01. A dental technician is mounting casts for a patient with normal Class I molar occlusion. During verification, which relationship should be present between the permanent first molars?
A. The distobuccal cusp of the maxillary first molar should contact the buccal groove of the mandibular first molar
B. The mesiobuccal cusp of the maxillary first molar should align with the buccal groove of the mandibular first molar
C. The mesiobuccal cusp of the mandibular first molar should align with the central fossa of the maxillary second molar
D. The maxillary first molar should be positioned directly distal to the mandibular first molar
Answer: B. The mesiobuccal cusp of the maxillary first molar should align with the buccal groove of the mandibular first molar
Rationale: In Angle Class I molar occlusion, the mesiobuccal cusp of the maxillary permanent first molar occludes with the buccal groove of the mandibular permanent first molar. This relationship is an important reference during diagnostic mounting and tooth arrangement.
02. While arranging mandibular posterior teeth for a complete denture, the technician notices that the occlusal plane is completely flat from the canine to the molars. Which natural occlusal curvature is missing?
A. Curve of Wilson
B. Curve of Monson
C. Curve of Spee
D. Compensating curve only in the frontal plane
Answer: C. Curve of Spee
Rationale: The Curve of Spee is the anteroposterior curvature extending from the mandibular canine through the buccal cusps of the posterior teeth. In complete dentures, an appropriate compensating curve helps maintain balanced articulation.
03. A patient’s diagnostic casts show that during right lateral movement, only the right maxillary and mandibular canines contact, while all posterior teeth separate. Which occlusal scheme is demonstrated?
A. Group function
B. Canine-guided occlusion
C. Bilateral balanced occlusion
D. Monoplane occlusion
Answer: B. Canine-guided occlusion
Rationale: In canine-guided occlusion, the canines on the working side contact during lateral movement and disclude the posterior teeth. This reduces lateral forces on posterior teeth.
04. During the waxing of a posterior crown, the technician accidentally makes a supporting cusp excessively high. What is the most likely clinical consequence?
A. Improved food escape
B. Premature occlusal contact
C. Increased proximal clearance
D. Reduced vertical dimension
Answer: B. Premature occlusal contact
Rationale: An excessively high supporting cusp can contact prematurely during closure or excursive movements. This may cause discomfort, occlusal trauma, crown loosening or the need for significant chairside adjustment.
05. A crown is fabricated for a maxillary first premolar. Which cusps are normally considered the functional or supporting cusps in the maxillary posterior arch?
A. Buccal cusps
B. Lingual cusps
C. Both buccal and lingual cusps equally
D. Distal marginal ridges only
Answer: B. Lingual cusps
Rationale: The lingual cusps of maxillary posterior teeth and the buccal cusps of mandibular posterior teeth are the main supporting cusps. They maintain vertical dimension and contact opposing fossae or marginal ridges.
06. An alginate impression is received in the laboratory but is left uncovered on the bench for several hours. The impression becomes shrunken and distorted. Which process caused this change?
A. Imbibition
B. Syneresis
C. Polymerization expansion
D. Hygroscopic expansion
Answer: B. Syneresis
Rationale: Syneresis is the loss of water from a hydrocolloid material, resulting in shrinkage. Alginate impressions should be poured promptly or stored for a limited time in a properly humid environment.
07. A technician mixes dental stone using considerably more water than recommended. What effect will this most likely have on the final cast?
A. Increased strength and reduced porosity
B. Reduced setting time and increased hardness
C. Reduced strength and increased porosity
D. Increased setting expansion only
Answer: C. Reduced strength and increased porosity
Rationale: Excess water creates greater space between gypsum crystals. After the excess water evaporates, more porosity remains, reducing the strength and surface hardness of the cast.
08. A heat-cured acrylic denture base develops internal porosity, particularly in thick areas. Which processing error is the most likely cause?
A. Using insufficient separating medium
B. Rapid heating that causes monomer boiling
C. Excessive polishing pressure
D. Keeping the flask under pressure during curing
Answer: B. Rapid heating that causes monomer boiling
Rationale: Rapid temperature elevation can cause the monomer to boil, especially in thick sections where the exothermic reaction raises the internal temperature. This produces gaseous porosity.
09. A clinician requests an impression material for multiple crown preparations with deep undercuts. The material must have good elastic recovery and should be removable without tearing. Which material is most appropriate?
A. Impression compound
B. Zinc oxide–eugenol paste
C. Addition silicone
D. Impression plaster
Answer: C. Addition silicone
Rationale: Addition silicone has excellent dimensional stability, elastic recovery and adequate tear resistance. It is commonly used for precise fixed prosthodontic impressions.
10. During metal-ceramic crown fabrication, the technician selects a ceramic with a coefficient of thermal expansion slightly lower than that of the metal substructure. Why is this relationship desirable?
A. It places the ceramic under slight residual compression
B. It places the ceramic under permanent tension
C. It prevents oxide formation on the metal
D. It eliminates the need for slow cooling
Answer: A. It places the ceramic under slight residual compression
Rationale: The metal should contract slightly more than the porcelain during cooling. This places the porcelain under mild compressive stress, which improves resistance to cracking.
11. A complete maxillary denture repeatedly loses retention during speech. Examination of the cast shows that the posterior palatal seal was not properly incorporated. What is the primary function of this seal?
A. Increase the vertical dimension
B. Compensate for acrylic shrinkage and maintain the posterior border seal
C. Prevent contact between posterior teeth
D. Create space for the tongue
Answer: B. Compensate for acrylic shrinkage and maintain the posterior border seal
Rationale: The posterior palatal seal maintains close adaptation of the denture’s posterior border, compensates for processing shrinkage and improves retention.
12. A severely resorbed mandibular ridge offers limited stability for a complete denture. The clinician records the position where muscular forces from the tongue and cheeks are balanced. Which concept is being used?
A. Altered cast technique
B. Neutral-zone technique
C. Split-cast technique
D. Face-bow transfer
Answer: B. Neutral-zone technique
Rationale: The neutral zone is the area where inward forces from the cheeks and lips are balanced by outward forces from the tongue. Positioning teeth and polished surfaces within this zone improves denture stability.
13. While finishing a mandibular complete denture, the technician considers reducing the distal extension short of the retromolar pads. What should be done?
A. Both retromolar pads should generally be covered
B. Only the anterior half of each retromolar pad should be covered
C. The denture should terminate in front of the retromolar pads
D. The pads should be relieved completely and left uncovered
Answer: A. Both retromolar pads should generally be covered
Rationale: The retromolar pad is a relatively stable anatomical landmark and should generally be covered by the mandibular denture base to improve support and establish proper extension.
14. After border molding, a maxillary custom tray produces an impression with a thick, rolled border in the labial vestibule. The patient experienced pain during lip movement. What is the most likely cause?
A. Underextended border
B. Overextended border
C. Insufficient tray adhesive
D. Excessive relief over the palate
Answer: B. Overextended border
Rationale: An excessively thick or long border can impinge on movable tissues during function. The border should be reduced and remolded to achieve functional extension without displacement.
15. A complete denture patient requires simultaneous contacts on both sides during lateral and protrusive movements to improve denture stability. Which occlusal scheme is indicated?
A. Canine-guided occlusion
B. Bilateral balanced occlusion
C. Mutually protected occlusion
D. Anterior guidance without posterior contact
Answer: B. Bilateral balanced occlusion
Rationale: Bilateral balanced occlusion aims to maintain simultaneous contacts on the working and non-working sides during excursions. This helps reduce tipping of complete dentures.
16. A root canal–treated premolar is being restored with a post, core and crown. The preparation includes approximately 2 mm of sound tooth structure extending above the finish line. What is the main benefit of this feature?
A. It creates a ferrule effect that improves fracture resistance
B. It increases ceramic translucency
C. It eliminates the need for a post
D. It prevents all forms of cement dissolution
Answer: A. It creates a ferrule effect that improves fracture resistance
Rationale: A circumferential band of sound coronal tooth structure helps the crown resist functional forces and reduces the risk of root or core fracture.
17. A technician is fabricating a conventional all-ceramic crown that requires sufficient bulk of ceramic at the facial margin. Which finish-line design is generally preferred?
A. Feather edge
B. Knife edge
C. Shoulder with a rounded internal angle
D. Reverse bevel
Answer: C. Shoulder with a rounded internal angle
Rationale: A shoulder or deep chamfer with rounded internal angles provides adequate space for ceramic and reduces stress concentration. Knife-edge margins may leave insufficient ceramic thickness.
18. A mandibular posterior fixed partial denture is planned for an area with limited vertical space but good ridge form. Which pontic design provides the best access for cleaning while avoiding tissue contact?
A. Saddle pontic
B. Modified ridge-lap pontic
C. Hygienic pontic
D. Ovate pontic
Answer: C. Hygienic pontic
Rationale: A hygienic pontic does not contact the residual ridge, allowing easy cleaning. It is primarily used in non-aesthetic posterior areas when adequate occlusogingival space is available.
19. A die is prepared for a full-coverage crown. The technician applies die spacer but stops approximately 0.5–1 mm short of the finish line. Why?
A. To prevent any cement space on the axial walls
B. To provide cement space while maintaining marginal adaptation
C. To increase die hardness at the margin
D. To make the crown intentionally loose
Answer: B. To provide cement space while maintaining marginal adaptation
Rationale: Die spacer creates space for luting cement and allows complete seating of the restoration. Keeping it away from the margin helps preserve accurate marginal fit.
20. A provisional crown fits the prepared tooth but the proximal contact is open. What is the most likely consequence if the problem is not corrected?
A. Improved periodontal health
B. Food impaction and tooth movement
C. Increased crown retention
D. Reduced plaque accumulation
Answer: B. Food impaction and tooth movement
Rationale: Open proximal contacts can allow food impaction and may permit adjacent teeth to move. This can compromise periodontal health and affect the fit of the definitive restoration.
21. During the design of a removable partial denture, an occlusal rest is placed on an abutment tooth. What is its primary function?
A. Provide vertical support and prevent tissueward movement
B. Retain acrylic resin mechanically
C. Create gingival displacement
D. Prevent all horizontal movement
Answer: A. Provide vertical support and prevent tissueward movement
Rationale: A properly prepared rest transmits occlusal forces along the long axis of the abutment and prevents the prosthesis from moving toward the supporting tissues.
22. A cast clasp arm is found to be too rigid to engage the planned undercut safely. Which modification would generally increase clasp flexibility?
A. Shorten and thicken the clasp arm
B. Increase its width throughout
C. Lengthen and taper the clasp arm
D. Place the tip above the survey line
Answer: C. Lengthen and taper the clasp arm
Rationale: Clasp flexibility increases as the arm becomes longer and more tapered and decreases as thickness increases. The terminal portion should engage the selected undercut.
23. A mandibular Kennedy Class I removable partial denture tends to rotate away from the distal-extension ridge when sticky food is consumed. Which component helps resist this rotation?
A. Direct retainer adjacent to the distal extension only
B. Indirect retainer positioned anterior to the fulcrum line
C. Minor connector placed directly over the ridge
D. Acrylic resin finishing line
Answer: B. Indirect retainer positioned anterior to the fulcrum line
Rationale: An indirect retainer is placed away from and usually anterior to the fulcrum line. It helps resist lifting or rotational displacement of a distal-extension denture base.
24. A distal-extension removable partial denture framework fits the teeth accurately, but the edentulous ridge has displaceable mucosa. Which laboratory procedure can improve adaptation of the denture base to the functional ridge form?
A. Dowel-pin technique
B. Altered cast technique
C. Refractory die technique
D. Double-pour crown technique
Answer: B. Altered cast technique
Rationale: The altered cast technique records the distal-extension ridge under controlled functional conditions while maintaining the accurate tooth-supported relationship of the framework.
25. A mandibular cast has only 5 mm of functional depth between the gingival margins and the floor of the mouth. Which major connector is generally more appropriate than a lingual bar?
A. Palatal strap
B. Lingual plate
C. Labial bar in every case
D. Horseshoe connector
Answer: B. Lingual plate
Rationale: A lingual bar requires adequate vertical space for the bar and gingival clearance. When space is insufficient, a properly designed lingual plate is often preferred.
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