Restorative & Materials · patient case question

Increasing the taper of a crown preparation adversely affects all of the following EXCEPT:

Patient case: Aesthetics, preparation taper and post-endodontic restoration

Scenario: Three restorative items.

Show answer and explanation

Correct answer: D. Aesthetics

A. Retention falls sharply as taper increases; the near-parallel walls are what resist removal along the path of insertion.
B. Resistance form also suffers. A tapered preparation offers less opposition to obliquely directed forces that would tip the restoration off.
C. Excessive taper worsens marginal fit and increases the cement film thickness at the margin.
D. Correct — this is the exception. Aesthetics is governed by the material, the margin design and the space available for porcelain, not by the convergence angle of the axial walls.

Note: The accepted optimum is about 6 to 10 degrees of total convergence. Too little taper risks undercuts and difficulty seating.