Department of Dental Materials, School of Dentistry, University of São Paulo, Av. Prof. Lineu Prestes, 2227 São Paulo, SP 05508-000, Brazil.
J Dent Res. 2011 Mar;90(3):365-70. doi: 10.1177/0022034510388039. Epub 2010 Nov 22.
The literature shows contradictory results regarding the role of composite shrinkage and elastic modulus as determinants of polymerization stress. The present study aimed at a better understanding of the test mechanics that could explain such divergences among studies. The hypothesis was that the effects of composite shrinkage and elastic modulus on stress depend upon the compliance of the testing system. A commonly used test apparatus was simulated by finite element analysis, with different compliance levels defined by the bonding substrate (steel, glass, composite, or acrylic). Composites with moduli between 1 and 12 GPa and shrinkage values between 0.5% and 6% were modeled. Shrinkage was simulated by thermal analogy. The hypothesis was confirmed. When shrinkage and modulus increased simultaneously, stress increased regardless of the substrate. However, if shrinkage and modulus were inversely related, their magnitudes and interaction with rod material determined the stress response.
文献表明，复合收缩和弹性模量在聚合应力中的作用存在矛盾的结果。本研究旨在更好地理解测试力学，以解释研究之间的这种分歧。假设是，复合收缩和弹性模量对应力的影响取决于测试系统的顺应性。通过有限元分析模拟了一种常用的测试仪器，通过粘合基底（钢、玻璃、复合材料或丙烯酸）定义不同的顺应性水平。模拟了模量在 1 到 12 GPa 之间、收缩值在 0.5%到 6%之间的复合材料。通过热模拟来模拟收缩。假设得到了证实。当收缩和模量同时增加时，无论基底如何，应力都会增加。然而，如果收缩和模量成反比，它们的大小和与棒材材料的相互作用决定了应力响应。
