Restorative & Materials · single question
A tooth has only about 0.5 mm of sound coronal structure remaining circumferentially before a planned crown. What is the main concern?
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Correct answer: A. Inadequate ferrule height/effect, compromising retention and resistance to fracture
Ferrule refers to the band of sound coronal tooth structure the crown margin encircles, critical for resisting functional forces and fracture, especially on endodontically treated teeth. With only about 0.5 mm of remaining structure, ferrule effect is severely compromised, and long-term prognosis is poor unless additional structure can be gained (e.g., crown lengthening or orthodontic extrusion).
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