Laboratory of Process Analysis and Plant Design, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15780, Athens, Greece.
Division of Removable Prosthodontics, University of Athens, Dental School, Athens, Greece.
Odontology. 2011 Jan;99(1):68-76. doi: 10.1007/s10266-010-0145-0. Epub 2011 Jan 27.
Physical weathering is usually responsible for the degradation of maxillofacial prosthetic elastomers and the replacement of prostheses. The purpose of this study was to investigate the effects of outdoor weathering on the physical properties of four nonpigmented facial prosthetics after 1 year of exposure. In addition, simple mathematical models were developed to correlate the measured properties with irradiation time, including parameters with physical meaning. Three different medical-grade polydimethyl siloxanes (PDMSs) and an experimental chlorinated polyethylene (CPE) were examined in this study. The samples were exposed to solar radiation for 1 year in Athens, Greece. Mechanical tests (compression and tensile) were performed using universal-type testing machine, and hardness measurements were performed with a durometer (Shore A). Thermal tests were also performed with a differential scanning calorimeter. Simple mathematical models were developed to describe the examined properties. Changes observed in the properties of examined materials, before and after the exposure, reflected the effect of weathering. More specifically, two of the silicone prosthetics (Elastomer 42, TechSIL 25) seemed to become harder and more brittle, different from the other silicone (M511) sample and the CPE sample, which became softer and more ductile. Moreover mathematical models correlate the measured properties with irradiation time, and their constants indicate that duration of exposure seems to increase the degradation. Significant changes in the mechanical and thermal properties of the examined materials were observed as a result of outdoor weathering. The effect of weathering on samples' properties was introduced through its effect on the mathematical models' parameters.
自然环境因素会导致颌面赝复体弹性体发生降解，进而需要更换修复体。本研究的目的是在 1 年的户外暴露后，调查户外环境对 4 种非着色颌面赝复体弹性体物理性能的影响。此外，还开发了简单的数学模型来关联测量性能与辐照时间，包括具有物理意义的参数。本研究中检验了 3 种不同的医用级聚二甲基硅氧烷（PDMS）和 1 种实验性氯化聚乙烯（CPE）。将样本暴露在希腊雅典的太阳辐射下 1 年。使用万能试验机进行机械测试（压缩和拉伸），并用硬度计（邵氏 A）进行硬度测量。还使用差示扫描量热仪进行了热测试。开发了简单的数学模型来描述所研究的性能。暴露前后被检材料性能的变化反映了风化的影响。具体而言，两种硅酮赝复体（Elastomer 42、TechSIL 25）似乎变得更硬更脆，与另一种硅酮（M511）样品和 CPE 样品不同，后者变得更软更具延展性。此外，数学模型将测量的性能与辐照时间相关联，其常数表明暴露时间似乎会增加降解。由于户外风化，被检材料的机械和热性能发生了显著变化。风化对样品性能的影响是通过其对数学模型参数的影响来引入的。
