Giannini Marcelo, Silva Alessandra Peres, Cavalli Vanessa, Paes Leme Adriana Franco
Department of Restorative Dentistry - Operative Dentistry Section, Piracicaba Dental School, Campinas State University, Piracicaba, SP, Brazil.
J Appl Oral Sci. 2006 Apr;14(2):82-7. doi: 10.1590/s1678-77572006000200004.
The aim of this study was to evaluate the effects of carbamide peroxide-based bleaching agents (CPG) containing fluoride (CF) or calcium (CCa) on the ultimate tensile strength of enamel (UTS).
A "cube-like" resin composite structure was built-up on the occlusal surface of twenty-two sound third molars to facilitate specimen preparation for the micro-tensile test. The restored teeth were serially sectioned in buccal-lingual direction in slices with approximate 0.7 mm thickness. Each slice was trimmed with a fine diamond bur to reduce the buccal, internal slope enamel of the cusps to a dumb-bell shape with a cross-sectional area at the "neck" of less than 0.5 mm(2). The samples were randomly divided into 12 groups (n=11). The control groups were not submitted to the bleaching regimen. Specimens were treated with 10% CPG gel or with 10% CPG formulations containing CF (0.2% and 0.5%) or CCa (0.05% and 0.2%). Bleached groups received the application of the 10% CPGs for 6 hours/day at 37 degrees C, during 14 consecutive days and were stored in artificial saliva (AS) or 100% relative humidity (RH) among each application. After bleaching, specimens were tested with the microtensile method at 0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey test (5%).
No significant difference was observed between groups stored in AS or RH. Specimens treated with CF or CCa presented similar UTS as unbleached control groups.
Either 10% CPG formulations containing CF or CCa can preserve the UTS after bleaching regimen.
本研究旨在评估含氟（CF）或钙（CCa）的过氧化脲类漂白剂（CPG）对牙釉质极限拉伸强度（UTS）的影响。
在22颗完好的第三磨牙咬合面构建“立方体型”树脂复合材料结构，以便为微拉伸试验制备标本。将修复后的牙齿沿颊舌向依次切成约0.7毫米厚的切片。用细金刚砂车针修整每片切片，将牙尖的颊侧、内部倾斜牙釉质修整成哑铃形，“颈部”横截面积小于0.5平方毫米。样本随机分为12组（n = 11）。对照组未接受漂白方案。标本用10% CPG凝胶或含CF（0.2%和0.5%）或CCa（0.05%和0.2%）的10% CPG制剂处理。漂白组在37℃下每天使用10% CPGs 6小时，连续14天，并在每次使用期间储存在人工唾液（AS）或100%相对湿度（RH）环境中。漂白后，用微拉伸法以0.5毫米/分钟的速度对标本进行测试。数据采用双向方差分析和Tukey检验（5%）进行分析。
储存在AS或RH环境中的组之间未观察到显著差异。用CF或CCa处理的标本与未漂白的对照组相比，UTS相似。
含CF或CCa的10% CPG制剂在漂白方案后均可保留UTS。
