Number of Teeth and All-Cause and Cancer Mortality in a Japanese Community: The Takayama Study.

Background: The association between the number of teeth and mortality among community-dwelling people has been examined in many epidemiological studies. However, few Japanese studies have included cancer mortality as an endpoint. We prospectively investigated the association between number of remaining teeth and all-cause and cancer mortality in a Japanese community.

Methods: This study included participants in the Takayama Study who were aged 35-70 years old at baseline in 1992. Information on the number of remaining teeth was obtained from 11,273 participants via questionnaire at the second survey in 2002. The response rate was 66.9%. Deaths and their causes were ascertained during 11.8 years of follow-up.

Results: A total of 1,098 deaths (435 cancer-related and 235 cardiovascular-related) were identified during the follow-up period. After adjusting for covariates, participants with 0 to 9 teeth were at moderate but significantly increased risk of all-cause mortality (hazard ratio [HR] 1.19; 95% confidence interval [CI], 1.03-1.39) and cancer mortality (HR 1.31; 95% CI, 1.03-1.67) compared to those with 20 or more teeth. With regard to cancer site, a significant association was observed for lung cancer (HR for 0-9 teeth vs. 20 or more teeth, 1.75; 95% CI, 1.08-2.83). This association was somewhat strengthened among never-smokers (HR 3.56; 95% CI, 1.02-12.45).

Conclusions: We observed that a lower number of remaining teeth was significantly associated with increased risk from all-cause and lung cancer mortality. Further studies on the number of teeth and lung and other types of cancer are needed.