Heymann所提出，每晚在病人牙托裡放入10~15 % carbamide perox ide 連
續配戴幾個禮拜。與唾液或水接觸時， 10~15 % carbamide peroxide可以分
解成3.6~5.4% H2O2 及 6.4-9.6% carbamide (urea)。H2O2不僅為美白成分，
本實驗分成in vitro與in vivo。在in vitro部份反應1與8小時之後，觀
察到分別在5 mM 和0.01 mM H2O2會明顯造成hNOK細胞生存率、ROS含
情況上升。粒線體copy number無伴隨濃度呈現相關性(1小時, r =－0.395；
越大(1小時, r =0.3728；8小時，r =0.873)，與核DNA氧化傷害也呈現正相
關(1 小時, r=0.606；8小時,r=0.863)。在in vivo，24位受試者連續使用美白
Due to the popular demanding of beauty smile, tooth whitening has become
a trend in recent years. There are two techniques that dentists use to whiten vital teeth, “in-office bleeching”and “at-home bleeching”. In this study, we focused mainly on home bleeching technique. Home bleaching was first described and published in 1989 by Haywood and Heyman. They put 10-15 % carbamide peroxide in patient-made mouthguard and require users to wear them at night for several weeks. When carbamide peroxide contacts with water or saliva, about 10-15% of carbamide peroxide is degraded to 3.6-5.4% H2O2 and 6.4-9.6% carbamide(urea).
H2O2 not only is a bleaching component but also a strong oxidant and oxidizing substance that can break down into free radicals. These free radicals will diffuse into enamel to degrade chromogen in order to reach whitening effect. The purpose for this study was to investigate tooth bleaching drug in human oral cells.
The experiment is divided into in vitro and in vivo.In the in vitro part of the response at 1 and 8 hours, resulted in significantly decline in hNOK cell survival, ROS content, GSH, mitochondrial membrane potential .On the other hand, the LDH release,the oxidative damage of nuclear DNA, cell apoptosis will increase when the in 5 mM and 0.01 mM of H2O2, respectively. The copy number of mitochondrial showed no correlation with the concentration (1 hr, r =- 0.395; 8 hr, r =- 0.223).On the other hand, according to the spending time and the amount of the concentration,the correlation and the degree of mtDNA4977 become greater (1 hour, r = 0.3728; 8 hours, r = 0.873) . And the oxidative damage of nuclear DNA is also a positive correlation with mtDNA4977(1 hour,r =0.606；8 hour, r=0.863)
In vivo study, 24 subjects use the teeth bleaching reagent for one month.
And they wear the mouthguard that with the teeth bleaching reagent in 8 hours
before sleeping daily.We obtain the mtDNA4977 have significant statistics(P <
0.05)from the first hour,the first day,the seventh day,the 14th day,and the 30th day between before and after using the teeth bleaching reagent.The 30th day after stop using the bleaching reagent is not statistically significant and the copy number are also not a statistically significant.
Therefore, teeth bleaching reagent can cause on by oxidative stress human
oral cell with various degrees, and even the impact of mitochondrial DNA
changes. The future, we hope that the result of this study combined with clinical
data. Not to harm a large number of injuries in the normal human oral cells, the pick to choose the appropriate concentration for teeth bleaching and the effect
can be achieved and the scope to achieve security.