Table 2.

Summary of output measures (VAS: Visual analog scale, XeQLOS: Xerostomia- Related Quality of Life Scale developed by University of Michigan.).

Study and year	Comparator	Subjective outcome measures	Objective outcome measures	Conclusion of the study
Wong et al. 2015 [13]	Pilocarpine	XeQLOS	Whole saliva produced •Spit method in a preweighed dry plastic container, conducted at baseline and at 4, 6, 9 and 15 months after the date of randomization	No significant difference in comparison to Pilocarpine. ALTENS was shown Superior due to lower toxicity
Vijayan et al. 2014 [14]	Before and after	Not assessed	Saliva flow •Spit method into a calibrated cup, collected during the test sessions.	TENS double the production of saliva
Wong et al. 2003 [15]	Pilocarpine	Five item xerostomia symptoms questioner with a VAS	Saliva flow •Spit method in a preweighed dry plastic container, performed at baseline and 6, 8, and 12 weeks after treatment began and at 3, 6, and 12 months after treatment completion.	Suggest that ALTENS treatment improve whole saliva production. Group A had the greatest improvement.
Lakshman et al. 2015 [16]	Healthy group	Not assessed	Salivary flow •Spit method collected in a glass beaker. Collected before and during the test sessions.	TENS increased salivary flow after daily use.
Paim et al. 2019 [17]	Control group	Self-perception of salivary flow (SPSF) and Quality of life (QL)	Salivary flow •Sialometry-using silicon sialagogue Collected before and immediately after each session.	The effect of the TENS lasted for 6 months after TENS therapy