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Objectives:The present study aimed to comparatively evaluate the influence of oral rinse solutions and tooth brushing on stainability of thermoplastic tooth colored prosthetic materials, using computerized spectrophotometry before and after immersion. Materials and Methods:Fifty-six samples (Twenty-eight samples of each material); Acetal resin and polyether ether keton(PEEK) were constructed in the form of discs (10 mm in diameter and 2 mm in thickness). Samples were randomly divided into 4 subgroups (n=7) according to the oral rise solutions (chlorhexidine, benzydamine HCl, alcohol-free mouthwash) and artificial saliva as control. Simulated tooth brushing of samples for 4 min with rotary instruments was applied before immersion in mouth rinses. The mean of color values (L*,a*,b*) of each specimen were measured before and one week after exposure with a Reflective spectrophotometer.Results: regardless to staining solutions totally it was shown that Acetal resin material group recorded higher color change mean value (4.75±0.52 ∆E) than PEEK material group mean value (4.64±0.66 ∆E).The difference between both materials groups means values was statistically nonsignificant as indicated by two-way ANOVA (F=0.31, P=0.5748>0.05). On the other hand Listerine zero recorded the highest color change mean value (5.05±0.5 ∆E) followed by Tantum V solution mean value (4.91±0.37∆E) then CHX solution mean value (4.52±0.7 ∆E) while A. saliva solution recorded the lowest color change mean value (4.29±0.52 ∆E).Conclusions:1-There was a highly significant difference between alcohol free, benzydamine HCL & CHX mouth rinses. The listerine zero showed the highest value in staining potential while CHX was the lowest regarding acetal 2-Among the two thermoplastic restorative materials and although statisticaly non significant, PEEK was found to be the higher color stable material and the higher stain was taken up by acetal resin. 3-There were no significant differences between the discoloration effects of different mouth washes used in this study on PEEK material. Azza A. El-Segai, et al.

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Purpose:To evaluate the effect of simulated wear against human enamel on the surface roughness of monolithic zirconia and gold alloy under different occlusal loads. Materials and Methods:Forty rectangular plate specimens (6×6×2) mm, were prepared from monolithic zirconia (Bruxzir, n=20) and type IV gold (Begostar, n=20) forming two experimental groups. Forty premolar teeth freshly extracted for orthodontic purpose were sectioned mesio-distally and only the cusp tips of the buccal halves were used as antagonists in the wear simulation testing procedure. All of the specimens were mounted to chewing simulator with the cusp antagonists, half of them were subjected to (50000 chewing cycles under 50N load), the other half subjected to (50000 chewing cycles under 150N load) cyclic loading. Data were submitted to two-way ANOVA, and statistical significance was set at p < 0.05. Results:With low load (50 N), it was found that gold alloy group recorded statistically significant higher roughness change mean value (0.00085±0.001 Ra) than Bruxzir group mean value (-0.00079±0.0023 Ra). The difference between groups was statistically significant as indicated by student t-test (t=2.08, p=0.0492 < 0.05). While, enamel cusp antagonist of gold alloy group recorded non-statistically significant higher roughness change mean value (0.01867±0.024 Ra) than enamel cusp antagonist of Bruxzir group mean value (0.016567±0.0013 Ra). The difference between groups was statistically non-significant as indicated by student t-test (t=1.7, p=0.1043> 0.05). With high load (150 N), it was found that gold alloy group recorded statistically non-significant higher roughness change mean value (0.00135±0.0017 Ra) than Bruxzir group mean value (-0.00052±0.003 Ra). The difference between groups was statistically non-significant as indicated by student t-test (t=1.648, p=0.1135 > 0.05). While, enamel cusp antagonist of gold alloy group recorded statistically non-significant higher roughness loss mean value (0.00219±0.005 Ra) than enamel cusp antagonist of Bruxzir group mean value (-0.00021±0.005 Ra). The difference between groups was statistically non-significant as indicated by student t-test (t=1.15, p=0.2615> 0.05).Conclusions: 1. Monolithic zirconia do not become as rough as type IV gold when subjected to simulated mastication cycles at low (50 N) load, although they were not significantly different from each other at high (150 N) load. 2. Although being non-significant, there was a correlation between roughness change of both monolithic zirconia and gold substrates, and that of their enamel antagonists.(682) Khaled Haggag, et al.

Objectives:The present study aimed to comparatively evaluate the color variations of three different commercially available provisional restorative materials, using computerized spectrophotometry before and after immersion in artificial saliva and three other different mouth rinses Materials and Methods: One hundred and twenty samples (40 of each material; Revotek LC, TempSpan, Jet tooth shade) were prepared in the form of discs (10 mm diameter and 2 mm thickness), and these samples were randomly divided into 4 subgroups for the solutions; chlorohexidine, Tantum V and Oracin mouth washes and artificial saliva(n=10). The discoloration solutions were changed twice a day throughout the three weeks. The color values (L*,a*,b*) of each specimen were measured before and after exposure with a Reflective spectrophotometer.Results: regardless to staining solutions, it was shown that TempSpan material group recorded the highest color change mean value (3.68±0.39∆E) followed by Revotek LC material group mean value (1.56±0.27∆E) while Jet tooth shade material group recorded the lowest color change mean value (1.4±0.46 ∆E).on the other hand, A. saliva recorded the highest color change mean value (2.78±1.2 ∆E) followed by Tantum V solution mean value(1.72±0.31∆E) then Oracin solution mean value (1.5±0.4∆E) while CHX staining solution recorded the lowest color change mean value (1.32±0.4 ∆E). Conclusions:1-All the bis-acryl resins and PMMA-based provisional materials showed clinically perceptible color changes after exposure to oral rinses. 2-Among the three provisional restorative materials, Tempspan was found to be significantly the least color stable material and the least stain was taken up by Jet. 3-There were no significant differences between the discoloration effects of Tantum V, Oracin and Chlorohexidine mouth washes on the three tested provisional materials.