Therapeutic Potential of Low-level Laser Photobiomodulation on Adjuvant Induced Temporomandibular Joint Arthritis in A Rat Model

Objective: To test the efficacy of low-level laser therapy (LLLT) to alleviate temporomandibular TMJ induced arthritis
in rats. Materials and methods: Rats were randomly allocated to three groups: group I (sham control), group II
(arthritis) where animals were subjected to arthritis induction using complete Freund’s adjuvant followed by LLLT (0
j/cm2), and group III (LLLT) where animals were subjected to arthritis induction followed by LLLT (38 j/cm2). One and
three weeks after treatment onset, rats were euthanized and specimens were subjected to histological,
histomorphometric, and histochemical analysis. Results: The sham group showed normal histology. The arthritic group
showed severe changes with surface irregularity, loss of condylar zones, hypocellularity, and bone resorption. The
articular disc was significantly increased in thickness (P=0.0005), while the condylar cartilage was atrophied
(P<0.0001). LLLT treatment caused significant enhancement of disc (P<0.0001) and cartilage thickness (P=0.0001)
compared to the arthritic group after three weeks. The histological structure of TMJs appeared more regularly arranged
than the arthritis group with better results after three weeks, where articular surfaces showed uniform outlines,
chondrocytes were well arranged, less osteochondral detachment was detected, and subchondral bone showed arranged
trabeculae. However, LLLT did not restore complete normal architecture as compared to the sham group .Conclusions:
LLLT can significantly promote the regeneration and healing of arthritic TMJs. However, longer follow-up periods or
different laser doses may be recommended to restore normal tissue architecture.