Ito K, Nishikata J, Murai S
Department of Periodontology, Nihon University School of Dentistry, Tokyo, Japan.
J Periodontol. 1993 Jun;64(6):547-52. doi: 10.1902/jop.1993.64.6.547.
A scanning electron microscopy (SEM) study was conducted to evaluate the effects of Nd:YAG laser radiation on removal of a root surface smear layer after root planing in comparison with citric acid treatment. The experimental materials were 15 human teeth affected by severe periodontal disease, which were extracted because of a hopeless prognosis. The teeth had at least 5 mm of attachment loss on the proximal surface tested. After removing all visible calculus using an ultrasonic scaler, each proximal surface was vigorously scaled and root planed with a Gracey curet. Thirty specimens were cut from the root-planed proximal surfaces and assigned randomly to one of two groups: Group A (25 specimens) was divided into 5 subgroups and irradiated with a Nd:YAG laser, using non-contact delivery (3 mm beam diameter, distance from the tip to the specimen 5 cm), at a measured power of 20 W for 0.3, 0.5, 1.0, 2.0, or 3.0 seconds corresponding to energy densities of 84.93, 141.54, 283.09, 566.17, or 849.26 J/cm2; Group B (5 specimens) was not irradiated, but treated for 3 minutes with saturated citric acid (pH 1). The center of each specimen in Group A was used as the experimental area (Exp A) treated by laser irradiation and the peripheral area of the specimen served as a control (Cont A). In Group B, one half of the specimen was used as the experimental area (Exp B) treated by citric acid and the other half served as a control (Cont B). The specimens were then fixed and examined by SEM. The surface of the root-planed specimens (Cont A and B) was irregular, corresponding to the presence of a smear layer, and had an amorphous appearance. Both root surfaces of Exp A and B exhibited clear orifices of dentinal tubules and intertubular dentin without a smear layer. Although the root surface of Exp A showed clear orifices of dentinal tubules with a flat morphology, the root surface of Exp B showed widened funnel-shaped dentinal tubule orifices with a fibrillar, mat-like morphology. The present results indicate that Nd:YAG radiation effectively removes the smear layer, uncovers dentinal tubules, and exposes collagen fibers on the root surface without widening the orifices of dentinal tubules after root planing.
进行了一项扫描电子显微镜（SEM）研究，以评估钕钇铝石榴石（Nd:YAG）激光辐射与柠檬酸处理相比，在根面平整后对去除根面玷污层的效果。实验材料为15颗患有严重牙周病的人牙，因预后无望而拔除。这些牙齿在测试的近中面至少有5毫米的附着丧失。使用超声洁治器去除所有可见牙石后，每个近中面用格雷斯刮治器大力刮治并进行根面平整。从根面平整后的近中面上切下30个标本，随机分为两组：A组（25个标本）分为5个亚组，使用非接触式传输（光束直径3毫米，尖端到标本的距离5厘米），以20瓦的测量功率，分别照射0.3、0.5、1.0、2.0或3.0秒，对应的能量密度分别为84.93、141.54、283.09、566.17或849.26焦/平方厘米；B组（5个标本）不进行照射，而是用饱和柠檬酸（pH 1）处理3分钟。A组每个标本的中心作为激光照射处理的实验区域（实验A），标本的周边区域作为对照（对照A）。在B组中，标本的一半作为柠檬酸处理的实验区域（实验B），另一半作为对照（对照B）。然后将标本固定并通过SEM检查。根面平整标本（对照A和B）的表面不规则，对应有玷污层，外观呈无定形。实验A和B的两个根面均显示出牙本质小管口及管间牙本质清晰，无玷污层。虽然实验A的根面显示出牙本质小管口清晰，形态扁平，但实验B的根面显示出牙本质小管口呈漏斗状增宽，形态为纤维状、毡样。目前的结果表明，Nd:YAG辐射能有效去除玷污层，暴露牙本质小管，并在根面平整后暴露根面的胶原纤维，而不使牙本质小管口增宽。
