Development of bonding system for altered dentin

本研究制备了5种不同降解阶段的改性自酸蚀底涂剂，并对其进行了光固化性能测试，结果表明：随着自酸蚀底涂剂贮存时间的延长，树脂与牙本质的结合强度降低，这主要是由于自酸蚀底涂剂中的功能单体发生了变化。为了解自酸蚀底涂层中功能单体的变化对牙本质粘结强度的影响，研究了自酸蚀底涂层降解阶段对树脂与牙本质粘结强度的影响，当HEMA水解5%的新鲜A液用于艾德Primer II粘结系统时，树脂与牙本质的平均粘结强度约为12 MPa。在改良的艾德Primer II条件下，当A液中的HEMA水解62%时，粘结强度保持在初始的平均值，当水解量超过62%时，粘结强度急剧下降至8 MPa。这种急剧的下降可能是由于HEMA降低了牙本质胶原网络的预充效力，由HEMA中甲基丙烯酰氧基酯部分的水解引起的液体A的降解引起了粘结强度的降低。具体地，当液体A中的HEMA水解67%时，观察到与牙本质的粘结强度急剧降低。我们发现，初始粘结强度保持，直到水解的HEMA的量达到62%。

It is well understood that the bond strength of resin to the dentin decreased when the storage period of self-etching primers is prolonged, due to the alteration of the functional monomers employed in the primer.In this study, we prepared a series of five altered self-etching primers with different degradated stages. The degradation stage effects of self-etching primer on the bond strength of resin to the dentin were examined to understand the degradation mechanism on the dentin bonding through the alteration of the functional monomer employed in self-etching primer.When the fresh liquid A, where the HEMA had hydrolyzed by 5%, was applied to the ED Primer II bonding system, the mean bond strength of resin to dentin was approximately 12 MPa. This initial mean bond strength to the dentin, conditioned by the altered ED Primer II, was maintained until the HEMA utilized in the liquid A had hydrolyzed by 62%.Furthermore, when the amount of hydrolyzed HEMA become more than 62%, the bond strength dramatically dropped down to 8 MPa. This dramatic decrease was probably due to the degradation of the priming efficacy of the dentinal collagen network by the HEMA.The degradation of the liquid A, caused by the hydrolysis of the methacryloxy ester portion in the HEMA, induces a decrease in the bond strength. Specifically, when HEMA in the liquid A had hydrolyzed by 67%, the dramatic decrease in the bond strength to the dentin was observed. We found the initial bond strength was maintained until the amount of hydrolyzed HEMA reached to 62%.