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BioMed Research International
Volume 2015 (2015), Article ID 381821, 7 pages
Research Article

Risk Factors for Reduced Salivary Flow Rate in a Japanese Population: The Hisayama Study

1Section of Preventive and Public Health Dentistry, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan
2Department of Preventive Dentistry and Dental Public Health, School of Dentistry, Aichi Gakuin University, Aichi 464-8650, Japan
3Department of Health Management, School of Oral Health Science, Kyushu Dental College, Kitakyushu 803-8580, Japan
4Division of Research Management, Center for Cohort Studies, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
5Department of Environmental Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan

Received 7 November 2014; Revised 20 January 2015; Accepted 23 January 2015

Academic Editor: Kazuhiko Kotani

Copyright © 2015 Kenji Takeuchi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The purpose of this study was to determine distinct risk factors causing reduced salivary flow rate in a community-dwelling population using a prospective cohort study design. This was a 5-year follow-up survey of 1,377 community-dwelling Japanese individuals aged ≥40 years. The salivary flow rate was evaluated at baseline and follow-up by collecting stimulated saliva. Data on demographic characteristics, use of medication, and general and oral health status were obtained at baseline. The relationship between reduced salivary flow rate during the follow-up period and its predictors was evaluated after adjustment for confounding factors. In a multivariate logistic regression model, higher age and plaque score and lower serum albumin levels were significantly associated with greater odds of an obvious reduction in salivary flow rate (age per decade, odds ratio [OR] = 1.25, 95% confidence interval [CI] = 1.03–1.51; serum albumin levels <4 g/dL, OR = 1.60, 95% CI = 1.04–2.46; plaque score ≥1, OR = 1.53, 95% CI = 1.04–2.24). In a multivariate linear regression model, age and plaque score remained independently associated with the increased rate of reduced salivary flow. These results suggest that aging and plaque score are important predictors of reduced salivary flow rate in Japanese adults.