Background In Western countries, the most important part of the face in communication is the mouth, whereas it is the eyes in Asian countries; thus oral health could be more important in social interactions in Western countries. Our aim was to examine differences in the association between oral health status and social isolation among older people by comparing Japan and England.

Methods We used cross-sectional information obtained from adults aged 65+ in two ongoing prospective cohort studies: The Japan Gerontological Evaluation Study (JAGES, N=120,195) and the English Longitudinal Study of Ageing (ELSA, N=3,958). The dependent variable, social isolation score (SIS) was calculated from five factors (marital status, social support from children, social support from family, social support from friends, and social partcipation). The independent variables were self-reported number of remaining teeth (0, 1–9, 10–19, ≥20) and denture use (≥20 teeth, ≤19 teeth with denture, ≤19 teeth without denture), while the covariates in the model were: sex, age, educational attainment, self-rated health, number of comorbidities, household annual equivalized income, mental health status, daily living activities, and smoking status. We examined associations between oral health status and SIS by applying an ordered logit model by country.

Results Compared to England, more Japanese participants were socially isolated (1.4% vs. 5.8%), but fewer were edentulous (13.1% vs. 7.7%). In both countries, poorer oral health further increased the odds of being socially isolated. Pooled analysis of the ordered logit model with an interaction term showed that the association of number of remaining teeth with SIS was stronger in edentulous participants and in England (odds ratio=1.50, 95% Confidence interval:1.26–1.80).

Conclusion In both countries, having fewer remaining teeth and not using dentures were associated with greater social isolation but the association was higher in England, as we hypothesized. Furthermore, even if they use dentures, participants in England could be more isolated. Our results suggest that higher social impact can be placed on maintaining teeth in Western culture than in Eastern culture.