STATEMENT OF PROBLEM: The use of weak and less durable materials in restoring teeth may result in weak restorations unable to withstand intraoral conditions. PURPOSE: The purposes of this study were to evaluate the effect of thermo-hydrolytic stress on the flexural strength and flexural modulus of core foundation composites with direct restorative composites and determine mass percentage of filler content. MATERIAL AND METHODS: A total of 216 specimens, from 9 brands of commercially available composites (Coreflo, DC Core, Photocore, APX, Litefil II A, Surefil, TPH Spectrum, Z100, and Z250) were fabricated following ISO Standard 4049. Flexural strength (MPa) and flexural modulus (GPa) were determined on bar-shaped specimens (25 x 2 x 2 mm) before and after storage in boiling water for 24 hours (n=12). The filler content in composite was determined by incineration using a thermogravimetric analyzer. The data were analyzed using 2-way analysis of variance and the Student t test (alpha=.05). RESULTS: Filler content of the tested composites was 66.6 to 81.8 mass %. Significant differences in both flexural strength and flexural modulus existed among materials, the effect of boiling and interaction (P<.05). Coreflo, DC Core, Z100, and Z250 demonstrated a significant decrease in flexural strength after boiling (P<.05). Z250 showed a significant decrease in flexural modulus after boiling (P=.001), while Surefil showed a significant increase in flexural modulus (P=.007). CONCLUSION: Within the limitations of this study, it can be concluded that composites were affected differently by moist heat stress. Some composites showed a degradation of flexural properties while some retained flexural properties. Stability of the composites varied among brands.
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机译：问题陈述：在修复牙齿时使用较弱且较不耐用的材料可能会导致脆弱的修复体无法承受口内疾病。目的：本研究的目的是评估热水解应力对具有直接修复性复合材料的芯基础复合材料的弯曲强度和弯曲模量的影响，并确定填料含量的质量百分比。材料和方法：按照ISO标准4049，从9个品牌的商用复合材料（Coreflo，DC Core，Photocore，APX，Litefil II A，Surefil，TPH Spectrum，Z100和Z250）制造了216个样品。弯曲强度在条形样品（25 x 2 x 2 mm）上将其在沸水中储存24小时（n = 12）之前和之后，测定其MPa（MPa）和弯曲模量（GPa）。复合物中的填料含量通过使用热重分析仪进行焚烧来确定。使用方差的2-way分析和Student t检验（alpha = .05）对数据进行分析。结果：测试的复合材料的填料含量为66.6至81.8质量％。材料之间的弯曲强度和弯曲模量都存在显着差异，沸腾和相互作用的影响（P <.05）。 Coreflo，DC Core，Z100和Z250在沸腾后表现出明显的抗弯强度降低（P <.05）。 Z250煮沸后弯曲模量显着降低（P = .001），而Surefil显示弯曲模量显着提高（P = .007）。结论：在本研究的范围内，可以得出结论，湿热应力对复合材料的影响不同。一些复合材料显示出弯曲性能的退化，而一些保留了弯曲性能。不同品牌的复合材料的稳定性各不相同。
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