White J M, Fagan M C, Goodis H E
Department of Restorative Dentistry, University of California, San Francisco.
J Periodontol. 1994 Mar;65(3):255-9. doi: 10.1902/jop.1994.65.3.255.
Lasers are being used for soft tissue removal, caries removal, and treatment of root surface sensitivity. One concern for laser safety is that the heat produced at the irradiated root surface may diffuse to the pulp causing irreversible pulpal damage. To test this heat diffusion, copper-constantan thermocouples were inserted into the radicular pulp canals of extracted teeth. Simulating direct exposure which might occur during gingival excision, superficial caries removal, and modification of the dentin surface for treatment of root surface sensitivity, a 2 mm2 area of the external root surface was uniformly irradiated with a pulsed Nd:YAG laser using a 320 microns diameter fiber optic contact probe. Power was varied from 0.3 to 3.0 W with frequencies of 10 and 20 Hz. Temperature changes during cavity preparations using a high speed handpiece with air coolant were also recorded. Repeated measures ANOVA (P < or = 0.05) indicated that intrapulpal temperatures increased as a function of power, frequency, and time. Intrapulpal temperatures decreased as remaining dentin thickness (0.2 to 2.0 mm) increased for each laser parameter. Irradiation of dentin using a Nd:YAG pulsed laser, within the treatment times, powers, and frequencies with adequate remaining dentin thickness, as outlined in this paper, should not cause devitalizing intrapulpal temperature rises.
激光正被用于软组织切除、龋齿去除以及牙根表面敏感的治疗。激光安全方面的一个担忧是，在受照射的牙根表面产生的热量可能扩散至牙髓，导致不可逆的牙髓损伤。为测试这种热扩散情况，将铜-康铜热电偶插入拔除牙齿的根管牙髓中。模拟在牙龈切除、浅表龋齿去除以及为治疗牙根表面敏感而对牙本质表面进行修整过程中可能发生的直接暴露，使用直径320微米的光纤接触探头，用脉冲Nd:YAG激光对牙根外表面2平方毫米的区域进行均匀照射。功率在0.3至3.0瓦之间变化，频率为10赫兹和20赫兹。还记录了使用带空气冷却剂的高速手机进行窝洞制备过程中的温度变化。重复测量方差分析（P≤0.05）表明，牙髓内温度随功率、频率和时间而升高。对于每个激光参数，随着剩余牙本质厚度（0.2至2.0毫米）增加，牙髓内温度降低。如本文所述，在有足够剩余牙本质厚度的治疗时间、功率和频率范围内，使用Nd:YAG脉冲激光照射牙本质不应导致牙髓内温度升高至使牙髓失活的程度。
