Repair Bond Strength of Ion-Releasing Resin Composites

Objectives: To investigate the repair bond strength of a universal composite restorative to commercially available and experimental ion-releasing resin composite materials.
Methods: Specimens (n = 8 per group) were produced from three commercially available ion-releasing composite materials (Activa BioActive-Restorative–AB, Cention Forte–CF, Beautifil II–BF), one experimental ion-releasing resin composite containing 20 wt% bioactive glass fillers (EX), and two conventional resin composites (Filtek Supreme XTE–FS, Ceram.X Spectra ST–CX), and aged by thermal cycling in artificial saliva (5000 cycles, 5–55°C). The substrate surfaces were then sandblasted (Al₂O₃, 50 µm) and silanized (Monobond Plus), and specimens were repaired using an adhesive (OptiBond FL) and universal resin composite (Ceram.X Spectra ST). After further thermal cycling in artificial saliva (5000 cycles, 5–55°C), microtensile repair bond strength was assessed and statistically analyzed using one-way ANOVA followed by Tukey’s post-hoc test (α = 0.05). Failure modes were determined by stereomicroscopy at 15x magnification.
Results: The highest mean repair bond strength values were obtained for AB, BF, and FS (53.8, 46.2, and 43.0 MPa, respectively), which did not differ significantly among each other. AB attained significantly higher bond strength than EX (p = 0.029), CX (p = 0.010), and CF (p = 0.001), and showed the highest incidence of cohesive failures (40%) among the groups. No significant bond strength differences were detected among BF, FS, EX, CX, and CF, with mean values ranging from 36.2–46.2 MPa.
Conclusions: Ion-releasing resin composites can be repaired with conventional universal composite and show repair bond strength values at least as high as those of conventional composite materials.