RESUMO
BACKGROUND: Detachment of denture acrylic resin artificial teeth from denture base resin is one of the most common problems presented by denture wearers. PURPOSE: This study investigated the shear bond strength (SBS) and fracture type of bonding interface of two commercial acrylic teeth (Vipi Dent Plus e Biolux) to two denture base resins (Vipi Cril e Lucitone 550) after immersion in potentially chromogenic beverages (coffee, cola soft drink, and red wine) or control solution (distilled water). MATERIALS AND METHODS: Maxillary central incisor acrylic teeth were placed at 45° to denture base resin and submitted to short polymerization cycle according to manufacturers. Specimens were divided according to the combination tooth/resin/solution (n = 8) and submitted to bond strength tests in a universal testing machine MTS-810 (0.5 mm/min). Subsequently, fracture area was analyzed by stereomicroscope at a magnification of ×10 and categorized into adhesive, cohesive, or mixed failure. RESULTS: The bond strength of teeth/denture base resins interface was not significantly affected by tested solutions (P > 0.087), except for Biolux teeth immersed in coffee (P < 0.01). In all conditions, the Vipi Dent Plus teeth showed higher bond strength to Lucitone and Vipi Cril resins when compared to Biolux teeth (P < 0.003). All specimens' failure modes were cohesive. CONCLUSIONS: The SBS of acrylic teeth to denture base resins was not generally influenced by immersion in the tested staining beverages.
RESUMO
The purpose of this study was to determine the antifungal efficacy of 4% chlorhexidine (CHX) and 2% sodium hypochlorite (NaOCl) on 24-hour Candida albicans biofilms. Candida albicans biofilms were developed on acrylic resin specimens, which were randomly assigned to 1 of 5 groups (n = 3 per group) exposed to 1 mL of 4% CHX for 2, 4, 6, 8, or 10 minutes. Biofilms in contact with 1 mL of distilled water or 2% NaOCl for 10 minutes were used as positive and negative controls (n = 3 per group), respectively. Specimens were analyzed with confocal laser scanning microscopy and a cell viability assay technique. The biovolume of the live subpopulation of the biofilm was calculated with biofilm image analysis software. Statistically significant differences (P < 0.05) in the biovolume of surviving cells were found among the positive control group and the 4-, 6-, 8-, and 10-minute experimental periods. The biovolumes found after 6-10 minutes of exposure to chlorhexidine were significantly different (P < 0.05) from the biovolume after 2 minutes of exposure. The most effective decrease of the biovolume was found after the use of the negative control (sodium hypochlorite) solution. Exposure to 10 minutes of 2% NaOCl removed fungal cells more effectively than all the experimental groups (P < 0.05). The 4% CHX solution showed an antifungal activity against C albicans biofilms but failed to decrease the biovolume to the levels of 2% NaOCl, which eliminated viable cells more effectively and appeared to be more effective in disrupting the attached biofilms.