Association of obesity with the eruption of first and second permanent molars in children: a systematic review

Background: Eruption timing of permanent teeth, particularly first and second molars, is of great importance due to its influence on occlusion, caries risk and timing of preventive and orthodontic intervention. Aim: To evaluate the evidence assessing the correlation between obesity and eruption time of first and second permanent molars in children under 16 years of age as compared to normal-weight children. A secondary aim was to assess the total number of erupted teeth in both groups. Methods: A systematic search of databases including PubMed, MEDLINE, EMBASE, Scopus and Web of Science was conducted. Studies that assessed the effect of body mass index (BMI), adjusted BMI or z scores on dental eruption were included. National Institute of Health ‘Quality Assessment Tool for Observational Cohort and Cross-sectional Studies’ was used to assess the quality of included papers. A random-effects model with its 95% confidence intervals (CIs) was considered for meta-analysis. Results: A total of 381 papers were screened following duplicate removal. Twenty-six papers were read in full text, of which 19 were excluded. Seven studies were included in this review; one was longitudinal, and six were cross-sectional in design. A positive association of dental eruption with obesity was noted in six studies. Two studies were included in the explorative meta-analysis, the results of which indicated that obese, 12-year-olds are likely to have one more erupted tooth than their counterparts with a mean difference (MD) of (0.99, 95% CI 0.628–1.352). Conclusion: There appears to be a positive correlation between obesity and dental eruption including the eruption timing of first and second permanent molars. Main risk of bias arises from the cross-sectional nature of included studies and lack of control of potential confounders. Further high-quality evidence is required to elucidate this association. Registration PROSPERO (CRD42017084368). Registration: PROSPERO (CRD42017084368).