Surface Roughness and Bacterial Adhesion of CAD/CAM and Conventional Provisional Restorative Materials

This study aimed to evaluate and compare the surface roughness (SR) and Streptococcus mutans adhesion of various provisional restorative materials fabricated using different manufacturing techniques, including traditional and computer-aided design/computer-aided manufacturing (CAD/CAM) methods. Disc-shaped specimens (n = 5) were prepared from four different materials: auto-polymerizing PEMA/PMMA (Dentalon Plus), bis-acrylic resin (Protemp 4) and two CAD/CAM PMMA blocks (Telio CAD, Vita CAD-Temp). All specimens were polished using a standardized protocol. SR was measured with a profilometer. For bacterial adhesion analysis, specimens were coated with artificial saliva to form a pellicle and incubated with S. mutans for 24 h. Adherent bacteria were quantified by confocal laser scanning microscopy and ImageJ/Fiji (version 2217 Stable) analysis. Group differences were analyzed using Welch's ANOVA with Games-Howell post-hoc tests, and the SR-adhesion relationship was assessed by Spearman's and Kendall's correlation (α = 0.05). A strong, positive correlation was found between SR and bacterial adhesion (Spearman's ρ = 0.803; Kendall's τ = 0.656; p < 0.001). Dentalon Plus exhibited the highest SR and significantly greater bacterial adhesion than both CAD/CAM blocks. Although Telio CAD and Vita CAD-Temp had similarly low SR, Telio CAD showed significantly lower bacterial adhesion (p < 0.001), with a very large effect size. Thus, comparable surface roughness did not correspond to comparable bacterial adhesion, indicating that SR alone did not account for the observed differences. Within the limitations of this study, it was concluded that although SR is an important determinant of bacterial adhesion, it did not fully explain the differences observed between materials. Highly cross-linked PMMA CAD/CAM materials (Telio CAD) demonstrated superior resistance to S. mutans adhesion.