Efficacy of Transcutaneous Electric Nerve Stimulation on Parotid Saliva Flow Rate in Relation to Age and Gender

STATEMENT OF THE PROBLEM Treatment with salivary substitutes and stimulation of salivary flow by either mechanical or pharmacologic methods has side effects and only provides symptomatic relief but no long-lasting results. PURPOSE To assess the effectiveness of extraoral transcutaneous electric nerve stimulation (TENS) as a mean of stimulating salivary function in healthy adult subjects; as well as to determine the gender and age-dependent changes in salivary flow rates of unstimulated and stimulated parotid saliva. MATERIALS AND METHOD Hundred patients were divided into two groups; Group I aged 20-40 and Group II aged ≥ 60 years. The TENS electrode pads were externally placed on the skin overlying the parotid glands. Unstimulated and stimulated parotid saliva was collected for 5 minutes each by using standardized collection techniques. RESULTS Eighty seven of 100 subjects demonstrated increased salivary flow when stimulated via the TENS unit. Ten experienced no increase and 3 experienced a decrease. The mean unstimulated salivary flow rate was 0.01872 ml/min in Group I and 0.0088 ml/min in Group II. The mean stimulated salivary flow rate was 0.03084 ml/min (SD= 0.01248) in Group I, and 0.01556 ml/min (SD 0.0101) in Group II. After stimulation, the amount of salivary flow increased significantly in both groups (p< 0.001). Statistical comparison of the two groups revealed them to be significantly different (p< 0.001), with Group I producing more saliva. Gender-wise, no statistically significant difference was seen among the subjects in Group I (p = 0.148), and those in Group II (p= 0.448). Out of 12 subjects with 0 baseline flows, 7 continued to have no flow. Five subjects observed side effects, although minimal and transient. CONCLUSION The TENS unit was effective in increasing parotid gland salivary flow in healthy subjects. There was age-related but no gender-related variability in parotid salivary flow rate.