Influence of Pigment and Opacifier on Dimensional Stability and Detail Reproduction of Maxillofacial Silicone Elastomer

Abstract

We evaluated the influence of chemical disinfection and accelerated aging on the dimensional stability and detail reproduction of a silicone elastomer containing an opacifier and/or a pigment. A total of 120 samples were fabricated from Silastic MDX 4-4210 silicone and divided into groups (n - 10) according to pigment and/or opacifier (ceramic powder and/or barium sulfate) and disinfectant solution (neutral soap, Efferdent, or 4% chlorhexidine). The specimens were disinfected 3 times per week during 60 days and then subjected to accelerated aging for 1008 hours. Dimensional stability and detail reproduction tests were performed after specimens' fabrication (baseline) and chemical disinfection and periodically during accelerated aging (252, 504, and 1008 hours). The results were analyzed using 3-way repeated-measures analysis of variance and the Tukey Honestly Significant Difference test (a = 0.05). All groups exhibited dimensional changes over time. The disinfectant, pigment, and time (P < 0.0001) affected the dimensional stability of silicone. Statistically significant dimensional differences were not observed between the tested groups. Accelerated aging influenced the dimensional stability of the samples. All groups scored 2 in the detail reproduction tests, which represents the full reproduction of 3 test grooves with accurate angles. Incorporation of opacifier and/or pigment alters the dimensional stability of silicones used in facial prosthetics but seems to have no influence on detail reproduction. Accelerated aging is responsible for most of the dimensional changes in Silastic MDX4 4210, but all dimensional changes measured in this study remained within the limits of stability necessary for this application.