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目的观察氟化物对过氧化脲类漂白剂渗透性及漂白效果的影响。方法选取2010年1月至2012年7月就诊于第三军医大学大坪医院野战外科研究所口腔科，因正畸治疗需要拔除第一前磨牙的12例患者的36颗离体牙，用标准茶溶液染色后，其中12颗样本经NaF处理后用过氧化脲进行漂白（A、B组），12颗样本使用过氧化脲漂白（C、D组），12颗样本放入去离子水中作为空白对照（E、F组）。用VITA比色板对受试牙漂白前后进行比色，然后分别从近远中向（A、C、E组）和唇舌向（B、D、F组）剖开，使用图像分析软件测量并比较剩余染色面积百分比。结果所有标本染色后色度均增加，着色范围为3．66～8．33个色阶。漂白治疗后A、B、C、D组的色阶改变为5～5．53个色阶。而空白对照（E、F组）无色阶改变。（1）近远中向剖开：A组唇侧剩余染色面积为28．6％～39．4％，舌侧剩余染色面积为58％～72％；C组唇侧剩余染色面积为29．3％～37．2％，舌侧剩余染色面积为57．6％～70．1％；E组两剖面显示全部牙本质均匀染色，面积百分比约96．97％～100％；A、C组间各剖面差异无统计学意义（P〉0．05），而二者与E组的差异均有统计学意义（P〈0．05）。（2）唇舌向剖开：B组唇侧和舌侧剖面剩余染色面积基本相等，为61．7％～68．7％；D组两剖面剩余染色面积为60．8％～66．3％，反映出相同的颜色改变的深度；F组两剖面染色面积为96．4～99．8％；B、D组间差异无统计学意义（P〉0．05），但与F组间差异均有统计学意义（P〈0．05）。结论着色牙漂白前局部氟化物处理对漂白效果无明显影响。

In vitro study of fluoride preconditioning in attenuating sensitivity induced by tooth bleaching

Objective To investigate whether the use of sodium fluoride before bleaching regimen would decrease bleaching efficacy of HP when compared with a placebo, and to confirm the applicability and reliability of the fluoride in clinic. Methods The crowns of 36 caries and developmental defect free human maxillary incisors were stained internal- ly with a standardised tea solution; 12 specimens were power bleached with light activated 35% hydrogen peroxide and 12 were placed in water; another 12 specimens were bleached by same agents after using 2%NaF. Both exposure times were 30 min. Vita shade guide was employed prior to and after tea staining and after power bleaching/water treatments. Eighteen specimens each from three group were sectioned mesio-distally. An additional 18 specimens from the bleach and the control group were sectioned labio-palatally. The stain area for each specimen was measured using image analy- sis software. Results With tea staining, the mean changes in Vita shade guide units （SGU） ranged from 3.66 to 8.33. Samples bleached and sectioned mesio-distally showed stain coverage of 28.6% ~ 39.4%, while palatal sections showed stain coverage of 58% - 72%. Control samples, whether sectioned mesio-distally or labio-palatally, showed staining throughout the dentine （97% - 100% coverage）. Conclusion The use of sodium fluoride before each bleaching regi- men does not affect the bleaching efficacy of hydrogen peroxide. Hydrogen peroxide bleaching gel demonstrates bleach- ing into dentine of uniform depth and there is no difference between the groups receiving the placebo and the fluoride treatment.