The effect of repeated sampling on paraffin-stimulated salivary flow rates in menopausal women.

Paraffin-stimulated whole-saliva samples of 12 post- and perimenopausal women were taken five times over a 7-week period. After 1 min of prestimulation, saliva was collected for 5 min under standardized conditions. Saliva was first collected on three consecutive days, and two additional samples were collected 6 and 7 weeks after the first. Salivary flow rates showed significant variation between samplings. The greatest difference appeared between the first and second collections. The increase in flow rates between these collections was significant (p = 0.003). The third successive collection also gave a significantly (p = 0.005) higher flow rate than the first. The 6-week and baseline samples were similar. The 7-week sample showed a significantly higher flow rate (p = 0.018) compared with the baseline value. These results stress the importance of standardization of sampling intervals when salivary flow rates are studied.