Antibacterial Efficacy of Hypochlorous Acid against Streptococcus mutans on Orthodontic Wires: An In Vitro Study

AimStreptococcus mutans plays a central role in the development of dental caries and white spot lesions in orthodontic patients. The prevention of biofilm formation on orthodontic appliances requires effective antimicrobial strategies. This in vitro study aimed to evaluate the antimicrobial efficacy of hypochlorous acid (HOCl) at concentrations of ۰.۲۵%, ۰.۷۵%, and ۱.۲۵% against Streptococcus mutans adhering to nickel–titanium (NiTi) and stainless steel orthodontic wires.MethodsOrthodontic wire segments made of NiTi and stainless steel (n = ۲۰) were inoculated with Streptococcus mutans (ATCC ۲۵۱۷۵) and exposed for ۳۰ seconds to HOCl at three different concentrations. A ۲% chlorhexidine solution served as the positive control, and sterile saline was used as the negative control. Antimicrobial activity was assessed using the agar diffusion method and turbidity-based bacterial growth evaluation following ۲۴ hours of incubation at ۳۷ °C. Data were analyzed using one-way analysis of variance (ANOVA) followed by Tukey’s post hoc test. Statistical significance was set at p < ۰.۰۵.ResultsHypochlorous acid at a concentration of ۱.۲۵% demonstrated the highest antimicrobial activity, producing significantly larger inhibition zones compared with ۰.۲۵% HOCl (p = ۰.۰۲۱), ۰.۷۵% HOCl (p = ۰.۰۴۹), and ۲% chlorhexidine (p=۰.۰۰۵). No statistically significant differences were observed between ۰.۲۵% HOCl, ۰.۷۵% HOCl, and ۲% chlorhexidine (p > ۰.۰۵). Stainless steel wires exhibited greater bacterial adhesion than NiTi wires. Sterile saline showed no antimicrobial effect.ConclusionWithin the limitations of this in vitro study, hypochlorous acid at a concentration of ۱.۲۵% exhibited superior antimicrobial activity against Streptococcus mutans compared with ۲% chlorhexidine. Lower HOCl concentrations (۰.۲۵% and ۰.۷۵%) demonstrated antimicrobial efficacy comparable to that of chlorhexidine, suggesting that reduced concentrations may be preferable in clinical practice to balance antimicrobial effectiveness while minimizing the potential risk of corrosion of orthodontic wires.

کلیدواژه ها:

Hypochlorous Acid ، Orthodontic Wires ، Streptococcus mutans