Majori M, Manzon L, Pane S, Bedini R
Technology and Health Department, Biomedical Engineering Unit, Italian National Institute of Health, Rome - Italy.
J Appl Biomater Biomech. 2005 May-Aug;3(2):128-33.
Caries prevention should be an important goal of the dentistry practitioner. In addition to traditional preventive techniques, laser beam has been a recent suggestion. This study aimed to evaluate Nd:YAG laser treatment effects on dental enamel surfaces, irradiated at different energy levels, by scanning electron microscopy (SEM) observations and surface micro-hardness tests to evaluate if caries prevention can be achieved by laser treatment. Forty human teeth were divided in four groups of 10 specimens each: in three groups the enamel surface was treated with three different laser beam energy levels, 60, 120 and 160 mJ, in one group the enamel was not lased. Five samples from each group were subjected to the Vickers microhardness test and five samples underwent SEM investigation. Results of the microhardness test demonstrated no significant differences between treated and non-treated dental enamel samples. SEM observation demonstrated a rougher enamel surface in all treated groups: the 60 mJ treated group showed tooth surfaces with vertical scratches, the 120 mJ treated group showed the enamel surface covered by craters and cracks, and the 160 mJ treated group showed a completely changed enamel structure with columns separated by voids and with a glass-like surface. These investigations demonstrated that dental enamel laser treatment at low energy levels (not >60 mJ) produces a protective glass-like surface, without the loss of its integrity and could be an advisable technique to prevent caries. Higher energy laser treatment leads to modifications of the enamel morphology such as craters and cracks, even if it does not cause any change in enamel hardness characteristics, which could be more useful in conservative dentistry.
龋齿预防应是牙科从业者的重要目标。除了传统的预防技术外，激光束最近也被提及。本研究旨在通过扫描电子显微镜（SEM）观察和表面显微硬度测试，评估不同能量水平照射下Nd:YAG激光对牙釉质表面的治疗效果，以评估激光治疗是否能实现龋齿预防。40颗人牙被分为四组，每组10个样本：三组牙釉质表面分别用三种不同的激光束能量水平（60、120和160 mJ）进行处理，一组牙釉质未接受激光照射。每组取5个样本进行维氏显微硬度测试，另外5个样本进行SEM研究。显微硬度测试结果表明，处理过的和未处理的牙釉质样本之间没有显著差异。SEM观察显示，所有处理组的牙釉质表面都更粗糙：60 mJ处理组的牙齿表面有垂直划痕，120 mJ处理组的牙釉质表面布满坑洼和裂纹，160 mJ处理组的牙釉质结构完全改变，柱状结构被空隙隔开，表面呈玻璃状。这些研究表明，低能量水平（不超过60 mJ）的牙釉质激光治疗可产生保护性的玻璃状表面，且不损失其完整性，可能是一种预防龋齿的可取技术。较高能量的激光治疗会导致牙釉质形态发生改变，如出现坑洼和裂纹，即使它不会引起牙釉质硬度特征的任何变化，这在保守牙科中可能更有用。
