Experimental studies included the following series of experiments: 1. TMJ inflammation was caused in 19 dogs by introduction of daily broth cultures of a golden staphilococcus in preliminary ligated duct of the parotid salivary gland; 2. in 47 rabbits TMJ was treated with a solution of silver nitrate; 3.  molecular mechanism of 1-minute HNLR action was studied in 14 sessions at power density of 4 mV/cm2 and the changes occurring in immediately irradiated tissues of parotid-temporal area (80 rabbits and 35 dogs); 4. whole animal body reaction (24 rabbits) to 10-minute HNLR action in 14 sessions at power density of 4 mV/cm2  was studied which was estimated by a condition of antioxidant system (AOS), circulatory system, morphological changes of internal organs; 5. HNLR influences on inflammatory, degeneration process in TMJ (106 rabbits, 15 dogs), and also changes in a joint at fracture of the articulate process of a mandible were studied. Physiotherapeutic installation УЛФ-01, with a wavelength of radiation 632.8 nanometers, power density of radiation on the body surface 4 mV/cm2, diameter of maculae on the parotid-temporal area from 2 to 3 cm was used. Laser therapy course of treatment was given to 361 patients with TMJ arthritis and arthrosis. In the experimental and clinical part of the work nonenzymatic link (contents of sulfhydryl and disulfide groups, ascorbic acid and its oxidized forms); and AOS enzyme link (enzymes - superoxide dismutase, catalase, glutationreductase) were studied.

   HNLR influence on the intact TMJ showed that after 7 sessions atrophic and dystrophic changes, thickening of osteal beams appeared, and the marrow in the articulate head of a mandible was replaced with a connective tissue. 10  minute HNLR influence was accompanied by the development of osteomyelofibrosis, arterial hypertension following hyperkinetic form, there was a marked accumulation of a hemosiderin in the cells of the reticular stroma of the spleen. Glycogen content in the cytoplasm of hepatocytes was reduced; there was vacuolization of the cytoplasm and in some places globular adiposity. Antioxidant system activation (Unithiol and Ascorbic acid solutions) before irradiation resulted in significant decrease of all the studied parametres of the circulatory system, and also to a complete lack of differences of indicators in this group and the control one.

  Conclusions. HNLR influence on TMJ on the body resulted in diphasic character of the reaction. It manifested in body function stimulation by small doses of radiation and in its damage by high doses that was registered at any level of the system organization (molecular, cellular, organic).

   Diphasic reaction of the body to HNLR is associated with the intensity of the substrate free radical oxidation. Moderate intensity of these reactions under the influence low doses is a condition for AOS cell and body tissue activation. High intensity of these reactions under the influence of high HNLR doses led to AOS function failure and development of cellular structured damage by the products of the free radical oxidation. In the experiment it manifested  by increased content of oxidized AOS equivalents in the blood; replacement of the active marrow by the connective tissue, thickening of the osteal beams in the articulate of the mandible process; the expressed lymphoid infiltration occurring in the cardiac muscle led to the development of arterial hypertension following hyperkinetic form.

        Use of antioxidants (Unithiolum and Ascorbic acid) before HNLR irradiation prevented the development of these by-effects. Influence on the temporal parotid tissues area depends on a dose, duration of influence and features of a disease course, it possesses cumulative effect.

    The results of biochemical, histochemical, morphological, immunologic, physiological studies allow to recommend  laser radiation use with a wavelength of 632.8 nanometers at power density of  4 mV/cm2, diameter of maculae from 2 to 3 cm on temporal parotid area for 1 minute during 7-14 sessions in the complex treatment of HNLR arthritises and arthroses and other diseases of the maxillofacial area