Prosthodontics & Occlusion · patient case question
Which contact represents the MOST damaging interaction between an opposing cusp ridge and cusp?
Patient case: Posterior crossbite — occlusal interferences
Scenario: Clinical photo of a patient with a posterior crossbite on the LEFT side. Three questions ask about interference between the opposing cusp ridges of #14 and #19. (In the exam image #18 was missing and #13 occluded normally with the lower arch.)
Show answer and explanation
Correct answer: D. The non-working (balancing) contact between the maxillary lingual cusp and the mandibular buccal cusp
- A. Anterior guidance on the lingual of maxillary incisors is a normal protective contact during protrusion.
- B. Working-side canine contact is protective — canine guidance disoccludes the posterior teeth and is a desirable feature.
- C. A centric stop in a central fossa is a physiologic holding contact, not an interference.
- D. Correct. Non-working (balancing) interferences are considered the most destructive occlusal contacts. They occur on the side opposite the direction of movement, place the condyle in an unstable orthopaedic position, and generate high loading because the elevator muscles act with a favourable lever arm.
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