Effect of opacifiers and UV absorbers on pigmented maxillofacial silicone elastomer, part 2: Mechanical properties after artificial aging

• Published in: The Journal of prosthetic dentistry 2013-06, Vol.109 (6), p.402-410
• Main Authors: Nguyen, Caroline Tram, DMD, MS, Chambers, Mark S., DMD, MS, Powers, John M., PhD, Kiat-amnuay, Sudarat, DDS, MS
• Format: Article
• Language: English
• Subjects: Coated Materials, Biocompatible; Colorimetry; Dentistry; Elasticity; Hardness; Materials Testing; Maxillofacial Prosthesis; Mechanical Phenomena; Prosthesis Coloring; Shear Strength; Silicone Elastomers; Sunscreening Agents; Tensile Strength; Time Factors; Ultraviolet Rays
• ISSN: 0022-3913; 1097-6841
• DOI: 10.1016/S0022-3913(13)60328-5

Statement of problem 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. Purpose 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. Material and methods 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 . 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. Results 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