Association between the number of missing/replaced teeth and Chronic Kidney Disease (CKD): cross-sectional analysis of NHANES data

This study aimed to investigate the association between the number of missing/replaced teeth and chronic kidney disease (CKD), and whether there is a dose-response relationship with markers of renal function. Utilizing data from the National Health and Nutrition Examination Survey (NHANES) 2011–2018, a cross-sectional analysis was conducted on 16,999 adults aged ≥ 30 years. The number of missing/replaced teeth was categorized into five groups: 0, 1–4, 5–10, 11–20, and > 20 teeth. Four progressively adjusted logistic regression models were used: Model 1 (unadjusted); Model 2 (adjusted for age, sex, race, marital status, family income-to-poverty ratio, and body mass index (BMI)); Model 3 (adjusted for hypertension and diabetes); Model 4 (fully adjusted for all covariates). Age-stratified analysis evaluated the modifying effect of age. Forest plots illustrated the correlations. Piecewise linear regression and box plots further analyzed the relationship between the number of missing teeth and renal function markers (estimated glomerular filtration rate (eGFR), urinary albumin-to-creatinine ratio (UACR)). A dose-response relationship was observed between the number of missing/replaced teeth and CKD risk. In the fully adjusted model (Model 4), extremely severe loss (> 20 teeth) remained associated with CKD (OR = 1.62, 95% CI: 1.06–2.47, p < 0.001). Age-stratified analysis revealed that even mild loss (1–4 teeth) significantly increased CKD risk in individuals ≤ 40 years (OR = 1.54, 95% CI: 1.13–2.08, p < 0.001), whereas the highest CKD risk in those > 60 years was associated with ≥ 20 missing/replaced teeth (OR = 1.96/1.88, 95% CI: 1.17–3.28/1.60–2.21, p < 0.001). Piecewise regression identified 6 missing teeth as the inflection point for eGFR and UACR changes. The number of missing/replaced teeth is significantly associated with CKD. Oral health may serve as a practical marker for CKD risk screening, particularly in young adults with mild tooth loss and older adults with severe tooth loss.