Nonlinear Association Between Blood Cadmium Levels and Periodontitis: A Cross-Sectional Study from NHANES 2011-2014

Objectives: The relationship between blood cadmium levels and the risk of periodontitis remains unclear. This study aimed to explore the association between blood cadmium concentrations and periodontitis in a large sample of the U.S. population from 2011 to 2014. Methods: This cross-sectional study analyzed data from 5,215 participants in the National Health and Nutrition Examination Survey (NHANES) 2011-2014. Blood cadmium levels were the exposure variable, and periodontitis was the outcome variable. Multivariate logistic regression and a two-piecewise linear regression model were used to examine the nonlinear relationship between blood cadmium levels and periodontitis. Stratified analyses were conducted to identify subgroups at higher risk. Results: The study identified a nonlinear relationship between blood cadmium levels and periodontitis risk. The threshold effect was observed at 0.37 µg/L and 1.20 µg/L. When blood cadmium levels were below 0.37 µg/L, the odds ratio (OR) for periodontitis was 0.88 (95% CI: 0.31, 2.48; p=0.81). For cadmium levels between 0.37 and 1.20 µg/L, the OR increased significantly to 12.40 (95% CI: 2.77, 55.57; p<0.001). When cadmium levels exceeded 1.20 µg/L, the OR decreased to 0.45 (95% CI: 0.06, 3.39; p=0.44). Conclusions: The study found a nonlinear association between blood cadmium levels and periodontitis risk in U.S. adults. The risk of periodontitis increased significantly when blood cadmium levels were between 0.37 and 1.20 µg/L.