Swift E J, Edwards G S, Perdigão J, Thompson J Y, Nunes M F, Ruddell D E, Negishi A
Department of Operative Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, NC 27599-7450, USA.
J Dent. 2001 Jul;29(5):347-53. doi: 10.1016/s0300-5712(01)00019-7.
The purpose of this study was to evaluate the Mark-III free-electron laser as a means of etching enamel surfaces, with potential application to resin bonding.
The FEL was tuned to wavelengths ranging from 3.0 to 9.2 microm. Specific wavelengths that are resonantly absorbed by phosphates, proteins, and water were used. First, bovine enamel was polished and exposed to static FEL exposures. Lased enamel was examined using scanning electron microscopy (SEM). Additional bovine enamel specimens were exposed to FEL at similar wavelengths, but with rastering to create treated rectangular areas on each specimen. Surface roughness was evaluated using profilometry and atomic force microscopy (AFM). Composite was bonded to the lased enamel, and shear bond strengths were determined using an Instron universal testing machine. As a control, the surface roughness of, and shear bond strengths to, acid-etched enamel were determined.
Static FEL exposures caused changes in the enamel ranging from an etched appearance to pits, cracks, and frank cratering. The surface roughness of lased enamel was much greater than that of acid-etched enamel, and was qualitatively different as well. Shear bond strengths of resin to acid-etched enamel were significantly higher than bond strengths to lased enamel.
Under the conditions used in this study, the FEL did not offer a practical and effective method of etching enamel for resin bonding. However, the ability of the FEL to deliver many specific wavelengths makes it an interesting tool for further research of laser effects on tooth structure.
本研究旨在评估Mark-III自由电子激光作为蚀刻牙釉质表面的一种手段，及其在树脂粘结方面的潜在应用。
将自由电子激光调谐至波长范围为3.0至9.2微米。使用了磷酸盐、蛋白质和水共振吸收的特定波长。首先，对牛牙釉质进行抛光，并使其暴露于自由电子激光的静态照射下。使用扫描电子显微镜（SEM）检查经激光照射的牙釉质。另外的牛牙釉质标本暴露于类似波长的自由电子激光下，但采用光栅扫描以在每个标本上创建处理过的矩形区域。使用轮廓仪和原子力显微镜（AFM）评估表面粗糙度。将复合材料粘结到经激光照射的牙釉质上，并使用Instron万能试验机测定剪切粘结强度。作为对照，测定酸蚀牙釉质的表面粗糙度和剪切粘结强度。
自由电子激光的静态照射导致牙釉质出现从蚀刻外观到凹坑、裂纹和明显坑洼等变化。经激光照射的牙釉质的表面粗糙度远大于酸蚀牙釉质，并且在性质上也有所不同。树脂与酸蚀牙釉质的剪切粘结强度显著高于与经激光照射牙釉质的粘结强度。
在本研究使用的条件下，自由电子激光并未提供一种用于树脂粘结的蚀刻牙釉质的实用有效方法。然而，自由电子激光能够产生多种特定波长的特性使其成为进一步研究激光对牙齿结构影响的有趣工具。
