Chromatic stability of acrylic resins of artificial eyes submitted to accelerated aging and polishing

Abstract

Esthetics and durability of materials used to fabricate artificial eyes has been an important eissue since artificial eyes are essential to restore esthetics and function, protect the remaining tissues and help with patients' psychological therapy. However, these materials are submitted to degrading effects of environmental agents on the physical properties of the acrylic resin.ObjectiveThis study assessed the color stability of acrylic resins used to fabricate sclera in three basic shades (N1, N2 and N3) when subjected to accelerated aging, mechanical and chemical polishing. Material and methodsSpecimens of each resin were fabricated and submitted to mechanical and chemical polishing. Chromatic analysis was performed before and after accelerated aging through ultraviolet reflection spectrophotometry. ResultsAll specimens revealed color alteration following polishing and accelerated aging. The resins presented statistically significant chromatic alteration (p<0.01) between the periods of 252 and 1008 h. ConclusionsBoth polishing methods presented no significant difference between the values of color derivatives of resins.

Chromatic changes to artificial irises produced using different techniques

“…We polymerized the resin in a microwave oven (Brastemp, SP, Brazil) at 60% maximum power (1400 W) for 3 min. 23,24 After polymerizing the resin, we opened the muffle again and removed the silicon that had filled the mold of the ocular cap to be pressed into each artificial iris button. We produced the artificial iris by painting a brown-colored oil paint (Acrilex Tintas Especiais SA, SP, Brazil) onto disks of black cardboard or onto the planar surface of the ocular cap (inverted painting), both with a diameter of 13 mm, during the same period and under the same lighting conditions, using an n.0 ref.…”

“…[16][17][18][19][20] With the aim of increasing the stability of the prosthesis color in the face of aging caused by the artificial iris paint exposure to environmental factors and minimizing the effects of the polymerization process, the use of prefabricated caps has won favor over other techniques of ocular prosthesis production. 17,[21][22][23][24] In conjunction with this technique, a protective varnish can be applied over the paint of the artificial iris to reduce chromatic changes. 2,17 In light of the aforementioned factors, this study's goal was to analyze the stability of the color of artificial iris buttons obtained by conventional painting techniques relative to those produced by inverted painting on a prefabricated cap or by conventional painting under the prefabricated cap, with or without the use of a protective varnish, after application of colorless acrylic resin over the paint.…”

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

“…This dispersion event leads to rupture and photochemical degradation of the molecule, which contributes to material degradation, color or brightness changes, loss of opacity, cracks, and increased stiffness. [31][32][33] Extrinsic factors (eg, absorption or adsorption of external substances) 32,34 and intrinsic factors (eg, matrix alterations, which are very common with aging) 35 may also have contributed to the observed color changes. 36,37 In general, the samples incorporating NPs showed significantly greater color stability compared with the control group ( Table 2).…”

Desenvolvimento e avaliação colorimétrica de íris digitalizada obtida através de impressão em etiqueta autocolante e em adesivo

“…A polimerização promoveu um efeito estatisticamente significativo sobre a estabilidade de cor da íris para todas as técnicas de pintura, em comparação com todos os períodos de envelhecimento acelerado. Depois de envelhecimento acelerado a técnica de pintura a óleo mostrou a estabilidade maior de cores melhor que com imagem digital (Goiato et al, 2010a).…”

“…Concluíram que a técnica de pintura a óleo mostrou a estabilidade maior de cores após o envelhecimento acelerado, comparada a técnica através impressão de imagens digitais (Goiato et al, 2010a).…”