This thesis study will investigate whether the regular use of antibacterial photodynamic therapy can alleviate dry mouth symptoms in patients with Sjogren's syndrome and thus be a potential addition to regular oral self-care habits that promote and maintain oral health.

Sjogren's syndrome is a chronic autoimmune disease that has a holistic impact on a patient's health. The most significant consequence in terms of oral health is the destruction of the salivary glands by the autoimmune reaction, leading to salivary gland failure and consequently dry mouth with reduced saliva secretion. Decreased saliva secretion predisposes to a number of oral health problems, and patients with Sjogren's syndrome are therefore at risk for conditions such as caries and periodontitis, an inflammatory periodontal disease. Regular visits to an oral health professional and good oral hygiene and eating habits and habits promote and maintain oral health. Treatments for dry mouth symptoms associated with Sjogren's syndrome aim to relieve oral symptoms by preserving, replacing and stimulating salivary gland secretion in ways that relieve local inflammation.

Regular home-use of specially designed antibacterial photodynamic therapy device in addition to standard oral self-care has been shown to destroy oral disease-causing bacteria in a way that bacteria cannot develop resistance to. In addition, the treatment method also stimulates saliva production through photobiomodulation. The aim of our study is therefore to investigate, by means of a clinical measurement, whether the regular use of the antibacterial photodynamic therapy device as part of oral self-care can have an effect on the amount of stimulated saliva secretion of a patient with Sjogren's syndrome during the ten-week study period. The aim is also to describe, by means of a questionnaire measuring the subjective symptoms of dry mouth, whether the treatment has an effect on the frequency of the typical symptoms of xerostomia.

Inclusion Criteria:

• Adult (minimum 18 years of age) person with Sjogren's syndrome, with dry mouth symptoms but some saliva secretion.
• Otherwise perceived health good, primary Sjögren's syndrome patient.
• No need for antibiotic prophylaxis at the time of a limited oral examination.
• Signed written informed consent.
• Subject's co-operation allows participation in the study.

Exclusion Criteria:

• Pregnancy and/or breastfeeding.
• Fungal infection in the mouth
• Poor oral health, such as caries lesions or advanced periodontitis.
• Fixed dentures, or orthodontics.
• No saliva secretion.
• Bisphosphonate drugs, multiple (more than two) medications in use.
• Participation in other oral health research at the same time.