Thompson Geoffrey A, Luo Qing
Program Director, Postgraduate Program in Prosthodontics, Marquette University School of Dentistry, Milwaukee, Wis.
Technical support engineer, Carl Zeiss Microscopy LLC, Thornwood, NY.
J Prosthet Dent. 2014 Sep;112(3):638-48. doi: 10.1016/j.prosdent.2014.04.008. Epub 2014 May 13.
Because polymer-based interim restorative materials are weak, even well-made restorations sometimes fail before the definitive restoration is ready for insertion. Therefore, knowing which fabrication procedures and service conditions affect mechanical properties is important, particularly over an extended period.
The purpose of this study was to evaluate the effect of thermal treatment, surface sealing, thermocycling, storage media, storage temperature, and age on autopolymerizing poly(methylmethacrylate) and bis-acryl interim restorative materials. Outcome measures were flexural strength, Vickers surface microhardness, and impact strength.
Flexural strength and microhardness of poly(methylmethacrylate) (Jet Acrylic) and 2 bis-acryl-composite resin (Protemp 3 Garant and Integrity) interim restorative materials were evaluated as affected by storage media, storage temperature, storage time, thermocycling, postpolymerization thermal treatment, or application of a surface sealer. In total, 2880 beam specimens (25×2×2 mm) were fabricated. Mechanical property analyses were made at 10 days, 30 days, 6 months, and 1 year after specimen preparation. Flexural strength was determined by using a 3-point bending test in a universal testing machine with a 1 kN load cell at a crosshead speed of 5.0 mm min(-1). Fracture specimens were recovered and used for determining Vickers microhardness. Measurements were made with a 0.1 N load and 15 second dwell time. Three microhardness measurements were made for each specimen, and the mean was used for reporting Vickers microhardness. Notched impact specimens (64×12.7×6.35 mm) were fabricated from Jet, Protemp 3 Garant, and Integrity interim restorative materials, yielding 288 impact specimens. Impact strengths were assessed at 10 days, 30 days, 6 months, and 1 year with a 2 J pendulum. The effects of the various experimental treatments were determined and rank ordered with analysis of variance, F ratios, and least square means differences Student t tests (α=.05).
All experimental treatments investigated had significant effects on flexural strength, with material (P<.001) and thermocycling (P<.001) being dominant. Moreover, all experimental treatments investigated had a significant overall impact on Vickers microhardness with material (P<.001) and Palaseal glaze (P<.001) showing large effects. Material (P<.001) and age (P=.010) had a significant effect on impact strength.
Mechanical properties of some interim polymeric materials can be improved by postpolymerization heat treatments or surface glazing. This procedure may extend the useful lifetime of some bis-acryl interim restorations.
由于基于聚合物的临时修复材料强度较弱，即使制作精良的修复体有时也会在最终修复体准备好插入之前失败。因此，了解哪些制作工艺和使用条件会影响机械性能非常重要，尤其是在较长时间内。
本研究的目的是评估热处理、表面密封、热循环、储存介质、储存温度和老化对自凝聚甲基丙烯酸甲酯和双丙烯酸酯临时修复材料的影响。结果指标为弯曲强度、维氏表面显微硬度和冲击强度。
评估了聚甲基丙烯酸甲酯（Jet Acrylic）和两种双丙烯酸酯复合树脂（Protemp 3 Garant和Integrity）临时修复材料的弯曲强度和显微硬度，这些材料受储存介质、储存温度、储存时间、热循环、后聚合热处理或表面密封剂应用的影响。总共制作了2880个梁状试样（25×2×2毫米）。在试样制备后的10天、30天、6个月和1年进行机械性能分析。弯曲强度通过在万能试验机上使用3点弯曲试验测定，载荷传感器为1 kN，十字头速度为5.0毫米/分钟（-1）。回收断裂试样用于测定维氏显微硬度。测量时施加0.1 N的载荷，保压时间为15秒。每个试样进行三次显微硬度测量，平均值用于报告维氏显微硬度。从Jet、Protemp 3 Garant和Integrity临时修复材料制作缺口冲击试样（64×12.7×6.35毫米），共得到288个冲击试样。在10天、30天、6个月和1年时用2 J摆锤评估冲击强度。通过方差分析、F比率和最小二乘均值差异学生t检验（α = 0.05）确定各种实验处理的效果并进行排序。
所有研究的实验处理对弯曲强度均有显著影响，其中材料（P < 0.001）和热循环（P < 0.001）的影响最为显著。此外，所有研究的实验处理对维氏显微硬度均有显著的总体影响，材料（P < 0.001）和Palaseal釉（P < 0.001）的影响较大。材料（P < 0.001）和老化（P = 0.010）对冲击强度有显著影响。
一些临时聚合物材料的机械性能可通过后聚合热处理或表面上釉得到改善。此方法可能会延长一些双丙烯酸酯临时修复体的使用寿命。
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