Fujii K, Arai K
Department of Dental Materials Science, School of Dentistry, Meikai University.
Shika Zairyo Kikai. 1990 Jul;9(4):561-76.
The purpose of this study is to clarify a cause of disintegration for posterior composite resins by long-term immersion in distilled water during the 3-year period. Three kinds of posterior composite resins [Bellfirm P (BP), Clearfil Posterior (CP) and Micro Jar (MJ)] and one conventional anterior composite resin [Clearfil FII (FII)] were prepared as to specimens with 20 mm diameter, and 1 mm in thickness. These specimens were immersed in distilled water at 37 +/- 1 degree C for 3 years. These specimens were observed by scanning electron microscope (SEM). The residuces in distilled water were analyzed by X-ray microdiffractometry, infrared (IR) and nuclear magnetic resonance (NMR) spectrometers. One posterior composite resin (microparticle filled resin) was eluted in water more than the other posterior and anterior composite resins with conventional fillers. In SEM observations, many air bubbles were found inside all sections of the four composite resins, because of all mixing type composite resins. The subsurface layer of all four composite resins showed signs of disintegration, but the center layer of the specimens was not disintegrated. Three cured composite resins except MJ had crystalline X-ray diffraction patterns before water immersion, but the cured MJ alone was amorphous. These peaks of crystals showed fillers of these composite resins respectively. X-ray diffraction patterns of the dissolved substances for three composite resins except BP were also crystalline, but the peaks of the crystals except CP were different from the peaks of the fillers respectively. In IR and 1H-NMR spectra of dissolved substances, an unreacted monomer could be detected in one posterior composite resin (BP), but not in the other composite resins. In 1H-NMR spectra of dissolved substances, new signals not found originally were observed in all four composite resins. Therefore, the progress of disintegration was demonstrated clearly. The dissolved substances of all four composite resins were shown as the disintegrated substances between resin matrixes and silane coupling agents. It is suggested that the disintegration of these composite resins by long-term water immersion is derived from hydrolysis.
本研究的目的是阐明后牙复合树脂在3年期间长期浸泡于蒸馏水中发生崩解的原因。制备了三种后牙复合树脂[Bellfirm P（BP）、Clearfil Posterior（CP）和Micro Jar（MJ）]以及一种传统的前牙复合树脂[Clearfil FII（FII）]，制成直径20mm、厚度1mm的标本。将这些标本在37±1℃的蒸馏水中浸泡3年。通过扫描电子显微镜（SEM）对这些标本进行观察。用X射线微衍射仪、红外（IR）光谱仪和核磁共振（NMR）光谱仪对蒸馏水中的残留物进行分析。一种后牙复合树脂（微粒填充树脂）在水中的洗脱量比其他含有传统填料的后牙和前牙复合树脂更多。在SEM观察中，由于所有复合树脂均为混合型，在四种复合树脂的所有切片内部均发现许多气泡。所有四种复合树脂的亚表层均显示出崩解迹象，但标本的中心层未崩解。除MJ外的三种固化复合树脂在水浸泡前具有晶体X射线衍射图谱，但单独的固化MJ为非晶态。这些晶体峰分别显示了这些复合树脂的填料。除BP外的三种复合树脂溶解物质的X射线衍射图谱也为晶体，但除CP外的晶体峰分别与填料的峰不同。在溶解物质的IR和1H-NMR光谱中，在一种后牙复合树脂（BP）中可检测到未反应的单体，但在其他复合树脂中未检测到。在溶解物质的1H-NMR光谱中，在所有四种复合树脂中均观察到原本未发现的新信号。因此，崩解的进展得到了明确证明。所有四种复合树脂的溶解物质显示为树脂基质和硅烷偶联剂之间的崩解物质。提示这些复合树脂长期水浸泡后的崩解源于水解作用。
