Sara Saffar Soflaei
1,2 
, Reza Ekrad-Ferezghi
2, Behnood Najjari
3, Mohammad Mobasheri
4, Seyed Mohammad Reza Mousavi
4, Arash Pourdad
5, Mohsen Moohebati
6,7, Gordon A. Ferns
8, Javad Sarabadani
9 , Habibollah Esmaily
10,11 , Majid Ghayour Mobarhan
2,1* 1 Metabolic Syndrome Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
2 International UNESCO Center for Health-Related Basic Sciences and Human Nutrition, Mashhad University of Medical Sciences, Mashhad, Iran
3 Faculty of Medicine, Birjand University of Medical Sciences, Birjand, Iran
4 Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
5 Faculty of Paramedicine, Mashhad University of Medical Sciences, Mashhad, Iran
6 Heart and Vascular Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
7 Department of Cardiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
8 Brighton and Sussex Medical School, Division of Medical Education, Brighton, UK
9 Department of Oral Medicine, Faculty of Dentistry and Dental Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
10 Department of Biostatistics, School of Health, Mashhad University of Medical Sciences, Mashhad, Iran
11 Social Determinants of Health Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
Abstract
Background. 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.
Methods. 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.
Results. 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).
Conclusion. Number of teeth is an independent predictor of all-cause mortality, especially in older individuals.