Impact of Vertical Facial Patterns and Oral Habits on Microbial Colonization in Children and Adolescents: A Cross-Sectional Study

Background The oral commissures represent a unique anatomical interface where intra- and extra-oral environments converge. This study aimed to investigate the association between vertical facial patterns and microbial colonisation at the oral commissures in children and adolescents. Methods A total of 150 healthy participants aged 8–18 years were equally divided into low-, norm-, and high-angle groups according to their cephalometric GoGn/SN values. Swab samples from both commissures were cultured for Candida species and Gram-positive bacteria. Commissural wetness, intra-oral pH, and oral habits were also recorded. Group differences were analysed using chi-square and ANOVA tests with effect sizes (α = 0.05). Results Vertical facial morphology showed a significant association with bacterial colonisation (p = 0.001). Gram-positive bacilli were absent in low-angle but frequent in norm- and high-angle individuals. Candida carriage (12.0%) showed no significant association with facial pattern (p = 0.103). Mouth breathing was significantly more prevalent in high-angle participants (p = 0.038), while lip-licking habits showed no intergroup difference. Conclusion Increased vertical facial dimension was strongly related to bacterial, but not fungal, colonisation at the oral commissures. Craniofacial morphology may therefore influence the local microbial ecology and should be considered a potential risk modifier in paediatric patients presenting with recurrent angular lesions. Trial registration: Not applicable.