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.

Influence of adding nanoparticles on the hardness, tear strength, and permanent deformation of facial silicone subjected to accelerated aging

“…Silicone was exposed to UV light at 60 ±3 C for the first 8 hours. In the remaining 4 hours, the water condensation procedure occurred without light at 45 ±3 C. This test was performed for 1008 hours, 5,6,8,9,11,17,26 simulating the deterioration caused by rain, moisture, and the UV rays of the sun. The tear strength specimens were ruptured and lost after the initial reading.…”

“…The greatest release of formaldehyde occurs in the first 72 hours. However, the release of the byproduct after this period continues indefinitely 6,43 and could be related to the main changes in the structure of the silicone. 30 Therefore, the nanoparticles decreased the hardness values, but they could not hinder the continuous polymerization degree of silicone.…”

“…16 Several studies have confirmed the effectiveness of nanoparticles in protecting silicone against color deterioration, since nanoparticles block the ultraviolet rays and so increase its durability. 3,5,6,[16][17][18][19][20][21][22] However, to increase material durability, other important properties should also be evaluated. 23,24 The hardness of silicone determines its flexibility and enables the prosthesis to mimic the skin texture as closely as possible, promoting greater comfort for the patient.…”

Antimicrobial activity of conventional and plant-extract disinfectant solutions on microbial biofilms on a maxillofacial polymer surface

“…[13][14][15][16] Conventional cleaning protocols involve mechanical biofilm removal (with manual toothbrushing or washing by hand with water and neutral soap), [21][22][23][24][25] effervescent solutions such as cleansing tablets, [22][23][24][25] sodium hypochlorite 0.5% to 1%, [26][27][28][29] and chlorhexidine 2% to 4%. 13,[22][23][24][30][31][32][33] However, frequent exposure to these solutions may interfere with the properties of silicone. [22][23][24][25][27][28][29]31,33,34 Thus, research is necessary to find alternative methods of disinfection using solutions that do not alter the silicone surface and that are harmless to individuals.…”

Bond strength between acrylic resin and maxillofacial silicone

“…Afterwards, the MDX 4-4210 facial silicone was weighed on a digital precision scale (BeL equipamentos Analíticos, Piracicaba, SP, Brazil) and manipulated according to the manufacturer's instructions under a controlled temperature (23±2ºC) and humidity (50±10%), in order to obtain a homogeneous mixture 15 . …”