Association between the number of teeth and all-cause mortality rate in the MASHAD Cohort Study

Previous studies have reported inconsistent results on the relationship between the number of teeth and all-cause mortality. There are several confounding factors in this relationship, especially age. We investigated the relationship between the number of teeth and all-cause mortality among residents in Mashhad, Iran.

Of 9704 participants of the Mashhad Stroke and Heart Atherosclerotic Disorder (MASHAD) study conducted in this cohort study, 395 participants were randomly recruited for dental examination. Baseline characteristics, including age, sex, and status of marriage, employment, and education, were collected for all the participants. The number of teeth was recorded by a dentist who also undertook a full dental examination. Individuals were followed up every three years, over 10 years, for the incidence of death. Data were analyzed using SPSS 20, and a P value of<0.05 was considered significant. The effect of confounders was reduced using multivariate logistic regression.

Among 387 eligible participants, the mean age was 48.60±8.24 years, and most were female. The number of teeth was significantly related to age (P<0.001), marital status (P=0.002), and educational attainment (P=0.001). Over ten years of follow-up, 15 of the participants died. Among baseline variables, only age was significantly associated with death (P=0.008). The number of teeth was significantly associated with all-cause mortality after adjustment for age, sex and marital status, employment, and educational attainment (P=0.003, OR=0.926, 95% CI: 0.880‒0.974).

Number of teeth is an independent predictor of all-cause mortality, especially in older individuals.