Prosthodontics & Occlusion · single question
A patient moves from maximum intercuspation (MIP) to end-to-end (edge-to-edge) incisal contact. What occurs?
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Correct answer: B. Both condyles translate
Movement from MIP (centric occlusion) forward (protrusion) to edge-to-edge incisal contact involves BILATERAL PROTRUSION. During protrusion, BOTH condyles translate forward (anteriorly) along the articular eminence. Pure rotation occurs in the early phase of opening (the first 20-25 mm), while translation occurs as opening continues or during protrusion. In this case, moving from MIP to end-to-end involves bilateral condylar translation (protrusion).
- A. INCORRECT. Pure bilateral rotation occurs in early hinge movement (first 20-25mm of opening from closed position) — not during protrusion to end-to-end.
- B. CORRECT. Moving from MIP to end-to-end incisal (protrusion) involves BILATERAL CONDYLAR TRANSLATION as both condyles slide forward along the articular eminence.
- C. INCORRECT. Unilateral translation (lateral movement/working side) occurs during lateral excursion — the working side condyle rotates while the balancing (non-working) side translates. This is a bilateral protrusive movement, not lateral.
- D. INCORRECT. Same as above — unilateral translation describes lateral excursion, not bilateral protrusion to end-to-end.
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