Prosthodontics & Occlusion · patient case question
The occlusal surface of the #3 retainer appears flattened compared with the contralateral crown. What process does this represent?
Patient case: Three-unit fixed partial denture that has become loose
Patient: Female, 61 years old
Chief Complaint: “My bridge feels loose when I bite.”
Background: Three-unit porcelain-fused-to-metal bridge from #3 to #5 placed eight years ago, replacing #4. Reports night-time clenching. No pain.
Vital Signs: BP 128/80 mmHg · HR 72 bpm
Findings: The prosthesis moves as a unit under digital pressure. Radiographs show short, markedly tapered abutment preparations with minimal occlusogingival height, and a flattened occlusal surface on the #3 retainer. No periapical radiolucency; both abutments respond within normal limits to percussion.
Show answer and explanation
Correct answer: D. Attrition
- A. Abrasion is wear from a foreign object — toothbrush and dentifrice most commonly — and produces cervical notching or incisal notching in habitual patterns, not flattening of an occlusal surface.
- B. Erosion is chemical dissolution by acid. It produces smooth, cupped, shiny concavities and typically spares restorative margins, which come to stand proud of the surrounding tooth. It does not selectively flatten an occluding surface.
- C. Abfraction describes wedge-shaped CERVICAL lesions attributed to occlusal flexure. It is a cervical phenomenon and does not affect the occlusal table.
- D. CORRECT. ATTRITION is wear produced by TOOTH-TO-TOOTH contact. It generates flat, polished, matching wear facets on opposing surfaces — and in this patient the reported clenching supplies the mechanism. Ceramic is harder than enamel, so a porcelain occlusal surface both wears and abrades the opposing dentition.
Note: ⚠️ SOURCE NOTE. The recall recorded this item with the options attrition, erosion, bruxism and 'unrestorable tooth surface', and no key. Bruxism is not a type of wear — it is the HABIT that causes attrition, so it cannot be the answer to a question asking what the defect IS. Keyed here to attrition, which is what the described appearance represents.
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