The influence of post length and crown ferrule length on the resistance to cyclic loading of @entity291 teeth with prefabricated XXXX posts.

@entity174 @entity24967 @entity1346 @entity702 @entity291 @entity616
PURPOSE: The purpose of this in vitro study was to evaluate the influence of post and ferrule length on the resistance to cyclic (fatigue) loading of teeth with prefabricated @entity702 posts (ParaPost) and crowns. MATERIALS AND METHODS: Ninety @entity291 teeth with similar dimensions were mounted in @entity616 with artificial @entity1346 periodontal ligaments. Combinations of post lengths of 5 mm, 7.5 mm, and 10 mm, and ferrule lengths (i.e., the vertical dentinal overlap of the crown) of 0 mm, 1.25 mm, and 2.5 mm made up 9 different groups consisting of 10 teeth each. The posts were cemented with @entity24967 cement. Composite-resin cores were made and crowns were cemented. Each test specimen underwent cyclic loading of 400 N with a frequency of 1 load per second at an angulation of 45 degrees to the long axis of the tooth. RESULTS: All but 2 specimens failed with a root @entity174 ; in the remaining 2 specimens the core lost retention. A large variation in the results between the various groups was observed. A nonparametric 2-way analysis for groups with a natural order revealed that the @entity174 resistance to cyclic loading increased statistically significantly with increasing ferrule length (P < 0.01), whereas increasing post length did not increase @entity174 resistance (P = 0.44). CONCLUSION: Ferrule length was more important than post length in increasing @entity174 resistance to cyclic loading of crowned teeth.
