ORE Part 1 Dental Anatomy & Occlusion 4 — Questions and Answers
Question 1: What is the 'Angle Class I molar relationship'?
- Mesiobuccal cusp of upper first molar occludes in the buccal groove of the lower first molar (Correct answer)
- Mesiobuccal cusp of upper molar occludes distal to the lower molar buccal groove
- Lower first molar is positioned mesial to upper first molar
- No specific cusp relationship — based on incisor position only
Correct answer: Mesiobuccal cusp of upper first molar occludes in the buccal groove of the lower first molar
Angle Class I: the mesiobuccal cusp of the maxillary first molar occludes in the buccal groove of the mandibular first molar. This is considered the ideal molar relationship.
Question 2: What is the 'working side' in lateral excursion of the mandible?
- The side towards which the mandible moves during lateral jaw movement (Correct answer)
- The side where the condyle moves straight
- The non-chewing side
- The side where the condyle makes a Bennett movement
Correct answer: The side towards which the mandible moves during lateral jaw movement
The working side (chewing side) is the side towards which the mandible moves in lateral excursion. The working-side condyle pivots and rotates; the balancing-side condyle makes a translatory Bennett movement.
Question 3: What is the formula for the primary dentition and how many primary teeth are there?
- I 2/2, C 1/1, M 2/2 = 20 teeth total (Correct answer)
- I 2/2, C 1/1, M 3/3 = 24 teeth
- I 1/1, C 1/1, M 2/2 = 16 teeth
- I 2/2, C 1/1, P 1/1, M 2/2 = 24 teeth
Correct answer: I 2/2, C 1/1, M 2/2 = 20 teeth total
The primary dentition has 20 teeth: 2 central incisors, 2 lateral incisors, 2 canines, 2 first molars, and 2 second molars per arch (10 upper, 10 lower). There are no premolars in the primary dentition.
Question 4: What is the typical eruption sequence of the mandibular permanent teeth?
- First molar, central incisor, lateral incisor, canine, first premolar, second premolar, second molar, third molar (Correct answer)
- Central incisor, lateral incisor, first molar, canine, first premolar, second premolar, second molar
- First molar, canine, incisors, premolars, second molar
- Incisors first in mandible, molars first in maxilla
Correct answer: First molar, central incisor, lateral incisor, canine, first premolar, second premolar, second molar, third molar
The mandibular permanent eruption sequence is typically: 1st molar (6yrs), central incisor (6–7), lateral incisor (7–8), canine (9–10), 1st premolar (10–11), 2nd premolar (11–12), 2nd molar (11–13), 3rd molar (17–21).
Question 5: What is 'mutually protected occlusion'?
- An occlusal scheme where posterior teeth protect anterior teeth in maximum intercuspation, and anterior teeth protect posterior teeth during excursive movements (Correct answer)
- An occlusion where all teeth share equal occlusal loading
- An occlusion requiring no restorative intervention
- An occlusal scheme used only for complete dentures
Correct answer: An occlusal scheme where posterior teeth protect anterior teeth in maximum intercuspation, and anterior teeth protect posterior teeth during excursive movements
In mutually protected (organically) occlusion: the posterior teeth protect anterior teeth from heavy vertical loading in MIP; the anterior teeth (canine guidance or group function) disocclude the posterior teeth during excursive movements.
ORE Part 1 Dental Anatomy & Occlusion 4
What is the 'Angle Class I molar relationship'?