The effects of electrostimulation on parotid saliva flow: a pilot study

Saliva is a critical fluid necessary for oral health. Medications, radiation therapy, and systemic conditions can decrease salivary function and increase a patient's risk for caries and other oral infections. Palliative management of xerostomia includes wetting agents such as ice chips and saliva substitutes. Systemic agents stimulate salivary flow but often have unfavorable side effects. All have met with limited success. The purpose of this study is to assess the effectiveness of transcutaneous electric nerve stimulation (TENS) as a means of stimulating salivary function in healthy adult subjects.

Twenty-two healthy, adult subjects with no history of salivary gland disorder enrolled in the protocol. The TENS electrode pads were placed externally on the skin overlying the parotid glands. Unstimulated saliva was collected for 5 minutes via the Carlson-Crittenden cup into preweighed vials using standardized collection techniques. The TENS unit was then activated and stimulated saliva collected for an additional 5 minutes.

Fifteen of 22 subjects demonstrated increased parotid salivary flow when stimulated via the TENS unit. Five experienced no increase and 2 experienced a decrease. The mean unstimulated salivary flow rate was 0.02418 mL/min (SD 0.03432) and mean stimulated salivary flow rate was 0.04946 mL/min (SD 0.04328). Statistical analysis of flow rates utilizing the paired t test demonstrated the difference to be statistically significant, P < .001. In 7 subjects with 0 baseline flow, 5 continued to have no flow.

The TENS unit was effective in increasing parotid gland salivary flow in two-thirds of healthy adult subjects. A further study in a cohort of patients with salivary gland disorders is warranted.