Hardness evaluation of prosthetic silicones containing opacifiers following chemical disinfection and accelerated aging

Abstract

We evaluated the effects of disinfection and aging on the hardness of silicones containing opacifiers and intended for use in facial prosthetics. A total of 90 samples were produced using a cylindrical metal mold 3 mm in height and 30 mm in diameter. The samples were fabricated from Silastic MDX 4-4210 silicone in three groups: GI contained no opacifier, GII contained barium sulfate (Ba), and GIII contained titanium dioxide (Ti). The samples were disinfected using effervescent tablets (Ef), neutral soap (Ns), or 4% chlorhexidine (Cl) 3 times a week for 60 days. After this period the samples underwent 1,008 hours of accelerated aging. The hardness was measured using a durometer immediately following the disinfection period and after 252, 504, and 1,008 hours of aging. The data were statistically analyzed using 3-way ANOVA and the Tukey test (p < .05). The GIII group exhibited the greatest variation in hardness regardless of elapsed time. All groups displayed greater hardness after 1,008 hours of accelerated aging independent of disinfectant type. All of the hardness values were within the clinically acceptable range.

Dynamic Mechanical Thermal Analysis of Maxillofacial Prosthetic Elastomers

“…38,45 The decrement of Tg values could be associated with decreased density of cross-links after disinfection procedures or chain scissions due to continuous polymerization of elastomer or absorption phenomena. Goiato et al 11,24 have reported possible increment in cross-linking density after disinfecting silicone maxillofacial elastomers using neutral soap and effervescent denture cleanser tablets. However, a decrement in elastic modulus has also been reported after using an antimicrobial solution, probably caused by chain-scission mechanisms.…”

“…16 Other disinfection solutions such as neutral soap, hypochlorites, and microwave treatment can apply. 2,11 Hypochlorites have been widely used for denture base and lining materials, and no detrimental effects have been recorded, especially when using solutions containing lower percentages of hypochlorite. 17 However, sodium hypochlorite has not been recommended as a disinfecting solution in maxillofacial elastomers because it could affect their physical properties.…”

Influence of nanoparticles on color stability, microhardness, and flexural strength of acrylic resins specific for ocular prosthesis

“…16,54 Ultraviolet light, humidity, and heat caused polymer degradation by altering the color stability, microhardness, and flexural strength of N1 acrylic resin. Accelerated aging may have caused degradation of the organic resin matrix, involving hydrolysis and decomposition of the polymeric chain.…”

“…Several studies have found satisfactory results by incorporating nanoparticles (NPs) into polymeric materials (mainly silicone elastomers used for facial prostheses), in terms of protecting such materials from degradation. [10][11][12][13][14][15][16] Research has…”

“…In the cosmetic industry, BaSO 4 is used in sunscreen lotions to create a physical barrier against ultraviolet rays and to provide a better product appearance. 15,16 In addition to improving polymer properties, it has been suggested that incorporating NPs into an organic polymer could provide resistance to environmental stress-related cracking and aging. 23 However, to date, no study has been performed to examine the influence of NPs on the physical and mechanical properties of acrylic resins specific for artificial sclera.…”