Nd-YAG 激光照射牙冠颈部髓腔内温度变化的实验研究

目的：测量 Nd-YAG 激光在不同能量功率及间隔时间照射下髓腔内的温度变化。方法：收集60颗离体恒牙，分为前牙、前磨牙、磨牙3组（n ＝20）。每组根据不同的激光照射功率（0．4 W、0．8 W）和不同的间隔时间（10 s、20 s）分为4个亚组（n ＝5）。离体牙根管预备完成后制备实验标本，数字化牙科 X 线机颊舌向平行照射牙体标本，图像分析软件测量颊侧颈部牙冠厚度。将温度测量仪中的 K 型热电偶固定在髓腔内，用波长1046 nm 的 Nd-YAG 激光通过直径200μm 的光导纤维沿颊侧牙冠颈部近远中方向移动照射10 s，观察激光照射下髓腔内的温度变化。结果：随着照射功率的增加，髓腔内温度上升幅度差异有显著性（P ＜0．01），在相同照射功率下，不同的间隔时间，髓腔内温度上升幅度差异有显著性（P ＜0．01）。在照射功率及间隔时间相同条件下，牙冠的厚度与髓腔内的温度变化相关。结论：激光脱敏照射导致的髓腔温度上升幅度与激光照射功率、照射间隔时间和照射部位牙体组织厚度相关。

Temperature variation in the pulp during Nd-YAG laser irradiation at tooth cervical protion in vitro

Objective:To observe the temperature vaxiation in the pulp chamber during Nd-YAG laser irradiation at tooth cervical portion.Methods:60 extracted permanent teeth were divided into 3 groups (anterior teeth,premolars and molars,n =20).The teeth in each group were further divided into 4 subgroups according to the laser power setting (0.4 W,0.8 W)and interval time(1 0 s,20 s)(n =5).After canal preparation the teeth were fixed and filmed using the parallel projection technique.the thickness of the buccal pulp chamber wall was measured by graphic analyzing software.The buccal cervical portion of the teeth was irradiated through 200 μm optical fiber,Temperature in the pulp was measured by K type thermo-electric couples fixed to the pulp chamber wall.Re-sults:The temperature inside the chamber increased with the higher power setting(P <0.01 ),under the same power setting,longer irradiation duration caused higher temperature rise(P <0.01 ).Greater chamber wall thickness was associated with lower temperature rise.Conclusion:The temperature rise in the pulp chamber during laser irradiation is correlated with laser power setting and the thickness of the irradiated tooth tissue.