Income inequality and periodontal diseases in rich countries: an ecological cross-sectional study

There are adverse effects of income inequality on morbidity and mortality. This relationship has not been adequately examined in relation to oral health. Aims: To examine the relationship between income inequality and periodontal disease in rich countries. Participants: Adults aged 35-44 years in 17 rich countries with populations of more than 2 million. Methods: National level data on periodontal disease, income inequality and absolute national income were collected from 17 rich countries with populations of more than 2m. Pearson and partial correlations were used to examine the relationship between income inequality and percentage of 35-44-year-old adults with periodontal pockets >= 4mm and >= 6mm deep, adjusting for absolute national income. Results: Higher levels of income inequality were significantly associated with higher levels of periodontal disease, independently of absolute national income. Absolute income was not associated with levels of periodontal disease in these 17 rich countries. Conclusion: Income inequality appears to be an important contextual determinant of periodontal disease. The results emphasise the importance of relative income rather than absolute income in relation to periodontal disease in rich countries.