A prospective cohort study exploring salivary microbial predictors of white spot lesions during fixed orthodontic...

White spot lesions (WSLs) are a common adverse outcome of fixed orthodontic treatment, prompting the search for salivary microbial predictors for early risk identification.

Sixty-four patients undergoing fixed metal self-ligating orthodontic treatment were categorized into WSL and non-WSL groups based on lesion development after 12 months. Clinical indices (DI-S, CI-S, OHI-S, GI) and unstimulated whole saliva samples were collected at baseline and after 12 months. The salivary microbiome was analyzed using 16S rRNA gene sequencing.

The prevalence of WSLs was 54.7% at the patient level. Clinical indices did not differ significantly between groups. Although overall microbial community structure was similar at baseline, several taxa were enriched in patients who later developed WSLs, including Actinomyces, Rothia and Granulicatella. After 12 months, the WSL group showed reduced phylogenetic diversity and a microbial profile enriched in acidogenic and anaerobic taxa. Functional prediction indicated increased carbohydrate metabolism and fermentative pathways in WSL patients.

WSL development during fixed orthodontic treatment was associated with baseline salivary microbial differences and treatment-related ecological shifts. Salivary microbiome profiling may help identify patients at higher risk and support early risk stratification and preventive strategies in orthodontic care.