AGD Fixed and Removable Prosthodontics 3 — Questions and Answers
Question 1: Which retention mechanism is used for an implant-retained overdenture that allows the most movement (stress-breaking) of the prosthesis?
- Ball-and-socket (stud) attachment (Correct answer)
- Bar-and-clip attachment
- Milled bar with telescopic crowns
- Rigid screw-retained bar
Correct answer: Ball-and-socket (stud) attachment
Ball-and-socket (stud) attachments allow multi-axial movement, providing the most stress-breaking action compared to more rigid attachment designs.
Question 2: What is the most critical factor in determining the path of withdrawal for a fixed partial denture (bridge) with multiple abutments?
- Shade selection of the pontic
- Parallelism of abutment teeth (Correct answer)
- Gingival contour of the edentulous ridge
- Type of cement used
Correct answer: Parallelism of abutment teeth
All abutment teeth must be parallel to one another along the chosen path of withdrawal so the fixed bridge can seat and be removed as a single unit.
Question 3: A sanitary (hygienic) pontic design is contraindicated in which clinical situation?
- Posterior mandibular edentulous space with good ridge height
- Anterior maxillary region where esthetics are critical (Correct answer)
- Patient with poor oral hygiene
- Long-span bridges
Correct answer: Anterior maxillary region where esthetics are critical
Sanitary pontics leave a visible gap between the pontic and ridge, making them unacceptable in the anterior maxilla where esthetics demand tissue contact.
Question 4: Which type of rest seat preparation is required for a reciprocal clasp located on the lingual surface of a molar in an RPD?
- Occlusal rest seat
- Cingulum rest seat
- Incisal notch rest seat
- Lingual rest seat (Correct answer)
Correct answer: Lingual rest seat
A lingual rest seat is prepared on the lingual surface of posterior teeth to support a lingual reciprocal arm and resist vertical displacement.
Question 5: When using a stock tray for a complete denture final impression, which modification is essential to achieve adequate peripheral extension?
- Perforating the tray with holes for mechanical retention
- Adding border-molding material (compound or PVS) around the periphery (Correct answer)
- Applying adhesive to the tissue surface only
- Reducing the posterior extent of the tray
Correct answer: Adding border-molding material (compound or PVS) around the periphery
Border molding establishes the functional width and depth of the vestibular periphery so the final impression accurately captures the denture-bearing area.
Question 6: A zirconia crown preparation requires how much occlusal reduction compared to a traditional porcelain-fused-to-metal (PFM) crown?
- More reduction (2.5–3.0 mm) due to zirconia's rigidity
- The same reduction (1.5–2.0 mm)
- Less reduction (1.0–1.5 mm) because zirconia is stronger (Correct answer)
- No reduction — zirconia is bonded directly to enamel
Correct answer: Less reduction (1.0–1.5 mm) because zirconia is stronger
Monolithic zirconia can achieve adequate strength with 1.0–1.5 mm of occlusal reduction due to its high fracture toughness, conserving more tooth structure than PFM.
Question 7: Which clinical sign most strongly suggests denture-induced fibrous hyperplasia (epulis fissuratum) in a complete denture wearer?
- Generalized erythema of the palatal mucosa
- Folds of hyperplastic tissue along the denture border in the vestibule (Correct answer)
- Candidal pseudomembrane on the denture-bearing tissue
- Petechiae on the soft palate
Correct answer: Folds of hyperplastic tissue along the denture border in the vestibule
Epulis fissuratum presents as folds of fibrous hyperplastic tissue in the vestibule caused by chronic irritation from an ill-fitting denture flange.
AGD Fixed and Removable Prosthodontics 3
Which retention mechanism is used for an implant-retained overdenture that allows the most movement (stress-breaking) of the prosthesis?