Effects of Nonsurgical Periodontal Treatment on Bacterial and Clinical Parameters in Down Syndrome Patients Based on 16S rRNA Gene Amplicon Sequencing

Individuals with Down syndrome (DS) are more susceptible to periodontal disease; however, microbial changes following treatment remain insufficiently understood. This study evaluated the effects of nonsurgical periodontal therapy on clinical outcomes and oral microbiome dynamics in 6 patients with DS using 16S rRNA gene amplicon sequencing. Bacterial diversity, composition, network structure, and predicted functional pathways were analyzed using dental plaque samples. Bleeding on probing decreased significantly (p=0.047) after treatment, with a trend toward reduction in periodontal inflamed surface area (p=0.05). The abundance of Fusobacteria at the class level decreased significantly after treatment. The abundance of Mogibacterium timidum was higher in the pretreatment group than in the posttreatment group. M. timidum was positively correlated with Treponema denticola and associated with multiple bacterial taxa in the network during pretreatment. Predicted functional pathways related to aromatic compound degradation were more abundant in posttreatment samples than in pretreatment samples. An increase in the abundance of Fusobacterium and the positive correlation between T. denticola and M. timidum, together with their associations with other periodontal pathogens before treatment, may contribute to the development of periodontitis in individuals with DS. Nonsurgical periodontal therapy produces measurable clinical improvement and promotes microbial shifts in patients with DS.