Objectives: Several studies have been conducted on the prevalence of hyposalivation in older adults but no population-based studies in younger adults. Therefore, our aims were to determine the prevalence of very low and low unstimulated (UWSFR) and stimulated (SWSFR) whole salivary flow rates in different age groups between 20 and 69 years, and to analyse the relationship between hyposalivation, subjective oral dryness and predictors of reduced flow rate.
Methods: A randomized and stratified cross-sectional study including 1427 dental patients was conducted. UWSFR and SWSFR were measured, numbers of remaining teeth recorded and a questionnaire answered regarding subjective oral dryness, general diseases, use of drugs, body mass index (BMI) and use of tobacco.
Results: The prevalence of very low (<0.1 ml/min) and low (0.10-0.19 ml/min) UWSFR was similar for different age groups up to 50 years, ranging between 10.9-17.8% and 17.3-22.7%, respectively. The prevalence of very low UWSFR was significantly higher for women aged 50-69 years than for younger women. For men, prevalence of very low UWSFR was higher at 60-69 years. The prevalence of very low (<0.7 ml/min) and low (0.70 - 0.99 ml/min) SWSFR was between 0-5.5% and 0.8-8.2%, respectively, for the different age groups 20-69 years. Multiple logistic regression revealed that age above 50 years, female gender, having fewer than 20 teeth, and taking xerogenic drugs significantly increased the risk of very low UWSFR. For very low SWSFR, only having fewer than 20 teeth and taking more than two drugs were significant. In the younger individuals (<50 years) only BMI > 25 for very low UWSFR and diagnosed disease for very low SWSFR were found significant. In this younger subset, female gender combined with having fewer than 27 teeth was significant for low UWSFR.
Conclusions: Hyposalivation is prevalent in younger adults, among whom it is associated with diagnosed disease and high BMI, while after age 50 years it is associated with medication. It is also associated with gender and with fewer remaining teeth.