Assessment of surface roughness and microbiological retention on custom abutments produced by different techniques and materials

The aims of this study were twofold: first, to investigate the surface roughness of different abutment materials prepared using various manufacturing methods; and, second, to evaluate colonization by Streptococcus mutans and Candida albicans according to abutment material and manufacturing method. Six material/manufacturing method combinations were investigated in this study, namely chromium–cobalt (Cr–Co) (prepared using casting, milling, and laser sintering) and titanium, zirconia, and anodized titanium (all prepared using milling); titanium (stock) abutments were used as the control group. Surface roughness of seven specimens from each group was evaluated using atomic force microscopy and scanning electron microscopy. Laser-sintered Cr–Co had the lowest values of R_a (mean ± SD = 4.8 ± 0.8  nm), R_q (mean ± SD = 7.0 ± 1.2 nm), and R_max (mean ± SD = 133.5 ± 31.7 nm), whereas milled zirconia had the highest values of R_a (mean ± SD = 112.9 ± 44.2 nm), R_q (mean ± SD = 142.8 ± 54.0 nm), and R_max (mean ± SD = 1,035.7 ± 350.4 nm). Three specimens from each group were infected with S. mutans and three with C. albicans, and microbial counts were evaluated after culture. Colonization of Streptococcus mutans was highest on milled zirconia (mean log₁₀ count ± SD = 5.87 ± 0.08) and lowest on milled Cr–Co (mean log₁₀ count ± SD = 4.04 ± 0.11). For C. albicans, colonization was highest on milled titanium stock (mean log₁₀ count ± SD = 6.62 ± 0.03) and lowest on milled anodized titanium (mean log₁₀ count ± SD = 6.13 ± 0.03). Differences in surface roughness and microbial colonization among groups can aid clinicians in selecting materials based on clinical relevance, considering their potential impact on outcomes.