Characteristics of Cytokine Response in Patients With Temporomandibular Disorders Treated With Occlusal Splint Therapy

The goal of this intervention study is to determine the effect of occlusal splint (OS) therapy on the concentration of inflammatory cytokines in serum and gingival crevicular fluid (GCF) in patients with temporomandibular disorders (TMDs).

Aims are:

* to determine cytokines level in GCF and serum before and after OS therapy
* to determine the degree of psychosocial dysfunction and oral health-related quality of life before and after OS therapy
* investigate the correlation between cytokines level in GCF and serum
* to determine the effect of OS on treatment outcomes, pain intensity, dysfunction, and psychosocial status of patients with painful TMD. Participants will be asked to complete self-assessment questionnaires, and GCF and blood samples will be collected before beginning of the OS therapy and at follow-up examinations one month and two months after.

Temporomandibular disorder (TMD) is a multifactorial disease with complex etiopathogenesis. The main symptoms are persistent pain in the masticatory muscles and preauricular region, limitations in jaw function, and sounds in the temporomandibular joints. The most commonly used therapy is the occlusal splint (OS). The therapeutic effect of OS is attributed to various factors, however the exact mechanism is still unknown. One of the potential diagnostic methods is the use of molecular biomarkers. Studies have demonstrated a correlation between inflammatory cytokines and pain in TMD patients compared to healthy controls. Molecular biomarker levels can be determined from tissue samples and body fluids. Gingival crevicular fluid (GCF) is a serum exudate that enters the gingival sulcus from the gingival plexus of blood vessels and contains proteins, various cell types, electrolytes, cytokines, etc. Considering its composition, wide availability, non-invasive method, and speed of collection, GCF could be a new source of TMD biomarkers with potential diagnostic, prognostic, and therapeutic purposes.

Participants diagnosed with myalgia, arthralgia, headache attributed to TMP and/or painful disk displacement (with and without reduction) according to DC /TMD will be included in the study. Participants will be asked to complete self-assessment questionnaires: Graded Chronic Pain Scale (v2), Jaw Functional Limitation Scale-20, Patient Health Questionnaire-9, Genaral Anxiety Disorder-7, Patient Health Questionnaire-15, Oral Behaviors Checklist, Oral health Impact Profile, and Perceived Stress Scale-10. The occlusal splints will be fabricated from hard acrylic resin by the same dental technician in the dental laboratory. The GCF sample will be collected from the sulcus using sterile tweezers and sterile paper sticks and placed in an Eppendorf tube containing 250 µl of 0.9% NaCl solution. Blood samples will be collected in Vacutainers and stored at +4°C until centrifugation. For multicomplex quantitative analysis of proinflammatory cytokines (interleukin 1 beta (IL -1β), interleukin 6 (IL - 6), interleukin 7 (IL -7), interleukin 8 (IL -8), interleukin 13 (IL -13), tumor necrosis factor alpha (TNF-α)), adapted ProcartaPlex multiplex assays will be used.

Eligibility Criteria:
Inclusion Criteria:

* signed informed consent
* TMP pain screening scores ≥ 3
* patients with natural teeth
* diagnoses: myalgia, arthralgia, headache attributed to TMP and painful disc displacement (with and without reduction) according to axis I diagnostic criteria for temporomandibular disorders (DK/TMP)

Exclusion Criteria:

* degenerative joint disease and subluxation of the temporomandibular joint (TMJ)
* head trauma
* orofacial pain not associated with temporomandibular disorders
* patients with fixed or removable prostheses
* patients who are currently undergoing orthodontic therapy and/or using occlusal splints
* patients who used anti-inflammatory drugs and muscle relaxants 48 hours before data collection, and patients who use drugs with an impact on the immune system (such as antiproliferative immunosuppressants, corticosteroids and other immunosuppressants, antirheumatic drugs, DMARDs, anti-lymphocyte monoclonal antibodies and other immunomodulating drugs , antidepressants, antiepileptics)
* periodontitis
* pregnancy