Low-level laser therapy stimulates tissue repair and reduces the extracellular matrix degradation in rats with induced arthritis in the temporomandibular joint.

The objective of this study was to characterize morphological and biochemistry action of low-level laser therapy (LLLT) on induced arthritis in the temporomandibular joint (TMJ) of rats. Twenty-four male Wistar rats were randomly divided into groups with 12 animals each: (AG) group with arthritis induced in the left TMJ and (LG) group with arthritis induced in the left TMJ and treated with LLLT (830 nm, 30 mW, 3 J/cm(2)). Right TMJs in the AG group were used as noninjected control group (CG). Arthritis was induced by intra-articular injection of 50 µl Complete Freund's Adjuvant (CFA) and LLLT began 1 week after arthritis induction. Histopathological analysis was performed using sections stained with hematoxylin-eosin, Toluidine Blue, and picrosirius. Biochemical analysis was determined by the total concentration of sulfated glycosaminoglycans (GAGs) and evaluation of matrix metalloproteinases (MMP-2 and MMP-9). Statistical analysis was performed using paired and unpaired t tests, with p < 0.05. Compared to AG, LG had minor histopathological changes in the TMJ, smaller thickness of the articular disc in the anterior (p < 0.0001), middle (p < 0.0001) and posterior regions (p < 0.0001), high birefringence of collagen fibers in the anterior (p < 0.0001), middle (p < 0.0001) and posterior regions (p < 0.0001) on the articular disc, and statistically lower activity of MMP-2 latent (p < 0.0001), MMP-2 active (P = 0.02), MMP-9 latent (p < 0.0001), and MMP-9 active (p < 0.0001). These results suggest that LLLT can increase the remodeling and enhancing tissue repair in TMJ with induced arthritis.

Protocol on induction of TMJ articular disc degeneration in rats by utilization of botulinum toxin.

OBJECTIVE: To develop a model of experimental degeneration in the articular disc of the TMJ of rats through the use of botulinum toxin that can be used in future studies of degenerative diseases on fibrocartilage. METHODS: Aiming at the above-mentioned objective, 12 Lewis male rats were used and divided into two groups: CG, control group and DG, group of animals to which the botulinum toxin was administered (6 units/kg). The morphological analysis was carried out utilizing histological cuts stained with hematoxyline-eosine, toluidine blue and Picrosirius; the biochemical analysis was made by SDS-polyacrylamide gel electrophoresis. RESULTS: The DG showed peculiar characteristics regarding a degeneration joint disk, compatible with those described in literature as: reduction of cells number, general disorganization of cells direction and extracellular matrix, increase in glycosaminoglycans content and degradation of the tissue collagen. CONCLUSIONS: Based on the morphological and biochemical results, it was concluded that the proposed degeneration model showed to be satisfactory for futures studies of injuries and fibrocartilage regeneration processes.