Bağis Y H, Rueggeberg F A
University of Ankara School of Dentistry, Turkey.
Dent Mater. 1997 Nov;13(6):377-80. doi: 10.1016/s0109-5641(97)80110-8.
This research examined weight loss of commercial UDMA/TEGDMA- and Bis-GMA/TEGDMA-based resin composites at a variety of post-cure temperatures. Weight loss profiles of individual monomer components were also tested at elevated temperature: Bis-GMA, ethoxylated Bis-GMA (EBis-GMA), urethane dimethacrylate (UDMA), and triethyleneglycol dimethacrylate (TEGDMA).
Disc-shaped composite specimens (1 x 5 mm, approximately 50 mg) were light-cured and then isothermally post-cure heated in a thermogravimetric analysis (TGA) unit at either 50 degrees, 75 degrees, 100 degrees, 125 degrees or 150 degrees C. A single specimen was made for each post-cure temperature for each product (a total of 10 discs). Individual monomer components were heated to 800 degrees C. Filler and organic phase weight percentages were determined by ashing cured composite in the TGA. Weight loss differences between resin systems at various post-cure temperatures were analyzed using linear regression.
For each type of composite, loss of volatile component increased with both elevated post-cure temperature as well as duration of heat exposure. Using recommended post-cure temperature and time (125 degrees C for 7.5 minutes), there was no difference in weight loss profile between the two products: both exhibited 1.3% loss of resin component. After 10 min of heating, the Bis-GMA-based product always demonstrated a greater weight loss than the UDMA material. Weight loss could not be attributed to any specific monomer.
Specimen weight loss during post-cure heating may result in a depletion of leachable, unreacted material at the restoration surface, possibly enhancing material properties at that location. This decrease would also potentially reduce the biological impact of leachable materials. Loss of volatile components from post-cure heating would affect the accuracy of infrared spectroscopic techniques in determining monomer conversion values.
本研究检测了市售基于UDMA/TEGDMA和Bis-GMA/TEGDMA的树脂复合材料在不同后固化温度下的重量损失。还在高温下测试了各单体成分的重量损失曲线：双酚A缩水甘油醚甲基丙烯酸酯（Bis-GMA）、乙氧基化双酚A缩水甘油醚甲基丙烯酸酯（EBis-GMA）、聚氨酯二甲基丙烯酸酯（UDMA）和三乙二醇二甲基丙烯酸酯（TEGDMA）。
将圆盘状复合材料试样（1×5mm，约50mg）进行光固化，然后在热重分析仪（TGA）中于50℃、75℃、100℃、125℃或150℃等温后固化加热。每种产品在每个后固化温度下制备一个试样（共10个圆盘）。将各单体成分加热至800℃。通过在TGA中灰化固化后的复合材料来测定填料和有机相的重量百分比。使用线性回归分析不同后固化温度下树脂体系之间的重量损失差异。
对于每种类型的复合材料，挥发性成分的损失随后固化温度的升高以及热暴露时间的延长而增加。采用推荐的后固化温度和时间（125℃，7.5分钟），两种产品的重量损失曲线没有差异：两者的树脂成分损失均为1.3%。加热10分钟后，基于Bis-GMA的产品的重量损失总是大于UDMA材料。重量损失不能归因于任何特定单体。
后固化加热过程中试样的重量损失可能会导致修复体表面可浸出的未反应物质减少，可能会增强该部位的材料性能。这种减少也可能会降低可浸出材料的生物学影响。后固化加热导致的挥发性成分损失会影响红外光谱技术在测定单体转化率值时的准确性。
