Influence of Investment, Disinfection, and Storage on the Microhardness of Ocular Resins

Abstract

Purpose: The longevity of an ocular prosthesis is directly related to the resistance to erosion of its material. The purpose of this study was to evaluate the effects of chemical disinfection and the method of investment on the microhardness of ocular prosthesis acrylic resin. Materials and Methods: Thirty-two test specimen investments were obtained in two silicones. A segment was cut in each test specimen, and each specimen was fixed in an acrylic disk. The specimens were then polished and submitted to the first microhardness test before immersion in distilled water and incubation for 2 months. During this 2-month period, the specimens were immersed in a water bath at 37• C and were disinfected daily; half were disinfected with neutral soap and the other half were disinfected with 4% chlorhexidine gluconate. After the storage phase and disinfection, a second microhardness test was performed. The surface microhardness values for the acrylic resins were submitted to ANOVA, followed by the Tukey test. Results: The disinfection and the period of storage did not statistically influence the surface microhardness of the acrylic resin, independent of the method of investment of the specimens (Zetalabor or Vipi Sil). The investment of specimens with Zetalabor silicone presented a greater surface hardness, independent of the type of disinfection and the period of storage. Conclusions: Based on these results, we suggest that the microhardness of the resin evaluated was not influenced by the method of disinfection or the time of storage used and was affected only by the investment material.

Chromatic changes to artificial irises produced using different techniques

“…We made the samples using modified metal matrices according to the technique established by Goiato et al 23 These matrices were rectangular, measuring 30 mm length, 20 mm width, and 2 mm thickness, with a 13-mm-diameter circular demarcation in the center (Fig. 1).…”

“…[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.…”

Color stability of maxillofacial silicone with nanoparticle pigment and opacifier submitted to disinfection and artificial aging

“…31,32 The process of chemical disinfection was accomplished three times a week for 60 days. 5,27,28,32 For disinfection with Efferdent, specimens were immersed for 15 min in a container containing an effervescent tablet dissolved in 250 mL of warm water with an initial temperature of 37…”

“…5,27,28 Specimens washed with neutral soap were thoroughly scrubbed with it by hand friction for 30 s and rinsed in running water. 32 Specimens disinfected with chlorhexidine were immersed in the solution for 10 min and rinsed in running water. 31 After each disinfection procedure, all specimens were stored in a lightproof black box (no incidence of natural or artificial light), with controlled conditions of temperature (23 ± 2…”

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

“…[4][5][6][7] For these reasons, white and colorless acrylic resins are the materials of choice for these prostheses. [6][7][8][9] One of the main reasons for refabrication of ocular prostheses is color degradation. Other problems affecting ocular prostheses include changes in the superficial microhardness and flexural strength over time, which directly influence material longevity.…”