Comparison of the Bond Strength to Titanium of Resin-Based Materials Fabricated by Additive and Subtractive Manufacturing Methods

Abstract

This in vitro study investigated the shear bond strength (SBS) between titanium abutments and resin-based CAD/CAM restorative materials fabricated using additive (3D printing) and subtractive (milling) methods. The aim was to assess how different surface treatments—primer only, phosphoric acid etching with primer, and sandblasting with primer—affect bonding performance. A total of 120 cylindrical specimens were prepared using four CAD/CAM materials and bonded to titanium disks using dual-cure resin cement. SBS was measured following ISO 10477:2020 guidelines, and surface morphology was analyzed via scanning electron microscopy (SEM). Two-way ANOVA revealed that both the material type and surface treatment had statistically significant effects on SBS (p < 0.001), with a notable interaction between them. Additively manufactured materials exhibited higher SBS values compared to subtractive ones. The highest bond strength was observed in the sandblasted Saremco Crowntec group, while the lowest was in the primer-only Cerasmart group. SEM images confirmed enhanced surface roughness in sandblasted specimens, and failure mode analysis showed more cohesive and mixed failures in mechanically treated groups. These findings underscore the importance of selecting appropriate surface conditioning protocols tailored to each material type to improve bonding effectiveness in implant-supported restorations.