脉冲Nd:YAG激光照射后牙本质的形态变化

目的:探讨用脉冲Nd:YAG激光脱敏的形态学依据。方法:选择离体上下颌第二恒磨牙,用单面金刚砂片垂直于牙长轴在(牙合)面牙尖下1.0 mm和2.5mm处切断,制成1.5 mm厚的牙片4张。用相同能量(1 w、10 Hz、100 mJ)激光分别以5 s、10 s、15 s和20 s照射4张牙片,在照射区形成4种不同的激光能量密度。牙片自然干燥后喷金,扫描电镜观察牙本质形态变化。结果:4种激光能量密度照射均可在牙本质小管口形成堵塞。随能量密度增加,牙本质熔融程度、深度和均质化增加,但在激光集中照射区域,有牙本质微裂及凹坑出现。结论:41.6 J/cm2的激光能量密度既可完善封闭牙本质小管,又不会导致微裂和凹坑结构发生,可作为激光脱敏的参考阈值。

Dentinal Morphological Changes after Nd:YAG Laser Irradiation

Objective:The purpose of this study was to investigate morphological changes of dentine after exposure to Nd: YAC laser. Methods: The second maxilla and mandible molar was selected, and slices with 1.5 mm thickness were prepared from each tooth by suing a high-speed bur. Two horizontal sections of shces were obtained, one at the occlusion enamel-dentinal junction and the other from the position of 1.5 mm lower than the enamel-dentinal junction. A square of 3 mm x 4 mm area on each of the four dentinal slices was irradiated under the laser with four different parameters (1 W, 10 Hz, 100 mj and with different time of 5 s, 10 s, 15s, 20s). After the specimens became dry and covered with gold, the morphological changes of each slice were observed with a scanning electronic microscope (SEM). Results: Laser with the above four parameters blocked dentinal tubule orifices. With the time of irradiation increased, the melting level and sealing depth of dentinal slices increased, but crack and pit were found in the region of irradiation. Conclusion: The density of 41.6 J/cm (10 Hz, 100 mj) can blocked dentinal tubule orifice, and will not cause large crack and pit structure.