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COMPLETE DENTURES (CD)

1. What is the neutral zone and what is its clinical significance in complete denture fabrication?
2. Describe the Hanau's quint and explain how each factor affects complete denture occlusion.
3. What is compensating curve? Differentiate between curve of Spee and curve of Wilson.
4. Explain the concept of "closest speaking space" (Silverman's space) and its role in determining vertical dimension of occlusion.
5. What are the factors affecting retention of complete dentures? How does post-dam enhance retention?
6. Describe the neutral zone technique - indications, armamentarium, and procedure.
7. What is flabby ridge? How do you manage it during impression making?
8. Differentiate between anatomic, semi-anatomic, and non-anatomic teeth. When would you select each?
9. Explain balanced occlusion in complete dentures. How does it differ from bilateral balanced occlusion?
10. What are the causes, diagnosis, and management of denture stomatitis?

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REMOVABLE PARTIAL DENTURES (RPD)

1. Describe Kennedy's classification with Applegate's rules. Give two clinical examples each for Class I and Class II.
2. What is a surveyor? Explain the uses of a dental surveyor in RPD design.
3. Describe the components of a clasp assembly. What are the differences between circumferential and bar clasps?
4. What is reciprocation in RPD design? Differentiate between active and passive reciprocation.
5. Explain the concept of "path of insertion" vs "path of displacement." How do you alter the path of insertion?
6. What are the biomechanical principles governing extension base RPDs? What is the difference between Class I and Class II lever systems?
7. Describe the RPI clasp system - components, advantages, and when you would use it.
8. What are the different types of connectors used in maxillary vs mandibular RPDs? Give indications for each.
9. Explain the concept of "stress-breaker" in RPD design. Types, advantages, and disadvantages.
10. How do you manage an existing deep anterior guidance in a patient requiring an RPD?

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FIXED PARTIAL DENTURES (FPD)

1. What is ferrule effect? What is the minimum ferrule required for post-retained crowns and why?
2. Describe the different types of finish lines (margins) used in FPD preparation. What are the advantages and disadvantages of each?
3. What is the significance of taper (convergence angle) in tooth preparation? What is the ideal taper and what are the consequences of over/under-tapering?
4. Explain the concept of "connector design" in FPD. What are the minimum dimensions of a rigid connector?
5. What are the indications and contraindications of cantilever FPDs? How do you manage forces on the abutment?
6. Describe the Maryland bridge - retention mechanism, tooth preparation, advantages, and failure modes.
7. What is the difference between working side, non-working side, and protrusive interferences? How do you manage them in FPD?
8. Explain the selection of abutment teeth using Ante's law. What are its limitations?
9. What are the different types of pontic designs? Describe the ridge lap, modified ridge lap, and ovate pontic.
10. What is the clinical significance of biological width? How does violation of biological width affect crown margins?

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FULL MOUTH REHABILITATION (FMR)

1. What are the indications for full mouth rehabilitation? Describe the concept of "conformative" vs "reorganized" approach.
2. What is the Pankey-Mann-Schuyler (PMS) philosophy? How does it differ from Dawson's approach?
3. Explain the role of a facebow transfer in full mouth rehabilitation. Differentiate between arbitrary and kinematic facebow.
4. How do you determine and record centric relation in a full mouth rehabilitation case? Describe at least two techniques.
5. What is occlusal vertical dimension (OVD)? How do you assess and establish OVD in a collapsed bite patient?
6. Describe the diagnostic wax-up and its role in FMR treatment planning. How is it used to fabricate provisional restorations?
7. What is a "mutually protected occlusion"? Contrast it with group function occlusion in terms of FMR outcomes.
8. How do you sequence the treatment in full mouth rehabilitation? What is the significance of the anterior/posterior sequencing debate?

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IMPLANTS

1. Explain osseointegration - definition, histological basis, and factors affecting it (Albrektsson's criteria).
2. What is the "implant stability quotient" (ISQ)? How is resonance frequency analysis (RFA) used clinically?
3. Describe the bone quality classification by Lekholm and Zarb. How does bone quality affect implant placement?
4. What is the platform switching concept? What are its claimed biological and prosthetic advantages?
5. Differentiate between external hex and internal connection implants. What are the biomechanical implications?
6. What are the prosthetic options for an edentulous mandible supported by implants? Compare 2-implant overdenture vs fixed hybrid prosthesis.
7. Explain the concept of immediate loading vs early loading vs conventional loading. What are the prerequisites for immediate loading?
8. What is peri-implantitis? How do you differentiate it from peri-implant mucositis? Describe management options.

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MAXILLOFACIAL PROSTHETICS

1. Classify maxillofacial prostheses. What materials are used for facial prostheses and what are the properties of silicone elastomers used in this field?
2. Describe the prosthodontic management of a patient following total maxillectomy (Brown Class IIb). What is an obturator and what are its phases?
3. What is a palatal augmentation prosthesis? What are its indications and how does it help in speech and deglutition?
4. Describe the role of osseointegrated implants in retention of auricular, nasal, and orbital prostheses. What are the site-specific considerations for each?

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Tips for the Viva

• For CD questions, always connect your answer to the biological/anatomical basis
• For RPD, draw the clasp assembly or survey lines if asked - examiners appreciate visual clarity
• For FPD, always mention biological width, emergence profile, and cementation protocols
• For FMR, know the major philosophies (Pankey-Mann, Dawson, Spear) and be able to compare them
• For implants, know Brånemark's original criteria and how contemporary protocols have evolved
• For maxillofacial, cite the Aramany classification for palatal defects and Brown classification for maxillectomy

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MDS PROSTHODONTICS - 50 VIVA QUESTIONS WITH ANSWERS

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COMPLETE DENTURES (CD)

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Q1. What is the neutral zone and its clinical significance in complete denture fabrication?

• Buccinator, orbicularis oris, and modiolus push inward
• Tongue pushes outward
• The zone between these opposing muscle forces is the neutral zone

• Artificial teeth placed within this zone experience minimal displacing forces - retention and stability are maximized
• Teeth placed buccal to neutral zone: cheeks and lips dislodge the denture
• Teeth placed lingual to neutral zone: tongue displaces the denture
• Particularly important in patients with resorbed ridges, microstomia, neurological conditions, and atypical tongue postures

1. Record the neutral zone using tissue conditioner, ZOE paste, or polyvinyl siloxane in a special tray/record base
2. The set material is used as a guide for teeth arrangement
3. Teeth are set in the space defined by the neutral zone impression

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Q2. Describe Hanau's Quint and explain how each factor affects complete denture occlusion.

"Incisal guidance varies directly with condylar guidance and cusp height, and inversely with compensating curve and the plane of occlusion."

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Q3. What is compensating curve? Differentiate between curve of Spee and curve of Wilson.

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Q4. Explain "closest speaking space" (Silverman's space) and its role in determining VDO.

• During production of sibilant sounds, the tongue tip approaches the palate just behind the upper anterior teeth
• The teeth come as close as possible without touching - usually 1-2 mm apart
• This represents the most closed position the mandible reaches during speech

• Ask the patient to say "sixty-six" or "Mississippi" repeatedly
• Observe the interincisal distance using a Boley gauge or visual assessment
• If closest speaking space = 1-2 mm: VDO is correct
• If closest speaking space > 2 mm: VDO is too low (dentures need to be increased)
• If teeth click during speech: VDO is too high

• Non-invasive method to verify VDO after denture insertion
• Can be used before denture construction in patients wearing old dentures
• Useful when other landmarks (rest position, facial measurements) are unreliable

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Q5. What are the factors affecting retention of complete dentures? How does post-dam enhance retention?

• Adhesion - molecular attraction between saliva and denture base/mucosa
• Cohesion - attraction within saliva molecules
• Interfacial surface tension - thin film of saliva resists separation (most important factor)
• Atmospheric pressure - negative pressure under the denture (acts when seal is intact)
• Capillary attraction - maintained by thin uniform saliva film

• Size and quality of basal seat (larger = better)
• Height and shape of residual ridges
• Palatal vault configuration (flat palate = poor retention)
• Muscle attachments and their proximity to denture borders

• Saliva quantity and quality (serous > mucous)
• Neuromuscular control

• Accuracy of impression and fit
• Border seal (peripheral seal)
• Denture base material and adaptation

• A ridge of acrylic or plaster placed along the posterior border of the maxillary denture
• Located at the junction of hard and soft palate (vibrating line)
• The soft tissues at this area are compressible (Ah line = 2 mm compressibility; vibrating line = 1 mm)
• Post-dam displaces soft tissue slightly, maintaining intimate contact
• Prevents air entry under the posterior border, maintaining atmospheric pressure retention
• Extent: from one hamular notch to the other, passing through the fovea palatinae

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Q6. Describe the neutral zone technique - indications, armamentarium, and procedure.

• Severely resorbed ridges (Atwood Class V and VI)
• Patients with uncontrolled muscular movements or neurological conditions (Parkinson's, stroke)
• Patients who failed with conventional dentures
• Patients with tongue that has spread to occupy the edentulous space
• Class III skeletal relationships

• Record bases with occlusal rims
• Tracing compound (green stick) or vinyl polysiloxane (addition silicone) as neutral zone material
• Tissue conditioner (VISCO-GEL, Coe-Comfort) for dynamic recording
• Inlay wax or plaster for stabilizing the record

1. Step 1 - Record VDO and CR using conventional record bases
2. Step 2 - Load neutral zone material onto the occlusal rim of the lower record base (material softened or unset PVS)
3. Step 3 - Insert in mouth at correct VDO and CR
4. Step 4 - Patient performs functional movements: swallowing, saying "ah," "ee," puffing cheeks, licking lips
5. Step 5 - Material sets - the outer surface is shaped by cheeks/lips; inner surface by tongue
6. Step 6 - Transfer to articulator - the set neutral zone record is used as a template
7. Step 7 - Set teeth within the space defined by the neutral zone record
8. Verification - compare tooth position with neutral zone index using clear acrylic template

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Q7. What is flabby ridge? How do you manage it during impression making?

• Displaces under impression material pressure - records an inaccurate/compressed position
• When pressure is removed, tissue rebounds = poor denture fit, rocking denture

1. Make a special tray with a window (hole) cut out over the flabby area
2. Make the border-molded impression of the stable areas with zinc oxide eugenol or PVS
3. Pour ZOE through the window over the flabby area - it flows without pressure (mucocompressive for stable areas, mucostatic for flabby area)

• Very low viscosity impression wax applied to flabby area with no pressure

1. First stage: Impression of firm areas using border-molded custom tray
2. Second stage: Flabby tissue recorded with light-bodied material through a window or in the tray with minimal pressure

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Q8. Differentiate between anatomic, semi-anatomic, and non-anatomic teeth. When would you select each?

• Good ridge form, adequate bone support
• Normal jaw relationships (Class I)
• Patients with good neuromuscular control
• When accurate jaw records can be obtained
• Young patients

• Moderate ridge resorption
• Slight discrepancies in jaw records
• Compromise choice

• Severely resorbed ridges (more susceptible to horizontal forces)
• Class II/III jaw relationships
• Patients with poor neuromuscular control or tremors
• Patients who cannot provide reliable jaw records
• Flabby ridges
• Lingualized occlusion scheme uses 0° lower teeth with 30° upper

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Q9. Explain balanced occlusion in complete dentures. How does it differ from bilateral balanced occlusion?

• Eliminates tipping/rocking of denture base
• Distributes occlusal forces over a larger area
• Prevents food from wedging under denture
• Improves stability during function

• Upper 30° teeth + lower 0° teeth
• Only lingual cusps of upper contact lower flat teeth
• Less horizontal force than full anatomic balance
• Reasonable esthetics and masticatory efficiency

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Q10. What are the causes, diagnosis, and management of denture stomatitis?

• Type I: Localized, pinpoint hyperemia (traumatic)
• Type II: Diffuse erythema covering the entire denture-bearing area
• Type III: Granular/papillary hyperplasia (inflammatory papillary hyperplasia)

• Candida albicans (most common - found in 90% cases; C. glabrata also implicated)
• Poor denture hygiene - plaque and biofilm accumulation on fitting surface
• Continuous denture wearing (24 hours)
• Ill-fitting dentures (trauma)
• Reduced salivary flow (xerostomia)
• Systemic factors: diabetes mellitus, immunosuppression, steroid inhalers, broad-spectrum antibiotics

• Clinical: Erythema under the denture
• Smear cytology showing pseudohyphae and blastospores
• Culture on Sabouraud's medium
• Biopsy if hyperplastic (Type III)

• Remove dentures at night (minimum 8 hours)
• Denture hygiene - brushing with soap, soaking in sodium hypochlorite (0.1%), chlorhexidine (0.12%)
• Correct ill-fitting dentures (reline/rebase or new denture)

• Nystatin - topical antifungal applied to fitting surface; 100,000 units/mL, 4x/day for 14 days; also treat dentures
• Miconazole gel - applied to fitting surface
• Fluconazole 150 mg single dose or 50 mg daily x 7-14 days (systemic, for resistant cases)

• Type III: Surgical excision of granular hyperplasia or electrosurgery before new dentures

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REMOVABLE PARTIAL DENTURES (RPD)

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Q11. Describe Kennedy's classification with Applegate's rules. Give two clinical examples each for Class I and Class II.

1. Classification should follow extraction, not precede it
2. If 3rd molar is missing and not replaced, it is not considered
3. If 3rd molar is present and to be used as abutment, it is considered
4. If 2nd molar is missing and not replaced, not considered
5. Most posterior edentulous area always determines classification
6. Edentulous areas other than the determining area are called "modifications"
7. Extent of modification area is not considered, only the number
8. Class IV has no modifications (any additional space makes it Class I, II, or III)

1. Missing teeth #17, 16, 15 and #25, 26, 27 - both sides posterior to the remaining dentition
2. Missing all mandibular molars and premolars bilaterally, canines and anteriors remaining

1. Missing teeth #14, 15, 16, 17 on left side only - with full dentition on right
2. Missing mandibular right molars (#46, 47) with intact left side and anteriors

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Q12. What is a surveyor? Explain the uses of a dental surveyor in RPD design.

• Vertical arm
• Horizontal arm
• Surveying table (tilting platform)
• Surveying tools (analyzing rod, undercut gauge, carbon marker, wax carver)

• The path of insertion is the direction along which the RPD is placed and removed
• The cast is tilted on the surveying table to find the most favorable path minimizing interferences

• The analyzing rod is replaced with an undercut gauge (0.01", 0.02", 0.03" = 0.25, 0.5, 0.75 mm)
• Determines amount of undercut on abutment teeth for clasp placement
• 0.01" (0.25 mm) = retentive undercut for cast clasps
• 0.02" (0.5 mm) = for wrought wire clasps
• 0.03" (0.75 mm) = for acrylic clasps

• Blocks out areas that would interfere with RPD insertion

• Identifies the height of contour (survey line/fulcrum line)
• Area above the survey line = suprabulge (bracing/reciprocal area)
• Area below survey line = infrabulge/undercut (retentive area)

• Carbon marker draws the survey line on each abutment tooth

• Paralleling wax rods allow blockout of non-retentive undercuts prior to duplication
• Determines amount and location of blockout

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Q13. Describe the components of a clasp assembly. Differences between circumferential and bar clasps.

1. Retentive arm - engages the undercut below the survey line; flexible; provides retention
2. Reciprocal arm - located suprabulge; rigid; opposes lateral forces from retentive arm during placement/removal
3. Rest - rigid; prevents movement toward mucosa; transmits occlusal forces to abutment tooth
4. Body/shoulder - connects the clasp to the major connector; non-flexible
5. Minor connector - joins clasp body to major connector

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Q14. What is reciprocation in RPD design? Differentiate between active and passive reciprocation.

• As the retentive arm tip traverses the height of contour during insertion/removal, it exerts a horizontal force on the tooth crown
• Without reciprocation, this force would tip the tooth in the direction of clasp approach

• The reciprocal element (arm) is in contact with the tooth at all times, including during the traverse of the retentive tip over the survey line
• Provides true simultaneous resistance
• Example: Rigid cast reciprocal arm positioned at the height of contour
• The reciprocal arm must be rigid (no flexibility); if it flexes, reciprocation is lost

• The reciprocating element is not in contact with the tooth during the critical moment when the retentive arm tip crosses the survey line
• It only contacts the tooth AFTER the retentive arm has fully engaged the undercut
• Example: Rigid lingual plate that rests in a prepared rest seat; the plate is not engaged during clasp traversal
• Less effective but sometimes used in compromised situations

• Reciprocal arm must be rigid (cast metal, not wrought wire)
• Must be located at or above the survey line
• Must contact the tooth over a broad area
• In RPI clasp: reciprocation is provided by the I-bar mesial rest and the lingual plate

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Q15. Explain "path of insertion" vs "path of displacement." How do you alter the path of insertion?

• The specific direction along which an RPD is placed onto (and removed from) the abutment teeth and residual ridges
• It is a single, definite path chosen during design
• Determined by surveying the diagnostic cast at various tilt angles

• The direction(s) in which forces tend to dislodge the RPD during function (occlusal loading, sticky foods, muscle action)
• Multiple potential paths of displacement exist (labial, buccal, lingual, inferiorly for maxillary RPD)
• Ideally, the path of insertion should differ from the most likely path of displacement

• The path of insertion IS the path of withdrawal (they are the same, opposite directions)
• Undercuts on abutment teeth relative to the path of insertion resist displacement along that same path
• Clasps provide additional resistance to displacement

1. Anterior tilt (tip anteriorly): Creates proximal undercuts on posterior abutments; useful for establishing guiding planes; may create interference anteriorly
2. Posterior tilt: Creates distal undercuts; less common
3. Lateral tilt (right or left): Creates undercuts on one side; used to equalize undercut distribution between two abutments
4. Combination tilt: Most commonly used in clinical practice

• Maximize guiding plane contact (long, parallel vertical surfaces)
• Equalize undercuts on abutments
• Minimize bone and soft tissue undercut interference
• Favorable clasp positioning (retentive undercut in desired location)
• Avoid esthetic problems from visible metal

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Q16. What are the biomechanical principles governing extension base RPDs? Class I vs Class II lever systems?

• The distal extension base is tooth-supported at one end and tissue-supported at the other
• The support is from two different tissues with different resiliency (tooth = 0.1 mm; mucosa = 0.5-2 mm)
• Under occlusal load, the base rotates around the most posterior rest = fulcrum

• Fulcrum in the middle (rest seat)
• Effort (occlusal load on extension base) at one end
• Resistance (retentive clasp arm trying to maintain contact with abutment) at the other end
• The distal extension base depresses into the tissue; the RPD framework tends to lift on the opposite side of the fulcrum, placing LIFTING force on the retentive clasp arm
• This means the clasp is STRESSED UPWARD, potentially damaging the abutment tooth
• Solution: use mesial rests, RPI clasps, stress breakers, or implant-assisted design

• Effort (load) and resistance are on the same side of the fulcrum
• Less leverage; more favorable for abutment teeth

1. Rotation around fulcrum line (most significant)
2. Horizontal movement (controlled by guiding planes)
3. Rotation around long axis of the arch
4. Rotation around vertical axis

• Use mesial rest seats (instead of distal) - shifts fulcrum anteriorly, reduces lever arm
• RPI (Rest, Proximal plate, I-bar) clasp - designed to minimize abutment stress
• Stress breakers - isolate the saddle from the framework mechanically
• Relining frequently - maintain tissue support to minimize rotation

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Q17. Describe the RPI clasp system - components, advantages, and when to use it.

1. When occlusal force is applied to the extension base, the base rotates downward (compresses tissue)
2. The I-bar tip moves AWAY from the undercut (disengages) - this is the key biomechanical advantage
3. The proximal plate also disengages slightly from the distal surface
4. This means the abutment tooth experiences MINIMAL torquing forces during function

• Least torquing force on abutment (designed to disengage under function)
• Esthetic (I-bar has minimal tooth coverage)
• Mesial rest reduces the lever arm
• Proximal plate provides excellent guiding plane and stability
• Good periodontal health (less plaque accumulation than circumferential clasps)

• All Class I and Class II RPDs (extension base situations)
• Periodontally compromised abutments (minimize forces)
• Esthetic zones where metal display is undesirable
• Short clinical crowns with limited undercut

• Deep buccal undercuts (I-bar cannot be placed)
• High frenal attachments interfering with bar path
• Shallow vestibule
• Soft tissue undercuts in the bar path

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Q18. Types of connectors used in maxillary vs mandibular RPDs. Indications for each.

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Q19. Explain the concept of "stress-breaker" in RPD design. Types, advantages, and disadvantages.

• Extension base saddles move under load (mucosal compressibility)
• If the framework is rigid, all this movement is transmitted as stress to the abutment teeth
• A stress breaker introduces a mechanical break or hinge point between the rigid framework and the extension base

• Reduces torquing forces on abutment teeth
• Beneficial for periodontally compromised abutments
• Reduces bone loss under extension base (controversial)

• Mechanically complex - more components, more potential failure points
• Difficult to clean
• Vertical support still transmitted to abutment (only torquing forces reduced)
• Increased bulk and patient discomfort
• Clinical studies have NOT consistently shown superior outcomes compared to well-designed non-stress-breaker RPDs
• Most periodontists/prosthodontists currently prefer good clasp design (RPI, mesial rests) over stress breakers

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Q20. How do you manage an existing deep anterior guidance in a patient requiring an RPD?

• During protrusion, posterior RPD teeth lose contact
• Possible dislodgment of RPD due to unilateral loading
• Increased stress on remaining anterior teeth

1. Measure the incisal guidance angle using the articulator
2. Assess whether it is natural (acceptable) or due to supraeruption, deep bite, etc.
3. Evaluate periodontal status of anterior teeth

• If anterior teeth are healthy and guidance is natural
• Set posterior RPD teeth to match existing guidance using compensating curve
• Ensure balanced occlusion is achieved with appropriate cusp heights

• If guidance is iatrogenic or excessive
• Selective reshaping of anterior teeth
• Crown placement on anterior teeth with reduced palatal inclination
• Indicated only if anterior teeth need restorations anyway

• Flat teeth are not affected by excessive incisal guidance discrepancy
• Reduces requirement for balanced occlusion

• Curve can partially compensate for steep incisal guidance

• Make provisional RPD, evaluate function, then finalize design

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FIXED PARTIAL DENTURES (FPD)

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Q21. What is ferrule effect? Minimum ferrule required for post-retained crowns and why?

• Minimum 1.5-2 mm of vertical tooth structure above the gingival finish line, circumferentially around the tooth
• This is not negotiable - without adequate ferrule, post-core-crown restorations have poor prognosis

1. Prevents wedging: The post transmits functional loads as a wedge within the root. The ferrule (metal collar) encircles and compresses the tooth structure, counteracting the wedging force
2. Distributes stress: Functional forces are distributed along the circumference of the ferrule rather than concentrating at the core-tooth junction
3. Prevents root fracture: Studies show that the FERRULE - not the post - is the primary factor in preventing root fracture
4. Resists crown removal forces: The mechanical interlock of the ferrule with tooth structure resists dislodging forces

• Sorensen and Engelman (1990) demonstrated that a 2 mm ferrule resulted in approximately 2x more resistance to fracture than no ferrule
• Post design, length, and material are SECONDARY to adequate ferrule effect

• If <1.5 mm of tooth structure remains: crown lengthening surgery or orthodontic extrusion before post-crown
• Failure to establish ferrule = predictable restoration failure

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Q22. Types of finish lines in FPD preparation. Advantages and disadvantages of each.

• Cast metal crowns: Chamfer or beveled shoulder
• PFM (metal-ceramic): Shoulder or chamfer (different margins for metal vs. ceramic areas)
  • Metal margin areas: Chamfer
  • Ceramic margin areas: Shoulder (1-1.2 mm)
• All-ceramic (zirconia, lithium disilicate): Chamfer (0.8-1 mm) or rounded shoulder (1.2 mm)
• Provisional crowns: Chamfer acceptable

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Q23. Significance of taper (convergence angle), ideal taper, and consequences of over/under-tapering.

• Adequate retention and resistance form
• Reasonable path of insertion
• Sufficient bulk of restorative material

• Retention form = resistance to removal along the path of insertion (vertical dislodgement)
• Resistance form = resistance to oblique/horizontal forces (tilting, lateral dislodgement)
• Retention is LOST first with overtapering
• As taper increases from 6° to 25°, retention drops dramatically

• Increase axial height (avoid reducing tooth excessively)
• Add grooves and boxes (increase resistance form)
• Crown lengthening surgery
• Consider smaller convergence angle

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Q24. Concept of "connector design" in FPD. Minimum dimensions of a rigid connector.

• Occluso-gingival height: 3 mm minimum (ideally 4 mm)
• Bucco-lingual width: 3 mm minimum (ideally 4 mm)
• Cross-sectional area: At least 9 mm² (ideally 12-16 mm²)

• Minimum cross-sectional area: 9 mm² (some authors recommend 12 mm² for posterior bridges)
• For zirconia: connector height ≥ 4 mm recommended

• Flexure under load transfers stress to the connectors (weakest point in FPD)
• Insufficient connector dimensions = fracture at the connector
• Most common FPD failure mode: connector fracture (especially in all-ceramic)

1. Pier abutment - middle abutment in a 5-unit FPD; if rigid connectors used, pier abutment acts as a class I lever fulcrum, placing extreme stress on the terminal abutments. Non-rigid connector breaks this force transmission
2. Tilted abutment - when abutment paths of insertion differ by >25°
3. Long-span FPD - reduces flexure stress

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Q25. Indications and contraindications of cantilever FPDs. How do you manage forces on the abutment?

• Missing maxillary lateral incisor with healthy canine and central incisor as abutments (most common)
• Missing mandibular second premolar (when first premolar and first molar are present and second molar is absent)
• Missing posterior teeth in elderly patients with intact strong abutments and minimal occlusal load
• Where a full-coverage preparation on the distal abutment would be unnecessarily destructive

• Posterior missing teeth with strong occlusal forces (bruxism, parafunctions)
• Compromised abutment (short crown, previous root canal, poor bone support)
• Long span cantilever
• Deep overbite with heavy loading on the pontic
• Young patients (high bite force)
• Patients with uncontrolled parafunction

1. Use TWO retainers (double abutment) - distributes forces
2. Occlusal reduction on pontic - reduce cusp height and occlusal table width (narrow pontic faciolingually reduces lever arm)
3. Ensure minimal occlusal contact on cantilever - light contact in ICP only; NO eccentric contact
4. Keep the cantilever SHORT - extend pontic only minimally beyond the abutment
5. Splint multiple abutment teeth if available
6. Regular monitoring - check for abutment mobility at recalls
7. Avoid in parafunctional patients or use night guard

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Q26. Describe the Maryland bridge - retention mechanism, tooth preparation, advantages, and failure modes.

• Metal wings are etched with electrolytic etching (originally) or sandblasted (now)
• Creates a microporous metal surface
• Resin cement (dual-cure composite resin) penetrates the microporosities = mechanical microlocking
• Also: adhesive resin bonding to etched enamel on abutment tooth

• Enamel reduction only (0.5 mm lingual enamel)
• Proximal guiding planes
• Occlusal rest seats (in lingual surface) to prevent rotation
• No significant tooth structure removal - conservative
• Contra-bevel on incisal edges (optional, for better retention)

• Very conservative (minimal tooth preparation)
• No local anesthesia needed in many cases
• Reversible (can be debonded)
• Good esthetics (no visible metal lingually)
• Less expensive than conventional FPD
• First-line treatment for congenitally missing lateral incisors in young patients

1. Debonding (most common) - failure at cement/metal or cement/tooth interface; seen in ~50% over 10 years
2. Porcelain fracture - if porcelain-fused wings used
3. Secondary caries - under the wing if bond fails partially
4. Caries of abutment
5. Wing fracture - if wing is too thin
6. Abutment tooth fracture (rare)

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Q27. Difference between working side, non-working side, and protrusive interferences. Management in FPD.

1. Before crown preparation: Diagnose and eliminate pre-existing interferences using selective occlusal adjustment
2. During tooth preparation: Ensure adequate occlusal reduction (1.5-2 mm) to allow ideal occlusal anatomy in restoration
3. During wax-up and try-in: Use articulating paper (thin, Bausch 8 µm) to check:
   • ICP contacts (even, light)
   • Lateral excursion: canine guidance or group function (no NWSI)
   • Protrusive excursion: anterior guidance (no posterior contacts)
4. At cementation: Recheck all excursive movements; adjust any hyperocclusion
5. Occlusal scheme preference:
   • Anterior teeth present: establish canine-protected occlusion (mutual protection)
   • If canines missing or weak: group function on working side; eliminate NWSI
   • Full mouth rehab: choose an occlusal scheme before starting

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Q28. Abutment selection using Ante's law. Limitations.

"The root surface area of the abutment teeth must equal or surpass that of the teeth to be replaced."

• Replacing maxillary first premolar (PDL ~234 mm²)
• Abutments: canine (273) + second premolar (220) = 493 mm² > 234 mm²
• Ante's law satisfied ✓

1. Does not account for bone loss: Derived from healthy tooth measurements; periodontally compromised abutments have reduced effective PDL area
2. Does not consider crown-root ratio: A molar with reduced bone height may have PDL area equal to a premolar
3. Does not account for direction of forces: Horizontal forces are more damaging than vertical; this isn't factored in
4. Does not consider tooth angulation, mobility, or occlusal forces
5. Empirical law: Not derived from controlled clinical trials; based on clinical observation
6. Violation does not always predict failure: Many long-span bridges with inadequate Ante's law compliance succeed clinically
7. Alternatives considered today: Periodontal status, bone support, occlusal forces, and parafunctions are more important clinical determinants

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Q29. Different types of pontic designs. Describe ridge lap, modified ridge lap, and ovate pontic.

• The pontic base is convex (egg-shaped) and fits into a prepared circular depression in the ridge mucosa
• The depression is created either at extraction time (placing ovate provisional immediately after extraction) or surgically
• Creates the appearance of a natural tooth emerging from the gingiva
• Superior esthetics - especially for anterior pontics in high-smile patients
• Requires healthy tissue and pre-planned socket management
• Not suitable if ridge has significant resorption

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Q30. What is the clinical significance of biological width? How does violation affect crown margins?

• Sulcular depth (sulcus): ~0.69 mm
• Junctional epithelium: ~0.97 mm
• Connective tissue attachment: ~1.07 mm
• Total biological width = 2.04 mm (junctional epithelium + connective tissue)
• Distance from crest of bone to base of sulcus = ~3 mm

1. Chronic gingival inflammation - persistent bleeding, swelling, erythema that does not resolve with local measures
2. Bone loss - the body resorbs bone apically to re-establish the 2 mm attachment zone
3. Recession - gingiva migrates apically, exposing the crown margin
4. Pocket formation - pseudo-pocket or true pocket forms
5. Pain and sensitivity at the gingival margin

• Bone sounding (transgingival probing under local anesthesia) to measure bone crest location
• Periapical radiograph (indirect)
• CBCT in challenging cases

• Keep subgingival margins at least 0.5 mm into the sulcus but NOT within 2 mm of the bone crest
• If insufficient tooth structure: crown lengthening surgery (osseous surgery to apically reposition bone crest) or orthodontic extrusion before crown preparation

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FULL MOUTH REHABILITATION (FMR)

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Q31. Indications for FMR. Conformative vs reorganized approach.

1. Severe tooth wear (attrition, erosion, abrasion, abfraction)
2. Collapsed occlusal vertical dimension (loss of posterior support)
3. Gross caries involving multiple teeth with loss of occlusal morphology
4. Multiple failing restorations requiring replacement
5. Combination of tooth loss and wear affecting both arches
6. Temporomandibular disorders requiring occlusal reconstruction
7. Periodontal disease with tooth migration, spacing, and occlusal changes
8. Congenital conditions (amelogenesis imperfecta, dentinogenesis imperfecta, ectodermal dysplasia)
9. Trauma affecting multiple teeth

• Existing jaw relationship and VDO are ACCEPTED and maintained
• All restorations are made to conform to the existing maximum intercuspation (ICP)
• Used when: existing occlusion is stable and acceptable, minimal changes needed, patients who can tolerate no change in VDO
• Simpler; less complex jaw records needed
• Risk: perpetuates existing occlusal problems if they exist

• Existing jaw relationship is NOT accepted
• New jaw relationship (usually centric relation, and/or new VDO) is established
• Restorations are fabricated to meet the NEW jaw position
• Used when: existing occlusion is deemed inadequate, loss of VDO requiring increase, TMD requiring position change, severe tooth wear
• Requires precise centric relation records, face-bow transfer, mounted study casts
• More complex; requires a verified, stable, comfortable CR position
• Diagnostic wax-up is mandatory before starting

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Q32. What is the Pankey-Mann-Schuyler (PMS) philosophy? How does it differ from Dawson's approach?

1. Know your patient (comprehensive diagnosis)
2. Know yourself (operator skill and limitations)
3. Know your materials (mechanical properties)
4. Apply this knowledge (clinical execution)

• Uses Pankey-Mann Instrument (PMI) - simplified articulator
• Establishes occlusion based on patient's existing anterior guidance
• Posterior occlusion is built to match the anterior guidance (the ABC principle)
• Bilateral balanced contacts in ICP; lateral excursions guided by existing anterior teeth (conformative to anterior)
• Advocates for a non-centric cusp (freedom in centric) - a small range of movement in CR-ICP
• Teeth restored in quadrant sequence (not all at once)

• Based on centric relation (CR) as the gold standard starting point
• CR = condyles in the most superoanterior position in the glenoid fossa, fully seated
• All restorations and jaw position changes based on CR, not on existing ICP
• Advocates for a specific musculoskeletal stable position (verified by bimanual manipulation)
• Load testing to detect muscle and joint tenderness
• More interventionist: existing ICP is treated as potentially incorrect
• Systematic, science-based approach with specific diagnostic protocol

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Q33. Role of a facebow transfer in FMR. Differentiate between arbitrary and kinematic facebow.

1. Transfers the maxillary cast to the articulator so it is oriented relative to the condylar elements in the same relationship as the maxilla is to the condyles in the patient
2. Allows correct simulation of mandibular movement - the arc of closure and all excursive movements will be reproduced accurately
3. Without a facebow: The maxillary cast is arbitrarily positioned; the arc of closure will be incorrect, leading to restorations that are high or out of occlusion after cementation
4. In FMR: Particularly critical because multiple restorations are being made; even small arc errors become significant clinically
5. Allows programming of the articulator with condylar inclination readings

• Records an estimated (arbitrary) location of the transverse hinge axis
• The reference point used is ~13 mm anterior to the tragus of the ear on the tragus-corner of eye line (approximately corresponds to the anatomic hinge axis in ~92% of patients)
• Quick and simple; adequate for most clinical situations
• Error introduced: ~0.2 mm vertical discrepancy - clinically acceptable
• Examples: Whip-Mix facebow, Hanau Spring bow

• Precisely locates the true (kinematic) hinge axis - the actual transverse axis of pure rotation of the condyles
• Requires patient to perform repeated opening/closing movements while the operator adjusts the axis pointer until a point of pure rotation is found
• Time-consuming (30-60 minutes per patient)
• Most accurate - zero arc-of-closure error
• Indicated: complex FMR, significant VDO changes (>4 mm), research, and when maximum accuracy is required
• Example: Stuart facebow, Denar Slidemaster

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Q34. How do you determine and record centric relation in FMR? Describe at least two techniques.

1. Patient supine (reclined chair)
2. Operator stands behind patient
3. Both thumbs placed on the chin (not on the lower teeth), four fingers cupped under the lower border of the mandible bilaterally
4. Thumbs apply gentle downward pressure; fingers guide the condyles superiorly and anteriorly
5. The mandible is guided through a gentle arc of rotation with NO translation
6. Record the position using leaf gauge or anterior deprogrammer first to decompress posterior teeth
7. Record material: polyvinylsiloxane (PVS) bite registration material (fast-setting, dimensionally stable)
8. Verification: Repeat 3 times; the record should be reproducible

1. A small acrylic anterior stop (Lucia jig) is placed between upper and lower anterior teeth
2. Patient wears for 15-30 minutes minimum - relaxes the elevating musculature (masseter, temporalis)
3. With posterior teeth deprogrammed (separated by the anterior jig), the mandible naturally seats in CR
4. Remove the jig and immediately record the jaw position with PVS
5. Advantage: Eliminates muscle engrams from habitual ICP; allows true condylar seating

• Leaf gauge (Long Centric): Progressive leaf gauge inserted anteriorly; thickness increased until posterior teeth are separated; patient taps on leaves; CR is found when arc is reproducible
• Gothic arch tracing (Arrow point tracing): Intraoral or extraoral stylus traces the apex of the arrow = CR
• Chin point guidance (Gysi): Older technique; limited reliability

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Q35. What is OVD? How do you assess and establish OVD in a collapsed bite patient?

1. Willis method: Distance from eye pupil to mouth angle = distance from base of nose to chin. If OVD is correct, these two distances are approximately equal
2. Freeway space evaluation: Measure RVD (patient at rest), subtract OVD (patient in occlusion); normal = 2-4 mm. If freeway space is >4 mm, OVD is reduced
3. Facial assessment: Deepened nasolabial folds, downturned lip commissures, "overclosed" appearance, chin approaching nose
4. Phonetic test: "S" sounds - if teeth come too close, OVD is low (insufficient freeway space)
5. Swallowing threshold (Pound's method): The OVD at which swallowing is most comfortable
6. Pre-extraction records if available

1. Step 1 - Determine the amount of OVD increase required:
   • Based on above assessments; typically 2-4 mm increase in wear cases; up to 6-8 mm in severe cases (with caution)
2. Step 2 - Provisional (transitional) restorations:
   • Construct provisional restorations at new OVD using acrylic provisionals
   • Patient wears provisionals for 3-6 months minimum to verify:
     • Muscle adaptation (no TMD symptoms)
     • Phonetics acceptable ("s" sound clearance 1-2 mm)
     • Esthetics acceptable
     • Patient comfort
3. Step 3 - If adaptation is successful: Fabricate definitive restorations at the verified new OVD
4. Large OVD increases (>4 mm): May require longer provisional period, monitoring of TMJ, gradual increases using overlay appliances before provisional restorations

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Q36. Describe the diagnostic wax-up and its role in FMR treatment planning.

1. Mount diagnostic casts on a semi-adjustable articulator using facebow and CR record
2. Occlusal analysis performed (mounted casts reveal discrepancies not visible intraorally)
3. Wax is added/removed on the casts to simulate the proposed restorations
4. Wax-up incorporates: ideal tooth morphology, occlusal scheme, anterior guidance, VDO

1. Communication with patient: Shows the patient what the final result will look like BEFORE any irreversible treatment begins
2. Communication with laboratory technician: Blueprint for the final restorations
3. Guide for tooth preparation:
   • Custom preparation guides are made from the wax-up (putty index)
   • Ensures adequate reduction in the right locations without over-preparation
4. Fabrication of provisional restorations:
   • A matrix (putty or vacuum-formed) is made from the wax-up
   • Provisional restorations are fabricated using bis-acryl or PMMA loaded into this matrix
   • The provisionals replicate the wax-up in the patient's mouth
5. Template for final restorations: Final crowns replicate the successful provisional outcome
6. Evaluation of anterior guidance: Can verify that new anterior guidance is aesthetically and phonetically correct before any tooth preparation
7. Esthetic preview: Mockup using the wax-up matrix with composite (no-prep mockup) allows patient to visualize esthetics
8. Occlusal analysis: Mounted casts reveal working, non-working, and protrusive contacts; wax-up resolves them

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Q37. What is "mutually protected occlusion"? Contrast with group function in FMR outcomes.

• In ICP (habitual occlusion): Posterior teeth provide the primary support; anterior teeth are slightly open (or light contact)
• In lateral excursion: The canine (and incisors in protrusion) alone guide the mandible; the posterior teeth DISCLUDE (separate)
• The posteriors protect the anteriors from horizontal forces (in ICP)
• The anteriors protect the posteriors from lateral forces (in excursions)
• Hence "mutually protected"

• Posterior teeth experience only vertical (axial) forces in ICP - most favorable for cusps, periodontal apparatus, and bone
• Minimal eccentric stress on posterior restorations (molars disclude in lateral)
• Canine has the best crown-root ratio; dense bone support; most capable of lateral guidance
• Cleanly defined occlusal scheme - easy to reproduce in lab

• During lateral excursion: MULTIPLE teeth on the working side share the lateral guidance simultaneously (canine + premolars + molars)
• No single tooth bears all lateral forces
• Non-working side: should have NO contacts (same as canine protection)

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Q38. How do you sequence treatment in full mouth rehabilitation?

• Comprehensive examination (periodontal, endodontic, TMD, occlusal)
• Diagnostic casts, mounted study casts, facebow, photographs
• Periodontal charting, radiographs (full mouth or CBCT)
• Identify the cause of failure/wear
• Verify CR and plan new OVD if needed

1. Oral hygiene instruction
2. Extraction of hopeless teeth
3. Periodontal treatment (scaling, root planing, possibly surgery)
4. Endodontic treatment of teeth requiring it
5. Core build-ups and post placements for RCT-treated teeth
6. Caries control (temporary fillings)
7. Orthodontics if needed (tooth alignment, space redistribution)

• Implant surgery after adequate healing of extraction sites (minimum 3-4 months)
• Implant healing period (3-6 months for osseointegration)

• Fabricate diagnostic wax-up on articulated casts
• Prepare diagnostic teeth and place provisional restorations at new OVD and CR
• Evaluate for 3-6 months: phonetics, esthetics, muscle adaptation, TMJ comfort

• Establish posterior support and VDO
• Then create anterior guidance conforming to this
• Rationale: Stable posterior stops first; anteriors built to match

• Establish anterior guidance and esthetics first
• Posteriors are built to satisfy anterior guidance and not interfere
• Rationale: Anterior guidance dictates posterior cusp angles

• All provisionals placed simultaneously
• Definitive restorations fabricated in sections but inserted in coordinated sequence
• Most predictable when provisionals have been verified

• Occlusal splint (night guard) to protect restorations
• Regular recall visits (3-6 monthly)
• Long-term monitoring

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IMPLANTS

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Q39. Explain osseointegration - definition, histological basis, and factors affecting it (Albrektsson's criteria).

• Bone-to-implant contact (BIC) is observed on histological sections
• No intervening fibrous tissue - this is the key distinction from fibro-osseous integration
• Bone is laid directly on the titanium surface
• The oxide layer (TiO2) on the titanium surface is biologically inert and allows protein adsorption, then osteoblast attachment
• In the early healing phase: blood clot forms, followed by fibrin scaffold, then mesenchymal cell migration and differentiation into osteoblasts
• Woven bone forms first (within 4-8 weeks), then remodels to lamellar bone over months
• BIC of 60-80% is considered good osseointegration

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Q40. What is ISQ? How is resonance frequency analysis (RFA) used clinically?

• A dimensionless scale from 1 to 100 that quantifies implant stability using resonance frequency analysis
• Higher ISQ = greater implant stability
• ISQ 70-80+: Excellent stability (suitable for immediate loading)
• ISQ 60-69: Adequate stability (conventional or early loading protocol)
• ISQ <60: Poor stability (submerged healing; re-evaluate at 8-12 weeks)
• ISQ <50: Very poor stability; implant failure likely imminent

1. Primary stability - mechanical interlocking of implant in bone (immediate after placement); depends on bone density and quantity, implant geometry, insertion technique
2. Secondary stability - biological stability from osseointegration (develops over 4-12 weeks)

• At placement: ISQ determined by primary stability
• Week 1-4: ISQ often DROPS as bone remodeling begins (primary stability decreasing before secondary begins)
• Week 4-12: ISQ rises as osseointegration matures (secondary stability)
• At final loading: ISQ should be at or above baseline value

1. Loading protocol decision: If ISQ >70 at placement, consider immediate loading
2. Monitor osseointegration: Serial ISQ measurements identify failing implants before clinical signs appear
3. Guide healing period: If ISQ at 8 weeks is still low, extend healing before loading
4. Research tool: Compare different implant systems, surfaces, surgical protocols
5. Diagnose peri-implantitis: Decreasing ISQ in a loaded implant suggests bone loss

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Q41. Bone quality classification by Lekholm and Zarb. Effect on implant placement.

• Underprepared (undersized) osteotomy - tap in implant to improve primary stability (condensation osteotomy with osteotomes)
• Platform switching may help
• Longer healing period (6 months)
• Avoid immediate loading
• Consider sinus augmentation if insufficient bone height
• Use implants with aggressive thread design for better engagement

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Q42. Platform switching concept. Biological and prosthetic advantages.

1. Reduced peri-implant bone loss:
   • The microgap (bacterial reservoir and micromovement zone) is moved away from the bone crest
   • Studies show platform switching reduces marginal bone loss by ~0.3-0.5 mm compared to conventional connections
   • Bone loss around regular connections: ~1.5-2 mm in first year; platform switching reduces this to ~0.5-0.9 mm
2. Preservation of biologic width:
   • The horizontal shift provides more space for junctional epithelium and connective tissue to form at the implant shoulder
   • Biological width is re-established on the horizontal platform rather than the vertical implant side
3. Preserves bone-implant contact:
   • The connective tissue "cap" sits on the horizontal platform, protecting bone from the microgap-related inflammation

1. Better emergence profile: Space between abutment and implant edge allows natural tooth-like emergence
2. Improved esthetics: More tissue volume preserved around the implant collar
3. Reduced stress concentration: The horizontal offset distributes stress more favorably at the implant-bone interface

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Q43. External hex vs internal connection implants. Biomechanical implications.

• Cone-in-cone design (minimum 8° taper angle)
• Cold welding effect under load - essentially no micromovement
• Best bacterial seal
• Most modern high-end systems use this

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Q44. Prosthetic options for an edentulous mandible with implants. Compare 2-implant overdenture vs fixed hybrid.

1. 2-Implant retained overdenture (ISROD - McGill consensus recommendation, 2002)
2. 4-implant overdenture (bar-retained or ball-retained)
3. Fixed implant-supported hybrid prosthesis (full arch) - typically 4-6 implants
4. Fixed ceramic bridge (usually 6+ implants)

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Q45. Immediate loading vs early loading vs conventional loading. Prerequisites for immediate loading.

• Adequate bone volume for full implant engagement
• Preferably Type I-III bone (Type IV is relative contraindication)
• Minimum bone height: 10 mm; width: 5-6 mm

• Insertion torque ≥35 Ncm (ideally 45-50 Ncm)
• ISQ ≥70 on Osstell
• High primary stability is the MOST important prerequisite

• No active smoking (smokers have higher failure rates; relative contraindication)
• No uncontrolled diabetes
• No systemic conditions affecting bone healing
• No parafunctional habits (bruxism = contraindication for single implants; possible for full-arch with rigid splinting)

• Cross-arch splinting (multiple implants should be splinted together) reduces micromovement significantly
• Immediate loading of single implants: controversial; reserved for anterior maxilla esthetics with optimal conditions
• Immediate loading of full-arch cases (All-on-4, All-on-6): widely accepted; cross-arch rigidity reduces per-implant micromovement

• Immediate loading of mandibular overdentures: high success rates (~95% comparable to conventional)
• Full-arch immediate loading (Novum, All-on-4): well-established protocols
• Immediate single crown in posterior: success rates slightly lower than conventional loading

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Q46. What is peri-implantitis? Differentiate from peri-implant mucositis. Management options.

• Reversible inflammatory reaction in the soft tissues only around a functioning implant
• NO supporting bone loss
• Analogous to gingivitis
• Signs: Bleeding on probing (BOP), erythema, swelling, suppuration possible
• Prevalence: ~43% of implants (Lang et al.)
• Reversible with treatment

• Inflammatory reaction in both soft AND hard tissues around a functioning implant
• With progressive bone loss beyond biological bone remodeling
• Analogous to periodontitis
• Signs: BOP + suppuration + probing depths ≥6 mm + radiographic bone loss
• Prevalence: ~22% of implants (Derks et al., 2016, JDSR)
• Not fully reversible; aim is to arrest progression

• Patient education + improved oral hygiene
• Professional cleaning (implant-compatible curettes, ultrasonic with plastic tips)
• Chlorhexidine rinse 0.12-0.2% for 2 weeks
• Resolution expected within 4-6 weeks

• Mechanical debridement (titanium curettes, ultrasonic, Er:YAG laser, Air-Flow with erythritol)
• Local antibiotic delivery (minocycline microspheres, doxycycline gel)
• Systemic antibiotics (Amoxicillin + Metronidazole - Mombelli protocol; or Doxycycline 100 mg)
• Photodynamic therapy
• Implant surface decontamination (citric acid, hydrogen peroxide, saline)

• Resective surgery: Open flap debridement + implantoplasty (reducing implant surface roughness in exposed areas) + osseous recontouring
• Regenerative surgery: Open flap debridement + bone graft + membrane (GTR) - for infrabony defects
• Implant removal - last resort; when bone loss is too extensive or implant is mobile

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MAXILLOFACIAL PROSTHETICS

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Q47. Classify maxillofacial prostheses. Materials used for facial prostheses. Properties of silicone elastomers.

1. Intraoral:
   • Obturator (palatals, velar, pharyngeal)
   • Palatal augmentation prosthesis
   • Tongue prosthesis
   • Trismus appliances
   • Stents and splints
2. Extraoral:
   • Auricular (ear) prosthesis
   • Nasal (nose) prosthesis
   • Orbital prosthesis (eye socket)
   • Ocular prosthesis (eye)
   • Facial prosthesis (cheek, forehead, composite)
3. Combination (intra+extraoral):
   • Palatal obturator + nasal prosthesis

1. Room Temperature Vulcanizing (RTV) silicone: MDX4-4210 (Dow Corning); most widely used
2. High Temperature Vulcanizing (HTV) silicone: Stronger but requires laboratory processing
3. Silastic Medical Grade: Used for cosmetic implants

• Biocompatibility: Non-toxic, non-irritant, hypoallergenic
• Flexibility and softness: Mimics skin; can be made to match Shore A hardness of facial tissue (~20-30)
• Pigmentation: Can be intrinsically and extrinsically pigmented with dry earth pigments, cosmetic pigments; can match any skin tone
• Optical properties: Can be made translucent; absorbs and scatters light similar to skin
• Durability: Resistant to UV degradation (with stabilizers), water, cleaning agents
• Tear resistance: High to withstand repeated removal
• Adhesion: Can bond to metal implant anchors

• Degrades over 1-3 years (UV exposure, skin oils, cleaning chemicals)
• Requires professional re-pigmentation/replacement
• Cannot be repaired easily (bonds to itself poorly)
• High-quality pigmented silicone is expensive
• Adhesive retention systems (skin adhesives) can cause skin reactions

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Q48. Prosthodontic management following total maxillectomy (Brown Class IIb). Phases of an obturator.

• Fabricated PRE-OPERATIVELY on a model of the un-resected maxilla
• Placed in the surgical field by the prosthodontist AT THE TIME OF SURGERY
• Made of acrylic resin; can be trimmed at the operating table
• Purposes:
  • Protect the surgical wound
  • Support the surgical packing
  • Provide initial speech and swallowing function
  • Psychologically important for patient waking without a defect
  • Acts as a surgical dressing
• Limitation: Does not fit the actual resection margins precisely; designed for protection, not function

• Fabricated 5-10 days post-operatively after the surgical packing is removed
• Modified or remade from impressions of the actual defect
• Worn during healing and tissue maturation phase (3-6 months)
• Modifications made as tissue heals (tissue conditioner, relining)
• Supports speech rehabilitation; allows eating
• Multiple adjustments expected as wound contracts and heals

• Fabricated after complete wound healing (6-12 months post-surgery)
• Final impression of stable, healed defect
• Precision fit; optimized for retention, support, stability
• Functional obturator portion: closes the palatal defect and obliterates the defect space (hollow bulb or solid depending on defect size)
• Nasal prosthesis component if needed
• Multiple retention devices (natural teeth, implants, magnets, clasps)

• Orbital prosthesis fabricated in conjunction with maxillary obturator
• May be implant-retained (zygomatic bone, remaining orbital rim)
• Often a composite facial prosthesis combining palatal obturator + nasal + orbital components

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Q49. What is a palatal augmentation prosthesis? Indications and how it helps speech and deglutition.

• Palatal drop prosthesis
• Palatal lowering prosthesis
• Palatal reshaping prosthesis

• Normal speech and swallowing require the tongue tip and dorsum to contact the hard palate at specific locations (alveolus for /t/, /d/, /n/; mid-palate for /s/, /sh/)
• If the tongue is limited in range of motion (partial glossectomy, neurological impairment), it cannot reach the palate
• A PAP adds acrylic to the palatal surface, effectively lowering the vault to meet the tongue

1. Post-glossectomy (partial or total tongue resection for oral cancer):
   • Most common indication
   • Tongue volume and mobility are reduced
   • PAP fills the vault so the tongue remnant can contact it for speech and swallowing
2. Neurological disorders:
   • Parkinson's disease (reduced tongue mobility)
   • CVA/stroke with dysarthria (flaccid or spastic tongue)
   • ALS/motor neuron disease
   • Cerebral palsy
3. Velopharyngeal insufficiency:
   • Prosthesis may include a palatal lift component as well

• Tongue tip or dorsum now contacts the augmented (lowered) palate
• Correct point of contact is re-established for lingual consonants (/t/, /d/, /n/, /l/, /s/)
• Improves intelligibility
• Palatography (EPG - electropalatography) can be used to design the augmentation precisely based on tongue contact patterns

• Normal bolus formation and propulsion require tongue-palate contact to create pressure
• PAP allows the tongue remnant to press against the palate, propelling the bolus posteriorly
• Reduces oral transit time
• Reduces aspiration risk in neurological patients with reduced tongue base propulsion
• Particularly beneficial for: liquid management, bolus control, drooling

• Conventional acrylic resin (heat-cured or auto-cured)
• Supported by remaining teeth (clasps) or implants
• Staged thickening: add increments over multiple visits as patient adapts
• Surface contoured to tongue contact pattern (individualized)

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Q50. Role of osseointegrated implants in retention of auricular, nasal, and orbital prostheses. Site-specific considerations.

• Allergic reactions, skin irritation, folliculitis
• Poor retention (especially with sweating, humidity)
• Daily application and removal; adhesive residue
• Cannot be used after radiation therapy (skin fragile)
• Patient compliance issues

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• Posterior to the auditory canal in the mastoid bone
• Standard: 3 implants in a triangular pattern (retroauricular mastoid region)
• Can use 2 implants for smaller prostheses

• Mastoid bone is cortical and dense = excellent osseointegration
• Implant length: 3-4 mm (limited bone thickness)
• Most commonly BONEBRIDGE (Cochlear) or Brånemark system extraoral implants used
• Bone thickness must be verified by CT scan (minimum 4 mm)

• Bar and clip system (most retentive; connects 2-3 implants)
• Individual magnets (Dyna magnets; easier to clean; lower retention)
• Ball attachments

• Children: implants placed after age 5 (preferably older) when mastoid bone is adequate
• Post-radiation: 150% higher failure rate; hyperbaric oxygen (20 pre-op, 10 post-op dives) before implant placement in irradiated bone
• Residual auricle tissue: may be used for additional stability

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• Nasal bone (glabella region, lateral nasal walls, nasal floor/pyriform aperture)
• Most challenging site due to thin bone quality
• Typically 2-3 implants placed symmetrically

• Nasal bones are very thin (3-4 mm typically)
• Implant length: 3-4 mm; diameter: narrow (3-3.75 mm)
• CT scan mandatory to map bone thickness
• Failure rates higher than mastoid (thin bone)
• Nasal cavity approximation - risk of perforation

• Bar and clip (preferred; multiple implants splinted)
• Magnets

• Prior nasal surgery or radiotherapy significantly complicates placement
• May need bone grafting in severely deficient nasal region
• Prosthetic margins must engage the nasal alar groove for camouflage

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• Orbital rim (zygomatic process of frontal bone, zygomatic arch, lateral orbital rim)
• Typically 3-4 implants around the orbit
• Superior orbital rim bone is thickest (4-5 mm) and preferred

• Thin bony walls; careful CT planning essential
• Risk of intracranial penetration in superior orbit
• Risk of infraorbital nerve damage
• Post-exenteration: bone may be irregular; scar tissue management

• Bar and clip system (most common for orbital)
• Magnets (allow prosthesis to align with slight movements)
• Superimagnets (rare; when bar not possible)

• Can be combined with maxillary obturator as composite craniofacial prosthesis
• Spectacle frames have been used as auxiliary retention (camouflages bar, improves retention)
• Post-radiation: mandatory HBO protocol; failure rates significantly higher
• Orbital skin is thin - no surgical access room; requires precise osteotomy
• Ball attachment on single implants: insufficient; at least 2 implants + bar recommended

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