The effect of low level laser therapy on bone healing in male rats

Abstract EN

The study aimed to evaluate the beneficial effect of low level laser therapy on bone healing, and to compare between the effect of using two doses (4 and 8 J/cm2) of laser.

Sixty adult male Wistar rats were used and randomly divided into three equal groups, control and two laser treatment groups 4J / cm² and 8J / cm².

Bone injury (2 mm in diameter osteotomy) (limited size bone stoma) was created by drilling in the right tibia bone of each animal after making 2cm length longitudinal skin incision on the anterio-lateral aspect of the leg by use scalpel, and displaced the anterior tibials muscle laterally.

After that the muscle was replaced and the incisions was sutured with 3/0 silk suture materials.

The two laser groups (4J/cm2 and 8J/cm2) are received a close-contact pulsed Gallium-Aluminum Arsenide Laser (GaAlAs) on the operation site (with energy density of 4 and 8J/cm2 in a wave length of 660nm, power output (50mw), pulsing rate 146 Hz.) immediately post operation then repeated the dose daily for seven successive days.

Control group left untreated.

Bone healing processes were followed-up by taking histopathological specimens after euthanasia of animals at 7, 14, 21 and 28 days after the surgical operation.

Results displayed that the laser therapy used in both doses were an evenly continuous enhance the healing process of the bone, by acceleration process of healing and reduce inflammation period in compared with the control group.

Histologically the bone defect in 4J/cm2 group was filled early with a dense mass of granulation tissue interposed with polydactyl projections of spike like bony trabeculae giving the shape of new developing bone.

The osteoblasts were seen large in size lining the bone trabiculae.

The trabecula containing numerous osteocytes.

Intra membranous and endochondral ossification were developed early.

The cartilage tissue was disappearing at 28 days and the calluses seem like more developed.

In 8J/cm2 group early visualization of both intramembranous and endochondral ossification surrounded by new periosteal tissue.

Thick and dense branching interconnected trabeculae were appearing fill the bone defect.

The endochondral ossification early invade the cartilage tissue from the periphery, also the intra membranous and the endochondral ossification were interconnected.

No signs of inflammation, and early disappear of granulation tissue were seen.

Finally thick highly cellularized woven bone was seen characterized by presence of wide multi-branched interconnected trabeculae connecting each other.

In conclusion the both doses (4 and 8J/cm2) were used seen effective in stimulating and enhance the bone healing, and the 8J/cm2 was given better stimulation effect than the 4J/cm2.