Disinfection with 1% sodium hypochlorite and peracetic acid altered the properties of roughness and color of the resins.

The purpose of this study was to assess flexural strength and color alteration of acrylic resins immersed in denture cleansers for different periods of time. Rectangular specimens (65 x 10 x 3mm) made from three heat-polymerized acrylic resins (Lucitone 550, QC-20 and Triplex) were assigned to three denture cleansers groups (Bony Plus, Corega Tabs and Efferdent Plus) and a control group (immersion in water). Soaking trials of 15 min and 8 h simulated 30 days of use. Flexural strength testing was carried out with 105 specimens on a universal testing machine. Color alterations were visually assessed by examination of photographs taken from 21 specimens. Flexural strength means (in MPa) were analyzed statistically by analysis of variance and Tukey's test at 5% significance level. There were significant differences (p<0.01) among the resins Lucitone (89.439 +/- 7.962), Triplex (88.024 +/- 5.167) and QC-20 (83.379 +/- 7.153). No significant differences (p>0.05) were found either among the denture cleansers (Bony Plus = 87.693 +/- 6.943; Corega Tabs = 86.955 +/- 7.114; Efferdent Plus = 86.195 +/- 7.865 and control = 86.536 +/- 7.012) or between the soaking periods (15 min = 86.875 +/- 7.625 and 8 h = 87.432 +/- 7.355) throughout the soaking cycles simulating 30 days of use. No color alterations were identified by visual examination. The findings of this study showed that chemical denture cleansers used according to the manufacturers' specifications did not cause flexural strength alterations or color changes in heat-polymerized acrylic resins submitted to soaking cycles that simulated 30 days of use.

No abstract

Disinfection for 10 min with 1% hypochlorite and glutaraldehyde is effective in disinfecting the internal aspect of heat-polymerised acrylic resin.

The purpose of this study was to evaluate the dentin shear bond strength of four adhesive systems (Adper Single Bond 2, Adper Prompt L-Pop, Magic Bond DE and Self Etch Bond) in regards to buccal and lingual surfaces and dentin depth. Forty extracted third molars had roots removed and crowns bisected in the mesiodistal direction. The buccal and lingual surfaces were fixed in a PVC/acrylic resin ring and were divided into buccal and lingual groups assigned to each selected adhesive. The same specimens prepared for the evaluation of superficial dentin shear resistance were used to evaluate the different depths of dentin. The specimens were identified and abraded at depths of 0.5, 1.0, 1.5 and 2.0 mm. Each depth was evaluated by ISO TR 11405 using an EMIC-2000 machine regulated at 0.5 mm/min with a 200 Kgf load cell. We performed statistical analyses on the results (ANOVA, Tukey and Scheffé tests). Data revealed statistical differences (p < 0.01) in the adhesive and depth variation as well as adhesive/depth interactions. The Adper Single Bond 2 demonstrated the highest mean values of shear bond strength. The Prompt L-Pop product, a self-etching adhesive, revealed higher mean values compared with Magic Bond DE and Self Etch Bond adhesives, a total and self-etching adhesive respectively. It may be concluded that the shear bond strength of dentin is dependent on material (adhesive system), substrate depth and adhesive/depth interaction.