Objective. Nd:YAP laser has several potentialities of clinical applications in endodontics. The aim of our study is to determine the safety range of irradiation parameters during endodontic application of Nd:YAP laser that can be used without damaging and overheating the periodontal tissue. Material and Methods. Twenty-seven caries-free single-rooted extracted human teeth were used. Crowns were sectioned to obtain 11 mm root canal length. Temperature increases at root surfaces were measured by a thermocouple during Nd:YAP laser irradiation of root canals at different energy densities. Canal irradiation was accomplished with a circular and retrograde movement from the apex until the cervical part of the canal during 10 seconds with an axial speed of 1 mm/s. Each irradiation was done in a canal irrigated continuously with 2.25% NaOCl solution. Results. Periodontal temperature increase depends on the value of energy density. Means and standard deviations of temperature increases at root surfaces were below 10°C (safe threshold level) when the average energy densities delivered per second were equal to or below 4981 J/cm2 and 9554 J/cm2, respectively, for irradiations using a fiber diameter of 320 μm and 200 μm. Conclusions. Within the limitations of this study and under specific irradiation conditions, Nd:YAP laser beam may be considered harmless for periodontal tissues during endodontic applications.
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机译：目的。 Nd：YAP激光在牙髓治疗方面具有多种临床应用潜力。我们研究的目的是确定在牙髓应用Nd：YAP激光过程中辐照参数的安全范围，该激光可以在不损坏和使牙周组织过热的情况下使用。材料与方法。使用了二十七颗无龋的单根拔出人类牙齿。切成冠状以得到11mm的根管长度。在不同能量密度的Nd：YAP激光照射根管期间，通过热电偶测量根部表面的温度升高。在10秒钟内，以1 mm / s的轴向速度，通过从根尖到根管的环形逆行运动来完成根管照射。每次照射均在用2.25％NaOCl溶液连续灌溉的导管中进行。结果。牙周温度的升高取决于能量密度的值。当每秒传递的平均能量密度等于或低于4981 J / cm 2 和9554 J / cm时，根部表面温度升高的平均值和标准偏差低于10°C（安全阈值水平） 2 分别用于使用320μm和200μm的纤维直径进行照射。结论。在这项研究的限制内以及在特定的照射条件下，Nd：YAP激光束在牙髓应用期间可能被认为对牙周组织无害。
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