Association Between Number of Missing Teeth and Abnormal Bowel Habits: A Cross-Sectional Study from NHANES 2005-2010

Background/Objectives Tooth loss may impair masticatory function, potentially affecting gastrointestinal health. This study examined the association between clinically examined tooth loss and abnormal bowel habits among US adults. Methods This cross-sectional study used NHANES 2005-2010 data. Adults aged [≥]20 with clinical oral examination (OHX) and Bristol Stool Scale (BSS) data were included. Missing teeth (0-28) were categorized as 0, 1-5, 6-10, 11-27, and 28. The primary outcome was abnormal bowel habits (BSS 1-2 or 6-7 vs. 3-5); secondary outcomes included constipation, diarrhea, and fecal incontinence symptoms. Survey-weighted logistic regression with progressive covariate adjustment was used, with Benjamini-Hochberg FDR correction for secondary outcomes. Results Among 9,988 participants (14.5% prevalence), the P-for-trend for abnormal bowel habits was significant (OR = 1.015, 95% CI: 1.006-1.024, P = 0.001), corroborated by omnibus Wald (P = 0.006) and restricted cubic spline analyses (P = 0.019). Complete edentulism was associated with 1.5-fold higher odds (OR = 1.545, P = 0.006). Constipation survived FDR correction (FDR-adjusted P = 0.032). Results were robust across most of five sensitivity analyses, with modest attenuation noted after denture use adjustment in a restricted subset. Conclusions Tooth loss was significantly associated with abnormal bowel habits, with constipation surviving FDR correction. These findings support the oral-gut axis hypothesis and highlight the importance of maintaining natural dentition for gastrointestinal health.