Microbiome variability and role of <i>Candida albicans</i> in site-specific dental plaques in orthodontic adolescent patients with white spot lesions

White spot lesions (WSLs) are a common complication of orthodontic treatment. However, the cariogenic discrepancy in the supragingival microbiome between demineralized and non-demineralized surfaces and the influence of <i>Candida albicans</i> associated with WSLs remain unexplored. This study investigated the changes in supragingival microbiome of orthodontic adolescents with WSLs, encompassing both demineralized and non-demineralized sites, and explored <i>C. albicans</i> colonization in these patients. Supragingival plaques were collected from 29 orthodontic adolescents with WSLs (categorized into demineralized and non-demineralized groups based on the presence/absence of demineralization at sampling sites) and 23 healthy orthodontic adolescents. Supragingival microbiome composition was evaluated using 16S rRNA sequencing, and <i>C. albicans</i> colonization was identified using fungal culture methods. The supragingival microbiome on non-demineralized surfaces showed intermediate cariogenic potential between demineralized and healthy states, but closer to the demineralized state. <i>C. albicans</i> exhibited a propensity for colonization in WSLs patients without site-specificity. <i>C. albicans</i> influenced bacterial composition, with <i>Streptococcus mutans</i> significantly enriched on the demineralized surfaces of <i>C. albicans</i>-positive patients. In orthodontic adolescents with WSLs, non-demineralized surfaces showed microbiome shifts, necessitating interventions to promote a healthy microbiome. <i>C. albicans</i> can impact microbiome composition and potentially contribute to WSLs pathogenesis.