Underlying pathways of social inequality in tooth loss: the mediating role of sugary beverages and diabetes.

BACKGROUND: Previous studies show social inequality in tooth loss, but the underlying pathways are not well understood. The aim was to investigate the mediated proportion of sugary beverages (SBs) and diabetes and the association between educational level and tooth loss, and to investigate whether the indirect effect of SBs and diabetes varied between educational groups in relation to tooth loss. METHODS: Data from 47,109 Danish men and women aged 50 years or older included in the Danish Diet, Cancer and Health Study was combined with data from Danish registers. Using natural effect models, SBs and diabetes were considered as mediators, and tooth loss was defined as having <15 teeth present. RESULTS: In total, 10,648 participants had tooth loss. The analyses showed that 3% (95% confidence interval 2-4%) of the social inequality in tooth loss was mediated through SBs and diabetes. The mediated proportion was mainly due to differential exposure to SBs and diabetes among lower educational groups. CONCLUSIONS: The findings show that SBs and diabetes to a minor degree contribute to tooth-loss inequalities. The explanation indicates that individuals in lower educational groups have higher consumption of SBs and more often suffer from diabetes than higher educational groups.

Social inequality in tooth loss, the mediating role of smoking and alcohol consumption.

OBJECTIVES: The objective of the study was to investigate the mediated proportion of smoking and alcohol consumption in the association between education and tooth loss. Further, the objective was, on the additive scale, to decompose the total effect of education on tooth loss into the direct effect of education, the natural indirect effect through smoking and alcohol consumption (differential exposure) and the mediated interaction between education, smoking and alcohol consumption on tooth loss (differential susceptibility). METHODS: The study was based on data from the Social Inequality in Cancer Cohort (SIC); a cohort constructed by seven pooled cohorts. The total study population comprised of 34 975 participants. With the use of natural effects models, we regarded smoking and alcohol consumption as intermediates; we investigated the role of smoking and alcohol consumption in mediating the effect of education on tooth loss. RESULTS: In total, 4924 participants had tooth loss defined as <15 teeth present. The results of the analyses, on the additive scale, showed 1202 (95% CI: 623-1781) additional persons with tooth loss per 10 000 persons among low compared to highly educated men. Among women, the analyses showed 1159 (95% CI: 959-1359) additional persons with tooth loss per 10 000 persons. The results, on the relative scale, showed that 11% (95% CI: 8%-15%) of the social inequality in tooth loss was jointly mediated by smoking and alcohol consumption among low-educated men. Among women with low education, the mediated proportion was 26% (95% CI: 19%-36%). CONCLUSION: Social inequality in tooth loss seems partly explained by differential exposure and differential susceptibility to smoking and alcohol consumption.