White D J, Kozak K M, Zoladz J R, Duschner H J, Götz H
University of Mainz, Mainz, Germany.
Compend Contin Educ Dent Suppl. 2000(29):S29-34; quiz S43.
Confocal laser scanning microscopy (CLSM) in reflection mode provides a useful means for nondestructive microscopic examination of the ultrastructural characteristics of hard tissues, including enamel and dentin. In this study, CLSM was used to examine the effects of in vitro bleaching on enamel and dentin. The crowns of extracted human third molars were sectioned below the occlusal fissure, revealing subsurface dentin and the outer surface ring of enamel. Specimens were polished with 1,200-grit alumina followed by fine polish lapidary film, and cut into four equal sections per tooth, allowing each tooth to serve as internal control. Sections were mounted in acrylate for handling and were bleached for 0, 15, and 30 hours in 0.25 g of commercial Opalescence whitening gel (10% carbamide peroxide), the 5.3% hydrogen peroxide gel used in Crest Whitestrips, or 5% HClO4 solution. Blank glycerin served as a control treatment. In vitro whitening was confirmed by colorimeter readings of delta b and delta L with a PR 650 spectrophotometer/colorimeter. Treated teeth were examined with CLSM comparing enamel surface, dentoenamel junction (DEJ), and dentin at approximately 5 microns subsurface to the polished surfaces under an oil immersion objective. A single sample from each treatment (30-hour whitening) was also examined by environmental variable pressure scanning electron microscopy (VP-SEM). Internal comparison of glycerin (no whitening) controls (0-, 15-, and 30-hour exposures) revealed reproducible ultrastructure, facilitating treatment comparisons. Whitened teeth revealed no significant micromorphological changes associated with the whitening process in subsurface enamel, DEJ, and dentin areas. The direct treatment of cross sections permitted simple access of all areas to whitening gel, thereby eliminating the possibility of diffusion limitation of the gel in producing artifacts. VP-SEM observations similarly showed no significant changes in the surfaces after treatment.
反射模式下的共聚焦激光扫描显微镜（CLSM）为硬组织（包括牙釉质和牙本质）超微结构特征的无损微观检查提供了一种有用的方法。在本研究中，CLSM用于检查体外漂白对牙釉质和牙本质的影响。将拔除的人类第三磨牙的牙冠在咬合裂隙下方进行切片，露出牙本质表层下部分和牙釉质外表面环。标本先用1200目氧化铝抛光，然后用精细抛光宝石薄膜抛光，每颗牙齿切成四个相等的部分，使每颗牙齿作为内部对照。切片安装在丙烯酸酯中以便处理，并在0.25克市售Opalescence美白凝胶（10%过氧化脲）、佳洁士美白牙贴中使用的5.3%过氧化氢凝胶或5%高氯酸溶液中漂白0、15和30小时。空白甘油用作对照处理。通过使用PR 650分光光度计/色度计测量Δb和ΔL的色度读数来确认体外美白效果。用CLSM检查处理过的牙齿，将牙釉质表面、牙釉质牙本质界（DEJ）和距抛光表面约5微米的牙本质表层下部分进行比较，观察时使用油浸物镜。每种处理（30小时美白）的单个样本也通过环境可变压力扫描电子显微镜（VP-SEM）进行检查。甘油（未美白）对照（0、15和30小时暴露）的内部比较显示超微结构具有可重复性，便于进行处理比较。美白后的牙齿在牙釉质表层下、DEJ和牙本质区域未显示与美白过程相关的明显微观形态变化。对横截面的直接处理使所有区域都能简单地接触到美白凝胶，从而消除了凝胶扩散限制产生假象的可能性。VP-SEM观察同样显示处理后表面没有明显变化。
