Cleaning solutions for orthodontic clear aligners

Purpose This in vitro study evaluated the antimicrobial efficacy of different cleaning solutions used for orthodontic clear aligners.Methods Eighty-four specimens were prepared from unused orthodontic clear aligners and randomly allocated to five experimental (alcohol, toothpaste, mouthwash, detergent, and effervescent disinfectant crystals) and two control groups (sterility and biofilm growth). After contamination with Streptococcus mutans, Lactobacillus casei, and Candida albicans, the samples were treated during 5-day protocol. Microbial growth (CFU/mL), culture medium pH, and volumetric surface roughness (Sa) were statistically analysed using Kruskal-Wallis and Mann-Whitney tests (α = 0.05).Results Mouthwash showed a significantly lower bacterial growth (9.01 ± 8.18 × 106 CFU/mL), lower pH ~ 5.5 at 48 h, and Sa = 9.01 ± 8.18 µm. In contrast, alcohol showed highest microbial load (15.94 ± 12.95 × 106 CFU/mL), in a more acidic environment (pH 4.5 at 96 h), and Sa = 15.94 ± 12.95 µm. Toothpaste, detergent, and crystals showed statistically similar and moderate antimicrobial efficacy (10.83 ± 6.74 < CFU/mL < 13.03 ± 7.78 × 106). Sterility control showed no microbial growth (CFU = 0; Sa = 4.80 ± 1.76 µm), while the growth control exhibited the highest biofilm formation (7.4 × 109 CFU/mL, p < 0.005) and degradation (Sa = 42.37 ± 28.08 µm).Conclusions Transparent night-time mouthwash was the most effective cleaning solution. Alcohol was associated to increased bacterial accumulation and surface degradation. Detergent, toothpaste, and effervescent disinfectant crystals showed comparable efficacy and may serve as accessible alternatives, with neutral detergent standing out as a cost-effective daily solution.