Sandblasting at 90o angle – optimal for resin-titanium bonding?

Abstract

Objective: Tradition wisdom tells us that kinetic energy is the greatest at perpendicular (i.e. 90o) when particles are hitting onto the surface. However, in a clinical or dental laboratory setting, such a ‘perfect’ system never exists due to operators’ skills or equipments/devices settings do not allow to do so. The aim of this study was to evaluate the effect of angle and distance for sandblasting on the shear bond strength between titanium and a bonded resin composite. Method: CP2 titanium coupons (150 mm×30 mm×1 mm) were sandblasted tribo-chemically with silica-coated alumina powder (110 μm, Rocatec, 3M ESPE, USA). A custom made jig was used under various contact angles of 45o, 60o, 75o and 90o at constant pressure (3.5 bar), time (15 s), and heights (5 mm, 10 mm and 15 mm). Then, the surfaces were primed with a silane primer (RelyX, 3M ESPE, USA) and 9 resin cement stubs (ø3.6×2 mm, RelyX Unicem Aplicap, 3M ESPE, USA) were bonded and cured on each group. Surface roughness (Ra) and images from scanning electron microscopy (SEM) was evaluated and examined the titanium surfaces before and after sandblasting. Shear bond strength (SBS) between the resin-titanium specimens was measured. Two-way ANOVA was used to test the statistical difference at α=0.05.

Result: A change in surface morphology was revealed by SEM. Ra was between 0.88±0.04mm (90o/5mm) to 1.17±0.17mm (60o/5mm). For SBS, an overall ranking of the angle was 75º > 90º > 45º > 60º. The75o and 90o were significantly higher than 45o and 60o(p<0.001). However, no significant difference in changes of sandblasting distance was observed.

Conclusion: Sandblasting at various distances and angles contributes differences in surface roughness. However, sandblasting at both 90o and 75o yielded higher SBS for resin-titanium bonding.