NBDE Dental Anatomy and Occlusion 2 — Questions and Answers
Question 1: Which cusp of the maxillary first molar is the smallest and least functional?
- Mesiobuccal cusp
- Distobuccal cusp
- Mesiolingual cusp
- Cusp of Carabelli (Correct answer)
Correct answer: Cusp of Carabelli
The cusp of Carabelli is an accessory cusp on the mesiolingual surface of the maxillary first molar and is the smallest, non-functional cusp.
Question 2: The mandibular first premolar differs from the second premolar in that it has:
- Two well-developed lingual cusps
- A transverse ridge connecting buccal and lingual cusps
- A highly developed lingual cusp nearly equal in height to the buccal
- A prominent mesiolingual developmental groove (Correct answer)
Correct answer: A prominent mesiolingual developmental groove
The mandibular first premolar has a prominent mesiolingual developmental groove that divides its occlusal surface, distinguishing it from the second premolar.
Question 3: During protrusive mandibular movement, which contacts are ideally present in a mutually protected occlusion?
- Only posterior tooth contacts
- Only anterior tooth contacts (Correct answer)
- Balanced contacts on both anterior and posterior teeth
- Canine contacts only
Correct answer: Only anterior tooth contacts
In mutually protected occlusion, protrusive movements are guided by anterior teeth, which disclude the posteriors to prevent wear.
Question 4: Which root of the maxillary first molar is most likely to be in close proximity to the maxillary sinus?
- Mesiobuccal root
- Distobuccal root
- Palatal root (Correct answer)
- All roots equally
Correct answer: Palatal root
The palatal root of the maxillary first molar is the longest and most often projects into or near the floor of the maxillary sinus.
Question 5: The angle formed between the long axis of a tooth and the occlusal plane is referred to as the:
- Inclination angle
- Axial inclination
- Cusp angle (Correct answer)
- Plane of occlusion angle
Correct answer: Cusp angle
Cusp angle is the angle formed by a line from cusp tip to base of the cusp in relation to the occlusal plane, influencing occlusal forces.
Question 6: Which permanent tooth has the longest root relative to its crown length?
- Maxillary central incisor
- Maxillary canine (Correct answer)
- Mandibular first molar
- Mandibular second premolar
Correct answer: Maxillary canine
The maxillary canine has the longest root of all teeth relative to its crown and is one of the most stable teeth in the arch.
Question 7: The distal surface of the mandibular first molar occludes primarily with which maxillary tooth?
- Maxillary first molar only
- Maxillary second premolar only
- Both maxillary second premolar and first molar (Correct answer)
- Maxillary second molar
Correct answer: Both maxillary second premolar and first molar
In Class I occlusion, the distal surface of the mandibular first molar occludes with the distal portion of the maxillary second premolar and the mesial portion of the maxillary first molar.
NBDE Dental Anatomy and Occlusion 2
Which cusp of the maxillary first molar is the smallest and least functional?