Abstract
Proper tooth alignment is important for oral and periodontal health, allowing better hygiene and reducing plaque build-up. While traditional braces are effective, clear aligners offer an aesthetic advantage and are also thought to promote better oral hygiene. However, their specific impact on the oral microbiome is not yet fully understood. This longitudinal study used 16S amplicon sequencing to study the oral microbiome (from saliva, subgingival, and supragingival samples) of 11 patients undergoing clear aligner treatment. Samples were collected at three time points: before treatment and at 3 and 6 months during therapy. Our results revealed large differences between the microbiomes of different oral sites but no significant overall changes in the oral microbiome composition due to orthodontic treatment. While some species-specific changes were observed, their effect sizes were very small. Although these results should be confirmed in a larger and more diverse cohort, they suggest that the treatment had a small or negligible impact. Given the observed stability of the oral microbiome in all three studied niches throughout the treatment and the known benefits to oral hygiene, clear aligners may present a favorable therapeutic alternative compared to fixed appliances.