Effect of Prior Application of Desensitizing Agent on the Teeth Submitted to In-Office Bleaching

Abstract This study aimed to quantify the penetration of hydrogen peroxide, color change evaluation, surface morphology, and composition after application of desensitizing agents before in-office bleaching. Fifty premolars were sectioned, an acetate buffer was placed in the pulp chamber and divided into five groups (n=10). In the positive control group, only the in-office bleaching gel was used, and in the negative control group, no treatment was used. Three different desensitizing agents were applied: Desensibilize KF2%® group; Mi Paste® group, and Desensibilize Nano-P® group. The bleaching procedure was carried out with 35% HP. The absorbance of the resulting solution was determined in a spectrophotometer. Color change was assessed by using a digital spectrophotometer. Four additional premolars were assigned to the same groups above for analysis under scanning electron microscope, as well as to evaluate the elemental composition with X-ray dispersive energy spectrometry. Data were subjected to ANOVA and Tukey's test (α=0.05). All products reduced the penetration of HP in the pulp chamber. Mi Paste and Nano P were the products that yielded the lowest HP penetration, which was similar to the negative control group (p<0.001). No significant difference was detected in color change (p<0.001). Concerning enamel morphology, the groups that were analyzed after bleaching were observed a greater deposition of desensitizing agents on the surface. The use of desensitizing agents before tooth bleaching seems to be an alternative to reduce adverse effects of the tooth.

摘要 本研究旨在评估诊室内漂白术前应用脱敏剂后，过氧化氢的渗透水平、色泽变化、表面形貌及成分变化。本研究选取50颗前磨牙行切割处理，于牙髓腔内置入醋酸缓冲液后将样本分为5组（每组n=10）。阳性对照组仅使用诊室内漂白凝胶，阴性对照组不施加任何干预措施。另设置3种脱敏剂实验组：Desensibilize KF2%®组、Mi Paste®组及Desensibilize Nano-P®组。漂白操作采用35%浓度的过氧化氢（HP）。通过分光光度法测定反应溶液的吸光度；采用数字分光光度计评估样本的色泽变化。另外选取4颗前磨牙按上述分组，行扫描电子显微镜（scanning electron microscope，SEM）下的表面形貌分析，并通过X射线能量色散谱（X-ray dispersive energy spectrometry）检测元素组成。所有数据采用方差分析（ANOVA）与Tukey检验进行统计学分析，检验水准设为α=0.05。
结果显示，所有受试脱敏剂均可降低牙髓腔内过氧化氢的渗透量。其中Mi Paste®组与Desensibilize Nano-P®组的过氧化氢渗透水平最低，与阴性对照组无显著统计学差异（p<0.001）。各组间色泽变化无显著差异（p<0.001）。关于牙釉质表面形貌，漂白后各组的牙釉质表面可见更多脱敏剂沉积。综上，牙齿漂白术前应用脱敏剂，可作为降低漂白治疗不良反应的可行方案。