The Changes of Microbiome Attached on Clear Aligners after Drinking Coca-Cola

This study aimed to investigate the changes in the microbiome on the inner surface of clear aligners following the consumption of Coca-Cola. The pH value and bacterial composition on the inner surface of clear aligners were assessed over five wearing cycles in three groups of subjects: those with a normal diet (Group A), those who drank Coca-Cola while wearing the aligners (Group C), and those who drank Coca-Cola after removing the aligners (Group B). Microbial analysis was performed using 16S rRNA gene sequencing and operational taxonomic unit (OTU) abundance profiling. The pH of the fluid inside the aligners significantly decreased immediately after Coca-Cola consumption (0 hour) in Groups B and C (p < 0.05). Group B exhibited the most pronounced decline in pH and alpha diversity at 12 hours, along with the highest beta diversity among the groups (p < 0.05). In Group A, the relative abundances of the phylum Actinobacteria was highest at 0 hour, Bacteroidetes at 12 hours, and class Actinobacteria, Gammaproteobacteria, and species Haemophilus influenzae peaked at 24 hours; conversely, Neisseria subflava showed the lowest abundance compared to Groups B and C (p < 0.05). Compared to Group C, Group B demonstrated higher levels of phylum Fusobacteria at 4 hours and 12 hours, and lower Actinobacteria abundance at 8 hours (p < 0.05). Consumption of Coca-Cola induces unfavorable changes in the microbiome on the inner surface of clear aligners. Notably, drinking Coca-Cola without wearing the aligners resulted in a lower pH and greater microbial imbalance, especially at 12 hours post-consumption.