Fracture strength of endodontically treated teeth restored with different strategies after mechanical cycling.

The aim of this study was to analyze the fracture strength of endodontically treated teeth with different coronal restoration strategies after mechanical cycling. Thirty bovine teeth were randomly allocated into three groups (n = 10): Group 1, cast metal post and core; Group 2, glass fiber post with a composite resin core; Group 3, glass fiber post with a glass prefabricated core. For post cementation, an etch and rinse multistep adhesive system and resin cement were used. The specimens were submitted to mechanical cycling (106 cycles, 90 N, 4 Hz, 37 ± 1 degree C) and immediately loaded in a universal testing machine. The statistical analysis (one-way ANOVA) did not indicate a significant difference among the tested groups (Group 1 = 593.9 ± 128.7 N; Group 2 = 554.4 ± 213.3 N; Group 3 = 427 ± 104.8 N; P = 0.06). With regard to fracture patterns, all Group 1 specimens demonstrated catastrophic failures, while the specimens in Groups 2 and 3 demonstrated core or core/post failure. Despite the similar fracture strength observed in the tested groups, teeth restored with composite resin or glass prefabricated cores demonstrated favorable failure patterns compared to the cast metal post and core group. This study demonstrates that a glass prefabricated core can be an acceptable alternative for the reconstruction of endodontically treated teeth.