DMD Dental Procedures & Techniques 2 — Questions and Answers
Question 1: What is the typical outline form of the endodontic access cavity for a maxillary first molar?
- Oval, buccolingually elongated
- Rhomboidal (triangular), with the base toward the buccal (Correct answer)
- Round, centered on the central fossa
- Trapezoidal, wider mesially than distally
Correct answer: Rhomboidal (triangular), with the base toward the buccal
The maxillary molar access is rhomboidal/triangular to reach the MB, DB, and palatal orifices, including the MB2.
Question 2: Where is the working length usually set during conventional root canal instrumentation?
- Exactly at the radiographic apex
- 1 mm beyond the radiographic apex
- Approximately 0.5–1 mm short of the radiographic apex (Correct answer)
- 3–4 mm short of the radiographic apex
Correct answer: Approximately 0.5–1 mm short of the radiographic apex
Ending 0.5–1 mm short of the radiographic apex approximates the apical constriction (minor diameter).
Question 3: During irrigation, sodium hypochlorite is extruded past the apex and the patient has sudden severe pain and swelling. What is the best immediate management?
- Stop, reassure the patient, apply cold compresses, and give analgesics, with antibiotics if infection develops (Correct answer)
- Inject more irrigant to dilute the hypochlorite
- Do an immediate incision and drainage of the swelling
- Obturate the canal right away to seal the apex
Correct answer: Stop, reassure the patient, apply cold compresses, and give analgesics, with antibiotics if infection develops
Hypochlorite accidents are managed supportively: cold compresses first, then analgesics, monitoring, and antibiotics or referral when needed.
Question 4: Which material is most commonly used as an intracanal medicament between endodontic appointments?
- Formocresol
- Zinc oxide–eugenol
- Calcium hydroxide paste (Correct answer)
- Glass ionomer cement
Correct answer: Calcium hydroxide paste
Calcium hydroxide's high pH makes it antibacterial and lets it dissolve tissue, which is why it is the standard interappointment medicament.
Question 5: What is the recommended minimum occlusal thickness for an amalgam restoration so it resists fracture?
- 0.5 mm
- 1.0 mm
- 3.0 mm
- 1.5–2.0 mm (Correct answer)
Correct answer: 1.5–2.0 mm
Amalgam is brittle and needs about 1.5–2.0 mm of bulk to withstand occlusal forces.
Question 6: Why is composite resin placed in increments of 2 mm or less in deep posterior preparations?
- To reduce polymerization shrinkage stress and ensure adequate light cure depth (Correct answer)
- To improve radiopacity
- To increase fluoride release
- To avoid needing a bonding agent
Correct answer: To reduce polymerization shrinkage stress and ensure adequate light cure depth
Thin increments cure fully and lower the C-factor shrinkage stress at the bonded margins.
Question 7: What cavosurface margin angle is ideal for an amalgam preparation?
- 45° bevel
- Approximately 90° (butt joint) (Correct answer)
- Long 60° bevel
- Chamfer
Correct answer: Approximately 90° (butt joint)
Amalgam has low edge strength, so a butt-joint margin is needed to prevent marginal fracture.
