a histiological study on the effects of the low power helium neon laser irradiation on a skin flap in the rats

introduction: the purpose of this study is to evaluated the effect of low power laser on the survival of a skin flap on the dorsum of the rats. materials and methods: fifty male rats were divided into five groups. the surgery was done under general anesthesia where a full thickness skin flap (including panniculus carnosus) from the dorsum of the rats were randomly dissected. the flap size was 20 mm/100 mm. the day of the surgery was day zero. the rats in the first group were irradiated daily from day 1 to day 7 post-surgery. in the second group, the rats were irradiated daily from day zero to day 7 every 6 hours. the rats of the third group were irradiated 5 days, before surgery, then the treatment was continued every day until the day of the surgery. on day zero, the animals were irradiated every 6 hours, then the animals were treated once a day from day 1 to day 7. the animals of the fourth group were treated as in third group 3 except, the treatment on the day of the surgery was omitted. the fifth group was a negative control group where all the animal were not irradiated after surgery. the energy density of the laser was 0.2 j/cm2. immediately after surgery, the size of the flap was recorded a on sterile transparent sheet and on day 7, the survived part of the flap was also recorded, then the animals were killed and the flaps were sampled, fixed, processed in paraffin and stained with hematoxylin and eosin. also toulidine blue was used to stain additional section. the number of the vessels, the number of points (in eye-peice graticule) on the vessels were counted and the number of the mast cells were also counted. the data were analyzed by the analysis of the variance. results: the size of the flaps at day zero were not significantly difference from the controls. the size of the flap and the point which were counted on the vessels on day 7 in the third group were significantly different from other groups. conclusion: the low power helium-neon laser radiation can produce vasodilation of blood vessels which may result in an increase in the flap survival.