中文摘要：

目的研究3种不同质量分数的家用牙齿漂白剂对人牙釉质结构和力学性能的影响，为评价市售家用牙齿漂白剂的安全性提供依据。方法将60块人牙釉质样本按随机数字化表法随机分至4组：10％过氧化脲组、15％过氧化脲组、20％过氧化脲组和蒸馏水对照组，每组15块。在漂白组样本表面涂布漂白剂并将其置于37℃恒温箱中，漂白8h后去净漂白剂，再将样本保存于蒸馏水中16h；蒸馏水对照组不做漂白处理。如此循环14d分别用原子力显微镜、衰减全反射红外测试仪、显微拉曼光谱仪、显微硬度仪检测各组漂白前后釉质表面形貌、化学结构及硬度、断裂韧性等力学特性。结果3个漂白组的釉质与对照组相比没有出现表面形貌、均方根表面粗糙度（P=0．774）、红外光谱中v2CO3 2-：v1v3PO4 3-（P=0．263）和显微硬度（P=0．829）的明显变化；10％、15％、20％过氧化脲组相对拉曼强度漂白后相对于漂白前的百分比分别为（105．74±11．34）％、（104．46±8．83）％和（99．52±9．32）％，与对照组[（97．62±7．46）％]相比差异均无统计学意义（P=0．062）；但3个漂白组荧光背景强度漂白后相对于漂白前的百分比分别为（20．86±7．23）％、（22．14±7．34）％和（21．10±7．59）％，与对照组[（100．78±3．70）％]相比差异均有统计学意义（P〈0．001）。同时，3个漂白组与对照组相比断裂韧性漂白后下降值差异亦有统计学意义（P=0．024、P=0．005、P=0．013）。结论在体外环境下，3种质量分数的家用牙齿漂白剂不会影响牙釉质中的无机物和显微硬度，但可能会造成牙釉质断裂韧性下降。

英文摘要：

Objective To investigate the effects of three differently concentrated at-home bleaching agents on the structure and the structure-related mechanical properties of human enamel. Methods Sixty enamel specimens were randomly divided into four groups and treated with 10% carbamide peroxide（ CP）, 15% CP, 20% CP and distilled water, respectively. The bleaching process was 8 h/day for 14 consecutive days. Baseline and final atomic force microscopy（AFM） surface detection, Raman spectroscopy, attenuated total reflectance-infrared spectroscopy （ ATR-IR）, microhardness and fracture toughness （FT） measurements were carried out before and after bleaching experiments. Results CP didn＇t change the morphology of enamel. Meanwhile, the three bleached groups and the control group had no significant difference in root mean square detection （ P = 0. 774）, v2 CO3 2- ： v1 v3 PO4 3 - （ p = 0. 263 ） and microhardness （ P = 0. 829）. The percentage of relative Raman intensity in the three bleached groups and the control group were （ 105.74 ± 11.34） %, （ 1194. 46 ± 8. 83 ） %, （ 99. 52 ± 9. 32 ） % and （ 97.62 ± 7.46 ） %, respectively. There was no significant difference among them （P = 0. 062）. However, the percentage of laser-induced fluorescence in the three bleached groups and the control group were （ 20. 86 ± 7. 23 ） % , （ 22. 14 ± 7. 34） %, （ 21.10 ± 7. 59 ） % and （ 100. 78 ± 3.70 ） %, respectively. There was significant difference between either of the bleached groups and the control group （ P 〈 0. 001 ） . Moreover, FT declined significantly in the three groups（P = 0. 024, P =0. 005, P = 0. 013） when compared with the control group. Conclusions Under in vitro condition, three differently concentrated at-home bleaching agents wouldn＇t induce the demineralization and the decline of microhardness on enamel. However, the decrease of FT on enamel seemed to be inevitable after bleaching.