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ABPros Prosthodontics practice questions

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Question 1Section A

Which maxillary edentulous ridge classification describes a ridge with adequate height and width in the anterior region but severe resorption in the posterior region?

  1. Class I
  2. Class III Correct answer.
  3. Class II
  4. Class IV

Explanation

Kennedy-style and residual ridge classifications grade the residual anatomy by location and severity of resorption. A ridge that is adequate anteriorly but severely resorbed posteriorly is described as Class III in the commonly taught edentulous ridge scheme. The key discriminator is the posterior resorption with preserved anterior form.

Question 2Section A

What is the primary purpose of a border-molded custom impression tray in complete denture fabrication?

  1. To register the centric relation position
  2. To capture the teeth in maximum intercuspation
  3. To record the functional width of the denture-bearing tissues Correct answer.
  4. To establish the vertical dimension of occlusion

Explanation

A custom tray with border molding records the functional and limiting movements of the vestibular and lingual tissues so the final impression captures the full denture-bearing area. Interocclusal records and vertical dimension are separate steps. The border-molded tray defines the peripheral seal and tissue extent.

Question 3Section A

A patient reports that a new maxillary complete denture falls when she opens widely. Which factor most likely explains this?

  1. Insufficient border seal in the distobuccal region
  2. Overextension into the pterygomandibular notch area Correct answer.
  3. Overextension of the buccal frenum notch
  4. Excessive posterior palatal seal

Explanation

Overextension into the movable pterygomandibular raphe region causes the denture to be dislodged during wide opening because the tissue moves and breaks the seal. Adequate border seal and relief of movable tissue prevent this. The distobuccal seal and palatal seal support retention rather than cause dislodgment on opening.

Question 4Section A

In a class I jaw relationship, the horizontal overlap of the maxillary anterior teeth over the mandibular anterior teeth is termed:

  1. Freeway space
  2. Curve of Spee
  3. Overjet Correct answer.
  4. Overbite

Explanation

Overjet is the horizontal distance between the incisal edges of maxillary and mandibular incisors. Overbite is the vertical overlap. Freeway space is the interocclusal clearance at rest, and the curve of Spee is the anteroposterior occlusal curvature.

Question 5Section A

Which material is most commonly used for the definitive cast in complete denture fabrication because of its dimensional accuracy and strength?

  1. Dental stone Correct answer.
  2. Model plaster
  3. Die stone
  4. Investment plaster

Explanation

Dental stone (Type III) offers a balance of strength, accuracy, and cost appropriate for complete denture casts. Model plaster is weaker and less accurate. Die stone is used for individual dies, and investment plaster is for casting.

Question 6Section A

What is the main function of the posterior palatal seal in a maxillary complete denture?

  1. To improve retention by creating a partial vacuum at the posterior border Correct answer.
  2. To reduce pressure on the median palatal raphe
  3. To prevent rotation of the denture during function
  4. To provide relief over the incisive papilla

Explanation

The posterior palatal seal compresses tissue at the junction of the hard and soft palate, creating a partial vacuum that enhances retention. Relief over the incisive papilla and raphe addresses pressure, not seal. Rotation control is achieved through other design features.

Question 7Section A

A patient's existing dentures show generalized loss of vertical dimension and increased lower facial height discrepancy. Which record is essential before fabricating new dentures?

  1. A protrusive record
  2. A facebow transfer
  3. A lateral cephalometric radiograph
  4. A centric relation record at the established vertical dimension Correct answer.

Explanation

When vertical dimension is altered, a centric relation record must be made at the corrected vertical dimension to transfer the maxillomandibular relationship accurately. A facebow orients the maxillary cast to the hinge axis but does not establish vertical dimension. Protrusive records are used for condylar guidance settings.

Question 8Section A

Which of the following best describes the neutral zone in complete denture prosthodontics?

  1. The interocclusal clearance at rest
  2. The area of the denture base with the least tissue support
  3. The region of the palate with the thinnest soft tissue
  4. The space where forces from the lips, cheeks, and tongue are in balance Correct answer.

Explanation

The neutral zone is the potential space where the outward forces of the tongue and the inward forces of the lips and cheeks are balanced. Positioning teeth within this zone improves stability. The other options describe unrelated anatomic or occlusal concepts.

Question 9Section A

A maxillary complete denture exhibits a rocking movement on the palate during function. Which factor most likely contributes?

  1. Adequate posterior palatal seal
  2. Excessive relief of the palatal vault Correct answer.
  3. Proper border molding
  4. Balanced occlusion

Explanation

Excessive relief over the palatal vault reduces tissue contact and support, allowing the denture to rock under occlusal load. Adequate seal, balanced occlusion, and proper border molding all promote stability. The rocking indicates loss of support contact.

Question 10Section A

Which occlusal scheme is most appropriate for a patient with a highly resorbed mandibular ridge and poor neuromuscular control?

  1. Monoplane posterior teeth Correct answer.
  2. Anatomic posterior teeth with steep cusps
  3. Crossbite posterior arrangement
  4. Lingualized occlusion with steep cusps

Explanation

Monoplane (zero-degree) posterior teeth reduce lateral forces and are favored when ridge support is poor or neuromuscular control is limited. Steep cusps increase lateral stress on resorbed ridges. Lingualized occlusion can be used but requires more precise control.

Question 11Section A

What is the principal advantage of a lingualized occlusal scheme in complete dentures?

  1. It concentrates occlusal forces along the lingual cusps for improved efficiency and stability Correct answer.
  2. It allows the use of flat occlusal surfaces
  3. It eliminates the need for balanced occlusion
  4. It reduces the vertical dimension of occlusion

Explanation

In lingualized occlusion, maxillary lingual cusps contact the central fossae of mandibular teeth, directing forces favorably and improving masticatory efficiency while maintaining stability. Balanced occlusion is still required. The scheme does not use flat surfaces or alter vertical dimension.

Question 12Section A

Which impression technique records the tissues in a functional rather than resting state for a mandibular complete denture?

  1. Open-mouth technique
  2. Mucocompressive technique Correct answer.
  3. Wash technique
  4. Mucostatic technique

Explanation

Mucocompressive techniques record the tissues under functional load, which is useful for mandibular ridges where support is limited. Mucostatic techniques record tissues at rest. Open-mouth and wash techniques are not classifications of functional versus resting state.

Question 13Section A

The incisive papilla in a maxillary complete denture should be positioned:

  1. At the midline near the incisal edges of the central incisors Correct answer.
  2. On the buccal slope of the ridge
  3. Over the posterior palatal seal
  4. Directly under the labial flange

Explanation

The incisive papilla serves as a landmark for positioning the maxillary central incisors, which are placed just labial and slightly anterior to it. It is not located under the labial flange, at the posterior seal, or on the buccal slope. This landmark helps restore anterior esthetics and phonetics.

Question 14Section A

A patient complains of a burning sensation under a new maxillary denture. Which cause should be evaluated first?

  1. Excessive vertical dimension
  2. Overextended buccal flange
  3. Insufficient posterior palatal seal
  4. Fungal infection related to denture hygiene Correct answer.

Explanation

Denture stomatitis, commonly caused by Candida, is a frequent cause of burning under a maxillary denture and should be evaluated with hygiene assessment and tissue examination. Overextension and occlusal errors can cause discomfort but are less specifically associated with burning. Seal deficiency affects retention.

Question 15Section A

Which factor most directly determines the choice of posterior tooth form in complete denture fabrication?

  1. Type of impression material used
  2. Residual ridge condition and neuromuscular control Correct answer.
  3. Color of the anterior teeth
  4. Patient's age

Explanation

Posterior tooth form is selected based on ridge support, occlusal forces, and the patient's ability to control the prosthesis. Age, anterior shade, and impression material do not determine posterior tooth form. Compromised ridges favor reduced cuspal inclines.

Question 16Section A

A facebow transfer is used in complete denture fabrication primarily to:

  1. Establish the vertical dimension of occlusion
  2. Orient the maxillary cast to the hinge axis of the articulator Correct answer.
  3. Record centric relation
  4. Determine the posterior palatal seal

Explanation

The facebow records the spatial relationship of the maxilla to the terminal hinge axis so the maxillary cast can be mounted in the articulator. Centric relation and vertical dimension are recorded separately. The palatal seal is determined clinically from the cast.

Question 17Section A

Which articulator feature allows simulation of the patient's condylar guidance during eccentric movements?

  1. Mounting plate
  2. Facebow fork
  3. Condylar housing with adjustable guidance Correct answer.
  4. Incisal guide table

Explanation

Adjustable condylar guidance in a semi-adjustable or fully adjustable articulator reproduces the patient's condylar path during eccentric movements. The incisal guide table controls anterior guidance. Mounting plates and facebow forks are transfer components.

Question 18Section A

A patient's existing maxillary denture shows a midline fracture. Which factor is most likely responsible?

  1. Insufficient relief of the incisive papilla
  2. Inadequate posterior palatal seal
  3. Excessive border molding
  4. Occlusal imbalance causing flexure Correct answer.

Explanation

Midline fractures of maxillary dentures commonly result from repeated flexure due to occlusal imbalance or a thin palatal area. Relief and seal issues do not directly cause flexure fractures. Border molding affects the seal, not structural failure.

Question 19Section A

What is the recommended minimum thickness for an acrylic resin palatal area to reduce fracture risk while maintaining comfort?

  1. 2.0 mm Correct answer.
  2. 0.5 mm
  3. 4.0 mm
  4. 1.0 mm

Explanation

A palatal thickness of approximately 2 mm provides adequate strength while remaining comfortable. Thinner areas (0.5-1.0 mm) increase fracture risk, and excessive thickness adds bulk and weight. This balance supports durability and patient tolerance.

Question 20Section A

Which phonetic sound is most useful for evaluating the vertical dimension of occlusion in complete dentures?

  1. /f/
  2. /m/
  3. /t/
  4. /s/ Correct answer.

Explanation

The /s/ sound is produced with a small interincisal clearance (closest speaking space) and is highly sensitive to vertical dimension changes. The /m/ sound assesses lip competence, /f/ assesses labiodental contact, and /t/ assesses tongue-palatal contact.

Question 21Section A

The closest speaking space in a patient with normal occlusion is typically:

  1. 0-1 mm
  2. 1-2 mm Correct answer.
  3. 5-6 mm
  4. 3-4 mm

Explanation

The closest speaking space is generally 1-2 mm between the incisal edges during pronunciation of sibilants. This small clearance is used to verify vertical dimension. Larger clearances suggest excessive vertical dimension.

Question 22Section A

Which condition is a contraindication to immediate complete denture placement?

  1. Good tissue health
  2. Presence of retained roots with acute infection Correct answer.
  3. Adequate bone support
  4. Patient preference for immediate placement

Explanation

Acute infection or retained roots with pathology must be resolved before immediate denture placement to avoid complications and poor healing. Adequate bone and healthy tissue support immediate placement. Patient preference alone is not a contraindication.

Question 23Section A

During fabrication of an immediate denture, which record is typically unavailable and must be estimated?

  1. Posterior palatal seal
  2. Vertical dimension of occlusion Correct answer.
  3. Anterior tooth position
  4. Centric relation

Explanation

Because the remaining anterior teeth are extracted at placement, the vertical dimension must often be estimated from the existing occlusion or pre-extraction records. Centric relation can be recorded, and anterior tooth position and palatal seal are established from casts and landmarks.

Question 24Section A

Which reline procedure is performed at the chairside using a material that sets in the mouth?

  1. Chairside reline Correct answer.
  2. Rebase
  3. Laboratory processed reline
  4. Remount

Explanation

A chairside reline uses a material such as autopolymerizing acrylic or a resilient liner that sets directly in the mouth. Laboratory relines and rebases are processed in the laboratory. A remount is an occlusal procedure, not a reline.

Question 25Section A

A patient presents with a mandibular denture that dislodges during swallowing. Which border is most likely overextended?

  1. Buccal flange
  2. Posterior palatal seal
  3. Labial flange
  4. Lingual flange in the retromylohyoid region Correct answer.

Explanation

Overextension into the retromylohyoid area interferes with tongue and floor-of-mouth movement during swallowing, dislodging the denture. Buccal and labial overextension typically cause soreness, and the posterior palatal seal applies to maxillary dentures.

Question 26Section A

Which material is most commonly used for the definitive denture base of a complete denture because of its ease of processing and repair?

  1. Type IV dental stone
  2. Heat-polymerized polymethyl methacrylate Correct answer.
  3. Cobalt-chromium alloy
  4. Addition silicone

Explanation

Heat-polymerized PMMA remains the standard denture base material because it is esthetic, easily processed, and readily repaired or relined. Metals and stone are not used as the primary base, and silicone is an impression material.

Question 27Section A

In a Kennedy Class I removable partial denture, the primary support at the distal extension is provided mainly by:

  1. The residual ridge and mucosa Correct answer.
  2. The clasps on the abutment teeth
  3. The rests on the anterior teeth
  4. The major connector

Explanation

Distal extension bases are tissue-supported distally, so the residual ridge and underlying mucosa bear the functional load. Abutment teeth provide only secondary support through the rests and clasp assembly.

Question 28Section A

The principal purpose of a rest seat on an abutment tooth for a removable partial denture is to:

  1. Improve the esthetics of the clasp assembly
  2. Prevent rotation of the framework during insertion
  3. Direct occlusal forces along the long axis of the tooth Correct answer.
  4. Provide frictional retention against dislodgment

Explanation

A properly prepared rest seat transmits functional loads axially to the abutment, minimizing torquing forces. Retention is provided by the clasp, not the rest.

Question 29Section A

Which impression material is described as rigid and is used to record the functional borders of a custom tray in complete denture fabrication?

  1. Alginate
  2. Light-body addition silicone
  3. Impression compound
  4. Zinc oxide-eugenol paste Correct answer.

Explanation

Zinc oxide-eugenol impression paste sets rigidly and is commonly used for final border molding and wash impressions. Alginate and light-body silicone are flexible, and compound is used mainly for border molding, not as the definitive wash in this context.

Question 30Section A

Which of the following is a typical indication for a fixed partial denture rather than a removable prosthesis?

  1. A patient with severe residual ridge resorption
  2. A completely edentulous maxilla
  3. A Kennedy Class I distal extension
  4. A single missing tooth bounded by sound abutments Correct answer.

Explanation

A bounded single-tooth space with sound adjacent abutments is the classic indication for a fixed partial denture. Edentulous arches and distal extensions require removable or implant-supported options.

Question 31Section A

The finish line of choice for a metal-ceramic crown is generally:

  1. A shoulder with a bevel
  2. A feather edge
  3. A knife edge
  4. A chamfer Correct answer.

Explanation

A chamfer provides adequate bulk for the metal substructure and a defined margin for the ceramic while preserving tooth structure. Feather and knife edges provide insufficient bulk, and a shoulder with a bevel is more typical for all-ceramic restorations.

Question 32Section A

The main reason for using a custom impression tray in complete denture fabrication is to:

  1. Reduce the total number of appointments
  2. Allow the use of alginate for the final impression
  3. Eliminate the need for border molding
  4. Control the thickness and distribution of impression material Correct answer.

Explanation

A custom tray ensures uniform, controlled thickness of impression material, which improves accuracy of the final impression. It does not eliminate border molding and is not chosen to shorten treatment.

Question 33Section A

In removable partial denture design, the retentive clasp arm engages which part of the abutment tooth?

  1. The middle third of the crown
  2. The gingival third of the crown Correct answer.
  3. The occlusal third of the crown
  4. The incisal edge

Explanation

The retentive clasp arm engages the undercut in the gingival third of the crown, where the tooth converges toward the gingiva. The occlusal and middle thirds are generally non-retentive.

Question 34Section A

A patient reports that a new mandibular removable partial denture lifts when they open their mouth widely. Which design element is most likely inadequate?

  1. The lingual bar
  2. The major connector
  3. The retentive clasp arms Correct answer.
  4. The occlusal rests

Explanation

Lifting of the prosthesis during mouth opening suggests insufficient retention, which is provided by the retentive clasp arms engaging the undercuts. Rests and connectors provide support and rigidity, not retention.

Question 35Section A

A fixed partial denture is planned across a span with a marked curve of Spee. Which consideration most directly affects the occlusal design of the pontic and retainers?

  1. Achieving mutually protected occlusion with the opposing arch Correct answer.
  2. Selecting the shade of the porcelain
  3. Determining the number of impressions
  4. Maximizing the thickness of the metal framework

Explanation

Occlusal design of retainers and pontics must harmonize with the opposing dentition to establish mutually protected occlusion and avoid interferences. Framework thickness, shade, and impression count do not determine occlusal design.

Question 36Section A

A patient presents with a maxillary complete denture that drops when they speak certain words. Which border area should be evaluated first for loss of seal?

  1. The buccal frenum notches
  2. The labial frenum notch
  3. The posterior palatal seal region Correct answer.
  4. The incisive papilla region

Explanation

Loss of the posterior palatal seal allows air to enter beneath the denture, breaking the seal during speech. The frenum notches and incisive papilla region are less likely to cause generalized loss of retention.

Question 37Section A

A patient with a new maxillary complete denture complains of food collecting under the denture. Which factor should be assessed?

  1. The incisal guidance angle
  2. The type of articulator used
  3. Border adaptation and seal Correct answer.
  4. The shade of the teeth

Explanation

Food trapping under a denture usually reflects inadequate border adaptation or loss of seal, allowing debris to enter. Shade, incisal guidance, and articulator type do not cause food collection.

Question 38Section A

A patient requires a cast metal removable partial denture framework. Which laboratory step most directly ensures the framework fits the abutment teeth?

  1. Using an irreversible hydrocolloid impression
  2. Polishing the framework after casting
  3. Waxing the framework on the master cast
  4. Duplication of the refractory cast from the master cast Correct answer.

Explanation

The master cast is duplicated to produce a refractory cast on which the framework is waxed and cast, ensuring accuracy and fit. Waxing directly on the master cast would not survive casting temperatures.

Question 39Section A

A patient's fixed partial denture has a pontic with a ridge lap design. Which clinical consequence is most likely?

  1. Improved esthetics with no drawbacks
  2. Increased retention of the retainer
  3. Reduced occlusal load on the abutments
  4. Difficulty in cleaning beneath the pontic Correct answer.

Explanation

A ridge lap pontic contacts the lingual slope of the ridge, creating an inaccessible area that is difficult to clean. It does not improve retention or reduce occlusal load.

Question 40Section A

A patient with a fully edentulous mandible has a very thin residual ridge. Which prosthesis design consideration is most important?

  1. Increasing the vertical dimension
  2. Reducing the occlusal table to a single tooth
  3. Maximizing the denture-bearing area and using a resilient impression Correct answer.
  4. Using only porcelain posterior teeth

Explanation

A thin ridge benefits from maximizing the denture-bearing area and using a functional, resilient impression to distribute load. Reducing to a single tooth, increasing vertical dimension, and porcelain teeth would be inappropriate.

Question 41Section A

The incisal guidance of a fixed partial denture should be designed primarily to:

  1. Reduce the need for a nightguard
  2. Increase the retention of the retainers
  3. Improve the shade match of the porcelain
  4. Provide anterior disclusion during eccentric movements Correct answer.

Explanation

Incisal guidance determines the path of disclusion of posterior teeth during protrusive and lateral movements, protecting them from harmful contacts. It does not affect retention, nightguard need, or shade.

Question 42Section A

A patient reports that their maxillary complete denture feels loose only when they chew on one side. Which factor most likely contributes?

  1. A high lip line
  2. Excessive incisal guidance
  3. A thick palatal area
  4. Inadequate border seal on the contralateral side Correct answer.

Explanation

When chewing on one side, the contralateral border seal may break if adaptation is inadequate, causing dislodgment. Incisal guidance, lip line, and palatal thickness do not explain this pattern.

Question 43Section A

Which property of a dental ceramic most closely matches enamel and makes it suitable for esthetic restorations?

  1. Translucency Correct answer.
  2. Solubility
  3. Thermal conductivity
  4. Radio-opacity

Explanation

Dental ceramics are chosen for esthetics largely because their translucency approximates enamel. Radio-opacity, conductivity, and solubility are not the esthetic-matching property.

Question 44Section A

A patient's existing fixed partial denture shows marginal staining and recurrent caries at the gingival margin. Which factor is most likely responsible?

  1. Adequate cementation
  2. Excessive occlusal contact
  3. Poor marginal adaptation with microleakage Correct answer.
  4. High polish on the pontic

Explanation

Marginal staining and recurrent caries typically result from poor marginal adaptation and microleakage. Excessive contact, polish, and adequate cementation would not produce these findings.

Question 45Section A

A patient with a removable partial denture complains of a metallic taste. Which factor is most likely?

  1. A high palatal vault
  2. Insufficient border molding
  3. Excessive acrylic resin thickness
  4. Galvanic interaction between dissimilar metals Correct answer.

Explanation

Metallic taste in a partial denture wearer often results from galvanic interaction between dissimilar metals in the mouth. Resin thickness, border molding, and palatal vault do not cause metallic taste.

Question 46Section A

In a complete denture, the polished surface should be shaped to:

  1. Maximize the thickness for strength
  2. Provide a flat vertical wall for esthetics
  3. Allow the tongue and cheeks to function against it without displacement Correct answer.
  4. Extend beyond the denture border for retention

Explanation

The polished surface should be contoured so that the tongue and cheeks can function against it without dislodging the denture, contributing to stability. Thickness, overextension, and flat walls do not serve this purpose.

Question 47Section A

Which of the following best explains why a metal-ceramic crown may show a grey shadow at the gingival margin?

  1. Insufficient thickness of the ceramic over the metal collar Correct answer.
  2. Use of a shoulder finish line
  3. A high-gloss finish
  4. Excessive ceramic thickness

Explanation

A grey shadow appears when the ceramic is too thin over the opaque metal, allowing the metal to show through. Excessive ceramic thickness, gloss, and shoulder finish lines do not cause the shadow.

Question 48Section A

A patient with a maxillary complete denture reports a gag reflex when the denture is seated. Which modification is most appropriate to evaluate first?

  1. Adding more acrylic to the labial flange
  2. Extending the denture further into the soft palate
  3. Reducing the posterior palatal seal extension over the soft palate Correct answer.
  4. Increasing the thickness of the palatal area

Explanation

Gagging is often caused by overextension of the posterior palatal seal onto the sensitive soft palate. Reducing that extension is the first step. Increasing thickness, extending further, and adding labial acrylic would worsen the problem.

Question 49Section A

A patient's fixed partial denture has a cantilever pontic. Which biomechanical principle is most critical to its success?

  1. Adequate support from the abutment to resist tipping forces Correct answer.
  2. Maximum porcelain thickness for esthetics
  3. A ridge lap design for cleaning
  4. Use of a single retainer

Explanation

A cantilever pontic creates tipping forces, so the abutment must provide adequate support and the design must minimize leverage. Porcelain thickness, ridge lap design, and single retainer use are not the critical principle.

Question 50Section A

A patient with a mandibular removable partial denture experiences soreness under the lingual bar. Which factor is most likely?

  1. Insufficient clasp retention
  2. The bar impinging on the lingual mucosa when the framework settles Correct answer.
  3. Adequate tissue adaptation
  4. Excessive relief under the rests

Explanation

Soreness under a lingual bar usually results from the bar contacting the mucosa when the framework settles under load. Excessive relief would reduce, not cause, soreness; adequate adaptation and retention are not the cause.