Genetic and Environmental Influences on Tooth Loss: A Twin Study of Middle-Aged and Older Adults in Qingdao, China.

OBJECTIVE

This study aimed to estimate the relative contributions of genetic and environmental factors on acquired tooth loss among middle-aged and older twins in Qingdao, China.

METHODS

A total of 377 complete twin pairs (240 monozygotic, 137 dizygotic) were recruited from the Qingdao Twin Registry in China, and acquired tooth loss was recorded through structured interviews. Heritability of acquired tooth loss was estimated using correlation analysis and structural equation model, adjusting for age and sex.

RESULTS

The median age of the twins was 50 years (IQR: 46-57). The polychoric correlations for monozygotic twins (0.67; 95% CI: 0.55-0.78) were more than twice as high as that for dizygotic twins (0.25; 95% CI: 0.03-0.48). Therefore, we fitted an additive, dominant, and unique environmental factors model and its nested submodels. Based on the Akaike information criterion, the additive and unique environmental factors model was selected as the preferred model. After adjusting for age and sex, the model indicated that 56.51% (95% CI: 43.21%-69.81%) of the variance in acquired tooth loss was attributable to additive genetic factors, and 43.49% (95% CI: 30.20%-56.79%) to unique environmental influences.

CONCLUSION

This study demonstrated that variation in acquired tooth loss is influenced by both additive genetic and unique environmental factors. These findings may assist in developing strategies for tooth loss prevention and oral health maintenance.