Abstract
This study evaluated color stability, surface roughness and flexural strength of acrylic resin after immersion in alkaline peroxide and alkaline hypochlorite solutions, simulating a five-year-period of use. Sixty disc-shaped (16 x 4 mm) and 60 rectangular specimens (65 x 10 x 3.3 mm) were prepared from heat-polymerized acrylic resin (Lucitone 550) and assigned to 3 groups (n = 20) of immersion (20 min): C1: distilled water; AP: warm water and one alkaline peroxide tablet; SH: 0.5% NaOCl solution. Color data (∆E) were determined by a colorimeter and also quantified according to the National Bureau of Standards units. A rugosimeter was used to measure roughness (μm) and the flexural strength (MPa) was measured using a universal testing machine. Data were evaluated by Kruskal-Wallis followed by Dunn tests (color stability and surface roughness) and by one-way ANOVA and Bonferroni test (flexural strength). For all tests was considered α = 0.05. AP {0.79 (0.66;1.42)} caused color alteration significantly higher than C1 {0.45 (0.37;0.57)} and SH {0.34 (0.25;0.42)}. The mean ∆Ε values quantified by NBS were classified as "trace" for C1 (0.43) and SH (0.31) and "slight" for AP (0.96). SH {-0.015 (-0.023;0.003)} caused significantly higher ΔRa than the C1 {0.000 (-0.004;0.010)} and AP {0.000 (-0.009;0.008)} groups. There was no statistically significant difference among the solutions for flexural strength (C1: 84.62 ± 16.00, AP: 85.63 ± 12.99, SH: 84.22 ± 14.72). It was concluded that immersion in alkaline peroxide and NaOCl solutions simulating a five-year of 20 min daily soaking did not cause clinically significant adverse effects on the heat-polymerized acrylic resin.
Highlights
The main chemical method of complete denture cleaning consists in immersing the prosthetic devices in solutions with solvent, detergent, antibacterial and antifungal actions [1]
Some studies indicated that the association of alkaline peroxide to brushing improved the effectiveness of hygiene [7,8]
The authors highlighted the importance of evaluating the adverse effects when such solutions are employed for longer periods of immersion, since damage to denture base materials may accumulate. Another important factor is the use of a short cycle immersion, which consists in a common hygiene routine among denture wearers, considering that an efficient immersion time is a denture cleanser request [2]
Summary
The main chemical method of complete denture cleaning consists in immersing the prosthetic devices in solutions with solvent, detergent, antibacterial and antifungal actions [1]. Flexural strength and surface roughness alterations of denture resins were evaluated after immersion in peroxide and NaOCl solutions at 0.05%, 0.5% and 1%, but in simulated periods of 7, 90, 180 and 365 days of use [4,9,10,11,12,13,14]. The authors highlighted the importance of evaluating the adverse effects when such solutions are employed for longer periods of immersion, since damage to denture base materials may accumulate Another important factor is the use of a short cycle immersion, which consists in a common hygiene routine among denture wearers, considering that an efficient immersion time is a denture cleanser request [2]. The work hypothesis was that the immersion in denture cleansers would not influence these properties of the acrylic resin
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