The Effects of Different Surface Treatments on the Shear Bond Strength of Composite Resin to Machined Titanium

Purpose: The purpose of this study was to evaluate the shear bond strength between machined titanium and composite resin using different surface treatments. Materials and Methods: Titanium (Ti-6Al-4V) specimens were ground with 600 grit SiC paper and randomly divided into 6 groups (n=20/group). Group #1 (Control): samples were sandblasted with 110 µm Al2O3 for 10 sec. Group #2 (Rocatec): samples were treated with the Rocatec system following the manufacturer\u27s directions but the silanization step was eliminated. Group #3 (Silano Pen): samples were treated with the Silano Pen system. Group #4 (H2SO4 etched): samples were sandblasted with 110 µm Al2O3 for 10 sec and etched with 48% H2SO4 for 60 minutes at 60oC. Group#5 (acid etching + Rocatec): samples received both treatments as described in Groups 4 and 2, respectively. Group #6 (acid etching + Silano Pen): samples received both treatments as described in Groups 4 and 3, respectively. Composite was bonded to the treated titanium surface, half of the specimens from each group (n=10/group) were subjected to thermocycling, and the samples were tested for shear bond strength in a universal testing machine. Representative samples from each group were evaluated with SEM. Results: Two-way ANOVA revealed that there were significant differences (p \u3c 0.05) in bond strength between the six groups of surface treatment and that thermocycling significantly decreased shear bond strength. There was no significant interaction (p = 0.07) between surface treatment and thermocycling status. With regard to the effect of surface treatment, a Tukey Post Hoc test showed that groups 3 (Silano Pen) and 6 (Silano Pen + H2SO4) showed significantly (p \u3c 0.05) greater bond strengths compared to the rest of the groups. There was no significant difference in the bond strength between the four other groups. Conclusion: 1) Silano Pen is effective in improving the bond strength of titanium to composite resin. 2) The silanization step in the Rocatec system is a critical step and eliminating it may dramatically alter its effectiveness. 3) Combining two surface treatments may not always result in an additive effect. 4) Thermocycling significantly decreased the bond strength regardless of the surface treatment used