Thesis (Ph.D.) - Cairo University - National Institute of Laser Enhanced Sciences - Department of Laser Application in Oral Surgery Dentistry

Aim of the study: To assess the effect of LLLT on the condylar growth in rabbits. Material and Methods: Thirty six male white Newzland rabbits with the mean age of 4 weeks and the mean weight of 1.5 kg were divided into two equal groups; The first group was the control group (not subjected to any irradiation), the second group was irradiated unilaterally (right side) by CW 870 nm Diode Laser, power output of 300 mW. The spot size was 4 mm circle; exposure was performed on the TMJ (a total of 10 minutes) for three sessions per week for4 weeks. The 2nd group was divided into three subgroups according to date of sacrificing; R1 sacrificed after 30 days of Laser exposure, R2 sacrificed after 60 days from the beginning of exposure and R3 sacrificed after 90 days from the beginning of exposure. Rabbits in both groups were sacrificed, and then mandibular lengths of both groups were taken. Results: Histomorphometric evaluation of the condylar layers was performed. Hyperplasia was observed in the fibro cartilaginous layer associated with hypertrophy in the chondroblasts and excessive newly formed bony trabeculae in the underlying bony structure.Conclusion: Low Level Laser (870 nm diode) in rabbits enhances mandibular growth by condylar bone growth and cartilage, while no increase in the fibrous tissues. XI This study encourages the use of LLLT during orthodontic treatment to shorten prolonged treatment

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