PHYSICOCHEMICAL CHANGE OF TOOTH STRUCTURE AND CLINICAL PROBLEMS IN DENTAL ESTHETIC BLEACHING

用含有6%过氧化钠和二氧化钛的漂白剂对牙本质进行漂白，二氧化钛是可见光反应的光催化剂。在漂白后立即或1天使用粘合剂系统（Clearfil MEGA Bond），并在每个表面粘接一个圆柱体（φ0.79mm，高度1mm）的复合树脂（Clearfil AP-X, A3）。30天后，在万能试验机（EZ试验）上进行微剪切粘结强度试验。制备未经漂白处理的标本作为对照。漂白后立即或1天使用相同的粘合剂系统，并在每个表面粘接相同的复合树脂圆柱体（φ3.18mm，高度3mm）。这些标本浸泡在0.5%碱性品红中。边际泄漏试验在染料渗透中进行。制备未经漂白处理的标本作为对照。实验结果如下：牙釉质微剪切黏结强度分别为对照组（48.38±13.93MPa）、漂白后1天（54.72±15.21MPa）和立即漂白后（37.55±12.92MPa），漂白后保存1天后恢复。牙本质微剪切黏结强度分别为44.16±13.13MPa（对照）、44.16±9.55MPa（漂白后1天）和35.71±12.21MPa（漂白后立即），漂白后保存1天后恢复。边际泄漏试验表明，染料渗透频率依次为漂白后立即、漂白后1天和对照。在漂白后的4.1天的储存可能不会降低染料的渗透。修复体的边缘故障会引起许多临床问题，因此边缘泄漏试验的结果对临床有重要意义。

Enamel or dentin was bleached by the bleaching agent containing 6% sodium peroxide and titanium dioxide that is visible-light-responsive photocatalyst.Immediately or 1 day after bleaching the adhesive system (Clearfil MEGA Bond) was applied and a cylinder(φ0.79mm, height 1mm) of composite resin (Clearfil AP-X, A3) was bonded on each surface. After 30 days the micro-shear bond strength test was performed in a universal-testing machine (EZ test). Specimens without bleaching procedure were prepared as controls.Immediately or 1 day after bleaching the same adhesive system was applied and cylinder (φ3.18mm, height 3mm) of the same composite resin was bonded on each surface. These specimens were immersed in 0.5% basic fuchsine. The marginal leakage test was performed in a dye penetration. Specimens without bleaching procedure were prepared as controls.The results were followed :1.The enamel micro-shear bond strengths were 48.38±13.93MPa(control),54.72±15.21MPa(1day after bleaching) and 37.55±12.92MPa (immediately after bleaching), and retuned after 1 day of storage after bleaching.2.The dentin micro-shear bond strengths were 44.16±13.13MPa (control),44.16±9.55MPa (1day after bleaching) and 35.71±12.21MPa (immediately after bleaching), and retuned after 1 day of storage after bleaching.3.The marginal leakage test showed the frequency of dye penetration increased in the order of immediately after bleaching, 1day after bleaching and control. This order was clear in enamel surface.4.1 day of storage after bleaching might not decrease the dye penetration.5.Marginal troubles of restorations cause many clinical problems, so the result of marginal leakage test is important for clinic.