Oral health status and oral microbiota profiles in children with neurodevelopmental disorders: an exploratory cross-sectional comparative study

Children with neurodevelopmental disorders (NDDs) may experience distinctive oral health challenges and alterations in oral microbial ecology. This study compared oral health status, oral hygiene and dietary habits, and oral microbiota composition between children with NDDs and children without diagnosed neurodevelopmental or neurological disorders. This exploratory cross-sectional comparative study included 71 children aged 3–17 years: 34 in the NDD group and 37 in the comparison group. Parents or legal guardians completed a structured questionnaire, and participants underwent a standardised dental examination. Oral microbiota analyses were performed using 16S rRNA gene sequencing of the V3–V4 region. Microbial diversity, community composition, differential taxonomic representation, and predicted functional profiles were assessed using QIIME 2, LEfSe, ANCOM-BC2, and PICRUSt2. No statistically significant between-group differences were detected in plaque accumulation or gingival inflammation. Class II malocclusion (69.2% vs. 29.7%; p = 0.002) and increased overbite (75.9% vs. 45.9%; p = 0.014) were more frequent in the NDD group. Caregiver-supervised brushing was more common in the NDD group, whereas mouthwash use was less frequent. Shannon diversity, Pielou’s evenness, and Simpson index values were higher in the NDD group, whereas richness estimates did not differ. Weighted UniFrac showed a modest group-related difference in community structure (R² = 0.039; p = 0.026), with substantial overlap between groups; the unweighted result was additionally limited by unequal dispersion. LEfSe identified higher representation of Prevotellaceae in the NDD group and of a Firmicutes-related lineage, including Streptococcaceae and Streptococcus , in the comparison group. However, no genus was robustly differentially abundant according to ANCOM-BC2 sensitivity analysis, and no predicted functional differences remained significant after false discovery rate correction. The two recruited groups differed in oral microbial evenness, community structure, and selected occlusal characteristics, while no statistically significant between-group differences were detected in plaque accumulation or gingival inflammation. Because recruitment site was completely aligned with study group, these differences cannot be attributed specifically to neurodevelopmental status. These hypothesis-generating findings require confirmation in larger, longitudinal, diagnostically stratified studies with comparable recruitment settings.