新型低收缩树脂基复合材料的摩擦系数及相关耐磨性

Palin W M, Fleming G J P, Burke F J T, Marquis P M, Pintado M R, Randall R C, Douglas W H

Biomaterials Unit, The University of Birmingham School of Dentistry, St Chad's Queensway, UK.

Dent Mater. 2005 Dec;21(12):1111-8. doi: 10.1016/j.dental.2005.03.002. Epub 2005 Aug 8.

OBJECTIVES

Frictional forces play a major role in the oral wear process of dental resin-based composites (RBCs) and it would be of interest to consider how the energy from friction is dissipated at the material surface. Consequently, the micromechanical wear properties of conventional methacrylate compared with novel oxirane RBCs were assessed.

METHOD

The frictional coefficient (mu), volume loss and Vickers hardness number (VHN) of oxirane (EXL596 and H1) and methacrylate RBCs (Z100 and Filtek Z250) were evaluated. Archard's wear equation was implemented to obtain the wear coefficient (K) and expressed as a 'fraction of friction' (K/micro) to indicate the dissipation of frictional energy that resulted in wear. Scanning electron microscopy (SEM) was used to qualitatively asses the wear facets of each RBC following 50000-cycles.

RESULTS

The mean frictional coefficients observed between the oxirane and methacrylate RBCs were not significantly different (P > 0.05). However, the volume loss of EXL596 and H1 (5.9 +/- 0.4 and 4.7 +/- 0.3 x 10(-2) mm(3)) was significantly increased compared with Z100 and Filtek Z250 (1.7 +/- 0.2 and 2.3 +/- 0.3 x 10(-2) mm(3)). The VHN of EXL596 and H1 was either significantly greater (P = 0.021) or similar (P = 0.089) to Filtek Z250, respectively. An increase in K/micro was reported for EXL596 and H1 (34.7 +/- 4.1 and 22.8+ /- 2.4 x 10(-4)) compared with Z100 and Filtek Z250 (8.50 +/- 0.7 x 10(-4) and 8.62 +/- 1.0 x 10(-4)) (P < 0.05). SEM images of the oxirane RBCs exhibited increased surface fatigue and delamination of the surface layers compared with the methacrylate RBC specimens following 50,000-cycles.

CONCLUSION

The significant decrease in wear resistance of the oxirane compared with methacrylate RBCs was unexpected since frictional coefficients and/or surface hardness were statistically similar. The decreased wear resistance of EXL596 and H1 compared with Z100 and Filtek Z250 was further explained by the increase in K/micro from wear theory and the associated increase in surface fatigue identified from SEM. The simplistic testing procedure combined with SEM utilized in the current investigation provided a greater insight into the wear mechanism by considering the effect of frictional energy at the specimen surface which may benefit the development of improved wear resistance for experimental RBC materials.

目的

摩擦力在牙科树脂基复合材料（RBCs）的口腔磨损过程中起主要作用，研究摩擦产生的能量如何在材料表面耗散具有重要意义。因此，评估了传统甲基丙烯酸酯类RBCs与新型环氧乙烷RBCs的微观力学磨损性能。

方法

评估了环氧乙烷（EXL596和H1）和甲基丙烯酸酯类RBCs（Z100和Filtek Z250）的摩擦系数（μ）、体积损失和维氏硬度值（VHN）。采用阿查德磨损方程计算磨损系数（K），并表示为“摩擦分数”（K/μ），以表明导致磨损的摩擦能量耗散情况。使用扫描电子显微镜（SEM）定性评估每种RBC在50000次摩擦后的磨损面。

结果

环氧乙烷和甲基丙烯酸酯类RBCs之间观察到的平均摩擦系数无显著差异（P>0.05）。然而，EXL596和H1的体积损失（5.9±0.4和4.7±0.3×10⁻²mm³）与Z100和Filtek Z250（1.7±0.2和2.3±0.3×10⁻²mm³）相比显著增加。EXL596和H1的VHN分别与Filtek Z250相比显著更高（P = 0.021）或相似（P = 0.089）。与Z100和Filtek Z250（8.50±0.7×10⁻⁴和8.62±1.0×10⁻⁴）相比，EXL596和H1的K/μ增加（34.7±4.1和22.8±2.4×10⁻⁴）（P<0.05）。50000次摩擦后，环氧乙烷RBCs的SEM图像显示，与甲基丙烯酸酯类RBCs标本相比，其表面疲劳增加，表面层分层。

结论

与甲基丙烯酸酯类RBCs相比，环氧乙烷的耐磨性显著降低出乎意料，因为摩擦系数和/或表面硬度在统计学上相似。从磨损理论的K/μ增加以及SEM确定的表面疲劳增加进一步解释了EXL596和H1与Z100和Filtek Z250相比耐磨性降低的原因。本研究中使用的简单测试程序与SEM相结合，通过考虑试样表面摩擦能量的影响，为磨损机制提供了更深入的了解，这可能有利于开发具有更高耐磨性的实验性RBC材料。