Edentulism or Poor Oral Hygiene: Which Is the Stronger Predictor for All-Cause Mortality?

Background: All-cause mortality consisting of several heterogeneous subgroups does not have a well-defined set of risk factors. Despite the well-described role of oral hygiene on mortality, the association between the condition of the existing dentition and mortality remains unclear. Therefore, we embarked on the current study to assess the association of oral hygiene self-care (OHS) with all-cause mortality. Methods: We assessed whether edentulism and the levels of OHS are associated with all-cause mortality in 476 subjects without missing values participating in the KOHH study using proportional hazard models. We designated the edentulous group as OHS0, and poor, fair, and good OHS groups as OHS1, OHS2, and OHS3, respectively. The self-reported OHS was validated against clinical measures of oral inflammation and dental cleanliness, i.e., gingival bleeding and plaque indices. We, then, compared all-cause mortality at three levels of OHS (poor, fair, good) to that of the edentulous group. To test whether the association of OHS to all-cause mortality was mediated by inflammation, we adjusted for CRP. Results: The validity of self-reported OHS was good demonstrating an inverse association with gingival inflammation and plaque index in a dose-response manner. The group with good OHS lived significantly longer, with a 50% lower risk of all-cause mortality. The Hazard ratio (HR) = 0.50 (95% confidence limit: 0.25-0.99), p = 0.045, in a model adjusted for age, smoking, body mass index, and education. Adjusting for CRP attenuated the association of OHS to all-cause mortality slightly, suggesting that this association was mediated, at least in part, by inflammation. In the final model, the poor OHS group exhibited HR = 0.98 (0.51-1.89), p = 0.95. The HR and p-value so close to 1 suggested poor OHS has a similar risk to edentulism. Conclusions: OHS was associated with reduced risk for all-cause mortality: the better OHS, the lower the risk for all-cause mortality. Poor oral hygiene showed a similar risk for all-cause mortality to edentulism.