NBDE Dental Anatomy and Occlusion 5 — Questions and Answers
Question 1: The primary function of the contact areas between adjacent teeth is to:
- Improve esthetics of the smile
- Protect the interdental papilla and maintain arch stability (Correct answer)
- Facilitate food accumulation for nutrient absorption
- Guide eruption of the adjacent tooth
Correct answer: Protect the interdental papilla and maintain arch stability
Proximal contact areas protect the underlying interdental papilla from food impaction and maintain the position and stability of teeth in the arch.
Question 2: Which statement about the mandibular canine is TRUE compared to the maxillary canine?
- It has a longer root
- Its crown is narrower mesiodistally (Correct answer)
- Its cusp tip is positioned more to the distal
- It has a more prominent cingulum
Correct answer: Its crown is narrower mesiodistally
The mandibular canine has a narrower mesiodistal crown width compared to the maxillary canine, giving it a more slender appearance.
Question 3: In a Class I molar relationship, the mesiobuccal cusp of the maxillary first molar occludes:
- In the central fossa of the mandibular first molar
- In the buccal groove of the mandibular first molar (Correct answer)
- Between the mandibular first and second molars
- On the distal marginal ridge of the mandibular first molar
Correct answer: In the buccal groove of the mandibular first molar
In Class I occlusion, the mesiobuccal cusp of the maxillary first molar occludes in the buccal groove of the mandibular first molar.
Question 4: Wear facets on the anterior teeth that do not match any opposing tooth surface in centric occlusion are most indicative of:
- Abrasion from toothbrushing
- Parafunctional excursive contact (bruxism) (Correct answer)
- Erosion from acid exposure
- Abfraction from occlusal stress
Correct answer: Parafunctional excursive contact (bruxism)
Non-centric wear facets that are shiny, flat, and match an opposing surface in excursion indicate parafunction (bruxism) during lateral or protrusive movements.
Question 5: The Frankfort horizontal plane is used in cephalometrics and is defined by which landmarks?
- Nasion, sella, and articulare
- Porion, orbitale, and the midsagittal plane (Correct answer)
- ANS, PNS, and the occlusal plane
- Gonion, gnathion, and menton
Correct answer: Porion, orbitale, and the midsagittal plane
The Frankfort horizontal plane is defined by the porion (top of the external auditory meatus) and the orbitale (lowest point of the orbital rim), oriented parallel to the floor.
Question 6: The developmental lobe that forms the lingual surface of anterior teeth is called the:
- Mesiobuccal lobe
- Distobuccal lobe
- Cingulum lobe (Correct answer)
- Mamelons lobe
Correct answer: Cingulum lobe
The cingulum is derived from the fourth (lingual) developmental lobe and forms the prominent lingual convexity of anterior teeth.
Question 7: Trifurcation of a molar root is most commonly associated with which tooth?
- Mandibular first molar
- Maxillary first molar (Correct answer)
- Mandibular second molar
- Maxillary second premolar
Correct answer: Maxillary first molar
The maxillary first molar characteristically has three roots (mesiobuccal, distobuccal, and palatal), creating a trifurcation that is an important landmark in periodontal assessment.
NBDE Dental Anatomy and Occlusion 5
The primary function of the contact areas between adjacent teeth is to: