Jeng J H, Chen K W, Lin C P, Chou H G, Lan W H
Graduate Institute of Clinical Dental Science, College of Medicine, National Taiwan University, Taipei.
J Formos Med Assoc. 1999 Apr;98(4):242-7.
The neodymium:yttrium-aluminum-garnet (Nd:YAG) laser has been used for treatment of dentinal hypersensitivity, eradicating periodontal pathogens, and facilitating calculus removal. However, Nd:YAG laser irradiation exerts potentially harmful effects on the tooth root surface. The purpose of this study was to examine the ultrastructural changes of the tooth root surface caused by Nd:YAG laser irradiation, and to determine whether chemical and mechanical preparations can correct these ultrastructural changes. Eighteen tooth specimens (3 x 3 x 0.5 mm) with healthy root surfaces were prepared and irradiated with an Nd:YAG laser at various power densities. Root surfaces were irradiated at 100 mJ at 20 pulses per second (pps) for 2 seconds followed by the application of citric acid (pH 1.2) or tetracycline solution (100 mg/mL) for 3 and 5 minutes, respectively, or ultrasonic scaling for 5 strokes of 3 seconds per stroke. As observed with low-vacuum scanning electron microscopy, (Wet-SEM), Nd:YAG laser irradiation at 70 to 100 mJ, 20 pps for 2 seconds caused surface cratering, areas of porosity, pitting, fissures, and lava-like structures in an area 140 to 280 microns in diameter. Irradiation of 50 mJ, 20 pps for 2 seconds, led to only mild surface charring. No evidence of morphologic changes was found when root surfaces were irradiated with the Nd:YAG laser at 20 mJ, 20 pps for 2 seconds or at 50 mJ, 10 pps for 8 seconds. The laser-induced lava-like structures were partially detached by citric acid (pH 1.2) etching and ultrasonic scaling, but not by tetracycline (100 mg/mL). These results indicate that chemical and mechanical preparations can be used effectively in conjunction with Nd:YAG laser irradiation for root surface preparation during both nonsurgical and surgical periodontal treatments.
钕钇铝石榴石（Nd:YAG）激光已被用于治疗牙本质过敏、根除牙周病原体以及辅助去除牙结石。然而，Nd:YAG激光照射会对牙根表面产生潜在的有害影响。本研究的目的是检查Nd:YAG激光照射引起的牙根表面超微结构变化，并确定化学和机械处理是否能够纠正这些超微结构变化。制备了18个牙根表面健康的牙齿标本（3×3×0.5毫米），并以不同的功率密度用Nd:YAG激光进行照射。牙根表面以每秒20脉冲（pps）的频率、100毫焦照射2秒，随后分别用柠檬酸（pH 1.2）或四环素溶液（100毫克/毫升）处理3分钟和5分钟，或进行超声洁治，每次3秒，共5次。如通过低真空扫描电子显微镜（湿SEM）观察到的，以每秒20脉冲、70至100毫焦照射2秒的Nd:YAG激光照射导致直径140至280微米的区域出现表面凹陷、孔隙区域、麻点、裂缝和熔岩样结构。以每秒20脉冲、50毫焦照射2秒，仅导致轻微的表面炭化。当牙根表面以每秒20脉冲、20毫焦照射2秒或以每秒10脉冲、50毫焦照射8秒时，未发现形态学变化的证据。激光诱导的熔岩样结构通过柠檬酸（pH 1.2）蚀刻和超声洁治部分脱落，但四环素（100毫克/毫升）处理无效。这些结果表明，在非手术和手术牙周治疗期间，化学和机械处理可与Nd:YAG激光照射有效结合用于牙根表面处理。
