Association Between Serum Vitamin D Levels and Periodontal Conditions According to Sleep Duration Using Data from Korea National Health and Nutrition Examination Survey

Purpose: This study aimed to investigate the association between vitamin D levels and periodontitis according to sleep duration in a representative sample of Korean adults. Materials and Methods: A total of 3535 subjects who participated in the sixth (2013-2014) Korea National Health and Nu-trition Examination Survey were examined. Vitamin D deficiency was defined as a 25-hydroxyvitamin D serum concentra-tion of < 20 ng/ml. Periodontal status was assessed with the community periodontal index (CPI). A high CPI was defined as a score >= 3. Multivariable logistic regression analyses were adjusted for sociodemographic variables, oral and general health behaviors, and systemic health status. All analyses used a complex sampling design, and a subgroup analysis was performed to determine estimates following stratification for sleep duration (<= 5, 6, 7-8, and >= 9 h per day). Results: Multivariable regression analysis indicated that among participants who slept for >= 9 h per day, those with vita-min D deficiency were 5.51 times (95% confidence interval = 2.04-14.89) more likely to have periodontitis than those with sufficient vitamin D levels. This association was not statistically significant in the other sleep duration groups. Conclusion: The findings of this study indicate that people with vitamin D deficiency who sleep 9 h or longer may also be statistically significantly more likely to have periodontitis.