Khaledi Amir Ali Reza, Pardis Soheil, Pourhatami Negar, Ardakani Zahra Hashemi
Department of Prosthodontics, Biomaterial Research Center, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
Department of Oral and Maxillofacial Pathology, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
Eur J Dent. 2016 Apr-Jun;10(2):259-263. doi: 10.4103/1305-7456.178295.
This study aimed to compare the dimensional accuracy of two indexing materials, an acrylic resin (GC pattern resin) and a castable composite (Bredent). The effect of time lapse until investment was also investigated.
Two standardized brass dies 15 mm apart were prepared and then 20 identical coping-bar assemblies were designed and fabricated by a rapid prototyping device. Each bar was sectioned at the center, and indices were fabricated from an acrylic resin or castable composite (n = 10 per group). The distances between the reference points were measured with a digital microscope at ×80 magnifications at 15 min, 60 min, and 24 h after indexing. Data were statically analyzed using repeated-measure ANOVA (α = 0.05).
The distance between the reference points without the coping being joined was considered as the baseline measurement (control group). The mean distance was 19.30 ± 0.04 mm between the reference points where the copings were not joined. When indexed with acrylic resin, the mean ± standard deviation (SD) dimensions were 19.27 ± 0.087 mm (15 min), 19.25 ± 0.09 mm (60 min), and 18.98 ± 0.1 mm (24 h). The mean ± SD dimensions for composite were 19.29 ± 0.087 mm (15 min), 19.28 ± 0.08 mm (60 min), and 19.26 ± 0.08 mm (24 h). All tested groups showed significant differences compared to the control group except when it was indexed with composite and where the distances were measured after 15 and 60 min (P > 0.05).
The most accurate indexed-assemblies belonged to castable composite at 15 and 60 min.
本研究旨在比较两种分度材料（一种丙烯酸树脂（GC 型树脂）和一种可铸型复合材料（Bredent））的尺寸精度。同时还研究了直至包埋前的时间间隔的影响。
制备两个相距 15 mm 的标准化黄铜模具，然后通过快速成型设备设计并制造 20 个相同的冠桩组件。每个杆在中心处截断，并用丙烯酸树脂或可铸型复合材料制作分度器（每组 n = 10）。在分度后 15 分钟、60 分钟和 24 小时，使用数码显微镜在 80 倍放大倍数下测量参考点之间的距离。数据采用重复测量方差分析进行统计学分析（α = 0.05）。
未连接冠时参考点之间的距离被视为基线测量值（对照组）。未连接冠时参考点之间的平均距离为 19.30 ± 0.04 mm。用丙烯酸树脂分度时，平均 ± 标准差（SD）尺寸为 19.27 ± 0.087 mm（15 分钟）、19.25 ± 0.09 mm（60 分钟）和 18.98 ± 0.1 mm（24 小时）。复合材料的平均 ± SD 尺寸为 19.29 ± 0.087 mm（15 分钟）、19.28 ± 0.08 mm（60 分钟）和 19.26 ± 0.08 mm（24 小时）。所有测试组与对照组相比均显示出显著差异，但用复合材料分度且在 15 分钟和 60 分钟后测量距离时除外（P > 0.05）。
在 15 分钟和 60 分钟时，尺寸精度最高的分度组件属于可铸型复合材料。
