ABSTRACT
Objective @# To investigate the effects of different occlusal veneer preparation designs and fiber posts on the fracture load and failure mode of endodontically treated maxillary premolars with pulp-piercing wedge-shaped defect．@*Methods @# 60 maxillary first premolars were randomly divided into group A and group B after Root Canal Therapy (RCT) and severe defects(n = 30) ．Group A was filled with glass fiber post and resin core，and group B was filled with resin core only．Then the occlusal veneer( G2) ，buccal-occlusal veneer( G3) and buccal-proximal-occlusal veneer ( G4 ) were applied to the isolated teeth．The teeth filled with composite resin ( G1 ) and full crown ( G5) were set as negative and positive control respectively，with 6 samples in each group．The sample was subjected to 5 000 hot and cold cycles and 20 000 vertical compression load aging．Finally，all the samples were loaded with static load until the sample broke at the speed of 0．5mm / min．The fracture load and failure mode of each sample were recorded. @*Results @# Both the fracture load in group A and B was G5 ＞G3 ＞G2 ＞G4 ＞G1，and the fracture load in G2，G3，G4，G5 was significantly higher than that in G1 (P＜0. 05) ，and there was no significant difference between group A and B (P＞0. 05) ．The fracture form of G3 was mostly unbonding of the repair body，which was conducive to re-repair．@*Conclusion @#Buccal ( occlusal) veneer is the most effective in repairing pulp-piercing wedge-shaped defects．The fiber post could not significantly enhance the fracture load of the pulp-piercing wedge- shaped defects teeth.
