The Effect of Silica Coating on the Bonding Strength of Veneering Composite Resin to Dental Alloys

Purpose: This study investigated the effect of silica coating (Rocatec ®-System, ESPE) on the bonding strength of veneering composite resin to dental alloys. Methods: Four kinds of alloy (Pt-Au, Co-Cr, Au-Ag-Pd, and pure titanium, size: 10×15×2 mm) were ground (# 600), and divided into three groups: alumina sandblasted group (Rocatec ®-Pre, SB), alumina sandblasted and adhesive primed group (Metal Primer II, GC, MP), and silica coated group (Rocatec ®-Plus, RP). Specimens for all groups were analyzed with SEM images (JSM-6301 F, Nihon Denshi) and the density of Si element with EPMA (EPMA 8705, Shimadzu). The shear bond strengths of composite resins (Solidex ®, Shofu) to alloys of ten specimens each were measured (Cross head speed: 1.0 mm/min). Failure loads were examined by one-factor ANOVA (Post-hoc test: Scheffé's F, α=0.05). Results: From the images and EPMA evaluation, the silica layer was recognized on all alloys and remained intact after ultrasonic cleaning. MP and RP showed significantly higher shear bond strengths than SB for every alloy. In the case of Pt-Au, RP showed significantly higher strengths than MP. However, in the case of Co-Cr, Au-Ag-Pd and titanium, there was no significant difference between MP and RP. Conclusions: According to the results of this study, Rocatec ®-System forms a firm silica layer and improves the surface for bonding of dental alloys.