The Effect of Titanium Tetrafluoride and Sodium Hypochlorite on the Shear Bond Strength of Methacrylate and Silorane Based Composite Resins: an In-Vitro Study

STATEMENT OF THE PROBLEM The bond strength of composites with different adhesive systems with dentin is an important factor in long term durability of composite restorations. The effect of titanium tetrafluoride (TiF4) as anti caries agent and sodium hypochlorite (NaOCl) as disinfectant on the shear bond of nanofilled and silorane based composite resins have not been investigated in previous studies. PURPOSE This study was conducted to determine bond strength between dentin and two composite systems, by means of shear bond test using TiF4 and NaOCl. MATERIALS AND METHOD Middle dentin of 60 intact extracted maxillary premolar teeth were exposed by sectioning the crowns at a depth of 2mm from central groove and parallel to the occlusal surface. Standardized smear layer was created using a 600-grit silicon carbide paper and then samples were embedded in acrylic resin blocks. Then the samples were randomly divided into 6 \groups summarized as Group I: Z350, Group II: Z350+ NaOCl, Group III: Z350+ TiF4, Group IV: P90, Group V: P90+ NaOCl, Group VI: P90+ TiF4 according to manufacturer's instruction. Then samples were subjected to shear bond strength (SBS) test using universal testing machine and data were analyzed using ANOVA and Tukey tests (p< 0.05). RESULTS Application of 5% NaOCl caused a significant decrease in SBS of nanofilled composite resin (p= 0.004), and also silorane based composite resin (p= 0.006). Application of 4% TiF4 caused a significant increase in SBS of silorane based composite resin (p= 0.001). The effect of TiF4 on nanofilled composite was not statistically significant. CONCLUSION Using TiF4 has a positive effect on increasing the shear bond while NaOCl has negative effect on bond strength.