Division of Biomaterials, University of Texas Health Science Center, San Antonio Texas.
J Biomed Mater Res B Appl Biomater. 2010 Aug;94(2):447-454. doi: 10.1002/jbm.b.31674.
Dimethacrylate dental composite resins exhibit inherently low toughness. Toughening of these materials may reduce the incidence of marginal and bulk fracture of composite restorations.
To determine if dimethacrylate dental restorative materials can be rubber-toughened, and if so, to identify a possible mechanism.
A filler composed of aggregates of polybutadiene/silica as well as irregularly-shaped silica slabs was produced by mixing silica with polybutadiene in dichloromethane. The dried filler was subsequently ground and sieved to < 25 microm. Polybutadiene/silica ratios were varied from 0:1 (control) to 0.5:1. EDAX analysis verified the composition of the complex filler. Filler was added to a bis-GMA/bis-EMA/TEGDMA resin system and fractured in three-point bend test mode at a crosshead speed of 1 mm/min. In addition, 1 bar was fractured at a crosshead speed of 0.001 mm/min to identify a possible mechanism for toughening.
In specimens fractured at 1 mm/min, flexural modulus is increased or maintained and flexural strength and energy to break increase as the amount of polybutadiene in the aggregates increases. Cavitation of high-rubber-containing aggregates is demonstrated. In the one specimen fractured at 0.001 mm/min, a marked increase in size of high-rubber-containing aggregates along with severe shear damage in the surrounding matrix is shown, suggesting that cavitation with subsequent absorption of energy during shear yielding is the likely mechanism behind the increase in energy to break in bars fractured at 1 mm/min.
These results indicate that dimethacrylate dental composite materials can be rubber toughened, which may potentially reduce marginal and bulk fractures of composite restorations, and consequently extend their service lifetime.
二甲基丙烯酸酯牙科复合树脂表现出固有低韧性。这些材料的增韧可能会降低复合修复体边缘和整体断裂的发生率。
确定二甲基丙烯酸酯牙科修复材料是否可以橡胶增韧，如果可以，确定可能的机制。
通过在二氯甲烷中将二氧化硅与聚丁二烯混合，制备由聚丁二烯/二氧化硅聚集体以及形状不规则的二氧化硅片组成的填料。干燥的填料随后被研磨并过筛至 < 25 微米。聚丁二烯/二氧化硅的比例从 0:1（对照）变化到 0.5:1。EDAX 分析验证了复杂填料的组成。将填料添加到 Bis-GMA/Bis-EMA/TEGDMA 树脂系统中，并在三点弯曲测试模式下以 1mm/min 的十字头速度断裂。此外，以 0.001mm/min 的十字头速度断裂 1 个样本，以识别增韧的可能机制。
在以 1mm/min 断裂的样品中，随着聚丁二烯在聚集体中的含量增加，弯曲模量增加或保持，弯曲强度和断裂能增加。高橡胶含量聚集体的空化得到证明。在以 0.001mm/min 断裂的一个样本中，高橡胶含量聚集体的尺寸明显增加，同时周围基质发生严重剪切损伤，表明在以 1mm/min 断裂的棒材中，断裂能增加的可能机制是空化随后在剪切屈服过程中吸收能量。
这些结果表明，二甲基丙烯酸酯牙科复合材料可以进行橡胶增韧，这可能会降低复合修复体的边缘和整体断裂，从而延长其使用寿命。
