In this patient the cusp tip of the canine is visibly flattened. What is the most likely explanation?

Correct answer: A. Premature contact with the opposing mandibular teeth

• A. CORRECT. A discretely flattened canine cusp is ATTRITION at a point of premature or excursive contact. The canine is meant to disclude the posterior teeth in lateral excursion, so it absorbs the excursive load; where the occlusal scheme is disturbed, that load concentrates and wears the tip flat. The finding is localised to the contacting surface, which is what distinguishes it.
• B. Amelogenesis imperfecta is a developmental defect present from eruption and affects the whole dentition, not a single worn cusp.
• C. Erosion produces smooth, cupped, generalised loss on multiple teeth and typically affects palatal or occlusal surfaces broadly — not one isolated cusp tip.
• D. Toothbrush abrasion produces horizontal notching at the CERVICAL region, not flattening of an incisal or cuspal tip.

Note: Distinguish the wear patterns by their location and distribution. Attrition sits on contacting surfaces and matches an opposing wear facet. Abrasion is cervical and follows a mechanical habit. Erosion is diffuse, smooth and cupped. Abfraction is a wedge-shaped cervical defect attributed to occlusal flexure. Multiple mechanisms frequently coexist in the same mouth.