A study on the morphological changes of the rat mandibular bone with TEA CO2 laser

Objective: The purpose of this study was to investigate the morphological c hanges of the bone structure induced by transversely excited, atmospheric T EA pressure CO2 laser irradiation, Moreover, the healing process at 3 weeks was also observed, Summary Background Data: It has been demonstrated that dental hard tissue can be removed by a long pulse of TEA CO2 laser irradiat ion with minimal thermal damage, However, there are few studies on the morp hological changes of the TEA CO2 laser on bone tissue. Methods: The TEA CO2 laser was irradiated on the surface of the rat mandibular bone under the f ollowing irradiation conditions: wavelength, 10.6 mu m; output, 95 mJ/pulse ; pulse repetition rate, 1 Hz; irradiation time, 7.5 mu sec/shot; spot size , 0.8 x 1.5 mm; energy density, 7.9 J/cm(2), Histological and scanning elec tron microscopic examinations were performed. Results: In the stereoscopic examination, a defect with clean-cut margins was produced. In the light mic roscopic examination, a basophilic line at the bottom of the defect was not ed, Examining the defect with SEM, a smear-like appearance and cone structu res were found. In the histological examination, a healing process by forma tion of new bones at the junction site was recognized. Conclusions: These f indings suggest that it is possible to remove bone tissues by TEA CO2 laser irradiation, However, a particle-like structure associated with a basophil ic line and melted surface indicated that some thermal damage was produced during the laser irradiation.