ORE Part 1 Dental Anatomy & Occlusion 2 — Questions and Answers
Question 1: What is 'freeway space' (interocclusal distance)?
- The space between maxillary and mandibular teeth when the mandible is in the rest position, typically 2–4 mm (Correct answer)
- The gap between adjacent teeth
- The space created by a missing tooth
- The distance between the condyle and glenoid fossa
Correct answer: The space between maxillary and mandibular teeth when the mandible is in the rest position, typically 2–4 mm
Freeway space (interocclusal clearance) is the vertical distance between the upper and lower teeth when the mandible is in rest position. It equals the difference between rest vertical dimension and occlusal vertical dimension.
Question 2: Which cusp is the 'key cusp' for occlusal stability in the mandibular first molar?
- Mesiolingual cusp (cusp of Carabelli equivalent — actually the dominant cusp of the lower first molar) (Correct answer)
- The buccal cusps collectively
- The distal cusp
- The distolingual cusp
Correct answer: Mesiolingual cusp (cusp of Carabelli equivalent — actually the dominant cusp of the lower first molar)
The mesiolingual cusp of the mandibular first molar is the largest and most functionally significant cusp, occluding into the central fossa of the upper first molar. It is critical to occlusal stability.
Question 3: What is the dental formula for the permanent human dentition?
- I 2/2, C 1/1, P 2/2, M 3/3 = 32 teeth total (Correct answer)
- I 2/2, C 1/1, P 2/2, M 2/2 = 28 teeth
- I 1/1, C 1/1, P 2/2, M 3/3 = 30 teeth
- I 2/2, C 2/2, P 2/2, M 3/3 = 36 teeth
Correct answer: I 2/2, C 1/1, P 2/2, M 3/3 = 32 teeth total
The permanent human dental formula is: 2 incisors, 1 canine, 2 premolars, 3 molars per quadrant, totalling 32 teeth (including third molars/wisdom teeth).
Question 4: What is 'centric occlusion' (maximum intercuspation, MIP)?
- The mandibular position of maximum tooth contact regardless of condylar position (Correct answer)
- The position of the mandible when the condyles are in centric relation
- The rest position of the mandible
- The position during chewing when vertical pressure is maximum
Correct answer: The mandibular position of maximum tooth contact regardless of condylar position
Centric occlusion (now termed Maximum Intercuspal Position — MIP) is the occlusal position where maximum tooth contact occurs. It may or may not coincide with centric relation (condyles in terminal hinge position).
Question 5: What is the purpose of the 'curve of Spee'?
- A naturally occurring anteroposterior curve of the occlusal plane facilitating efficient chewing and distributing occlusal forces (Correct answer)
- A measurement of overjet
- A classification of malocclusion severity
- A measure of curve in the condylar path
Correct answer: A naturally occurring anteroposterior curve of the occlusal plane facilitating efficient chewing and distributing occlusal forces
The Curve of Spee is the anteroposterior curvature of the dental occlusal plane (when viewed from the side). It reduces shear forces during function and is important in prosthodontic planning.
Question 6: What is the typical overjet and overbite in an ideal Class I occlusion?
- Overjet 2–4 mm; overbite 2–4 mm (covering approximately one-third of lower incisor) (Correct answer)
- Overjet 0 mm; overbite 0 mm
- Overjet 5–10 mm; overbite 6 mm
- Overjet 4 mm; overbite 0 mm (edge-to-edge)
Correct answer: Overjet 2–4 mm; overbite 2–4 mm (covering approximately one-third of lower incisor)
In an ideal Class I occlusion, the overjet (horizontal overlap) is 2–4 mm and the overbite (vertical overlap) is 2–4 mm, covering approximately one-third of the lower incisor crown height.
ORE Part 1 Dental Anatomy & Occlusion 2
What is 'freeway space' (interocclusal distance)?