Microanalysis and leaching behavior of bisphenol A in dental materials

本研究的目的是建立牙科树脂中双酚A的微量分析方法，然后确定双酚A是否是由未聚合的单体通过分解反应等方式产生的，同时也选择了聚合过程中双酚A含量可能减少的评估作为研究的主题。双酚A量的微量分析为了尽可能有效地消除碱金属离子的污染，采用石英容器对双酚A量进行微量分析。甲醇-水混合物的流动相以甲醇/水=80/20为宜，乙腈-水混合物的流动相以乙腈/水=60/40为宜。根据不同样品的性质，建立了优化设计的微量分析方法。双酚A相关化合物分解释放双酚A在a-…条件下，双酚A很容易分解为双酚A更多的是CIDIC或基本环境。另一方面，虽然Bis-GMA被分解成BHP，但没有观察到BHP生成双酚A。BHP是在水解过程中形成的中间体。由此可见，Bis-GMA生产双酚A的可能性很小，因为BHP的中间体在水解过程中是非常稳定的。以2，2‘-偶氮二异丁腈为引发剂时，双酚A与树脂固化过程中生成的自由基的相互作用随双酚A加入量的增加而增加。这说明双酚A是一种典型的阻聚剂。在过氧化苯甲酰(BPO)引发的聚合反应中，双酚A的诱导期比对苯二酚长，说明在BPO存在下，双酚A比对苯二酚具有更好的阻聚作用。据推测，牙科树脂在固化开始时不再存在双酚A，因为树脂中作为杂质的双酚A被与引发剂自由基的反应消耗。较少

The purposes of this study is to establish the method for microanalysis of bisphenol A contained in dental resins and then to ascertain whether bisphenol A is produced from unpolymerized monomers by decomposition reactions, etc. The evaluation of the possible reduction in bisphenol A amounts during polymerization was also chosen as the subject of the study.1. Microanalysis of bisphenol A amountsQuartz containers were used for microanalysis of bisphenol A amounts in order to eliminate the contamination with alkali metal ions as effectively as possible. A ratio of methanol/water=80/20 is most suitable for mobile phase of methanol-water mixture and a ratio of acetonitrile/water=60/40 for that of acetonitrile-water mixture. Microanalytical methods with the optimal design were established according to the properties of various test specimens.2. Bisphenol A release from bisphenol A related compounds caused by their decompositionBis-DMA was quite easily decomposed into bisphenol A under the a … More cidic or basic environment. On the other hand, the formation of bisphenol A from BHP was not observed, although Bis-GMA was decomposed into BHP which is an intermediate formed during hydrolysis. From the facts described above, it was concluded that there is little possibility of the production of bisphenol A from Bis-GMA, since BHP intermediate in hydrolysis is extremely stable.3. Interaction of bisphenol A with radicals formed during the cure of resinsInduction period increased with an increase in additional amounts of bisphenol A when 2,2'-azobis(isobutyronitrile) was used as an initiator. This revealed that bisphenol A is a typical polymerization inhibitor. Bisphenol A produced longer induction periods than hydroquinone in the polymerization initiated by benzoyl peroxide (BPO), which indicated that the former acts as an inhibitor more effectively than the latter in the presence of BPO. It was supposed that bisphenol A is no longer present in dental resins at the start of their curing, since bisphenol A contained in resins as an impurity is consumed by the reaction with initiator radicals. Less