Number of teeth is associated with all-cause and disease-specific mortality

BACKGROUND: Tooth loss has been shown to correlate with multiple systemic comorbidities. However, the associations between the number of remaining natural teeth (NoT) and all-cause mortality have not been explored extensively. We aimed to investigate whether having fewer NoT imposes a higher risk in mortality. We tested such hypotheses using three groups of NoT (20–28,10–19, and 0–9), edentulism and without functional dentition (NoT < 19). METHODS: The National Health and Nutrition Examination Survey in the United States (NHANES) (1999–2014) conducted dental examinations and provided linkage of mortality data. NHANES participants aged 20 years and older, without missing information of dental examination, age, gender, race, education, income, body-mass-index, smoking, physical activities, and existing systemic conditions [hypertension, total cardiovascular disease, diabetes, and stroke (N = 33,071; death = 3978), or with femoral neck bone mineral density measurement (N = 13,131; death = 1091)] were analyzed. Cox proportional hazard survival analyses were used to investigate risks of all-cause, heart disease, diabetes and cancer mortality associated with NoT in 3 groups, edentulism, or without functional dentition. RESULTS: Participants having fewer number of teeth had higher all-cause and disease-specific mortality. In fully-adjusted models, participants with NoT0-9 had the highest hazard ratio (HR) for all-cause mortality [HR(95%CI) = 1.46(1.25–1.71); p < .001], mortality from heart diseases [HR(95%CI) = 1.92(1.33–2.77); p < .001], from diabetes [HR(95%CI) = 1.67(1.05–2.66); p = 0.03], or cancer-related mortality [HR(95%CI) = 1.80(1.34–2.43); p < .001]. Risks for all-cause mortality were also higher among the edentulous [HR(95%CI) = 1.35(1.17–1.57); p < .001] or those without functional dentition [HR(95%CI) = 1.34(1.17–1.55); p < .001]. CONCLUSIONS: Having fewer NoT were associated with higher risks for all-cause mortality. More research is needed to explore possible biological implications and validate our findings. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12903-021-01934-0.