Surface Characteristics and Resin Bond Strength of Commercially Pure Titanium for Dental Applications: Effects of Additive Manufacturing Method and Build Orientation

Selective laser melting (SLM) and electron beam melting (EBM) enable the fabrication of commercially pure titanium, but the effects of the fabrication method and build orientation on surface characteristics and bonding remain unclear. This study evaluated the surface roughness, wettability, and shear bond strength of titanium fabricated by SLM and EBM at build orientations of 0°, 45°, and 90°, with titanium ingots intended for dental casting serving as reference specimens. The surfaces were wet-ground, air-abraded with 50 µm alumina particles, and treated with a 10-methacryloyloxydecyl dihydrogen phosphate-containing metal primer. Surface roughness (Sa), static water contact angles before and after primer application, and shear bond strength to a resin luting agent after 24 h of water storage were evaluated (n = 15/group). The EBM specimens fabricated at 90° exhibited significantly greater Sa values than the other groups (p < 0.05). Primer application significantly increased the water contact angle in all groups (p < 0.05), although group-dependent differences were observed. No significant differences in shear bond strength were detected among the fabrication conditions (p > 0.05). Thus, under the tested surface treatment conditions, differences in surface roughness and wettability were not accompanied by corresponding differences in the initial bond strength of commercially pure titanium.