Baroudi Kusai, Silikas Nick, Watts David C
Department of Paediatric Dentistry, University of Al-Baath, School of Dentistry, Hama, Syria.
Eur J Oral Sci. 2007 Dec;115(6):517-21. doi: 10.1111/j.1600-0722.2007.00487.x.
Creep behaviour of flowable composites was evaluated in relation to their filler fraction and the postcure period. Solid cylindrical specimens were prepared (4 x 6 mm) using steel moulds, with thorough light curing from multiple directions at 600 mW cm(-2). The specimens were divided into two groups (n=3/material) as follows: group I, loaded 5 min after preparation; and group II, loaded after storage for 1 month in water at 37+/-1 degrees C. A constant compressive stress of 36 MPa was applied to each specimen for 2 h followed by removal of the weight for 2 h of strain recovery. Axial strain measurements were obtained continuously over the total analysis time of 4 h. The maximum creep strain ranged from 2.04 to 7.69% and from 1.03 to 6.12% for groups I and II, respectively. Flowables that had the highest percentage of filler produced the lowest creep strain. The creep response decreased with 1 month of preload storage. Clinically, the finding of this study suggests that flowable composites are unsuitable for stress-bearing areas.
研究了可流动复合树脂的蠕变行为与其填料分数和后固化时间的关系。使用钢模具制备实心圆柱形试样（4×6毫米），并在600 mW/cm²的光照强度下从多个方向进行充分的光固化。将试样分为两组（每组n = 3），如下所示：第一组，制备后5分钟加载；第二组，在37±1℃的水中储存1个月后加载。对每个试样施加36 MPa的恒定压缩应力2小时，然后去除重量进行2小时的应变恢复。在4小时的总分析时间内连续测量轴向应变。第一组和第二组的最大蠕变应变分别为2.04%至7.69%和1.03%至6.12%。填料百分比最高的可流动复合树脂产生的蠕变应变最低。预加载储存1个月后，蠕变响应降低。临床上，本研究结果表明可流动复合树脂不适用于承受应力的区域。
