Temporomandibular joint disorders are ranked third among the most common stomatological diseases after dental caries and periodontal problems. Type of dysfunction is determined by environmental, genetic and psycho-emotional factors. It has been observed that increasing level of stress leads to the increase of harmful parafunctional habits in the stomatognathic system whose long-term effect prevents the ability of the organism to compensate and adapt the function, which contributes to the pain within the masticatory system. Nowadays applied methods in treatment of temporomandibular joint disorders are still under investigation. However, they have not been developed effectively yet. Satisfactory methods of masticatory muscle relaxation (with the exception for drug treatment) are only related to mental patients. Significant impact factor and psycho-emotional stress in the etiology of dysfunction indicate the need of the routine approach in the treatment of patients with temporomandibular joint disorders to be changed. The attempt to cooperate with a psychologist may facilitate the effectiveness of traditional rehabilitation of patients with dysfunction.

Introduction In the 30s of the previous century, Edmund Jacobson developed the method of progressive muscle relaxation, which is based on the premise that mental relaxation should naturally result from physical relaxation. The primary objective of Jacobson's relaxation is to increase patient's awareness associated with the feeling of muscle tension, no matter how intense it is. This method teaches patients how to take control over the factors causing stress, with simultaneous relaxation of skeletal muscles, and alternating tension and relaxation deliberately in the next group of striated muscle. Regular training is aimed at developing a habit of locating the tension and loosening individual muscle groups. Data from the literature indicates the usefulness of Jacobson's progressive muscle relaxation method as a supportive therapy for the treatment of neurological disorders, depression, anxiety, bronchial asthma, and cardiological conditions. Positive therapeutic results have also been reported in the treatment of peptic ulcer, chronic headache, tinnitus, sleep disorders, and psychological treatment of neurological conditions. The additional benefits of this therapeutic approach include reduced anxiety, decreased arterial hypertension and improved heart function, improved gastric and intestinal function, increased imagination and thought processes, increased trust between the patient and the physician, and improved control of one's mood. Jacobson's progressive muscle relaxation has not been used in the treatment of temporomandibular joint disorders. The above has become an inspiration to undertake research in this field. The significant impact of psycho-emotional factors and stress on the rise or worsening of dysfunction as well as cooperation with the psychologist can significantly influence the course and treatment of functional disorders. The elimination of psychological components in patients with temporomandibular joint disorders may contribute to the reduction of pain and frequency of parafunctional habits.

The aim of the study was to obtain data, documented test results as to the efficiency of progressive muscle relaxation in the treatment of pain caused by temporomandibular joint disorders, as a supplement to previous methods using occlusal splint and other physical therapies. The study also included the treatment of post-isometric muscle relaxation. In order to ensure an objective comparative evaluation of these two methods of adjunctive treatment, clinical studies and surveys were conducted. The aim of the study was to answer the following questions:

1. Does the use of Jacobson's progressive relaxation method will be beneficial to reduce pain and improve the functioning of the stomatognathic system being evaluated in clinical trials?
2. Does the relaxation method obtain a positive opinion of the patients and can complement the previously used prosthetic rehabilitation with occlusal splint as well as other physical therapies?
3. Which one of assessed methods (progressive muscle relaxation according to Jacobson and method of post- isometric relaxation) gains an advantage in the treatment used in the adjunctive therapy of temporomandibular joint disorders, and assessment of which according to their impact on muscle relaxation on the basis of the clinical trial and the results of the survey? Material and Methods The study included 100 patients of both sexes, aged from 20 to 35 years who were diagnosed with pain due to temporomandibular joint disorders accompanied with high muscle tension of masticatory muscles. The study included patients reported to prosthetic treatment to Department of Prosthodontics at the Jagiellonian University, Medical College in Krakow between 2014 and 2016. Patients were divided into two groups of 50 people each. In the group number I-test group, treatment was performed by progressive muscle relaxation according to Jacobson. In the group number II- control group, post-isometric muscle relaxation treatment was instituted. The following criteria the patients had to meet in order to be included in the study: good general health, painful form of temporomandibular joint disorders with high muscle tension, pain lasting for at least 3 weeks prior to admission, and also patients with full arches without previous orthodontic treatment.

The exclusion criteria included: joint component of functional disorders (pain in the temporomandibular joints, acoustic symptoms), deterioration of the posture resulting from relaxation training (aggravation of muscular pain, worsening of mental state) unstable musculoskeletal system (frequent painful muscle spasms), tetanus, other diseases that prevent the patient from continuing the study (fever), and the lack of the patient's informed consent.

The criterion for the allocation of patients to groups I and II was the consent to perform relaxation treatments for the treatment of functional disorders of the chewing organ and the lack of contraindications.

Relaxation therapy schedule was adapted to clinical and laboratory stages of occlusion splint. For the purposes of the research both physiotherapy and pharmacological treatment were eliminated. Following the purpose of the studies, comparative evaluation of two supporting methods of treatment were undertaken: for the patients with temporomandibular joint disorders, the performance of 5 cycles of progressive muscle relaxation according to Jacobson in the group I - the study one, and 5 cycles of post- isometric muscle relaxation in group II - control. The qualification and assignment of the patients into group I and II were based on the results of clinical and specialist examination. In group I the training was held twice a week and was conducted by a qualified psychologist. Each meeting lasted 45 minutes. The procedure was to tighten the subsequent muscle groups for 5-7 seconds, followed by a 20-second relaxation time. The basic part of the training performed during the first two meetings included alternating tension and relaxation of muscles in the limbs, abdomen and face based on Jacobson's classic training. The next session was modified taking into account the muscles of the neck and face, and the fourth and fifth sessions included exercises with which the patient was familiarized during earlier training, but done separately for each part of the face.In group II the treatment was conducted by a qualified physiotherapist and also was held twice a week, 45 minutes each, and next exercises were repeated three times.

Inclusion Criteria:

1. good general health
2. painful form of temporomandibular joint disorders- masticatory muscles pain with high muscle tension
3. pain lasting for at least 3 weeks prior to admission
4. patients with full arches without previous orthodontic treatment.

Exclusion Criteria:

1. joint component of functional disorders (pain in the temporomandibular joints, acoustic symptoms)
2. deterioration of the posture resulting from relaxation training (aggravation of muscular pain, worsening of mental state)
3. unstable musculoskeletal system (frequent painful muscle spasms), tetanus, other diseases that prevent the patient from continuing the study (fever)
4. the lack of the patient's informed consent.

The study included 100 patients of both sexes, aged from 20 to 35 years who were diagnosed with pain due to temporomandibular joint disorders accompanied with high muscle tension of masticatory muscles.