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Kuwait Board Prosthodontics study materials
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Kuwait Board Prosthodontics practice questions

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Question 1Diagnosis and Treatment Planning

A patient presents with a Kennedy Class I partially edentulous arch. Which statement best describes the location of the edentulous spaces?

  1. Bilateral edentulous areas posterior to the remaining natural teeth Correct answer.
  2. A unilateral edentulous space posterior to the remaining teeth
  3. A single edentulous space bounded by natural teeth on both sides
  4. An edentulous space anterior to the remaining abutment teeth

Explanation

In the Kennedy classification, Class I describes bilateral edentulous areas located posterior to the remaining natural teeth, meaning the denture base is tooth-bounded anteriorly and free-ended posteriorly. This free-end situation has major implications for support and rotational movement.

Question 2Diagnosis and Treatment Planning

During a diagnostic examination, which clinical finding most strongly indicates a need for a stabilized record base before final impression procedures?

  1. Excessive movable tissue on the residual ridge with poor denture-bearing support Correct answer.
  2. Adequate vestibular depth with a functional border seal
  3. Presence of a single isolated molar abutment
  4. A well-defined, keratinized residual ridge with firm attached tissue

Explanation

Excessive movable or displaceable tissue compromises the denture-bearing foundation, so a stabilized record base or altered cast technique is often required to capture the functional form of the tissues. Firm attached keratinized tissue provides more predictable support and does not demand the same correction.

Question 3Diagnosis and Treatment Planning

Which radiographic finding in a completely edentulous patient most directly alters the treatment plan toward surgical intervention before prosthesis fabrication?

  1. Slight thickening of the maxillary sinus mucosa
  2. Generalized mild ridge resorption with a uniform cortical outline
  3. A retained root fragment with a surrounding radiolucency Correct answer.
  4. A well-corticated mental foramen

Explanation

A retained root fragment with an associated radiolucency suggests infection or pathology that should be resolved surgically before any prosthesis is made. The other findings are common, often incidental, and do not independently mandate surgery.

Question 4Diagnosis and Treatment Planning

A patient reports that an existing maxillary complete denture drops during speech. Examination shows a thick, non-retentive posterior palatal seal and an overextended posterior border. Which step is most appropriate in the diagnostic phase?

  1. Reduce the occlusal vertical dimension to improve retention
  2. Assess the vibrating line and functional border extent before remake Correct answer.
  3. Add a postpalatal seal by scraping the cast arbitrarily
  4. Prescribe a soft liner to compensate for the border

Explanation

The diagnostic phase should identify the correct location of the vibrating line and the functional extent of the posterior border so the new prosthesis can achieve a proper seal. Arbitrary scraping or compensating with liners does not address the underlying anatomic and border errors.

Question 5Diagnosis and Treatment Planning

Which factor in the patient's medical history most strongly warrants deferral of elective complete denture impressions?

  1. Mild osteoarthritis of the knees
  2. Controlled hypertension with normal blood pressure readings
  3. Recent myocardial infarction within the past month Correct answer.
  4. Well-controlled type 2 diabetes with HbA1c of 6.5%

Explanation

A recent myocardial infarction within the preceding weeks is a recognized reason to postpone elective dental treatment because of the risk of cardiac complications. Well-controlled chronic conditions generally do not require deferral of routine prosthodontic care.

Question 6Diagnosis and Treatment Planning

A patient with a severely resorbed mandibular ridge and a history of two failed mandibular dentures is being planned. Which diagnostic consideration most appropriately guides the decision between implant-supported and conventional options?

  1. The color of the residual ridge mucosa
  2. The patient's ability to adapt, financial capacity, and anatomic bone availability Correct answer.
  3. The shade of the existing maxillary denture
  4. The number of previous dental visits

Explanation

Treatment planning for a severely resorbed mandible weighs adaptive capacity, financial resources, and available bone volume against implant and conventional options. These factors determine whether an implant-retained prosthesis is realistic and appropriate.

Question 7Diagnosis and Treatment Planning

In assessing a partially edentulous arch, which concept explains why a distal extension base tends to rotate around the most posterior abutment?

  1. The fulcrum effect of the abutment under functional loading Correct answer.
  2. The presence of a rigid major connector
  3. The use of a resilient soft liner
  4. The absence of periodontal ligament on natural teeth

Explanation

A distal extension base behaves as a lever, rotating around the most posterior abutment under occlusal load. This fulcrum effect explains why stress distribution and design of the extension base are critical.

Question 8Diagnosis and Treatment Planning

Which clinical measurement is most directly used to determine the occlusal vertical dimension in a completely edentulous patient?

  1. The resting vertical dimension minus the freeway space Correct answer.
  2. The interpupillary distance
  3. The width of the maxillary arch
  4. The depth of the labial vestibule

Explanation

Occlusal vertical dimension is estimated by subtracting the freeway space from the resting vertical dimension measured between selected facial reference points. This yields a physiologic starting point for record fabrication.

Question 9Diagnosis and Treatment Planning

A patient exhibits a pronounced gag reflex during maxillary impression procedures. Which modification to the treatment plan is most appropriate?

  1. Use a smaller custom tray and reduce the amount of material Correct answer.
  2. Place the patient in a supine position throughout
  3. Use a larger stock tray to reduce pressure points
  4. Increase the amount of impression material to speed the procedure

Explanation

A smaller custom tray with a reduced volume of impression material decreases palatal coverage and material overflow, reducing stimulation of the gag reflex. A supine position and larger material loads tend to worsen the response.

Question 10Diagnosis and Treatment Planning

Which occlusal scheme is most commonly recommended for a conventional complete denture to promote bilateral balanced occlusion?

  1. Anatomic posterior teeth arranged with compensating curves Correct answer.
  2. Lingualized occlusion with no balancing contacts
  3. Monoplane occlusion with flat cusps and no balancing contacts
  4. Crossbite posterior arrangement

Explanation

Anatomic posterior teeth arranged with compensating curves facilitate bilateral balanced occlusion, distributing contacts in eccentric movements. Balanced contacts help stabilize the dentures during function.

Question 11Diagnosis and Treatment Planning

A patient with a maxillary complete denture reports chronic soreness under the denture base. Examination reveals a uniform erythematous area on the hard palate. Which diagnosis is most consistent with this presentation?

  1. Denture stomatitis Correct answer.
  2. Traumatic neuroma
  3. Residual ridge resorption
  4. Epulis fissuratum

Explanation

Denture stomatitis presents as erythema of the denture-bearing mucosa, often under a maxillary complete denture, and is frequently associated with Candida. It is a mucosal inflammatory response rather than a fibrous or neural lesion.

Question 12Diagnosis and Treatment Planning

Which finding on a diagnostic cast most strongly suggests the need for a surgical vestibuloplasty before mandibular denture fabrication?

  1. A broad, well-rounded residual ridge
  2. A shallow vestibule with minimal attached mucosa Correct answer.
  3. A prominent genial tubercle covered by mucosa
  4. A slightly undercut lingual flange area

Explanation

A shallow vestibule with minimal attached mucosa compromises border seal and retention, and may warrant preprosthetic surgery. A broad ridge and covered tubercle are generally manageable prosthodontically.

Question 13Diagnosis and Treatment Planning

In treatment planning for a patient with generalized moderate chronic periodontitis and several mobile abutment teeth, which principle most appropriately guides abutment selection?

  1. Select only anterior teeth regardless of bone support
  2. Select teeth based on their shade match to the prosthesis
  3. Select abutments with the greatest mobility to distribute load
  4. Select the most strategic teeth with adequate bone support after periodontal stabilization Correct answer.

Explanation

Abutment selection should follow periodontal stabilization and favor strategic teeth with sufficient bone support to withstand functional loads. Mobility and shade are not valid primary criteria for abutment choice.

Question 14Diagnosis and Treatment Planning

Which diagnostic record is most useful for evaluating the patient's existing occlusion and guidance patterns before fabricating a new prosthesis?

  1. A photograph of the smile line
  2. A panoramic radiograph alone
  3. Mounted diagnostic casts with a facebow record Correct answer.
  4. A single periapical radiograph

Explanation

Mounted diagnostic casts with a facebow record allow evaluation of occlusal relationships, guidance patterns, and arch coordination in a simulated articulator environment. This information guides the design of the new occlusion.

Question 15Diagnosis and Treatment Planning

A patient requests replacement of an existing removable partial denture and reports that food collects under the major connector. Which design consideration most directly addresses this complaint?

  1. Improving the adaptation of the major connector to the tissue and tooth surfaces Correct answer.
  2. Using a more flexible framework alloy
  3. Increasing the rigidity of the major connector
  4. Reducing the number of clasp assemblies

Explanation

Food entrapment under a major connector is most often related to poor adaptation to the underlying tissues and teeth. Improving adaptation reduces the space where debris accumulates. Rigidity and clasp number are separate design issues.

Question 16Diagnosis and Treatment Planning

Which factor most strongly contraindicates the use of a resilient soft denture liner as a definitive treatment for a patient with chronic denture-bearing tissue irritation?

  1. The liner distributes occlusal forces
  2. The liner may harbor microorganisms and mask underlying causes of irritation Correct answer.
  3. The liner improves adaptation to the ridge
  4. The liner is easy to replace

Explanation

Soft liners can accumulate microorganisms and may simply mask the underlying cause of tissue irritation rather than resolve it. Definitive management should first identify and correct the source of the problem.

Question 17Diagnosis and Treatment Planning

A patient presents with a severely resorbed maxilla and a flat palatal vault. Which impression technique is most appropriate to capture the functional form of the denture-bearing tissues?

  1. A bite registration taken without an impression
  2. A single rigid stock tray impression with heavy-body material
  3. A custom tray with border molding and a wash impression Correct answer.
  4. An intraoral scan without border molding

Explanation

A custom tray with border molding and a wash impression captures the functional border and tissue form, which is essential in a flat, resorbed maxilla. Stock trays and scans without border molding cannot record the functional periphery.

Question 18Diagnosis and Treatment Planning

Which clinical sign most reliably distinguishes a tooth-supported from a mucosa-supported removable partial denture design decision?

  1. The depth of the lingual vestibule
  2. The presence of a free-end edentulous space Correct answer.
  3. The color of the abutment teeth
  4. The number of anterior teeth present

Explanation

A free-end edentulous space creates a mucosa-supported distal extension, whereas a tooth-bounded space permits tooth-supported design. This distinction drives the choice of rests, connectors, and base design.

Question 19Diagnosis and Treatment Planning

A patient with a history of head and neck radiation is being planned for a mandibular complete denture. Which consideration most directly affects the treatment plan?

  1. Elimination of the gag reflex
  2. Improved bone density from radiation
  3. Increased risk of osteoradionecrosis and reduced mucosal tolerance Correct answer.
  4. Reduced need for border molding

Explanation

Radiation therapy increases the risk of osteoradionecrosis and reduces mucosal tolerance, so the plan must minimize trauma and consider the timing and extent of surgery. Radiation does not improve bone density or eliminate protective reflexes.

Question 20Diagnosis and Treatment Planning

Which measurement best guides the selection of a posterior palatal seal's anterior limit during maxillary denture fabrication?

  1. The crest of the residual ridge
  2. The vibrating line at the junction of the movable and immovable palate Correct answer.
  3. The width of the anterior teeth
  4. The depth of the labial frenum

Explanation

The vibrating line marks the junction between movable and relatively immovable palatal tissues and guides the anterior extent of the posterior palatal seal. Placing the seal appropriately maintains border seal during function.

Question 21Diagnosis and Treatment Planning

A patient reports that a maxillary complete denture dislodges during yawning and wide mouth opening. Which border is most likely deficient?

  1. The lingual border
  2. The incisal border
  3. The labial and buccal borders
  4. The posterior palatal border Correct answer.

Explanation

Loss of seal during wide mouth opening often indicates a deficient posterior palatal seal, since the palatal tissues move and break the seal. Labial and buccal borders tend to affect other movements such as smiling and speech.

Question 22Diagnosis and Treatment Planning

Which diagnostic approach is most appropriate to evaluate the patient's vertical and horizontal jaw relationship before fabricating a fixed prosthesis?

  1. A photograph of the existing restorations
  2. A facebow transfer and centric relation record Correct answer.
  3. A periodontal probing chart
  4. A single panoramic radiograph

Explanation

A facebow transfer combined with a centric relation record allows evaluation of the maxillomandibular relationship in the articulator. This is essential for planning occlusal relationships in fixed prosthodontics.

Question 23Diagnosis and Treatment Planning

A patient has an existing maxillary complete denture with a severely worn occlusal surface and reduced vertical dimension. Which diagnostic step most appropriately precedes fabrication of a new prosthesis?

  1. Replace the denture without adjusting vertical dimension
  2. Reduce the existing vertical dimension further
  3. Evaluate the patient's adaptive tolerance to an increased vertical dimension using a provisional approach Correct answer.
  4. Immediately increase vertical dimension in the existing denture

Explanation

When increasing vertical dimension is planned, evaluating the patient's tolerance through a provisional or trial approach reduces the risk of discomfort. Abrupt changes without assessment may lead to functional problems.

Question 24Diagnosis and Treatment Planning

Which factor most strongly influences the decision to use a lingualized occlusal scheme in a complete denture?

  1. The need to improve esthetics in the anterior region
  2. The desire to reduce lateral forces while maintaining centric contacts Correct answer.
  3. The number of remaining mandibular teeth
  4. The patient's preference for a specific tooth shade

Explanation

Lingualized occlusion places the maxillary lingual cusps into the mandibular central fossae, which can reduce lateral forces while preserving centric contacts. It is a functional design choice rather than an esthetic or shade-driven one.

Question 25Diagnosis and Treatment Planning

Which clinical scenario most appropriately indicates the use of a surgical template during implant placement for a prosthodontic patient?

  1. A patient requesting only a diagnostic wax-up
  2. Multiple implants planned for a fixed prosthesis with restricted anatomic space Correct answer.
  3. A patient with an existing removable partial denture
  4. A single implant in a wide edentulous space with abundant bone

Explanation

A surgical template is most valuable when multiple implants must be placed in a prosthetically driven position, especially with limited anatomic space. It transfers the planned position from the wax-up to the surgical site.

Question 26Diagnosis and Treatment Planning

During the initial prosthodontic examination, which extraoral finding is most relevant to planning the vertical dimension and anterior tooth display of a new maxillary complete denture?

  1. The resting muscle tone of the masseter on clenching
  2. The length of the upper lip at rest and the amount of incisor display on smiling Correct answer.
  3. The degree of mandibular lateral deviation on opening
  4. The presence of a torus mandibularis on palpation

Explanation

Lip length at rest and the amount of incisor display during smiling are key guides for arranging the maxillary anterior teeth and setting the incisal plane. These soft-tissue landmarks link the planned occlusal vertical dimension to acceptable esthetics. The other findings inform function or surgery rather than anterior tooth position.

Question 27Diagnosis and Treatment Planning

A patient presents with a single missing mandibular first molar bounded by sound teeth mesially and distally. Which diagnostic finding most directly supports choosing a fixed partial denture over a removable partial denture for this space?

  1. Presence of a shallow buccal vestibule at the edentulous site
  2. Adequate crown height and periodontal support on both adjacent abutments Correct answer.
  3. A deep lingual undercut on the adjacent premolar
  4. A short clinical crown on the adjacent molar

Explanation

A bounded space with two sound, well-supported abutments is the classic indication for a fixed partial denture, since the abutments can carry the load and provide predictable retention. Crown height and periodontal support determine whether the abutments can serve as fixed retainers. The other findings either complicate the design or favor a removable approach.

Question 28Diagnosis and Treatment Planning

A patient reports a history of infective endocarditis and requires a maxillary complete denture. Which pre-procedural consideration most appropriately guides the treatment plan?

  1. Consultation with the physician regarding antibiotic prophylaxis before procedures that cause gingival bleeding Correct answer.
  2. Deferral of all impression procedures until the denture is fabricated in a single visit
  3. Routine prescription of a prolonged antibiotic course after each adjustment appointment
  4. Use of a soft liner at every recall to reduce the need for prophylaxis

Explanation

For patients with a history of infective endocarditis, current guidance centers on physician consultation and prophylaxis for procedures that cause significant gingival or mucosal bleeding. The prosthodontic plan should be coordinated with the medical team rather than decided unilaterally. Routine post-adjustment antibiotics and single-visit fabrication are not standard measures.

Question 29Diagnosis and Treatment Planning

A patient with a Kennedy Class I mandibular arch shows a markedly reduced residual ridge and a history of denture instability. Which diagnostic step best predicts the load-bearing capacity of the denture-bearing mucosa before finalizing the design?

  1. Palpation of the residual ridge to assess its consistency and displaceability Correct answer.
  2. Assessment of the buccal shelf width on the diagnostic cast
  3. Recording of the freeway space with the lips lightly closed
  4. Measurement of the maximal mouth opening in millimeters

Explanation

Palpation distinguishes firm, fibrous, or displaceable mucosa and indicates how well the tissue will tolerate functional load, which directly affects the prognosis of a mucosa-supported base. This information complements cast assessment of ridge form and border extension. Mouth opening and freeway space describe function, not tissue load tolerance.

Question 30Diagnosis and Treatment Planning

A patient scheduled for a maxillary complete denture has a prominent incisive papilla located close to the crest of the ridge. Which treatment-planning consequence is most appropriate to anticipate?

  1. The incisal edges of the central incisors should be positioned near the papilla to preserve a natural appearance Correct answer.
  2. The denture base should be relieved over the papilla to prevent a fulcrum effect
  3. The posterior palatal seal should be moved anteriorly to avoid the papilla
  4. The occlusal plane should be lowered until it contacts the papilla

Explanation

The incisive papilla is a stable landmark that remains relatively constant despite ridge resorption, so it is used to guide the labial position and incisal edge of the maxillary central incisors. A prominent papilla near the crest therefore helps rather than hinders anterior tooth placement. The papilla has no role in posterior seal location or occlusal plane height.

Question 31Fixed Prosthodontics

When preparing a vital posterior tooth for a full-coverage metal-ceramic crown, which remaining axial wall thickness is generally recommended to support the restoration and protect the pulp?

  1. 0.3 mm
  2. 3.0 mm or more
  3. 1.0 mm or more Correct answer.
  4. 0.6 mm

Explanation

Adequate axial reduction preserves a dentine wall thick enough to resist functional stress and to allow the laboratory technician to build a sound metal framework with porcelain coverage. Roughly 1.0 mm of remaining axial wall is the commonly taught minimum for posterior metal-ceramic preparations, balancing pulp protection against over-reduction. Thinner residual walls risk flexure and fracture under occlusal load.

Question 32Fixed Prosthodontics

A crown margin is placed in enamel just supragingivally on a maxillary premolar. Which property of enamel most directly justifies preferring this location over subgingival dentine?

  1. Higher modulus of elasticity
  2. Presence of a thicker smear layer
  3. Greater bondable mineral content and cleansability Correct answer.
  4. Reduced thermal conductivity

Explanation

Enamel provides a highly mineralised, etchable substrate and, when supragingival, remains accessible to plaque control and impression making. Supragingival enamel margins are associated with better gingival health and easier verification of fit. These advantages, rather than elasticity or conductivity, drive margin placement decisions.

Question 33Fixed Prosthodontics

During try-in of a metal-ceramic single crown, the restoration seats fully on the die but shows a 200-micron gap at the margin intraorally. Which is the most likely cause?

  1. Excessive porcelain thickness on the occlusal surface
  2. A distortion or flash at the internal casting surface Correct answer.
  3. Insufficient die spacer application
  4. An interproximal contact that is too tight

Explanation

A discrepancy between die and intraoral seating usually reflects an interference inside the restoration, such as casting nodules, flash, or distortion that prevents complete seating. Removing internal irregularities typically allows full seating. Occlusal porcelain thickness and die spacer affect fit less directly than internal interference.

Question 34Fixed Prosthodontics

Which impression technique is most appropriate for capturing a supragingival finish line on a single posterior crown when gingival crevicular fluid is minimal?

  1. Single-step dual-arch impression with light-body around the margin Correct answer.
  2. Addition-cured silicone monophase in a stock tray with retraction cord in place
  3. Single-viscosity heavy-body putty wash
  4. Two-step putty-wash with a spaced tray

Explanation

A dual-arch (triple-tray) impression captures the prepared tooth and the opposing arch simultaneously and is well suited to supragingival margins where moisture control is straightforward. Light-body material around the margin records finish-line detail while the heavier material supports the tray. It is efficient and accurate for single units.

Question 35Fixed Prosthodontics

A patient reports a sharp, brief pain on biting that disappears immediately when pressure is released, localised to a recently cemented crown. Which finding best explains this?

  1. Reversible pulpitis from thermal stimulus
  2. Cracked tooth syndrome in an adjacent molar
  3. Chronic apical periodontitis
  4. Occlusal premature contact on the restoration Correct answer.

Explanation

Pain elicited only on biting and relieved instantly on release is characteristic of a high spot or premature occlusal contact loading the periodontal ligament. Adjusting the occlusion typically resolves the symptom. Thermal sensitivity and spontaneous pain point to pulpal pathology instead.

Question 36Fixed Prosthodontics

In a metal-ceramic crown, which design feature of the metal framework is essential to support the porcelain and prevent chipping at the facial cervical region?

  1. A metal collar or a porcelain butt margin with adequate metal support Correct answer.
  2. A highly polished internal surface
  3. An open facial metal-free zone without backing
  4. A knife-edge metal margin

Explanation

Porcelain requires a metal substructure beneath it to resist tensile stress; a metal collar or a properly supported porcelain butt joint at the cervical area prevents flexure and chipping. The framework must be thick enough and shaped to support the veneering ceramic. Removing all facial metal without support increases fracture risk.

Question 37Fixed Prosthodontics

Which factor most strongly determines the retention of a complete-coverage crown on a short clinical crown?

  1. Colour of the cement used
  2. Smoothness of the occlusal surface
  3. Surface area of the axial walls and taper Correct answer.
  4. Thickness of the porcelain veneer

Explanation

Retention of a cemented crown depends primarily on the total surface area of the axial walls and their convergence angle; greater area and minimal taper increase frictional resistance. When crown height is limited, additional surface area or auxiliary features may be needed. Cement colour and porcelain thickness do not influence retention.

Question 38Fixed Prosthodontics

A maxillary central incisor requires a full-coverage crown. Which finish-line configuration is generally preferred for a ceramic or metal-ceramic restoration on the facial aspect?

  1. An undercut finish line
  2. A bevel with no distinct finish line
  3. A 90-degree shoulder or a chamfer with adequate width Correct answer.
  4. A feather edge

Explanation

A shoulder or wide chamfer provides sufficient bulk of restorative material at the margin and allows the technician to create an aesthetic, well-supported cervical contour. Feather edges and bevels are prone to distortion and poor aesthetics with ceramic. Undercuts would prevent seating.

Question 39Fixed Prosthodontics

A patient with a deep overbite and parafunctional habit receives a single metal-ceramic crown. Which occlusal scheme adjustment is most appropriate to reduce risk of porcelain fracture?

  1. Create a mutually protected occlusion with light centric contacts and no working-side interference Correct answer.
  2. Establish heavy centric stops on the restoration
  3. Leave the restoration slightly out of occlusion
  4. Increase the cuspal incline of the restoration

Explanation

A mutually protected occlusion with light, even centric contacts and freedom from excursive interferences minimises concentrated forces on the porcelain. Heavy or premature contacts and steep inclines increase the risk of chipping. Leaving a restoration out of occlusion is not acceptable because it may lead to overeruption and instability.

Question 40Fixed Prosthodontics

During cementation of a zirconia crown with a resin-based cement, which surface treatment of the intaglio surface is most appropriate?

  1. Application of a dentine bonding agent only
  2. Application of hydrofluoric acid gel
  3. Etching with phosphoric acid
  4. Alumina particle abrasion followed by a phosphate monomer-containing primer Correct answer.

Explanation

Zirconia is not etchable with hydrofluoric acid because of its polycrystalline structure, so mechanical abrasion with alumina particles followed by a phosphate-monomer primer is used to improve resin bonding. Phosphoric acid and hydrofluoric acid do not create retentive surfaces on zirconia. The primer promotes chemical adhesion to the resin cement.

Question 41Fixed Prosthodontics

A provisional acrylic resin crown is placed on a prepared premolar. Which feature is most important to prevent gingival inflammation during the provisional phase?

  1. An open proximal contact
  2. A rough, unpolished surface to retain plaque
  3. Highly polished and well-contoured margins and embrasures Correct answer.
  4. A slightly oversized proximal contact

Explanation

Provisional restorations should have smooth, well-adapted margins and properly contoured embrasures to allow plaque control and protect the gingiva. Rough surfaces and open contacts promote plaque accumulation and food impaction. A slightly oversized contact may cause discomfort but is less directly linked to inflammation than surface quality and contour.

Question 42Fixed Prosthodontics

Which is the primary purpose of using die spacer during fabrication of a metal-ceramic crown?

  1. To increase the retention of the crown
  2. To reduce the strength of the metal framework
  3. To provide space for the luting cement Correct answer.
  4. To improve the aesthetics of the porcelain

Explanation

Die spacer creates a uniform space between the die and the restoration, allowing room for the cement film and enabling complete seating. It also helps control the thickness of the cement layer. It does not primarily affect retention, aesthetics, or framework strength.

Question 43Fixed Prosthodontics

A patient presents with a fractured metal-ceramic crown on a mandibular molar with recurrent caries beneath the margin. Which is the most appropriate management?

  1. Recement the fractured crown with zinc phosphate cement
  2. Repair the fracture with composite without removing the crown
  3. Leave the crown in place and monitor
  4. Replace the restoration after removing caries and re-preparing the tooth Correct answer.

Explanation

Recurrent caries and a fractured restoration indicate the crown must be removed, the caries excavated, and the tooth re-prepared before a new restoration is made. Recementing or repairing over caries does not address the underlying disease. Monitoring allows progression of caries and loss of tooth structure.

Question 44Fixed Prosthodontics

Which property of a luting agent is most important when cementing a long-span metal-ceramic fixed partial denture with limited retention?

  1. Long working time only
  2. High compressive strength and low film thickness Correct answer.
  3. Opaque colour
  4. High solubility in oral fluids

Explanation

For a long-span restoration with limited retention, the cement must provide high compressive strength while maintaining a low film thickness to allow complete seating. Low film thickness ensures the restoration seats fully without hydraulic resistance. High solubility and colour are not desirable properties for this purpose.

Question 45Fixed Prosthodontics

A clinician is preparing a tooth for an all-ceramic lithium disilicate crown. Which preparation feature is most critical to ensure adequate strength of the restoration?

  1. A knife-edge finish line
  2. A feather-edge margin
  3. A minimum occlusal reduction of about 1.5 mm and axial reduction of about 1.0 mm Correct answer.
  4. Minimal occlusal reduction of 0.3 mm

Explanation

Lithium disilicate requires sufficient thickness to withstand occlusal forces; approximately 1.5 mm occlusal and 1.0 mm axial reduction are generally recommended. Inadequate reduction leads to thin ceramic that is prone to fracture. Feather and knife-edge margins do not provide adequate support.

Question 46Fixed Prosthodontics

Which statement best describes the role of the ferrule effect in a tooth restored with a post and core and crown?

  1. It improves the aesthetics of the crown
  2. It increases the retention of the post within the root canal
  3. It eliminates the need for a core build-up
  4. It provides a circumferential collar of dentine that resists fracture of the root Correct answer.

Explanation

A ferrule is a circumferential band of dentine, ideally at least 1.5 to 2 mm in height, that encircles the crown margin and helps resist root fracture by distributing forces. It does not primarily retain the post or affect aesthetics. A core is still required to replace lost coronal tooth structure.

Question 47Fixed Prosthodontics

A patient reports that a recently placed metal-ceramic crown feels "high" when biting. Which initial step is most appropriate?

  1. Replace the crown immediately
  2. Perform endodontic treatment
  3. Prescribe antibiotics
  4. Check and adjust the occlusion with articulating paper Correct answer.

Explanation

A perceived high bite after crown placement is usually due to a premature occlusal contact, which can be identified and adjusted with articulating paper. Adjusting the occlusion is conservative and often resolves the symptom. Replacing the crown or prescribing antibiotics is premature without confirming the cause.

Question 48Fixed Prosthodontics

Which factor is most likely to cause a poor marginal fit of a metal-ceramic crown?

  1. Use of a light-body wash impression
  2. Excessive occlusal clearance
  3. Properly trimmed dies
  4. Inadequate die spacer application Correct answer.

Explanation

Inadequate die spacer can lead to insufficient internal relief, causing the restoration to bind and preventing complete seating, which results in a poor marginal fit. Excessive occlusal clearance and proper die trimming do not cause marginal misfit. A light-body wash improves impression accuracy.

Question 49Fixed Prosthodontics

A patient with a history of bruxism needs a single posterior crown. Which restorative material is generally preferred for its wear resistance and strength?

  1. Composite resin
  2. Feldspathic porcelain
  3. Acrylic resin
  4. Monolithic zirconia Correct answer.

Explanation

Monolithic zirconia has high flexural strength and wear resistance, making it suitable for patients with bruxism. Feldspathic porcelain is more prone to fracture under heavy parafunctional forces. Acrylic and composite resins wear rapidly and are not appropriate for long-term posterior restorations in bruxers.

Question 50Fixed Prosthodontics

Which is the most appropriate method to verify the marginal fit of a crown intraorally before cementation?

  1. Checking the colour match
  2. Palpation of the occlusal surface
  3. Bitewing radiograph only
  4. Visual inspection with magnification and a sharp explorer Correct answer.

Explanation

Visual inspection with magnification and a sharp explorer allows detection of marginal discrepancies and overhangs. Radiographs can supplement but are not sufficient alone. Palpation and colour matching do not assess marginal fit.