Abstract Objectives Oral health is an important part of general health and well‐being and shares risk factors, such as poor diet, with obesity. The published literature assessing the association between obesity and oral health in early childhood is sparse and inconsistent. The objective of this study was to investigate associations between overweight/obesity (measured by body mass index) and dental outcomes (caries, plaque index and gingival index) both cross‐sectionally and longitudinally, taking account of potential confounding factors, based on data collected at age 2 and age 5 within the Australian Study of Mothers' and Infants' Life Events Affecting Oral Health (SMILE) birth cohort study. Methods This study used data from 1174 SMILE participants. Associations between overweight/obesity and dental outcomes were assessed using generalized linear regression models for the modified Poisson family with log link to estimate prevalence ratios. Cross‐sectional and longitudinal models were fitted, after minimal and full adjustment for potential confounders. Results Approximately 12% of the participants were overweight/obese at 2 years and 9% at 5 years. Between 2 and 5 years, the prevalence of caries increased from approximately 4% to 24%, at least mild plaque accumulation increased from 37% to 90% and at least mild inflammation from 27% to 68%. There were no associations between overweight/obesity and the prevalence of dental caries; prevalence ratios (PR) [95% confidence interval (CI)] after adjustment for age and sex were 0.9 (0.3, 2.4) cross‐sectionally at 2 years, 1.0 (0.6, 1.5) cross‐sectionally at 5 years, and 1.0 (0.6, 1.5) for overweight/obesity at 2 years and caries at 5 years. Prevalence ratios were all around the value of 1 for the other dental outcomes and also after adjustment for additional confounders. Conclusions There were no associations between overweight/obesity and dental caries, plaque index or gingival index in this cohort of preschool children. However, associations may emerge as the children become older, and it will be possible to extend analyses to include data collected at age 7 in the near future.

Association between overweight/obesity and dental outcomes in early childhood: Findings from an Australian cohort study