مجله دانشکده دندانپزشکی اصفهان (Jan 2008)
Histological study of effect of low level laser GaAs on rate and quality of bone formation in distraction osteogenesis in rabbit
Abstract
Introduction: Although distraction osteogenesis is a surprising modality in treatment of many ofdeformities in craniofacial region, but often tolerance of distractor devices is hard and problematicfor many of patients. If low level lasers can increase rate of ossification, cause shortening oftreatment duration, and cause lessening of problems of patients. Therefore, purpose of this studywas determination of effectiveness of low level laser in acceleration of new bone formation andconsequently shortening of treatment period and decrease of problems of distractor device.Materials and Method: In this study, after corticotomy, distractor devices were placed inmandibular body of 18 white zelanian rabbits and after 5 days, were activated at a rate of 1mm/dayfor 10 days. 9 rabbits were exposed to 7 doses of GaAs laser with power of 200 μw every other dayand other 9 rabbits received no laser. Then, the rabbits were periodically sacrificed in the 10th, 20thand 40th days of consolidation period and obtained samples were studied by scanning electronmicroscopy and light microscopy and then analyzed by Mann-Whitney method ( = 0.05).Results: In SEM and histological examinations, the amount and orientation of fibroblasts andfibrous tissue in the 10th day was greater in laser group than in control group. In the 20th day, inaddition to fibrous tissue, the amount of woven bone was greater in laser group than that in controlgroup but the degree of their difference wasn't significant and really was smaller as compared withthe 10th day. In the 40th days in each of two groups of laser and control, woven and lamellar bonewere seen but no significant difference of new bone formation was found in the laser group ascompared with control group. It appears that laser radiation in initial stages of distraction is moreeffective than end stages.Conclusion: Probably PH changes in cell oxidation and reduction (Redox regulation) is anetiologic factor in incidence of this process; as though in initial stages that PH of tissue is inreduction limit because of trauma,radiation is more effective than late stages that PH of tissue ismore stable. For the best result, it is necessary extensive researches about distraction protocol andlaser radiation.Key Words: Distraction osteogenesis, GaAs laser, histology, scanning electron microscopy, light
