Robinson F G, Rueggeberg F A, Lockwood P E
Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta 30912, USA.
J Forensic Sci. 1998 Nov;43(6):1163-7.
With increasing use of direct esthetic restorative materials, the identity of a body may rely upon knowledge of temperature effects on this class of dental restorations. This research examined the effect of atmospheric gas on thermal decomposition and color change of a wide variety of direct esthetic restorative materials. Cured discs (4 x 1 and 8 x 1 mm) were made using manufacturer's directions: traditional glass ionomer (Fuji II), light-curable resonomer (Fuji II LC), compomer (Geristore), and three types of resin composites--highly filled, urethane-based (Occlusin), and two Bis-GMA/TEGDMA resins: hybrid (Herculite XRV) and microfill (Silux Plus). Three replications of each material were heated at 5 degrees C/min in a thermogravimetric analysis unit using either room air or nitrogen purge to simulate different thermal environments. First derivative values of percent weight loss with respect to temperature were obtained to determine temperatures associated with increased decomposition rates. Room-air heating showed greater numbers of decomposition events than did nitrogen-heated discs. The only material decomposing less than 200 degrees C in either atmosphere was traditional glass ionomer. The majority of decomposition occurred between 200 degrees and 500 degrees C for all materials. Only products containing glass ionomer components decomposed between 600 degrees and 800 degrees C. Room-air heating resulted in ash white discs at 800 degrees C and higher. Specimens heated in nitrogen were gray to black at 600 degrees C and higher. Heating atmosphere greatly affected color, and some products demonstrated distinguishing color changes: glass ionomers, in particular, showed characteristic color features. An atlas was constructed from color change of specimens recovered after 200 degrees, 400 degrees, 600 degrees, 800 degrees, and 1000 degrees C compared with non-heated controls.
随着直接美学修复材料使用的增加，确定尸体身份可能依赖于了解温度对这类牙科修复体的影响。本研究考察了大气气体对多种直接美学修复材料热分解和颜色变化的影响。按照制造商的说明制作固化圆盘（4×1和8×1毫米）：传统玻璃离子水门汀（富士II型）、光固化树脂水门汀（富士II型LC）、复合体（杰里斯托）以及三种树脂复合材料——高填料、聚氨酯基（奥克卢辛），还有两种双酚A缩水甘油醚/三乙二醇二甲基丙烯酸酯树脂：混合型（赫库利特XRV）和微填料型（西卢克斯Plus）。每种材料取三个复制品，在热重分析仪中以5℃/分钟的速度加热，使用室内空气或氮气吹扫来模拟不同的热环境。获取重量损失百分比相对于温度的一阶导数值，以确定与分解速率增加相关的温度。与氮气加热的圆盘相比，室内空气加热显示出更多的分解事件。在两种气氛中，唯一在低于200℃时分解的材料是传统玻璃离子水门汀。所有材料的大部分分解发生在200℃至500℃之间。只有含玻璃离子水门汀成分的产品在600℃至800℃之间分解。在800℃及更高温度下，室内空气加热导致圆盘变为灰白色。在600℃及更高温度下，在氮气中加热的试样变为灰色至黑色。加热气氛对颜色有很大影响，一些产品表现出明显的颜色变化：特别是玻璃离子水门汀显示出特征性的颜色特征。根据200℃、400℃、600℃、800℃和1000℃加热后回收的试样与未加热对照相比的颜色变化构建了一个图谱。
