Evaluation and comparison of antimicrobial property of chitosan nanoparticles on nickel-titanium archwires: an in vivo study

INTRODUCTION: Fixed orthodontic appliances can serve as a breeding ground for bacterial accumulation and colonization, which are responsible for the development of white spot lesions (WSLs). OBJECTIVE: This study evaluated and compared the antibacterial activity of chitosan nanoparticle-coated and uncoated nickel-titanium (NiTi) orthodontic archwires against Streptococcus mutans (S. mutans) and Lactobacillus acidophilus (L. acidophilus). MATERIAL AND METHODS: Thirty patients received 0.016-in NiTi archwires, using a split-mouth design. Sixty archwires were randomized into two groups: Group A, nanochitosan-coated (n = 30, experimental), and Group B, uncoated (n = 30, control). Allocation was determined using sequentially numbered, opaque, sealed envelopes prepared by an independent researcher, with assignments concealed until allocation. The ionic gelation technique was used for coating. After six weeks in the oral cavity, archwires were retrieved, and bacterial presence was evaluated as Colony Forming Units (CFUs), through culture formation. RESULTS: A statistically significant difference was observed in the mean CFU counts of S. mutans and L. acidophilus between the experimental and control groups (p < 0.001). The mean CFU values for S. mutans were 0.12 × 106 CFU/ml (SD ± 0.38; experimental) and 1.82 × 106 CFU/ml (SD ± 0.69; control). For L. acidophilus, mean CFUs were 0.036 × 106 CFU/ml (SD ± 0.06; experimental) and 1.96 × 106 CFU/ml (SD ± 0.65; control). CONCLUSION: Orthodontic archwires coated with nanochitosan demonstrated significantly greater antimicrobial activity against S. mutans and L. acidophilus compared with uncoated archwires.