Kumar Naresh, Shortall Adrian
Department of Science of Dental Materials, Institute of Dentistry, Liaquat University of Medical and Health Sciences, Jamshoro, Pakistan.
J Investig Clin Dent. 2014 Aug;5(3):237-42. doi: 10.1111/jicd.12043. Epub 2013 Jun 14.
The aim of the present study was to evaluate the bi-axial flexural strength of experimental unfilled resins and resin-based composites at varying deformation rates following 1-week dry, 1-week wet, and 13-week wet storage regimes.
A total of 270 disc-shaped specimens (12 mm diameter, 1 mm thickness) of either unfilled resins or experimental resin-based composites comprising of three groups (n = 90) were fabricated. Three groups of each unfilled resin and resin-based composites (n = 90) were stored for 1 week under dry conditions, and at 1 and 13 weeks under wet conditions (37 ± 1°C) before testing. The bi-axial flexural strength of each unfilled resin and resin-based composites group was determined at a 0.1, 1, and 10 mm/min deformation rate (n = 30).
The unfilled resins revealed a deformation rate dependence following all storage regimes; however, the addition of fillers in the unfilled resins modified such reliance following the 1-week dry and 13-week wet storage regimes. In contrast, a lower bi-axial flexural strength of the 1-week wet resin-based composites specimens at a 0.1 mm/min deformation rate was identified.
A lower bi-axial flexural strength of the 1-week wet resin-based composites specimens at a low deformation rate suggests that premature failure of resin-based composites restorations might occur in patients with parafunctional habits, such as bruxism.
本研究旨在评估实验性无填料树脂和树脂基复合材料在1周干燥、1周潮湿及13周潮湿储存条件下，不同变形速率下的双轴弯曲强度。
制备了共270个圆盘形试样（直径12毫米，厚度1毫米），分别为无填料树脂或由三组组成的实验性树脂基复合材料（n = 90）。每组无填料树脂和树脂基复合材料中的三组（n = 90）在测试前分别在干燥条件下储存1周，在潮湿条件下（37±1°C）储存1周和13周。以0.1、1和10毫米/分钟的变形速率测定每组无填料树脂和树脂基复合材料的双轴弯曲强度（n = 30）。
所有储存条件下，无填料树脂均表现出变形速率依赖性；然而，在1周干燥和13周潮湿储存条件下，无填料树脂中添加填料改变了这种依赖性。相比之下，在0.1毫米/分钟变形速率下，1周潮湿的树脂基复合材料试样的双轴弯曲强度较低。
1周潮湿的树脂基复合材料试样在低变形速率下双轴弯曲强度较低，这表明在有磨牙症等副功能习惯的患者中，树脂基复合材料修复体可能会过早失效。
