Evaluation of the Effects of Different Orthodontic Wire Material Compositions and Cross-Sectional Forms on In Vitro Streptococcus mutans Adhesion

Introduction:The present in vitro study was conducted to evaluate the effects of different orthodontic wire materials and cross-sectional geometries on Streptococcus mutans biofilm formation and bacterial viability. Materials and Methods:The study examined three distinct wire materials: Stainless steel (SS), nickel-titanium (NiTi), and copper containing nickel-titanium (Cu-NiTi).Each material was prepared in two cross-sectional forms: round (0.016″) and rectangular (0.016″ × 0.022″).Twelve samples from each group were incubated with S. mutans ATCC 25175 strain at 37 °C and 5% CO 2 for 24 hours.The measurement of biofilm biomass was conducted by means of crystal violet staining at OD 570 .The assessment of bacterial viability was conducted through the quantification of colony-forming units (CFU/mL) following a process of vortex-ultrasonication separation.The subsequent analysis of the data was conducted using two-way analysis of variance (Robust analysis of variance) and Holm-corrected post-hoc tests.The level of statistical significance was set at p< 0.05. Results:The composition of the wire material and the cross-sectional shape of the wire exhibited a significant impact on the accumulation of biofilm and bacterial adhesion (p< 0.001).Rectangular cross-section NiTi wires demonstrated the highest OD 570 and CFU values, while Cu-NiTi (both cross-sections) and round cross-section SS wires exhibited the lowest bacterial loads (p< 0.001).A higher degree of biofilm accumulation was observed in rectangular cross-section wires compared to round cross-section wires (p< 0.001). Conclusion:The composition and geometry of the wire material jointly affect bacterial adhesion on orthodontic arch wires.In addition, Cu-NiTi wires demonstrated a reduced tendency for biofilm accumulation, an outcome that can be attributed to the inherent antimicrobial properties of copper.The findings emphasize the significance of material selection and wire design in minimizing microbial colonization during orthodontic treatment.