EFDA Provisional Crown Fabrication 3 — Questions and Answers
Question 1: Which of the following best describes the 'indirect' method of provisional crown fabrication?
- The crown is made chairside directly in the patient's mouth
- The crown is fabricated on a diagnostic cast outside the mouth (Correct answer)
- The crown is ordered from a dental laboratory
- The crown is formed using a thermoplastic matrix heated in the mouth
Correct answer: The crown is fabricated on a diagnostic cast outside the mouth
The indirect method involves fabricating the provisional on a study model or working cast outside the patient's mouth, reducing intraoral exposure to heat and monomer.
Question 2: Contour errors on the proximal surfaces of a provisional crown can cause:
- Increased sensitivity to cold
- Food impaction and periodontal irritation (Correct answer)
- Premature wear of opposing enamel
- Discoloration of the provisional material
Correct answer: Food impaction and periodontal irritation
Improper proximal contours create open contacts or ledges that trap food, leading to periodontal inflammation and patient discomfort.
Question 3: A provisional crown shows a 'rocking' motion when seated. This most likely indicates:
- Inadequate cement
- An internal interference or undercut (Correct answer)
- Occlusal hypercontact
- Excessive marginal flash
Correct answer: An internal interference or undercut
A rocking motion indicates an internal high spot or undercut preventing complete and stable seating of the provisional crown.
Question 4: What is the significance of the 'critical zone' (0–3 mm from the gingival margin) on a provisional crown?
- It determines the occlusal vertical dimension
- It must be highly polished to prevent plaque accumulation and tissue irritation (Correct answer)
- It is where the provisional is most likely to fracture
- It requires the use of glass ionomer cement
Correct answer: It must be highly polished to prevent plaque accumulation and tissue irritation
The gingival third of the provisional must be smooth and well-polished because surface roughness in this zone promotes bacterial adhesion and gingival inflammation.
Question 5: If a patient reports that their provisional crown feels 'high' after anesthesia wears off, the EFDA should:
- Advise the patient to wait as it will settle
- Reappoint the patient and adjust the occlusion (Correct answer)
- Recement the provisional with more material
- Remove the provisional and recheck the preparation
Correct answer: Reappoint the patient and adjust the occlusion
Occlusal premature contacts cause discomfort and potential damage; the patient must be seen to adjust the occlusion of the provisional.
Question 6: Which of the following indicates the provisional crown has adequate emergence profile?
- The crown contacts the adjacent teeth at the gingival margin
- The crown contours support and mimic natural tooth emergence from the tissue (Correct answer)
- The crown is completely subgingival at all margins
- The crown has a flat, vertical profile from the margin to the contact area
Correct answer: The crown contours support and mimic natural tooth emergence from the tissue
A proper emergence profile replicates the natural tooth shape as it exits the tissue, supporting the gingiva without impinging on it.
Question 7: What effect does eugenol-containing temporary cement have on subsequent resin bonding for the final restoration?
- It enhances the bond strength of composite resin cements
- It inhibits polymerization of resin-based cements, reducing bond strength (Correct answer)
- It has no effect on resin polymerization
- It accelerates the setting of resin cements
Correct answer: It inhibits polymerization of resin-based cements, reducing bond strength
Eugenol is well-documented to inhibit the polymerization of resin-based cements, which can significantly reduce final crown retention.
EFDA Provisional Crown Fabrication 3
Which of the following best describes the 'indirect' method of provisional crown fabrication?