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

PAN Li-feng; ZHOU Wei-bing; LIU Huai-yu; SUN Shan-shan; AN Jian-ping

Abstract：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.