Thonemann B M, Federlin M, Schmalz G, Hiller K A
Dental School, University of Regensburg, Germany.
Dent Mater. 1997 May;13(3):192-7. doi: 10.1016/S0109-5641(97)80026-7.
Morphological changes in terms of marginal expansion have been observed at the dentin-composite interface of resin composite restorations with the scanning electron microscope (SEM), which could not be described with the criteria conventionally used for quantitative marginal analysis. The purpose of the present study was to elucidate the influence of marginal expansion upon marginal integrity and clarify the cause of these morphological changes.
A total of 22 extracted human molars were restored with Class II resin composite restorations, with and without the use of a dentin bonding agent. The cervical restoration margin was located below the cemento-enamel-junction (CEJ). The marginal adaptation at the dentin- and enamel-composite interfaces was evaluated and measured on replicas using quantitative SEM analysis after different storage periods. The chemical composition of the marginal expansion was determined qualitatively by EDX (Energy Dispersive X-Ray) analysis using original tooth samples. The results obtained from quantitative SEM analysis were statistically analyzed by applying the Mann-Whitney U-test and the error rates method.
Significantly less marginal expansion occurred at the enamel interface than at the dentin-composite interface (p < or = 0.01). Within the dentin, less marginal expansion was observed with the use of a dentin bonding agent than without a dentin bonding agent (p < or = 0.05). At 1 y, a significant (p < or = 0.05) decrease in marginal expansion was observed in both groups. EDX analysis revealed that the chemical composition of the marginal expansion is comparable to the resin composite, since peaks for silicon, barium and ytterbium could be found at these sites.
In Class II resin composite restorations below the CEJ, partial disruption of the adhesive bond may occur initially when curing the restoration. Water sorption causes gap reduction by hygroscopic expansion, seen in the SEM as a volume increase. Thus, the observed morphological changes can be regarded as an early sign of insufficient adhesion between composite and dentin at sites where disruption of the bond occurred initially, whether or not a dentin bonding agent was used.
用扫描电子显微镜（SEM）观察到树脂复合材料修复体的牙本质 - 复合材料界面处存在边缘扩展方面的形态学变化，而传统用于定量边缘分析的标准无法描述这些变化。本研究的目的是阐明边缘扩展对边缘完整性的影响，并明确这些形态学变化的原因。
总共22颗拔除的人磨牙用II类树脂复合材料修复，分为使用和不使用牙本质粘结剂两组。修复体颈部边缘位于牙骨质 - 釉质界（CEJ）下方。在不同储存期后，使用定量SEM分析在复制模型上评估和测量牙本质 - 复合材料界面及釉质 - 复合材料界面的边缘适应性。使用原始牙齿样本通过能谱X射线（EDX）分析对边缘扩展的化学成分进行定性测定。通过应用曼 - 惠特尼U检验和误差率法对定量SEM分析获得的结果进行统计学分析。
釉质界面处的边缘扩展明显少于牙本质 - 复合材料界面（p≤0.01）。在牙本质内，使用牙本质粘结剂时观察到的边缘扩展比不使用牙本质粘结剂时少（p≤0.05）。在1年时，两组的边缘扩展均有显著（p≤0.05）下降。EDX分析表明，边缘扩展的化学成分与树脂复合材料相当，因为在这些部位可发现硅、钡和镱的峰值。
在CEJ下方的II类树脂复合材料修复体中，修复体固化时最初可能会发生粘结的部分破坏。吸水通过吸湿膨胀导致间隙减小，在SEM中表现为体积增加。因此，观察到的形态学变化可被视为在最初发生粘结破坏的部位，复合材料与牙本质之间粘结不足的早期迹象，无论是否使用了牙本质粘结剂。
