AGD Fixed and Removable Prosthodontics 4 — Questions and Answers
Question 1: Which cementation agent provides the highest film thickness tolerance and is most biocompatible for cementing a final all-ceramic crown?
- Zinc phosphate cement
- Resin-modified glass ionomer (RMGI) (Correct answer)
- Zinc oxide eugenol (ZOE) cement
- Polycarboxylate cement
Correct answer: Resin-modified glass ionomer (RMGI)
Resin-modified glass ionomer cement offers fluoride release, adhesion to tooth structure, and acceptable biocompatibility with low solubility, making it suitable for all-ceramic restorations.
Question 2: When recording the centric relation (CR) for a complete denture patient, which technique minimizes muscle engrams and guides the condyles to their most superior, anterior, and medially seated position?
- Bimanual manipulation (Dawson technique) (Correct answer)
- Gothic arch (needle point) tracing
- Chew-in technique
- Swallowing method
Correct answer: Bimanual manipulation (Dawson technique)
Dawson's bimanual manipulation guides both condyles simultaneously to a repeatable, musculoskeletally stable position, considered the most reliable method for recording CR.
Question 3: A patient reports that their new complete maxillary denture causes gagging. The most likely prosthodontic cause is:
- Insufficient vertical dimension of occlusion
- Over-extension of the posterior palatal seal area (Correct answer)
- Under-extension of the labial flange
- Incorrect tooth arrangement
Correct answer: Over-extension of the posterior palatal seal area
Over-extension beyond the vibrating line into the soft palate or a posterior border that is too thick stimulates the gag reflex.
Question 4: In fixed prosthodontics, the 'anti-rotation' feature of a preparation is most critical when designing restorations for which tooth?
- Mandibular second molar
- Maxillary central incisor (Correct answer)
- Mandibular canine
- Maxillary first premolar
Correct answer: Maxillary central incisor
Maxillary central incisors have a circular cross-section, making anti-rotation features (grooves, boxes) essential to prevent the crown from rotating on the prepared tooth.
Question 5: Which Kennedy classification describes an edentulous arch with bilateral posterior edentulous areas (distal extensions)?
- Kennedy Class I (Correct answer)
- Kennedy Class II
- Kennedy Class III
- Kennedy Class IV
Correct answer: Kennedy Class I
Kennedy Class I is defined as bilateral distal extension edentulous areas, requiring a tooth-and-tissue-supported RPD.
Question 6: A mandibular lingual bar major connector should be positioned at least how far below the free gingival margin?
- 1 mm
- 2–3 mm
- 4–5 mm (Correct answer)
- 6–8 mm
Correct answer: 4–5 mm
The superior border of a lingual bar must be 4–5 mm below the free gingival margin to avoid impinging on the gingiva and to clear the floor of the mouth.
Question 7: Which material is contraindicated for use as a temporary (provisional) crown under a rubber dam if the final restoration will be bonded with resin cement?
- Bis-acryl composite resin
- PMMA (polymethyl methacrylate)
- Eugenol-containing provisional cement (Correct answer)
- Zinc oxide non-eugenol cement
Correct answer: Eugenol-containing provisional cement
Eugenol from provisional cements penetrates dentinal tubules and inhibits polymerization of resin cements, leading to bond failure of the final restoration.
AGD Fixed and Removable Prosthodontics 4
Which cementation agent provides the highest film thickness tolerance and is most biocompatible for cementing a final all-ceramic crown?