São José dos Campos School of Dentistry, UNESP.
J Appl Oral Sci. 2005 Jun;13(2):204-11. doi: 10.1590/s1678-77572005000200021.
Since bleaching has become a popular procedure, the effect of peroxides on dental hard tissues is of great interest in research.
The aim of this in vitro study was to perform a qualitative analysis of the human enamel after the application of in-office bleaching agents, using Scanning Electron Microscopy (SEM).
Twenty intact human third molars extracted for orthodontic reasons were randomly divided into four groups (n=5) treated as follows: G1- storage in artificial saliva (control group); G2- four 30-minute applications of 35% carbamide peroxide (total exposure: 2h); G3- four 2-hour exposures to 35% carbamide peroxide (total exposure: 8h); G4- two applications of 35% hydrogen peroxide, which was light-activated with halogen lamp at 700mW/cm² during 7min and remained in contact with enamel for 20min (total exposure: 40min). All bleaching treatments adopted in this study followed the application protocols advised by manufacturers. Evaluation of groups submitted to 35% carbamide peroxide was carried out after two time intervals (30 minutes and 2 hours per session), following the extreme situations recommended by the manufacturer. Specimens were prepared for SEM analysis performing gold sputter coating under vacuum and were examined using 15kV at 500x and 2000x magnification.
Morphological alterations on the enamel surface were similarly detected after bleaching with either 35% carbamide peroxide or 35% hydrogen peroxide. Surface porosities were characteristic of an erosive process that took place on human enamel. Depression areas, including the formation of craters, and exposure of enamel rods could also be detected.
Bleaching effects on enamel morphology were randomly distributed throughout enamel surface and various degrees of enamel damage could be noticed.
In-office bleaching materials may adversely affect enamel morphology and therefore should be used with caution.
本体外研究旨在使用扫描电子显微镜（SEM）对应用诊室用漂白剂后人类牙釉质进行定性分析。
二十颗因正畸原因而拔出的完整第三磨牙随机分为四组（n=5），分别进行如下处理：G1-储存在人工唾液中（对照组）；G2-四次 35%过氧脲（总暴露时间：2 小时），每次 30 分钟；G3-四次 35%过氧脲，每次 2 小时（总暴露时间：8 小时）；G4-两次应用 35%过氧化氢，用卤素灯以 700mW/cm²光激活 7 分钟，并保持与牙釉质接触 20 分钟（总暴露时间：40 分钟）。本研究中采用的所有漂白处理均遵循制造商建议的应用方案。在两个时间间隔（每次 30 分钟和 2 小时）后对接受 35%过氧脲处理的组进行评估，遵循制造商推荐的极端情况。使用真空下的金溅射涂层对 SEM 分析进行标本制备，并在 15kV、500x 和 2000x 放大倍数下进行检查。
在用 35%过氧脲或 35%过氧化氢漂白后，牙釉质表面的形态变化相似。表面孔隙度是牙釉质发生侵蚀性过程的特征。还可以检测到凹陷区域，包括火山口形成和牙釉柱暴露。
牙釉质形态的漂白效果随机分布在牙釉质表面，并且可以注意到不同程度的牙釉质损伤。
诊室用漂白材料可能会对牙釉质形态产生不利影响，因此应谨慎使用。
