The mutual effect of dental caries on NAFLD and liver fibrosis: Results from the NHANES and MR study

Abstract

Background & Aims: Dental caries and non-alcoholic fatty liver disease (NAFLD) overlap in risk factors and etiology, but the relationship remains unexplored.. Methods 6650 participants of the National Health and Nutrition Examination Survey (NHANES), 2017–2020 were included. Two multivariable logistic regression models were employed to evaluate the relationship among untreated dental caries (UDC) and liver conditions of NAFLD and fibrosis, with adjustments for demographics, lifestyle and medical history. Further more, two-sample Mendelian randomization (MR) was performed with caries as exposure and NAFLD with NAFLD-related conditions as outcome, and vice versa for bidirectional causality validation. Results In the observational research, UDCs were notably associated with NAFLD (OR: 1.40, 95% CI: 1.06–1.86) and significant fibrosis (SF) (OR: 1.29, 95% CI: 1.03–1.62). NAFLD and SF showed significant associations with UDCs (OR: 1.40, 95% CI: 1.08–1.83; OR: 1.62, 95% CI: 1.26–2.08). In MR analysis, dental caries had an insignificant risk towards liver conditions. In contrast, caries were insignificantly protected by liver conditions. Conclusions Observational studies suggested a significant association between UDC and liver conditions of NAFLD and fibrosis. However, MR suggested an insignificant causal relationship of caries with liver conditions; reversely, liver conditions had a protective effect on caries.