[Resistance to cyclic fatigue of pulpless teeth with flared root canals restored with three kinds of post-and-cores].

PURPOSE: To observe the resistance to cyclic fatigue of maxillary incisors with flared canals restored with three post-and-core materials. METHODS: Standard cylindrical samples with flared canals were made of 48 human maxillary central incisors and were assigned randomly to two groups (without ferrule and 2mm ferrule). Each main group was then divided into 3 sub-groups of 8 specimens and restored with cast metal post-core-crown,carbon fiber+resin composite post-core-crown ,and glass fiber+resin composite post-core-crown, respectively. Each group was subjected to a cyclic fatigue test, and the numbers of load cycles that had tooth fracture were measured with cyclic fatigue testing machine. All data were analyzed statistically for two-way ANOVA with SPSS 12.0 software package. RESULTS: Fiber+resin composite post-core-crown showed significantly higher fatigue strength than cast metal post-core-crown in the two groups(P<0.05). Preparing dentin ferrules increased significantly fatigue resistance(P<0.05). CONCLUSION: Fiber post-and-core system may get a long fatigue life in restoring pulpless teeth.Dentin ferrule preparation is necessary to enhance resistance to cyclic fatigue.