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Histopathological Evaluation of the Effects of Low-level Laser Therapy on the Healing of Experimental Cryosurgical Wound in Normal Rat Skin

Introduction: This research aimed to study the healing process of cryosurgical wounds after topical application of low-level laser and to evaluate its effects for the prevention of healing complications. 
Materials  and Methods: A total of 50 healthy  male Wistar  rats with an average  weight   of 200-250 g were selected and randomly divided into two main groups. In control group (N=25), cryosurgery was done without using of low-level laser. In experimental group (N=25), cryosurgery was done and the low-level laser was used for 10 days post-surgery. Each main group was divided into five subgroups (n=5) according to histopathological evaluation date (3, 7, 14, 21 and 28 days post-surgical) and healing process was evaluated on the wound specimens harvested at above-mentioned days. The full- thickness wounds were harvested   in 40 mm in length and 20 mm in width and the specimens were stained using hematoxylin- eosin and Masson’s Trichrome staining. The healing process  was evaluated  and compared  in groups by observation of granulation tissue and collagen fibers amounts, epithelial gap size, the number of inflammatory cells, and the rate of angiogenesis. Data were collected and statistically analyzed and compared between the experimental and control groups on specific days using the Kruskal-Wallis and Dan post hoc statistical tests. 
Results:  The obtained data were compared between the experimental and control groups    on different days using the Kruskal-Wallis and Dan post hoc statistical tests. The statistical results revealed significant differences between groups (P<0.05) in all mentioned variables. It revealed that the healing process in the experimental group took place at least one week earlier than the control group. 
Conclusion: The results of this animal study showed that the low-level laser therapy on an experimental cryosurgical wound not only accelerates the healing process but also can be effective in the prevention of healing complications. The authors suggest further research to extend the results to human applications.