Abstract
BACKGROUND: This prospective study aims to investigate the comparative effects of clear aligners (CA) and traditional removable appliances (RA) on the cariogenic risk of patients in mixed dentition, focusing on the oral microbiome. METHODS: 25 children were included and assigned into CA and RA groups. Supragingival plaque and saliva samples were collected, and clinical parameters including Decay-missing-filled teeth index (DMFT), Plaque Index (PI) and Gorelick Index (GI) were recorded before treatment (T(0)) and after 6-month follow-up (T(1)). DNA was extracted from supragingival plaque and saliva and analyzed via 16S rDNA gene sequencing. RESULTS: Clinical parameters showed no statistically significant difference between groups at each time point or within group over time (p > 0.05). In both RA and CA groups, saliva exhibited significantly higher alpha diversity compared to supragingival plaque at T(1), as indicated by the significantly higher Chao1 and Shannon indexes (p < 0.05). Regarding beta diversity, significant difference was observed in saliva and supragingival plaque samples between T(0) and T(1) within group RA (p < 0.05, Adonis), whereas no such significance was noted in the CA group (p > 0.05, Adonis). At the genus level, Lactobacillus exhibited a statistically significant increase in saliva and supragingival plaque of group RA from T(0) to T(1) (p < 0.05), and an increasing trend in the group CA without statistical significance (p > 0.05). At T(1), Lactobacillus levels were comparable between groups, whereas species-level analysis revealed distinct cariogenic species. CONCLUSION: Both clear aligners and traditional removable appliances resulted in elevated cariogenic risk of patients in mixed dentition at the microbial level. Distinct alterations in cariogenic species were observed to be induced by various orthodontic appliances.