 4. Occlusal rims.
Answer:

Occlusal rims Definition:

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

Factors Controlling It:

1. Relationship of natural teeth to the bone:

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

2. Relationship of occlusal rims to edentulous ridge:

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

3. Standard dimensions:

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

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

4. Clinical guidelines:

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

5. Techniques for fabrications:

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

Impression And Mouth Preparation Short Answers

Question 1. Buccal shelf area
Answer:

Area of Buccal shelf :

Between buccal frenum & anterior border of the masseter

Boundaries of Buccal shelf :

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

Significance of Buccal shelf :

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

Question 2. Ridge Augmentation
Answer:

Definition:

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

Methods of Ridge Augmentation:

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

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

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

Question 4. Mylohyoid ridge  importance
Answer:

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

Read And Learn More: Prosthodontics Question And Answers

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

These are those areas where stresses are directed are right angle

Significance:

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

Primary Stress-Bearing Areas In Maxilla:

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

Primary Stress Bearing Areas In Mandible:

• The postero-lateral slopes of the residual alveolar ridge

Secondary stress-bearing area:

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

Question 6. Retromolar papilla
Answer:

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

Question 7. Objectives of complete denture impressions
Answer:

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

Question 8. Diagnostic casts.
Answer:

Requirements:

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

Uses:

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

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

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

Question 10. Retention in maxilla
Answer:

Retention factors present in maxilla are

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

Question 11. Maxillary anatomical structures
Answer:

Limiting structures:

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

Supporting structures:

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

Question 13. Final impression methods in complete denture
Answer:

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

Question 14. Realeff effect
Answer:

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

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

Factors Affecting Realeff Effect

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

Question 15. Materials used for master impression.
Answer:

Requirements:

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

Materials Used:

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

Question 16. Anterior & posterior vibrating lines.
Answer:

1. Anterior Vibrating Lines:

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

Method to Measure:

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

2. Posterior Vibrating Line:

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

Method to Measure:

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

Question 17. Modiolus.
Answer:

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

They are:

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

Question 18. Hamular notch.
Answer:

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

Significance:

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

Question 19. Retromylohyoid fossa.
Answer:

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

Boundaries:

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

Question 20. Syneresis & imbibition.
Answer:

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

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

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

Impression And Mouth Preparation Long Essays

Question 1. Define impression. Discuss in detail the most widely accepted technique of making an impression in complete dentures.
Answer:

Impression:

A complete denture impression is a negative registration of the entire denture bearing, stabilizing & border seal areas present in the edentulous mouth.

Impression Techniques:

1. Mucostatic
2. Mucocompressive
3. Selective pressure technique
   • It is the most widely accepted impression technique
   • In this technique, forces are confined to stress-bearing areas whereas non-stress-bearing areas are relived

Technique:

• Primary impression is made with overextended borders Primary cast is prepared from it
• Undercuts are blocked with wax on cast Relief wax is adapted over relief areas on cast
• A spacer is adapted throughout the extent of the special tray
• Separating media like cold mold seal or tin foil is applied over cast
• Special tray with a handle is fabricated
• It should be 2 mm short of sulcus
• Materials used for it are: Shellac, cold cure acrylic, Type II impression compound
• Wax spacer is then scraped off
• Border moulding is done using greenstick compound
• Relief wax is removed
• Escape holes are made over the tray
• Secondary impression material is loaded over the tray
• It is then seated in the patient’s mouth and the secondary impression is made.

Materials Used:

Question 2. Define impression.
Or
Discuss various impression procedures in the complete denture.
Or
Add a note on selection of impression materials.
Answer:

Impression:

A complete denture impression is a negative registration of the entire denture bearing, stabilizing & border seal areas present in the edentulous mouth.

Impression Procedures:

1. Custom Tray Impression:
   • Design a custom tray with a spacer
   • It should be 2 mm short of sulcus
   • Border molding is done
   • It results in recording the sulcus in dynamic function
   • Spacer is scraped
   • The impression is recorded by ZOE
   • It results in recording the stress-bearing areas un- der pressure & non stress-bearing ares are relieved.
2. Tray Compound:
   • The impression made using tray impression compound
   • The impression is refined & trimmed
   • The metal wire is attached to tray compound to act as a handle
   • Treat it as a custom tray
   • Border molding done
   • Wash impression is made over it

Read And Learn More: Prosthodontics Question And Answers

Selection Of Materials:

• They should be fluid enough to adapt to oral tissues
• Should be viscous enough to be contained in the tray that is seated in the mouth
• While in the mouth, they should set into a rubbery or rigid solid in a reasonable amount of time
• The set impression should not tear or distort when removed
• The impression made should be dimensionally stable
• Stability should be maintained after the removal of a cast so that a second or third cast can be made
• The material should be biocompatible
• It should be cost-effective
• Should be nontoxic
• Should be acceptable to patients with pleasant odor and color
• Should have adequate shelf life Easy to use with minimum equipment Should have adequate strength

Question 3. Define retention, stability, and support in the complete denture. Discuss various factors affecting retention.
Or 
Define complete denture retention. Enumerate various factors of retention.
Or
Write in detail about retention in complete dentures.

Answer:

• Retention: That quality inherent in the prosthesis which resists the force of gravity, adhesiveness of foods, and the forces associated with the opening of the jaws
• Stability: The quality of the denture to be firm, steady & constant, to resist displacement by functional stresses & not to be subject to change of position when forces are applied
• Support: Resistance to vertical forces of mastication, occlusal forces & other forces applied in a direction toward the denture-bearing area

Factors Affecting Retention:

1. Anatomical factors:

• Size of denture bearing area:
  • The retention increases with an increase in the size of the denture-bearing area
  • Maxillary dentures are more retentive than mandibular as it has 24 cm² compared to that 14 cm²

• Quality of denture bearing area:
  • Displaceability of the tissues influences the retention of denture
  • Displacement of tissues during impression making
  • Result in tissue rebounding
  • Leads to loss of retention of dentures

2. Physiological factors:

• Saliva:
  • Thick & ropy saliva-loss of retention
  • Thin & watery saliva- compromised retention
  • Ptyalism- gagging
  • Xerostomia-Soreness & irritation

3. Physical factors:

• Adhesion:
  • The physical attraction of unlike molecules to one another
  • The amount of adhesion present is proportional to the denture base area
  • In xerostomia there is no adhesion

• Cohesion:
  • The physical attraction of like molecules for each other
  • Act within the film of saliva
  • Watery serous saliva- more retentive

• Interfacial surface tension:
  • The tension or resistance to separation possessed by the film of liquid between two well-adapted surfaces
  • Present within film of thin saliva
  • Useful in retention of the maxillary denture
  • Depends on the presence of air at the margins of liquid & solid contact

• • To attain maximum interfacial tension
  • Saliva should be thin
  • Perfect adaptation
  • Covering large denture area
  • Presence of good cohesive & adhesive forces

• Capillarity attraction:
  • That quality or state, because of surface tension causes elevation or depression of the surface of a liquid that is in contact with a solid
  • Presence of close adaptation between denture & the mucosa increases surface contact
  • Results in an increase in retention
  • Factors:
    1. Close adaptation
    2. Greater surface area
    3. A thin film of saliva
• Atmospheric pressure & peripheral seal:
  • It prevents air entry between the denture & soft tissue
  • To obtain it denture borders should rest on soft & resilient tissues
  • On application of forces, a vacuum has created that aid in retention
  • This is a natural suction of denture
  • It is directly proportional to the denture base area

4. Mechanical factors:

• Undercuts
• Retentive springs
• Magnetic forces
•  Denture adhesives
• Suction chambers & suction discs

5. Muscular factors:

• The balance should be between the forces acting from the buccal musculature & tongue

Question 4. Define complete denture impression. Discuss impression theories & techniques in treating complete denture patients.
Answer:

Complete Denture Impression:

A complete denture impression is a negative registration of the entire denture bearing, stabilizing & border seal areas present in the edentulous mouth.

Impression Theories:

1. Mucostatic Impression:

• By Richardson:
  • The impression is made with the oral mucous meme- brane & the jaws in a normal relaxed condition
  • The material of choice is impression plaster

2. Mucocompressive Impression:

• By Carole Jones:
  • Records oral tissues in a functional & displaced form
  • Dentures made by this technique tend to get displaced due to the tissue rebound at rest
  • This leads to residual ridge resorption

3. Selective Pressure Theory:

• By Boucher:
  • The impression is made to extend over as much denture-bearing area as possible without interfering with the limiting structures at function & rest
  • Forces are confined to the stress-bearing areas
  • Non-stress-bearing areas are relieved

Techniques of Impression:

1. Custom Tray Impression:

• Design a custom tray with a spacer
• It should be 2 mm short of the sulcus
• Border molding is done
• It results in recording the sulcus in dynamic function
• Spacer is scraped
• The impression is recorded by ZOE
• It results in recording the stress-bearing areas un- der pressure & non stress-bearing ares are relieved

2. Tray Compound:

• The impression made using tray impression compound •
• The impression is refined & trimmed
• The metal wire is attached to the tray compound to act as a handle
• Treat it as a custom tray
• Border moulding done
• Wash impression made over it

Question 5. Define impression. Discuss biological considerations for a maxillary impression.
Answer:

Complete Denture Impression:

A complete denture impression is a negative registration of the entire denture bearing, stabilizing & border seal areas present in the edentulous mouth.

Biological Considerations:

• The anatomy of the edentulous ridge in the maxilla is important in designing of complete denture
• Some parts of the ridge are capable of withstanding forces compared to others
• Thus it is considered before impression making

Limiting Structures:

• Labial frenum:
  • It is limiting structure of the Maxilla & Mandible
  • It is a fibrous band
  • Covered by mucous membrane
    • Extention: Labial aspect of residual ridge to lip
    • Maxillary: Passive due to absence of muscle fibres

Recorded In Impression:

Recorded in impression as a V shaped notch

• Requirement: Notch should be narrow & deep

• Labial vestibule:
  • That portion of the oral cavity which is bounded on one side by the teeth, gingival & alveolar ridge & on the other side by the lips & cheeks
  • Presence of orbicularis oris
  • It has an indirect displacing effect on the denture
•  Buccal frenum:
  • It separates the labial & buccal vestibule
  • Muscles attachments present: Levator anguli oris, orbicularis oris & buccinator
  • It needs greater clearance on the buccal flange of the denture

• Buccal vestibule:
  • It extends from buccal frenum to the hamular notch
  • Its size varies with: contraction of muscle, the position of mandible & amount of bone loss in maxilla
• Hamular notch:
  • Depression present between maxillary tuberosity & hamulus of medial pterygoid plate
  • Can be easily displaced to achieve posterior pala tal seal

Supporting Structures:

1. Primary Stress Bearing Areas:

•  Hard palate:
  • Trabeculae pattern of it perpendicular to direction of forces acting on it
  • Thus it acts as primary stress-bearing area

• Postero-lateral slopes of residual ridge:
  • Ridge rapidly resorbs following extraction of teeth
  • Resilient submucosa over it provides support to the denture

2. Secondary Stress Bearing Areas:

1. Rugae:
   • It is a secondary support area in maxilla
   • It is covered by thin mucosa

1. • Location:
     1. In the anterior region of the palatal mucosa
     2. At the angle of occlusal plane of the residual ridge
   • Significance: Important in speech
   • Precautions During Fabrication:
     1. Should not distort this area while impression making
     2. Metal denture should reproduce this area to make it comfortable
2. Maxillary tuberosity:
   1. Bulbous extension of residual alveolar ridge in 2nd 3rd molar region
   2. It is least likely to resorb

Relief Areas:

• Incisive papilla
• Location:
  • Midline behind central incisors
• Reason for Relieving:
  • It is exit point of nasopalatine nerves & vessels
  • If it is not relieved it compresses vessels & nerves
• Results:
  • Necrosis of the area
  • Paraesthesia of the anterior palate

1. Cuspid eminence:

• Bony elevation on residual alveolar ridge
• Location: between canine & 1st premolar

2. Mid-palatine raphe:

• Median suture area
• As it is covered by thin mucosa, it should be relieved

3. Fovea palatine:

• Coalescence of ducts of mucous glands
• Determines position of the posterior border of denture
• Relieved because of presence of ducts

Question 6. Describe mandibular anatomical structures.
Answer:

Limiting Structures:

• Labial frenum:
  • Active due to the presence of muscle incisive & orbicularis oris
  • It is fibrous band
  • Covered by mucous membrane
  • Extention: labial aspect of the residual ridge to lip
  • Recorded In Impression: Recorded in impression as a V-shaped notch
  • Requirement: Notch should be narrow & deep
    
• Labial vestibule:
  • That portion of oral cavity which is bounded on one side by the teeth, gingiva & alveolar ridge & on the other side by the lips & cheeks
  • Influences retention of dentures
• Buccal frenum:
  • Contains fibres of the buccinator
  • Prevent displacement of denture

Buccal vestibule:

• • Extends from buccal frenum to retromolar region
  • Bound by alveolar ridge & buccinator
  • Influenced by masseter
  • Notch is produced in denture flange called masseteric notch
• Lingual frenum:
  • Effects stability of denture high frenal attachment is called tongue tie

Alveololingual sulcus:

• Has 3 regions:

1. 1. Anterior region
      • From lingual frenum to pre-mylohyoid fossa
   2. Middle region
      • From pre-mylohyoid fossa to the distal part of mylohyoid ridge
   3. Posterior region
      • In the region of retro mylohyoid fossa
      • Determines lateral throat form

• Retromolar pad:
  • Forms posterior seal of denture
  • Location: Distal to the third molar
  • Consists of: Loose connective tissues, mucosal glands
  • Boundaries:
    1. Posteriorly: temporalis
    2. Lateral: buccinator
    3. Medial: Pterygomandibular raphe & superior constrictor

• Pterygomandibular raphe:
  • Extend: Hamular process to mylohyoid ridge
  • Muscles attached:
    • Postero- medially- superior constrictor
    • Antero-laterally-buccinator

Supporting Structures:

1. Buccal shelf area:

• Between buccal frenum & anterior border of the masseter
• Boundaries:
  • Medial: crest of the ridge
  • Distal: retromolar pad
  • Lateral: external oblique ridge
• Significance: Width increases with resorption of ridge
• Serves as primary stress bearing area

2. Residual alveolar ridge:

• Flat with concave denture-bearing surface
• On resorption inclines outward

Relief Areas:

 Mylohyoid ridge:

• Lies close to the inferior border of the mandible
• Covered with mucosa so should be relieved

3. Mental foramen:

• Location: Between 1st & 2nd premolar region
• Relieved as it may lead to paraesthesia

4. Genial tubercle:

• Location: anterior on the lingual side of body of the mandible
• Increases due to resorption

5. Torus mandibularis:

• Location: on lingual side near premolar region (b)
• Covered by a thin mucosa
• Relieved or surgically removed

Question 7. Discuss principles & objectives of making impressions for completely edentulous patients.
Or
What are the objectives of impression making
Answer:

Principles Of Impression Making:

1. Presence of healthy oral tissues
2. Inclusion of all supporting & limiting tissues
3. Borders within anatomical and physiological limitations
4. Border molding – physiological type
5. Space between material & tray
6. Not damaging the tissues
7. Application of selective pressure technique
8. Use of guiding mechanism
9. Use of dimensionally stable materials
10. Similarity to the form of dentures

Objectives Of Impression Making:

1. Retention:

“That quality inherent in the prosthesis which resists the force of gravity, adhesiveness of foods, and the forces associated with the opening of the jaws”.

• Factors:

1. 1. Anatomical factors:
      • Size of denture-bearing area
      • Quality of denture-bearing area
   2.  Physiological factors:
      • Saliva
   3.  Physical factors:
      • Adhesion
      • Cohesion
      • Interfacial surface tension
      • Capillary attraction
      • Atmospheric pressure
   4. Mechanical factors:
      • Undercuts
      • Retentive springs
      • Magnetic forces
      • Denture adhesives
      • Suction chambers & suction discs
   5. Muscular factors:

• • • The balance should be between the forces acting from the buccal musculature and tounge

2. Stability:

• The quality of the denture to be firm, steady & constant, to resist displacement by functional stresses & not to be subject to change of position when forces are applied
• It withstands horizontal forces
  • Factors:
    1. The vertical height of the residual ridge
    2. Quality of soft tissue
    3. Quality of impression
    4. Occlusal rims
    5. Teeth arrangement
    6. Shape of denture

3. Support:

• Resistance to vertical forces of mastication, occlusal forces & other forces applied in a direction toward the denture-bearing area
• The denture base should cover as much denture-bearing area as possible
• Results in the distribution of forces over wider area
• This leads to a reduction of force per unit area

Called Snow Shoe Effect:

4. Aesthetics:

• Thicker flange leads to fullness of the mouth

5. Preservation of Remaining Structures:

• Muller stated that the preservation of what remains is more important rather than to replace what is lost.
• Stress is provided over the stress-bearing area.
• Relief is provided over non-stress-bearing areas.
• Prevent damage to oral structures.
• Avoid overextension of dentures.

Question 8. Define stability & discuss factors affecting it.
Answer:

Stability:

• “The quality of denture to be firm, steady & constant, to resist displacement by functional stresses & not to be subject to change of position when forces are applied”.
• It withstands horizontal forces

Factors:

1. Vertical height of residual ridge:

• A ridge with an adequate height of ridge provides sufficient support
• Resorbed ridge causes loss of stability or reduced stability of the denture

2. Quality of soft tissue:

• Adequate submucosa is required for good stability
• Excessive submucosa results in poor stability

3. Quality of impression:

• The impression should be:
  • Accurate
  • Smooth surface
  • Devoid of voids
  • Not wrap on removal Dimensional stable

4. Occlusal plane:

• Should be parallel to ridge
• Should divide interarch space equally

5. Teeth arrangement:

• Teeth are arranged in a neutral zone
• That is balance is achieved in between tongue & buccal musculature

6. Shape of denture:

• Polished surface should resemble oral structures
• Should not interfere with the functioning of oral structures

 Complete Dentures Short Answers

Question 1. Parts of complete denture
Answer:

1. Denture base: The part of a denture that rests on the foundation tissues and to which teeth are attached
2. Denture flange: The part of a denture base that extends from the cervical ends of the teeth to the denture border
3. Denture borders: The margin of the denture base at the junction of the polished surface and impression surface
4. Denture teeth: They function to improve esthetics, phonetics, and mastication

Question 2. Steps in the fabrication of complete denture
Answer:

• Diagnosis and treatment planning
• Making diagnostic casts
• Mouth preparation
• Primary impression
• Primary cast
• Fabrication of custom trays
• Secondary impression
• Master cast
• Fabrication of occlusal rims
• Recording jaw relations
• Articulation
• Arrangement of artificial teeth
• Try in
• Processing of denture
• Insertion
• Post-insertion review and maintenance

Question 3. Effects of aging.
Answer:

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

Question 4. Metal dentures.
Answer:

Indications of Metal dentures:

• Tooth supported dentures
• Reduced interocclusal space
• High occlusal forces
• Acrylic allergy

Advantages of Metal dentures:

• Improved retention & stability
• Improved thermal conductivity
• Comfortable for patients
• Easy to maintain

Read And Learn More: Prosthodontics Question And Answers

Disadvantages of Metal dentures:

• Difficult to reline
• Trimming is difficult
• Difficult to correct underextensions
• Fewer aesthetics

Question 5. Gagging
Answer:

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

Causes of Gagging:

• Over-extended denture borders
• Unstable occlusal conditions
• Systemic conditions
• Alcoholism, smoking

Features of Gagging:

• Causes displacement of denture
• Triggered by tactile stimulation of the soft palate, posterior part of the tongue & fauces

Site of Gagging:

• Posterior part of the maxillary denture
• Distolingual part of mandibular denture

Gagging Treatment:

• Correction of overextended dentures
• Correction of occlusal vertical dimensions and occlusal prematurities

Question 6. Angular cheilitis.
Answer:

Etiology:

• It occurs at the angle of the mouth among persons having deep commissural folds secondary to the overclosure of the mouth
• It can occur among persons with lip-licking habits, denture-wearing, or deficiency of riboflavin, vitamin B_12, and folic acid

Angular cheilitis Clinical Features:

• The infection starts due to the colonization of fungi in the skin folds following the deposition of saliva due to re-peated lip-licking
• Patients often have soreness, erythema, and fissuring at the corner of the mouth
• In some cases, it may extend over the adjacent skin sur- faces

Angular cheilitis Treatment:

• Lip balm
• Topical antiseptics
• Topical antifungal cream
• Topical steroid ointment
• Nutritional supplements

Question 7. Kelly’s combination syndrome.
Answer:

It was identified by Kelly in 1972 in patients wearing a maxillary complete denture opposing a mandibular distal extension prosthesis

Pathogenesis:

• It occurs in a sequential manner
• The patient tends to concentrate the occlusal load on  remaining natural teeth
• Results in more force acting on the anterior portion of the maxillary denture
• Increased resorption of the anterior part of the maxilla
• The labial flange will displace and irritate labial vestibule • Posteriorly there will be fibrous overgrowth in maxillary tuberosity
• The shift of occlusal plane posteriorly downwards pro- duces resorption in the mandibular distal extension denture-bearing area
• Mandible shifts anteriorly during occlusion
• There is
  • Decrease in vertical dimension at occlusion
  • Decrease in retention and stability of a denture
  • Disocclusion of lower anterior
  • Reduced periodontal support of anterior teeth

Question 8. Infection control
Answer:

Methods:

• Immunization:
  • Vaccination for Hepatitis B for all dental personnel
• Personal barrier:
  • Hand washing before gloving & after degloving
  • Gloves Protect against contamination
  • Changed between patients & for the same patient is torn or worn out
    • Face mask:
      1. Protects from inhalation of aerosols
      2. Prevents spatter from patient’s mouth
      3. Prevents droplets from contaminated solution
      4. Protective clothing
      5. Gown with long sleeves, high neck & long knee length
    • Eyewear:
      1. Prevention of bacterial/viral contact
• Surgical asepsis:
  • Preparation of surgical site
  • Draping the patient
  • Isolation
• Surface asepsis:
  • Sterilization of instruments
  • Use of disposable instruments
• Disposal of waste: Methods
  • Incineration
  • Burial in a landfill
  • |Sterilization

Question 9. Hypermobile ridge tissue.
Answer:

Hypermobile ridge tissue Cause:

• Due to excessive residual ridge resorption Management:
• Small tissues which do not interfere with tissue functioning:
  • Left untreated: Impression is made using the mucositis technique
  • Large tissues: removed surgically

Question 10. Polished surface.
Answer:

• It is defined as that portion of a surface of a denture that extends in an occlusal direction from the border of the denture and includes the palatal surfaces
• It is the part of the denture base which is usually polished and it includes the buccal and lingual surfaces of the teeth
• It refers to the external surfaces of the lingual, buccal, and labial flanges and the external palatal surface of the denture
• It should be well polished and smooth to avoid the collection of food debris
• It should be harmonious with the oral structures
• They should not interfere with the action of oral mus- culture

Question 11. Denture irritation hyperplasia.
Answer:

The hyperplastic reaction of 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

Question 12. Xerostomia.
Answer:

It refers to a subjective sensation of a dry mouth, but not always, associated with salivary hypofunction

Etiology:

1. Developmental:
   1. Salivary gland aplasia
2. Water/metabolic loss:
   • Impaired fluid intake
   • Hemorrhage
   • Vomiting/diarrhea
3. Latrogenic:
   • Medications:
     • Antihistamines: Diphenhydramine
     • Decongestants: Pseudoephedrine
     • Antidepressants: Amitriptyline
     • Antipsychotic: Haloperidol
     • Antihypertensive: Methyldopa, CCB
     • Anticholinergic: Atropine
4. Radiation therapy of head & neck:
   1. Both stimulated & unstimulated salivary flow decreases with increasing radiotherapy.
   2. Systemic Diseases:
      • Sjogren’s syndrome
      • Diabetes mellitus
      • Diabetes insipidus
      • HIV infections
      • Psychological disorders.
      • Graft-versus-host disease
5. Local factors:
   • Decreased mastication.
   • Smoking
   • Mouth breathing

Question 13. Functions of saliva.
Answer: 

Question 14. Combination syndrome.
Answer:

It was identified by Kelly in 1972 in patients wearing a maxillary complete denture opposing a mandibular distal extension prosthesis

Pathogenesis:

• It occurs in a sequential manner
• The patient tends to concentrate the occlusal load on re- remaining natural teeth Results in more force acting on the anterior portion of the maxillary denture
• Increased resorption of the anterior part of the maxilla
• The labial flange will displace and irritate the labial vestibule Posteriorly there will be fibrous overgrowth in the maxillary tuberosity
• The shift of occlusal plane posteriorly downwards pro- duces resorption in the mandibular distal extension denture-bearing area
• Mandible shifts anteriorly during occlusion
• There is
• Decrease in vertical dimension at occlusion
• Decrease in retention and stability of the denture
• Disocclusion of lower anterior
• Reduced periodontal support of anterior teeth