Fracture resistance of teeth with direct composite restorations reflecting different restorative designs in fractured root canal treated anterior teeth: an in-vitro study

Objective: Restoration of fractured root canal-treated maxillary incisors based on recent advances in adhesive dentistry and minimal invasive principles, which are topics of great importance. In particular, the aim of the present study was to evaluate the fracture resistance of a corono-radicular direct composite restoration compared with fibre post composite restorations and direct conventional composite restorations. Materials and methods: A total of 45 freshly extracted sound maxillary central incisors were used in the study. The teeth were randomly divided into three groups of 15 each. The groups were: group I (CDC), conventional direct composite postendodontic restoration; group II (FPC), fibre post placement and direct composite postendodontic restoration; group III (CRC), corono-radicular composite postendodontic restoration. The fracture resistance was measured using a universal testing machine and a 130 degrees angle of loading. Results: One-way ANOVA depicted a significant difference (P = 0.028) among the three groups with the mean fracture load of group CRC being the highest, at 1045.2 ± 355.7 N. The FPC group had the significantly least fracture resistance load, with 426.7 ± 245.3 N. Conclusions: Within the parameters of this study, the corono-radicular composite restorations had significantly higher fracture resistance than conventional direct composite and fibre post restorations when 50% of the crown structure was lost in fractured root canal-treated maxillary incisors. Keywords: coronal restoration, glass fibre post, monoblock effect, monolithic restoration, root canal treated teeth