Purpose:The aim of the study was to investigate the effectiveness of interferential current therapy on salivary gland function in Primary Sjogren's Syndrome (pSS).

Methods:Thirty six pSS were included in the study. Patients were randomly divided into 2 groups (Group 1 (treatment group) n=18; Group II (placebo group) n=18). Salivary flow rate measurement (SFRM), Oral Health-Related Quality of Life-United Kingdom Questionnaire (OHRQOL-UK), Oral Health Impact Profile-14 (OHIP-14), Health Assessment Questionnaire (HAQ), Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI), Pittsburgh Sleep Quality Index (PSQI) and Short Form-36 (SF-36) were used for evaluation. All evaluations were done pre-, posttreatment, at 3. month, at 6. month and at 9. month. Clinical pilates exercises and interferential current therapy were applied to Group I while clinical pilates exercises and interferential current therapy as placebo was applied to Group II. All treatments were given three times a week for 8 weeks.

Inclusion Criteria:

• To be diagnosed with pSS according to the 2016 European League Against Rheumatism American / College of Rheumatology Classification Criteria,
• To be in the 3rd and 4th grade according to the Chisholm-Mason Grading System,
• be in the age range of 25-65 years,
• To be stable on drug use for at least 3 months or longer, (f) To have agreed to participate in the study.

Exclusion Criteria:

• To use antipsychotic, antidepressant, antihypertensive, medical agent for Parkinson's,
• Presence of viral infection,
• Presence of Diabetes Mellitus,
• Receiving head and neck radiotherapy/chemotherapy,
• Having a head and neck malignancy,
• Having undergone head and neck surgery,
• Presence of dehydration,
• Pregnancy,
• Using cigarettes and alcohol,
• Cognitive problems that affect cooperation,
• having any other disease that may affect their functions.

The physiotherapist performing the evaluation was blinded to the groups.