A Comparative Analysis of Feeding Practices and Oral Immunity in Infants.

: Infant feeding practices play a crucial role in shaping the oral microbiome, modulating inflammatory responses, and maintaining epithelial health during the first year of life. Breastfeeding promotes the growth of beneficial bacteria and supports a diverse, stable microbial community. In contrast, formula feeding is associated with increased colonization by potentially pathogenic bacteria, such as Staphylococcus and Escherichia coli, which may elevate the risk of infections, oral diseases, and inflammation. This study investigates the effects of breastfeeding versus formula feeding on oral bacterial growth, epithelial cell integrity, and interleukin-17 (IL-17) expression in infants aged 1-12 months. : A total of 60 infants (30 breastfed and 30 formula-fed) were recruited from pediatric clinics in the Qassim region. Microbial cultures quantified bacterial colony-forming units (CFUs), and epithelial cell morphology was assessed through the microscopic analysis of mucosal scrapings. IL-17 concentrations were quantified from the oral mucosa through enzyme-linked immunosorbent assay. Statistical analyses, including t-tests and chi-square tests, compared bacterial loads, IL-17 levels, and indicators of epithelial health between groups. Adjustment for potential confounders was achieved through multivariate statistical analysis. : Formula-fed infants showed significantly higher IL-17 levels than breastfed infants ( < 0.001), indicating a stronger pro-inflammatory profile. Breastfed infants exhibited lower inflammation, improved epithelial health, and reduced cellular debris compared to formula-fed infants, who had higher bacterial loads. A significant correlation was found between epithelial health and bacterial clustering, with clearer epithelial cells associated with lower bacterial colonization. : Formula feeding was associated with increased salivary IL-17 levels, greater bacterial colonization, and compromised epithelial integrity, indicating a heightened pro-inflammatory state and potential vulnerability to mucosal irritation or infection. Breastfeeding appeared to confer protective effects by promoting healthier microbial balance, epithelial integrity, and reducing inflammatory responses. These findings underscore the immunological and microbial benefits of breastfeeding in supporting oral health during infancy.