Al-Darwish Mohammed, Hurley Ryan K, Drummond James L
Dental Department, Hamad Medical Corp, Doha, Qatar.
J Prosthet Dent. 2007 May;97(5):266-70. doi: 10.1016/j.prosdent.2006.09.001.
A fiber-reinforced composite resin system has been introduced for posterior restorations; however, little information is known regarding possible degradation of its flexure strength with respect to aging and cyclic loading.
The aim of this in vitro study was to determine whether the fiber reinforcement improved the flexure strength of an indirect composite resin aged in air and water for 3 months and then subjected to static and cyclic loading.
The materials tested in this study, non-fiber-reinforced composite resin (n=160) (Tescera Dentin) and fiber-reinforced composite resin (n=160) (Tescera U-beam and Rod), were fabricated as bars, 25.0 x 4.5 x 4.5 mm, and polished with 120- to 320-grit silicon carbide grinding paper. The static (n=15) and cyclical (n=25) flexure strengths (MPa) of specimens were tested initially and after 3 months' aging in air and water. The specimens were tested in 3-point loading in their respective aging media at a loading rate of 2 mm/min. Cyclic testing followed the staircase approach of either 1000 cycles or until specimen fracture. Statistical analysis for the static-loaded specimens consisted of a 3-way analysis of variance (media, aging, and fiber-reinforced versus unreinforced) (alpha=.05), whereas the cyclic-loaded specimens used confidence levels of .95 for the respective variables (media, aging, and fiber-reinforced versus unreinforced) and to compare static versus cyclic loading.
The statistical analysis of the static specimens showed no significant difference between control (unaged) groups and aged groups and aging media, but a significant difference (P<.001) between reinforced versus unreinforced specimens. For the cyclic-loaded specimens, the confidence levels at .95 showed no difference between control (unaged) groups and aged groups and aging media (air or water), but a difference between reinforced versus unreinforced specimens, and static-loaded versus cyclic-loaded specimens. During testing, the specimens separated into several pieces when the fiber reinforcement was on the compressive side, whereas the specimen remained intact when the fiber reinforcement was on the tensile side.
When compared to indirect composite resin without fiber reinforcement, the addition of fibers is an effective method to improve the flexure strength of indirect composite resin for the materials tested.
一种纤维增强复合树脂系统已被引入用于后牙修复；然而，关于其弯曲强度随老化和循环加载可能发生的降解，所知信息甚少。
本体外研究的目的是确定纤维增强是否能提高间接复合树脂在空气和水中老化3个月后再进行静态和循环加载时的弯曲强度。
本研究中测试的材料，非纤维增强复合树脂（n = 160）（Tescera牙本质）和纤维增强复合树脂（n = 160）（Tescera U型梁和棒），被制作成25.0×4.5×4.5毫米的棒状，并使用120至320目碳化硅砂纸进行抛光。在初始状态以及在空气和水中老化3个月后，对标本的静态（n = 15）和循环（n = 25）弯曲强度（MPa）进行测试。标本在各自的老化介质中以2毫米/分钟的加载速率进行三点加载测试。循环测试遵循阶梯法，进行1000次循环或直至标本断裂。对静态加载标本的统计分析包括三因素方差分析（介质、老化以及纤维增强与未增强）（α = 0.05），而对循环加载标本，对各自变量（介质、老化以及纤维增强与未增强）使用0.95的置信水平，并比较静态与循环加载。
对静态标本的统计分析表明，对照组（未老化）与老化组以及老化介质之间无显著差异，但增强标本与未增强标本之间存在显著差异（P < 0.001）。对于循环加载标本，0.95的置信水平表明对照组（未老化）与老化组以及老化介质（空气或水）之间无差异，但增强标本与未增强标本之间以及静态加载标本与循环加载标本之间存在差异。在测试过程中，当纤维增强位于压缩侧时，标本会分成几块，而当纤维增强位于拉伸侧时，标本保持完整。
与未进行纤维增强的间接复合树脂相比，添加纤维是提高所测试材料的间接复合树脂弯曲强度的有效方法。
