Evaluation of Antibacterial Properties and Cytological Impact of TiO ₂ -coated Orthodontic Brackets: A Split-mouth Randomized Trial

Aim and Objectives The study aimed to evaluate the antibacterial efficacy of titanium dioxide (TiO 2 ) nanoparticle-coated stainless-steel orthodontic brackets and to assess cytological changes in the adjacent oral mucosa. The goal was to determine if TiO 2 coatings reduce bacterial colonization and biofilm formation while ensuring biocompatibility with surrounding tissues. Materials and Methods This split-mouth randomized controlled trial was conducted on a sample of 30 patients who needed orthodontic treatment, aged between 16 and 30 years. TiO 2 -coated brackets were bonded on one maxillary quadrant, and non-coated brackets on the opposite side, with sides alternated to avoid bias. Brackets were coated using a dip-coating method followed by the process of annealing. Plaque samples were collected at 30 and 60 days post-bonding and cultured on blood agar for bacterial quantification. Microscopic analysis was performed using oil immersion field counts. Buccal mucosa samples were collected before bonding (T0) and at 30 days (T1), in order to assess cytological changes via exfoliative cytology using Giemsa staining. Results The TiO 2 -coated bracket group showed a slight but significant increase in bacterial culture grading from 1 (interquartile range [IQR]: 0-1) at T1 to 1 (IQR: 1-1) at T2, whereas the non-coated group increased from 2 (IQR: 2-3) to 3 (IQR: 2-3). TiO 2 -coated brackets consistently demonstrated significantly lower bacterial culture gradings than non-coated brackets at both T1 and T2 ( P < .0001). Bacterial cell counts remained stable over time within groups, but were significantly lower in the TiO 2 -coated group [2 (IQR: 1-2) at T1; 2 (IQR: 1.25-2) at T2] compared to the non-coated group [3 (IQR: 3-4) at both time points] ( P < .0001). Cytological analysis revealed no significant increase in polymorphonuclear leukocytes or evidence of inflammation, degeneration, or malignancy in the TiO 2 group, supporting its biocompatibility. Conclusion TiO 2 nanoparticle coatings on stainless-steel orthodontic brackets have been shown to markedly reduce bacterial colonization and inhibit biofilm formation. Importantly, these coatings preserve the cytological integrity of the surrounding oral mucosa, indicating their biocompatibility. By limiting microbial accumulation, TiO 2 -coated brackets may contribute to improved oral hygiene during orthodontic therapy. This preventive effect has the potential to reduce common complications such as white spot lesions and gingivitis. However, further long-term clinical studies are necessary to validate these promising outcomes throughout the entire course of orthodontic treatment.