Suitability of Direct Resin Composites in Restoring Endodontically Treated Teeth (ETT)

(1) Background: The in vitro study aimed to investigate mechanical characteristics of resin composites and their suitability in direct restauration of endodontically treated teeth (ETT). (2) Methods: 38 endodontically treated premolars with occlusal access cavities were directly restored using the following resin composites and adhesives: Tetric Evo Ceram^® + Syntac classic^® (n = 10), Venus Diamond^® + iBond Total-Etch^® (n = 10), Grandio^® + Solobond M^® (n = 9), Estelite^® Sigma Quick + Bond Force^® (n = 9). After thermocycling, the elastic modulus, shear-bond-strength, fracture load (Fmax) and fracture mode distribution were evaluated. Statistical analysis: one-way ANOVA, t-test, Kruskal-Wallis test; p < 0.05. (3) Results: Grandio^® showed the highest E-modulus (15,857.9 MPa) which was significant to Venus Diamond^® (13,058.83 MPa), Tetric Evo Ceram^® (8636.0 MPa) and Estelite^® Sigma Quick (7004.58 MPa). The highest shear-bond-strength was observed for Solobond M^® (17.28 MPa), followed by iBond^® (16.61 MPa), Syntac classic^® (16.41 MPa) and Bond Force^® (8.37 MPa, p < 0.05). The highest fracture load (Fmax) was estimated for ETT restored with Venus Diamond^® (1106.83 N), followed by Estelite^® Sigma Quick (1030.1 N), Tetric Evo Ceram^® (1029 N) and Grandio^® (921 N). Fracture-mode distribution did not show any significant differences. (4) Conclusions: The observed resin composites and adhesives show reliable mechanical characteristics and seem to be suitable for direct restoration of endodontically treated teeth.