DDS Doctor of Dental Surgery MCQ 3 — Questions and Answers
Question 1: Which tooth surface is most susceptible to root caries in the elderly population?
- Occlusal surface
- Buccal surface below the CEJ (Correct answer)
- Lingual surface
- Proximal surface above the contact
Correct answer: Buccal surface below the CEJ
Exposed root surfaces, especially buccal surfaces below the CEJ, are most susceptible to root caries due to gingival recession common in elderly patients.
Question 2: Which tooth movement produces the greatest amount of root resorption during orthodontic treatment?
- Tipping
- Rotation
- Intrusion (Correct answer)
- Extrusion
Correct answer: Intrusion
Intrusive tooth movement produces the greatest root resorption because it concentrates force at the root apex.
Question 3: A removable partial denture major connector for a mandibular arch should be located:
- On the cingula of anterior teeth
- At least 3–4 mm from the gingival margins (Correct answer)
- Directly over the ridge crest
- On the labial surface of anterior teeth
Correct answer: At least 3–4 mm from the gingival margins
Mandibular major connectors must be placed at least 3–4 mm from the gingival margins to avoid impingement on gingival tissues.
Question 4: Which periodontal fiber group is responsible for resisting intrusive forces on the tooth?
- Alveolar crest fibers
- Horizontal fibers
- Oblique fibers (Correct answer)
- Apical fibers
Correct answer: Oblique fibers
Oblique fibers, the most numerous PDL fibers, run from cementum in a coronal direction to alveolar bone and primarily resist intrusive (axial) forces.
Question 5: Zinc oxide eugenol temporary cement should NOT be used under which type of restoration?
- Metal crowns
- Porcelain-fused-to-metal crowns
- Composite resin restorations (Correct answer)
- Amalgam restorations
Correct answer: Composite resin restorations
Eugenol inhibits the polymerization of composite resin, so ZOE cements are contraindicated as bases or temporaries under composite restorations.
Question 6: Which local anesthetic has the longest duration of action among those used in dentistry?
- Lidocaine
- Mepivacaine
- Prilocaine
- Bupivacaine (Correct answer)
Correct answer: Bupivacaine
Bupivacaine (Marcaine) has the longest duration of action, providing pulpal anesthesia for up to 90 minutes and soft-tissue anesthesia for 4–9 hours.
Question 7: A patient develops trismus after an inferior alveolar nerve block. The most likely cause is:
- Needle tip contacting the mandibular condyle
- Hematoma formation in the medial pterygoid muscle (Correct answer)
- Allergic reaction to the anesthetic
- Injection into the parotid gland
Correct answer: Hematoma formation in the medial pterygoid muscle
Trismus after an IAN block most commonly results from hematoma or direct trauma to the medial pterygoid muscle from the needle.
DDS Doctor of Dental Surgery MCQ 3
Which tooth surface is most susceptible to root caries in the elderly population?