Statement of problem

The climate of tropical Southeast Asia includes high humidity and ultraviolet radiation that reduce the lifespan of silicone prostheses by inducing changes in their mechanical properties and color stability. Studies on the surface roughness (SR) and mechanical properties of different silicone elastomers (SEs) subjected to the natural tropical weather of Southeast Asia are lacking.

Purpose

The purpose of this in vitro study was to evaluate the SR, tensile strength (TS), and percentage elongation (% E) of different SEs subjected to outdoor weathering in the Malaysian climate.

Material and methods

Type-II dumbbell-shaped specimens (N-120) (nonweathered=15, weathered=15) were made from 3 room-temperature vulcanized (A-2000, A-2006, and A-103) and 1 heat-temperature vulcanized (M-511) silicone (Factor II). For 6 months, weathered specimens were subjected to outdoor weathering inside a custom exposure rack. Simultaneously, the nonweathered specimens were kept in a dehumidifier. Subsequently, the SR was measured with a profilometer; TS and % E were measured by using a universal testing machine. Two-way ANOVA was used to compare the means of the tested properties of the nonweathered and weathered specimens, and pairwise comparison was carried out between the silicones (α=.05).

Results

After outdoor weathering, the SR, TS, and % E were adversely affected by weathering in the Malaysian environment. Among the silicone materials, A-2000 showed the least TS changes (2.51 MPa), while A-2006 demonstrated significant changes in percentage elongation after outdoor weathering (266.5%). M-511 exhibited the highest mean value (2.50 μm) for SR changes. In addition, A-103 SE showed statistically significant differences in most pairwise comparisons for all 3 dependent variables.

Conclusions

Based on the evaluation of mechanical properties, A-103 can be suggested as a suitable silicone for maxillofacial prostheses fabricated for tropical climates. However, A-2000 can be a suitable alternative, although significant changes to surface roughness were detected after outdoor weathering.

中文翻译：

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热带户外风化对颌面有机硅表面粗糙度和力学性能的影响

问题陈述

热带东南亚的气候包括高湿度和紫外线辐射，它们会通过诱导硅胶假肢的机械性能和颜色稳定性的变化来缩短硅胶假肢的使用寿命。缺乏对东南亚自然热带气候下不同有机硅弹性体（SE）的表面粗糙度（SR）和机械性能的研究。

目的

这项体外研究的目的是评估在马来西亚气候下经受户外风化的不同 SE 的 SR、拉伸强度 (TS) 和伸长率百分比 (% E)。

材料与方法

II型哑铃形试样（N-120）（非风化=15，风化=15）由3个室温硫化（A-2000、A-2006和A-103）和1个热温硫化（ M-511) 硅胶（Factor II）。在 6 个月的时间里，风化的样品在定制的暴露架内进行户外风化。同时，将未风化的标本保存在除湿机中。随后，用轮廓仪测量 SR；TS和％E是通过使用万能试验机测量的。双向方差分析用于比较未风化和风化样品的测试性能平均值，并在有机硅之间进行成对比较（α=.05）。

结果

在户外风化之后，SR、TS ​​和 % E 受到马来西亚环境中风化的不利影响。在有机硅材料中，A-2000 的 TS 变化最小 (2.51 MPa)，而 A-2006 在户外风化后的伸长率百分比变化显着 (266.5%)。M-511 的 SR 变化平均值最高（2.50 μm）。此外，A-103 SE 在所有 3 个因变量的大多数成对比较中显示出统计学上的显着差异。

结论

基于对机械性能的评估，A-103 可被推荐为适合热带气候的颌面修复体的有机硅。然而，A-2000 可能是一个合适的替代品，尽管在户外风化后检测到表面粗糙度的显着变化。