林輝2006-08-232018-06-292006-08-232018-06-292000-07-31http://ntur.lib.ntu.edu.tw//handle/246246/29532Sudden trauma or trauma associated with occlusal disharmonies or extreme clenching and gritting can produce vertical root fractures. The crack line usually appear near the development groove and can extend toward the root or horizontally across the tooth. The defect need not be a complete fracture, but may extend through part of the root or crown. When a vertical root fracture occurs, the tooth is extracted, endodontic treatment is completed extraorally, and the crack line is cemented with one of restoratives. However, the long-term prognosis are poor. Lasers were used to alternative treatment for cracked teeth. Results from the previous studies have not supported the findings that there was any fusion of the root fracture with either laser. The research tried to use a medium energy continuous-wave CO2 laser and a developed DP-bioactive glass paste to fuse or bridge the crack line. The DP-bioactive glass have a strong absorption band in wavelength of 10.6 mm. DP-bioactive glass and enamel/dentine are expected to be melted and fused together after expose to the CO2 laser. The study was divided into three parts, 1. the compositional and structural changes in tooth enamel as well as dentine after the CO2 laser irradiate; 2. the phase transformation and recrystallization of DP-bioactive glass paste during expose to the CO2 laser; 3. the thermal interaction and bridging mechanism between DP-bioactive glass paste and enamel/dentine when they subject to the CO2 laser. The present report will be focused on the first part of the study to further analyze for changes in laser-irradiated human tooth enamel/dentine by means of x-ray diffractometer (XRD), scanning electron microscopy (SEM), differential thermal analysis/thermogravimetric analysis (DTA/TGA), and Fouries transforming infrared spectroscopy (FTIR). After exposed to CO2 laser, there were no significant difference in x-ray diffraction patterns of enamels compared to that of before laser treated. But a small peak belonging to a-TCP appeared at the position of 2q=30.78°. After treated with CO2 laser, both powder dentine and block dentine showed much sharper in all the peaks of the diffraction patterns because of grain growth and better crystallinity. a-TCP and b-TCP were identified after laser treated. In FTIR analysis, a HPO4 -2 absorption band could be traced in the dentine without laser treatment but disappeared after exposed to laser. No significant change in the absorption band of HPO4 -2 in the FTIR curves of enamel before and after laser treatment. A crater with glass-like and melted structure would be formed both on the surface of dentine and enamel after exposed to medium energy CO2 laser. We believe these thermal data should serve as a useful guide both to predict and to aid in the future studies for the thermal interaction and bridging mechanism between DP-bioactive glass paste and enamel/dentine when they subject to the CO2 laser.application/pdf76689 bytesapplication/pdfzh-TW國立臺灣大學醫學工程學研究所DP-bioactive glassCO2 laserphase transformationthermal behaviorreporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/29532/1/892320B002153M08.pdf