Abstract
BACKGROUND: WHO calls to end the global oral health crisis, as oral diseases impact more people than all other noncommunicable diseases (NCDs) combined. Obesity, a global epidemic, is the fifth leading cause of death worldwide. Both caries and obesity substantially contribute to the global NCDs burden and share common risk factors including commercial determinants of health. However, the relationship between caries and obesity has been inconsistently reported and it has been suggested that sex may play a role. Therefore, the aim of this study was to investigate the sex-specific association between body mass index (BMI) and dental caries in a national sample of Lithuanian adults and early elderly, adjusting for common risk factors. METHODS: The study was based on data from the Lithuanian National Oral Health Survey (2017–2019), comprising a stratified random sample of 1405 adults aged 34–78 from major cities and suburban/rural areas. Information on sociodemographic factors, health-related behaviors, height, and weight was collected using the WHO Oral Health Questionnaire, BMI index was calculated and categorized per WHO criteria. Caries experience was assessed at a surface level and recorded as intact, decayed, missing, or filled surfaces. The count of decayed-, missing-, and filled surfaces (D(3)MFS), and counts of individual components, namely, the total numbers of decayed surfaces (D(3)S), filled surfaces (FS) and missing teeth (MT) were also recorded. Negative binomial regression analyses were conducted. Ratios of means (RMs) with 95% confidence intervals (CI) for the associations were estimated, accounting for the natural logarithm of age and common risk factors. RESULTS: The study included 886 (67%) females, mean age 55.2 (SD 11.7) years and 441 (33%) males, mean age 54.0 (SD 12.1) years. Males with obesity had an average of 37% more missing teeth (adjusted RM 1.37; 95% CI 1.01, 1.85), and males with overweight had an average of 41% fewer D(3)S than normal-weight males (adjusted RM 0.59; 95% CI 0.39, 0.86). Overweight females had an average of 33% and obese 74% more missing teeth than normal-weight females (adjusted RM 1.33; 95% CI 1.10, 1.61 and adjusted RM 1.74; 95% CI 1.43, 2.15, respectively). Moreover, obese females had an average D(3)MFS that was 14% higher than normal-weight females (adjusted RM 1.14; 95% CI 1.05, 1.24). The crude inverse associations between obesity and FS in females disappeared after the adjustment for common risk factors. CONCLUSION: Sex-specific associations between caries and overweight/obesity were observed. The associations were stronger and more pronounced in females, with a notable BMI-related gradient in tooth loss. Some sex-specific associations diminished after adjusting for the common risk factors, partly supporting the common risk factor approach. Our findings may inform gender- and sex-responsive public health strategies simultaneously targeting overweight/obesity and caries. Future studies should confirm our findings, including a more comprehensive set of common risk factors and performing sufficiently powered age-stratified sex-specific analyses. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12903-025-06736-2.