Isolation of Microorganisms in Used Orthodontic Aligners Using Culture Media in the South Indian Population – An Observational Study

Background: Clear aligners have transformed orthodontic treatment by offering a removable, esthetic alternative to fixed appliances. However, prolonged intraoral wear makes them susceptible to microbial colonisation. Aim: To isolate and identify microorganisms present on used orthodontic aligners and assess the effect of different oral hygiene practices on microbial load. Materials & Methods: Fifteen patients undergoing clear aligner therapy were grouped based on oral hygiene practices: once-daily brushing, twice-daily brushing, and twice-daily brushing with mouthwash. Used aligners (worn for two weeks) were sampled using sterile swabs, cultured on blood agar and Sabouraud dextrose agar, and analysed using Gram staining and biochemical tests. Statistical analysis included ANOVA, Tukey’s post hoc, and Chi-square tests. Results: All samples exhibited bacterial growth, predominantly Streptococcus mutans, with no fungal growth. Mean colony- forming units (CFU) were significantly lower in patients using both brushing and mouthwash compared to other groups (p < 0.001). Conclusion: Oral hygiene significantly influences bacterial colonisation on aligners. Twice-daily brushing with adjunctive mouthwash is effective in reducing microbial load.