Color and structural changes of a maxillofacial elastomer: The effects of accelerated photoaging, disinfection and type of pigments

Purpose: The aim of this study was to investigate the color and structural changes of a maxillofacial silicone colored with 2 different pigments, after photoaging and immersion in disinfectants. Methods: Ninety-six cylindrical specimens were fabricated and divided into 3 equal groups. The specimens of the first group consisted of unpigmented silicone (Multisil Epithetik), those of the second group consisted of unpigmented silicone, colored with red functional liquid pigment (Cosmesil Reactive 0.2% wt). The specimens of the third group were fabricated using unpigmented silicone colored with red powder pigment Cosmesil Dry at 0.2% wt. Specimens of each group were divided into 4 equal subgroups (immersed in soap solution, ethanol 95° or distilled water or placed in a photoaging apparatus for 174 hours). Structural changes were examined by infrared spectroscopy (ATR-FTIR) before and after aging. Color changes (ΔE*) were measured using the CIE L*a*b* system. Two-way ANOVA and Tukey’s test for post hoc comparison were used at a = 0.05. Results: Infrared spectroscopy showed no structural changes after immersion in solutions and photoaging, for all the materials tested. No statistically significant differences for ΔE* among the tested groups were found. Conclusions: It can be concluded that no structural changes of pigmented and unpigmented silicone elastomers were observed among all aging procedures. Recorded color changes for the materials tested were within the limits of clinical acceptability after all aging procedures. Immersion in distilled water presented the best color stability, whereas photoaging, the poorest, for all materials. © 2015 Wichtig Publishing

Dynamic mechanical properties of a maxillofacial silicone elastomer incorporating a ZnO additive: The effect of artificial aging

The main objective of the current study was to investigate the dynamic mechanical properties of a room-temperature vulcanizing silicone incorporating different fractions of zinc oxide (ZnO) after indoor and outdoor photoaging. Forty-eight samples were produced by adding different amounts of ZnO into a commercial maxillofacial silicone (EPISIL-E). The samples were divided into 4 groups containing 0.0, 0.2, 0.5, and 1 wt% ZnO additive, respectively. Samples were exposed to sunlight (subgroup 2), ultraviolet (subgroup 3), and fluorescence (subgroup 4) aging, whereas nonaged samples comprised the control subgroup (subgroup 1). Dynamic mechanical analysis was used to determine the storage modulus (E′), loss modulus (E″), and damping capacity (tanδ). General linear statistic model was conducted to evaluate the effects of aging, testing frequency, and composition on the dynamic mechanical properties of the silicone with the ZnO additive. Post hoc analysis was performed using Tukey test. Statistical analysis revealed a significant impact of composition on tanδ (P < 0.05). Aging influenced E′ and E″ (P < 0.01). The combination of aging and composition had a significant effect on all dynamic properties (P < 0.01). Copyright © 2010 by Mutaz B. Habal, MD