Evaluation of Microbial Colonisation on Clear Aligners With Different Cleaning Methods: A Prospective In Vivo Cross-Over Study.

Objective: To compare the effects of five cleaning methods on oral microorganism levels in patients undergoing clear aligner treatment.

Materials and methods: This single-centre prospective study consisted of 22 patients with mild-moderate malocclusions and treated by clear aligners (Invisalign system). Patients were instructed to use a toothbrush alone to clean the first set of aligners (Week 1), followed by a toothbrush and toothpaste for the second set (Week 2); a toothbrush and Invisalign Cleaning Crystals for the third set (Week 3); a toothbrush and Corega Proguard & Retainer Daily Cleansing Tablets for the fourth set (Week 4); and a toothbrush and Prokudent Removable Orthodontic Appliance Cleaning Tablets for the fifth set (Week 5). Stimulated saliva and biofilm samples within aligners were collected weekly and cultured to quantify mutans streptococci (MS) and yeast levels.

Results: The amount of mutans streptococci in saliva decreased from 65538 to 31154 CFU/mL over 5 weeks; however, no significant differences were found between any of the weeks. A large effect size was observed between weeks 1 and 3 (0.548). Biofilm-associated MS was recorded highest in the first week (658 CFU/mL) and the lowest in the fifth week (64 CFU/mL), which showed moderate effect size compared to week 1 (0.369) and week 4 (0.353), whereas no significant differences were found between the weeks. Yeast levels remained consistently low, showing no significant differences across the groups.

Conclusion: Although a downward trend in mutans streptococci and yeast levels was observed, the decrease was not statistically significant in any of the weeks.