Polychronakis Nick, Sarafianou Aspasia, Zissis Alcibiadis, Papadopoulos Triantafillos
Removable Prosthodontics, Dental School, National and Kapodistrian University of Athens, Greece.
Department of Prosthodontics, Dental School, National and Kapodistrian University of Athens, Greece.
Acta Stomatol Croat. 2017 Dec;51(4):309-315. doi: 10.15644/asc51/4/5.
The aim of the present study was to evaluate the influence of thermocycling on the flexural strength of a polyamide base denture material.
A polyamide denture base material (Valplast) was tested, whereas a PMMA material (Vertex) was used as a control. Thirty specimens of each material were fabricated for flexural strength testing according to ISO 1567. They were prepared and stored in water at 37°C for 48 hours. The specimens of each material were divided into three equal groups (n=10). Flexural strength testing was performed immediately after water storage and after thermocycling (5°C / 55°C, 2 c/min) for 3000 and 5000 cycles. A three point flexural test was performed on a universal testing machine at a crosshead speed of 5 mm/min. The final flexural strength was calculated using the formula: F = 3 PL/2 bd. A two-way ANOVA with post-hoc analysis using Tukey's procedure was applied at .05 level of statistical significance.
A statistically significant reduction in flexural strength was recorded after thermocycling at 3000 cycles for PMMA and at 5000 cycles for both materials. The flexural strength of PMMA was significantly higher compared to polyamide for all the conditions tested (p<0.05).
Thermocycling had a significant adverse effect on the flexural strength of polyamide and PMMA denture base materials.
本研究旨在评估热循环对聚酰胺基托义齿材料弯曲强度的影响。
测试一种聚酰胺义齿基托材料（Valplast），同时使用一种聚甲基丙烯酸甲酯材料（Vertex）作为对照。根据ISO 1567制备每种材料的30个试样用于弯曲强度测试。将它们制备好并在37°C水中储存48小时。每种材料的试样分为三个相等的组（n = 10）。在储水后以及热循环（5°C / 55°C，2℃/分钟）3000次和5000次后立即进行弯曲强度测试。在万能试验机上以5毫米/分钟的十字头速度进行三点弯曲试验。使用公式F = 3PL / 2bd计算最终弯曲强度。采用Tukey法进行事后分析的双向方差分析，统计学显著性水平为0.05。
对于聚甲基丙烯酸甲酯，热循环3000次后以及对于两种材料热循环5000次后，弯曲强度均有统计学意义的降低。在所有测试条件下，聚甲基丙烯酸甲酯的弯曲强度均显著高于聚酰胺（p < 0.05）。
热循环对聚酰胺和聚甲基丙烯酸甲酯义齿基托材料的弯曲强度有显著不利影响。
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