Study on the laser effect on tooth movement in cleft site

1989 Fiscal Year Final Research Report Summary

• Project/Area Number: 63570955
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: 小児・社会系歯学
• Research Institution: Tokyo Medical and Dental Univ.
• Principal Investigator: MOTOHASHI Nobuyoshi Tokyo Medical and Dental Univ., The 2nd Dept. of Orthodontics, lecturer, 歯学部, 講師 (10134735)
• Co-Investigator(Kenkyū-buntansha): SUSAMI Takafumi Tokyo Medical and Dental Univ., The 2nd Dept. of Orthodontics, lecturer, 歯学部, 助手, (80179184)
• Project Period (FY): 1988 – 1990
• Keywords: cleft lip and palate / scar tissue / tooth movement / laser / bone graft

Research Abstract

Present study is carried out to investigate the biological response of the bone grafting area through the laser irradiation. The experimental model of the bone grafting site was made by the extraction of the second and the third molar of rat. Rats were divided into three groups; extraction of molars and no grafting, bone powder grafting after extraction and bone marrow grafting. The effects on the healing process by tooth movement and through He-Ne laser irradiation were examined. Bone powder was prepared from rat calvaria and bone marrow was obtained from rat tibia. First molar was moved distally with lOg force by orthodontic spring. Laser ( 8.0 J/cm^2 ) was irradiated at 24-hour intervals.
The healing process was proceeded as follows: One day after extraction, the cavity was filled with the blood clot and inflammatory cells, and re-epithelialization was commenced. After one week, re-epithelialization was almost completed. Collagen fiber formation and new bone apposition were confirmed. After two weeks, inflammatory response was diminished, however, fiber production and bone formation were still continuing. In the bone powder grafting group, the bone powders were found within the clot at the first day after experiment. After one week, many osteoclasts were surrounded the bone powders and some of the bone powders were resorbed. The bone powder resorption was reduced at two week and binding bone powder with newly formed alveolar bone was observed. In the bone marrow grafting group, healing process was almost similar to that of non-grafting group. The findings obtained by tooth movement were coincident with previous reports. No specific effect on the healing process through the laser irradiation could detected in this study.