Weiger R, Kuhn A, Löst C
Department of Conservative Dentistry, School of Dental Medicine, University of Tübingen, Germany.
J Endod. 1993 May;19(5):239-41. doi: 10.1016/S0099-2399(06)81299-9.
Time-dependent changes in the pH value of various types of sodium perborate solutions used as bleaching agents were evaluated. Sodium perborate-monohydrate (MH), sodium perborate-trihydrate (TRH), and sodium perborate-tetrahydrate are available. Each perborate was mixed with 10%, 15%, or 30% fresh hydrogen peroxide or with bidistilled water in a powder to liquid ratio of 2 g:1 ml, respectively. The pH values were recorded at baseline and after 1h, 1 day, 3 days, and 7 days, respectively. At baseline the pH values of MH, TRH, and tetrahydrate in conjunction with 30% H2O2 were 8.7, 7.0, and 7.5, respectively. The pH increased significantly with decreasing concentrations of H2O2. For TRH, MH, and tetrahydrate mixed with bidistilled water more alkaline values were measured at baseline and after 1 h. Due to solidification of the samples, the pH could not be determined for MH starting day 1 and for TRH starting day 3. In conclusion, the pH of bleaching pastes depends on the content of water of crystallization in sodium perborate, H2O2 concentration, and time of measurement. The bulk of the mixtures recorded reached alkaline pH values of 10 to 11. It is recommended that the pH of the mixture being used be checked to avoid potential postbleaching root resorption.
对用作漂白剂的各类过硼酸钠溶液的pH值随时间的变化进行了评估。有一水合过硼酸钠（MH）、三水合过硼酸钠（TRH）和四水合过硼酸钠。每种过硼酸盐分别以2 g:1 ml的粉液比与10%、15%或30%的新鲜过氧化氢或双蒸水混合。分别在基线以及1小时、1天、3天和7天后记录pH值。基线时，MH、TRH和四水合物与30% H2O2混合时的pH值分别为8.7、7.0和7.5。pH值随H2O2浓度降低而显著升高。对于TRH、MH和与双蒸水混合的四水合物，在基线和1小时后测得的pH值更高。由于样品凝固，从第1天开始无法测定MH的pH值，从第3天开始无法测定TRH的pH值。总之，漂白糊剂的pH值取决于过硼酸钠的结晶水含量、H2O2浓度和测量时间。所记录混合物的大部分pH值达到了10至11的碱性范围。建议检查所用混合物的pH值，以避免潜在的漂白后牙根吸收。
