Effects of additive manufacturing technology and build angle on surface characteristics and microbial adhesion of 3D-printed dental zirconia: An invitro study

Background Microbial colonization on 3D-printed zirconia abutments elevates the risk of peri-implantitis. While additive manufacturing (AM) parameters significantly influence surface roughness and morphology, evidence regarding their impact on bacterial adhesion remains unclear. This study investigated the effects of AM technology and build angles on the surface characteristics and initial microbial adhesion of 3D-printed zirconia. Methods Zirconia discs were fabricated using material jetting (MJ) and digital light processing (DLP) technologies with three build angles (0°, 45°, and 90°), respectively. The surface topographic features and roughness were analyzed using scanning electron microscopy and laser scanning microscopy, respectively. The surface wettability was evaluated via water contact angle measurements. Streptococcus gordonii (S. gordonii) was used to assess bacterial adhesion, which was evaluated via colony-forming unit counts (n = 6) and visualized through SEM imaging. Two-way ANOVA and post hoc Tukey tests were performed for statistical analyses. Results AM technology and build angle significantly affected the surface characteristics of 3D-printed zirconia. Significant interactions were observed for S_a, S_dr, S_tr, and V_vv (all p < 0.05). DLP-45° showed the roughest surface, while DLP-0° was the smoothest. Water contact angle varied significantly with both factors (p < 0.05), with MJ-45° showing the highest wettability. For S. gordonii adhesion, a significant interaction was found (p < 0.05), and AM method showed a main effect (p = 0.0104), while build angle alone was not significant (p = 0.0642). The least adhesion occurred in MJ-45° and DLP-0°, with no consistent correlation between S_a and bacterial adhesion. Conclusions Printing layer thickness and build angle significantly influenced DLP-printed zirconia’s surface roughness and water contact angle. Furthermore, they significantly impacted the adhesion of S. gordonii to zirconia surfaces.