Department of Oral Health Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, BC, Canada.
J Prosthet Dent. 2013 Jun;109(6):402-10. doi: 10.1016/S0022-3913(13)60328-5.
There are reports of dissatisfaction with color instability and reduced lifetime of extraoral maxillofacial prostheses. Previous studies showed that UV mineral-based light-protecting agent (LP) improved color stability of MDX4-4210/Type A silicone elastomer. However, effects of this agent and opacifiers on mechanical properties of the elastomer are unknown.
The purpose of this study was to evaluate the effect of 2 commonly used opacifiers and LP, a new opacifier, when combined with pigments on the mechanical properties of MDX4-4210/Type A silicone elastomer before and after artificial aging.
Two commonly used opacifiers, titanium white dry pigment (TW) and silicone intrinsic white (SW) and LP were each combined with MDX4-4210/type A. Artists' oil pigment was then combined with the LP and TW groups, and silicone intrinsic pigments were combined with the SW group with 5 colors (no pigment=control, red, yellow, blue, or a combination of the 3 pigments). Ten dumbbell-shaped and 10 trouser-shaped specimens of each opacifier + pigment mixture, plus a control group with no opacifier and no pigment, were made for a total of 320 specimens. Half of the specimens (n=5) were aged in a chamber at 450 kJ/m(2). Specimens were tested for hardness (ASTM D2240), tensile strength (ASTM D412), tear strength (ASTM D624), and percentage elongation in a universal testing machine. A 3-way ANOVA and the Fisher PLSD test were performed (α=.05) for each mechanical property.
After accelerated aging, values of Shore A hardness were the lowest for LP with all 5 pigments and the control, followed by SW and TW (P<.001). After accelerated aging, tear strength, tensile strength, and elongation decreased significantly (P<.001) for LP, whereas changes for SW and TW varied depending on the pigment.
The mechanical properties of specimens with the light-protecting opacifier were adversely affected after being subjected to artificial aging. SW and TW preserved the mechanical properties of silicone in this study.
有报道称，口腔颌面赝复体的颜色稳定性和使用寿命不满意。先前的研究表明，UV 矿物基光保护剂（LP）提高了 MDX4-4210/A 型硅橡胶的颜色稳定性。然而，该剂和不透明剂对弹性体力学性能的影响尚不清楚。
本研究的目的是评估两种常用的不透明剂和 LP（一种新的不透明剂）与颜料结合使用对 MDX4-4210/A 型硅橡胶人工老化前后力学性能的影响。
将两种常用的不透明剂钛白粉干颜料（TW）和硅酮内白（SW）与 LP 分别结合，然后将艺术家油颜料与 LP 和 TW 组结合，将硅酮内颜料与 SW 组结合，颜色为 5 种（无颜料=对照、红、黄、蓝或 3 种颜料的组合）。每组不透明剂+颜料混合物各制作 10 个哑铃形和 10 个裤形试件，外加无不透明剂和无颜料的对照组，共 320 个试件。将一半试件（n=5）在 450kJ/m2 的腔室内老化。在万能试验机上测试硬度（ASTM D2240）、拉伸强度（ASTM D412）、撕裂强度（ASTM D624）和伸长率。对每种力学性能进行三因素方差分析和 Fisher PLSD 检验（α=0.05）。
加速老化后，含所有 5 种颜料和对照组的 LP 的邵氏 A 硬度值最低，其次是 SW 和 TW（P<.001）。加速老化后，LP 的撕裂强度、拉伸强度和伸长率显著降低（P<.001），而 SW 和 TW 的变化取决于颜料。
经人工老化后，含光保护不透明剂的试件力学性能受到不利影响。SW 和 TW 在本研究中保持了硅橡胶的力学性能。
