Influence of different universal adhesives on fracture resistance of endodontically treated teeth

Objective: To examine the influence of different universal adhesives on fracture resistance of endodontically restored teeth.
Materials and Methods: Fifty sound maxillary premolars were collected. MOD cavity and root canal treatment were performed in 40 teeth only. The width of the cavity was one-third of the inter-cuspal distance at the occlusal portion and one-third of the bucco-lingual width of proximal boxes. The floor of the cavity was coronally prepared by 1 mm to the CEJ. The cavo-surface margins were prepared at a butt joint. All samples were assorted into five equal groups (N=10): group I: intact teeth (+ve control), group II: prepared unrestored (-ve control), groups III, IV, and V: these groups had root canal treatment and standardized MOD cavities then restored with final resin composite restorations (Filtek Z350 XT) by using three types of adhesive systems; Single Bond Universal, All-Bond Universal and Tetric N-Bond Universal, respectively. The teeth were mounted to universal testing machine and subjected to compressive load at crosshead speed 0.5 mm/min. Fracture modes were evaluated under a stereomicroscope at magnification of 12X. Statistical analysis was performed using SPSS, version 20.0.
Results: There was significant improvement in fracture resistance in restored teeth (group III, IV and V) than unrestored teeth (group II), but didn't reach the fracture resistance of sound teeth (group I). There was no significant difference between restored groups.
Conclusions: According to the limitations of this study, resin composite restoration of endodontically treated teeth using different universal adhesives improve fracture resistance of these teeth.