Unité de Recherches Biomatériaux Innovants et Interfaces, Faculté de chirurgie dentaire, Université Paris Descartes, France.
Dent Mater. 2012 May;28(5):529-34. doi: 10.1016/j.dental.2011.12.003. Epub 2012 Jan 9.
The aim of this study was to thermo-polymerize under high pressure four commercially available dental resin composites to obtain and characterize composite blocks suitable for CAD/CAM procedures.
Gradia (GC, Japan), Vita VM LC (Vita Zahnfabrik, Germany), Grandio (VOCO, Germany), and EsthetX (Dentsply, Germany), were selected for this study. Paradigm (3 M ESPE, USA), a CAD/CAM composite block, was included for comparison. Composite blocks were obtained through polymerization at high-temperature high-pressure (HT/HP). Samples for mechanical/physical characterizations were cut from Paradigm and HT/HP composite blocks while control samples were obtained by photo-polymerizing (PP) the materials in molds. Flexural strength (σ(f)), fracture toughness (K(IC)), hardness, and density (ρ) were determined and compared by pairwise t-tests (α=0.05). Fractured surfaces were characterized under a scanning electron microscope.
The results have shown that HT/HP polymerization resulted in a significant (p<0.05) increase in σ(f), hardness, and ρ for all composites investigated. Even if K(IC) of all materials was increased by HT/HP polymerization, significant increases were detected only for Gradia and EsthetX. The Weibull modulus of HT/HP polymerized composites was higher than that of PP counterparts. HT/HP materials had higher σ(f), Weibull modulus, and K(IC) compared to Paradigm. The most significant SEM observation of fractured K(IC) specimens from all the materials tested was the presence of fewer and smaller voids in HT/HP polymerized composites.
The results of this study suggest that HT/HP polymerization could be used to obtain dental resin composite blocks with superior mechanical properties, suitable for CAD/CAM processing.
本研究旨在通过高温高压聚合四种市售牙科树脂复合材料，获得并表征适用于 CAD/CAM 工艺的复合块。
选择 Gradia（GC，日本）、Vita VM LC（Vita Zahnfabrik，德国）、Grandio（VOCO，德国）和 EsthetX（Dentsply，德国）进行本研究。Paradigm（3M ESPE，美国），一种 CAD/CAM 复合块，也被包括在内进行比较。复合块通过高温高压（HT/HP）聚合获得。用于机械/物理特性表征的样品从 Paradigm 和 HT/HP 复合块中切割，而对照样品则通过在模具中光聚合（PP）材料获得。通过配对 t 检验（α=0.05）确定并比较了弯曲强度（σ(f)）、断裂韧性（K(IC)）、硬度和密度（ρ）。在扫描电子显微镜下对断裂表面进行了表征。
结果表明，HT/HP 聚合导致所有研究的复合材料的σ(f)、硬度和ρ显著增加（p<0.05）。即使所有材料的 K(IC)都通过 HT/HP 聚合增加，但仅在 Gradia 和 EsthetX 中检测到显著增加。HT/HP 聚合复合材料的威布尔模量高于 PP 对应物。HT/HP 材料的σ(f)、威布尔模量和 K(IC)均高于 Paradigm。从所有测试材料的断裂 K(IC)试样的最显著的 SEM 观察是 HT/HP 聚合复合材料中存在更少和更小的空隙。
本研究结果表明，HT/HP 聚合可用于获得具有优异机械性能的牙科树脂复合材料块，适用于 CAD/CAM 加工。
