Fracture resistance of endodontically treated teeth restored with glass fiber posts of different lengths.

STATEMENT OF PROBLEM: Endodontically treated teeth are known to have reduced structural strength. Glass fiber posts may influence fracture resistance and should be evaluated.

PURPOSE: The purpose of this study was to evaluate the influence of glass fiber post length on the fracture resistance of endodontically treated teeth.

MATERIAL AND METHODS: Forty intact human maxillary canines were selected and divided into 4 groups, the control group consisting of teeth restored with a custom gold cast post and core, with a length of two-thirds of the root. Other groups received prefabricated glass fiber posts in different lengths: group 1/3, removal of one-third of the sealing material (5 mm); group 1/2, removal of one-half of the sealing material (7.5 mm); and group 2/3, removal of two-thirds of the sealing material (10 mm). All the posts were cemented with resin cement, and the specimens with glass fiber posts received a composite resin core. All the specimens were restored with a metal crown and submitted to a compressive load until failure occurred. The results were evaluated by 1-way ANOVA, and the all pairwise multiple comparison procedures (Tukey honestly significantly difference test) (α=.05).

RESULTS: The ANOVA showed significant differences among the groups (P<.002). The Tukey test showed that the control group presented significantly higher resistance to static load than the other groups (control group, 634.94 N; group 1/3, 200.01 N; group 1/2, 212.17 N; and group 2/3, 236.08 N). Although teeth restored with a cast post and core supported a higher compressive load, all of them fractured in a catastrophic manner. For teeth restored with glass fiber posts, the failure occurred at the junction between the composite resin core and the root.

CONCLUSION: The length of glass fiber posts did not influence fracture load, but cast post and cores that extended two-thirds of the root length had significantly greater fracture resistance than glass fiber posts.