AGD Prosthodontics: Fixed and Removable 4 — Questions and Answers
Question 1: When evaluating a patient for implant-supported prosthetics, the minimum bone height above the inferior alveolar nerve for a mandibular implant is generally considered to be:
- 1 mm
- 2 mm (Correct answer)
- 4 mm
- 8 mm
Correct answer: 2 mm
A minimum of 2 mm of bone between the implant apex and the inferior alveolar nerve is required to prevent nerve injury, though most clinicians prefer more.
Question 2: Acrylic resin denture teeth wear much faster than porcelain teeth. The primary clinical significance of this fact is:
- Acrylic teeth cannot be used in complete dentures
- Acrylic teeth require more frequent replacement than porcelain
- Wear of acrylic teeth can reduce vertical dimension of occlusion over time (Correct answer)
- Porcelain teeth are always preferred for posterior denture teeth
Correct answer: Wear of acrylic teeth can reduce vertical dimension of occlusion over time
Progressive occlusal wear of acrylic denture teeth reduces the vertical dimension of occlusion, leading to overclosure, TMD symptoms, and poor esthetics.
Question 3: The most common cause of fracture of a maxillary complete denture along the midline is:
- Excessive vertical dimension of occlusion
- Flexural fatigue from repeated bending during function (Correct answer)
- Porosity in the acrylic resin
- Improper placement of the anterior teeth
Correct answer: Flexural fatigue from repeated bending during function
The maxillary denture flexes during function due to the resilient palatal mucosa acting as a fulcrum, causing repeated bending stress and fatigue fracture at the midline.
Question 4: A provisional restoration is left in place for several months before the final impression. The primary risk associated with this practice is:
- Sensitization of the pulp to resin materials
- Gingival overgrowth and margin migration affecting the finish line (Correct answer)
- Discoloration of the preparation
- Increased patient sensitivity to temperature
Correct answer: Gingival overgrowth and margin migration affecting the finish line
Prolonged temporization can allow gingival tissue changes—either overgrowth onto the finish line or recession—complicating the final impression and fit.
Question 5: The phenomenon of 'combination syndrome' is associated with:
- A mandibular complete denture opposing a maxillary Kennedy Class I RPD
- A maxillary complete denture opposing a mandibular Class I RPD with natural anteriors (Correct answer)
- Bilateral posterior tooth loss opposing a complete upper denture
- Anterior tooth loss combined with posterior crossbite
Correct answer: A maxillary complete denture opposing a mandibular Class I RPD with natural anteriors
Combination syndrome occurs when a maxillary complete denture opposes mandibular natural anterior teeth and a distal-extension RPD, causing bone loss in the anterior maxilla and posterior mandible.
Question 6: Which of the following best describes the role of a face-bow record in fixed prosthodontics?
- It records the centric relation position of the mandible
- It transfers the maxillary cast to an articulator in the same relationship to the hinge axis (Correct answer)
- It measures the interocclusal distance at rest position
- It records protrusive and lateral excursions for articulator programming
Correct answer: It transfers the maxillary cast to an articulator in the same relationship to the hinge axis
The face-bow records the spatial relationship of the maxillary arch to the transverse hinge axis, allowing accurate mounting on an articulator.
Question 7: When a patient presents with pain under a new partial denture that worsens after meals, the most likely cause is:
- Allergic reaction to the metal framework
- Food impaction under the denture base causing tissue trauma (Correct answer)
- Excessive clasp pressure on the abutment teeth
- An improperly recorded centric relation
Correct answer: Food impaction under the denture base causing tissue trauma
Food particles trapped between the denture base and the underlying soft tissue cause pressure and ulceration, which intensify after eating and are relieved by removing and cleaning the denture.
AGD Prosthodontics: Fixed and Removable 4
When evaluating a patient for implant-supported prosthetics, the minimum bone height above the inferior alveolar nerve for a mandibular implant is generally considered to be: