Salivary flow and aging: a cross-sectional estimate of the annual decline per year of age

OBJECTIVE: Although reduced salivary flow is often linked to aging, the extent of this decline across different age groups remains unclear. This study investigated the relationship between salivary flow and age, accounting for type 2 diabetes (T2D), polypharmacy, and fiber intake, aiming to estimate an annual rate of decline. STUDY DESIGN: Adults and elderly participants (mean age 54 ± 11 years) were recruited for this cross-sectional study. Resting salivary flow (RSF), stimulated salivary flow (SSF), pH, buffering capacity, viscoelasticity, medication intake and, T2D diagnosis were the main variables analyzed. Participants were classified as having hyposalivation if RSF < 0.1 mL/min or SSF < 0.7 mL/min. Associations were tested using unadjusted and adjusted robust linear regression (P < .05). RESULTS: Sialometry was completed for 166 individuals. Hyposalivation was identified in 31% by RSF and 89% by SSF. Among adults under 60 years(n = 118), 28 (24%) had RSF hyposalivation and 99 (85%) had SSF hyposalivation. Older participants had significantly lower RSF and SSF. Salivary flow was estimated to decrease by 0.005 mL/min per year of age, independent of T2D and medication use. CONCLUSION: Salivary flow is associated with age, independent of T2D and medication use. Although the decline appears predictable (0.005ml/min/year), its clinical relevance warrants further investigation through longitudinal studies.