Evaluation of Staphylococcus spp adhesion ocular prosthesis acrylic resin and chromatic change of artificial iris buttons fabricated with different techniques and colors after chemical disinfection

Abstract

Considering that ocular prostheses restore esthetics and patient's self-esteem, the materials used for prosthesis fabrication should present appropriate properties regarding indication and reliability after the disinfection procedures. So, the aim of this study was to assess the effectiveness of different disinfectant solutions against two species of Staphylococcus spp. cultured on ocular prosthesis acrylic resin. In addition, the chromatic change of artificial iris buttons fabricated with different techniques was also evaluated before and after polymerization and disinfection. For the microbiology tests acrylic specimens were fabricated (1.0 cm in diameter and 0.3 cm in thickness) and divided according to disinfection solution used: distilled water for 10, 15, 30 min and 6 h (control-CTL); treated with neutral soap (NES) for 30 min; treated with Opti-FreeÒ (OPT) for 30 min and 6 h; treated with EfferdentÒ (EFF) for 15 min; and treated with (0.5%, 2% and 4%) chlorhexidine gluconate (CHX) for 10 min. Biofilm cultures were formed on liner surface for three different points: initial (24h), intermediate (48h) and mature (72h), and then the specimens were randomly assigned to one of disinfectant treatments. After the treatments, the specimens were vortexed to disrupt the biofilm, and residual cells were counted (cell/mL). For the color meansurations a total of 150 samples simulating ocular prosthesis were fabricated with blue artificial irises while 150 samples were fabricated with brown irises. For each color, 50 samples were fabricated according to one of the following techniques: PE - conventional technique, CA - prefabricated cap, and PI - inverted painting. A total of 10 specimens of each technique was submitted to disinfection with neutral soap (NES), Opti-Free (OPF) and 4% chlorhexidine (CHX). The control samples remained immersed in saline solution (C1) or exposed to dry environment (C2). The disinfection was conducted for 240 days and the disinfected samples remained immersed in saline during this period. Chromatic change was measured using a spectrophotometer according to the CIE L*a*b system before polymerization of the colorless resin (B1); after sample fabrication (B2); and after 60 (T1), 120 (T2) and 240 (T3) days of disinfection and storage. The chromatic change (”E) was calculated between the periods B2 and B1 (B2B1), T1 and B2 (T1B2), T2 and B2 (T2B2), and T3 and B2 (T3B2). The results were analyzed using analysis of variance (ANOVA) and Tukey-Kramer test (±=0.05). There was significant reduction (P<0.001) of cells counting for the treatments with CHX during 10 minutes and EFF during 15 minutes in comparison to the control groups of each strain in all periods of biofilm development. The treatment with 4% CHX during 10 minutes presented high antimicrobial activity against Staphylococcus spp. in all periods of biofilm culture (P<0.0001). For chromatic change, all samples presented alteration in artificial iris button color after polymerization of the colorless resin, disinfection and storage. Considering the analysis after polymerization of the colorless resin, the artificial iris buttons fabricated with the CA technique showed the highest values of chromatic change (P<0.05) for both colors. For the brown irises, the PI samples presented the lowest values of chromatic change (P<0.05). Considering the chromatic change during disinfection and storage, the PE and CA samples exhibited greater stability for both colors. The artificial iris buttons disinfected with CHX showed significantly higher values of chromatic change in comparison to the other disinfectant solutions and control groups for both colors. It was concluded that the disinfectants with alkaline peroxide and chlorhexidine gluconate were effective against Staphylococcus spp. biofilm cultured on the acrylic resin during all periods of biofilm culture. In addition, there was significant difference in chromatic change after disinfection and storage of artificia