Biofilm formation and Streptococcus mutans adhesion on different coated and noncoated nickel-titanium archwires: An in vitro study

Abstract Aim: The orthodontic archwires used in routine practice are coated with esthetic coatings to keep up with the aesthetic demand among patients seeking orthodontic treatment, which have been reported to increase the surface roughness (SR) of archwires and lead to an increase in bacterial and plaque accumulation. This in vitro study aims to compare the biofilm formation and bacterial adherence between esthetic coated and noncoated archwires. Material and Methods: This experimental in vitro study was conducted using three aesthetic coated and two noncoated nickel-titanium (NiTi) archwires ( n = 5/group). The archwires were subjected to artificially cultured Streptococcus mutans broth followed by colony count assessment (CFU) and crystal violet staining assay to determine S. mutans adhesion and biofilm formation. Statistical analysis was performed using the SPSS software for inter-group and intra-group comparisons of CFU and biofilm formation (optical density) with one-way ANOVA with post hoc Tukey’s test and Mann–Whitney’s U test. Results: A significant difference in CFU/biofilm was observed at 3% sucrose concentration between the tested archwires ( P = 0.029) and epoxy coated (Libral) archwire had higher S. mutans adhesion when compared to its noncoated counterpart ( P = 0.035). The biofilm formation however showed no statistical difference between the tested archwires. Conclusion: A significant difference was noted in S. mutans adherence (CFU/biofilm) under 3% sucrose condition, with greater S. mutans adherence in epoxy coated archwire. In vivo use of aesthetic coated archwires is at a similar risk of biofilm accumulation as their noncoated counterparts.