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In this study, the surface hardness of five light-cured composite resins were evaluated, namely: filled (Estelite), nanofil (AElite), unfilled (Valux Plus), hybrid (Tetric ceram), and Ormocer-based (Admira) composite resins. The microhardness values of composite specimens were measured at the top and bottom surfaces after 24 hours or 30 days of immersion in different solutions (tea, coffee, Turkish coffee, mouthwash, cola, and distilled water). Comparisons were made with univariate analysis of variance and Duncan's multiple range test. It was found that rough specimens of reinforced nano-hybrid composite material immersed in cola for 30 days had the lowest surface hardness (33.20), whereas rough specimens of hybrid composite material immersed in cola for 24 hours had the highest surface hardness (156.00). In both tea and coffee, the top surfaces tended to be harder than the bottom ones. In conclusion, the five different materials exhibited different hardnesses, and that the hardness values of composite materials were statistically different in different immersion solutions.

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Occlusal reduction, determined using a computerized analysis system, did not influence the postoperative pain in teeth diagnosed as symptomatic apical periodontitis.

The aim of this study was to determine the solubility of dental cements in artificial saliva of different pH values. A total of 180 specimens-20 specimens (20 mm diameter×1.5 mm thickness) for each dental cement-were prepared. After the specimens were weighed, they were set in the media with different pH values. After 24 hours, 72 hours, seven days, and 28 days, the specimens were taken out, dried in a desiccator, and re-weighed. Percentage of solubility at each time period was calculated as 100 per cent times weight loss divided by the initial weight of the specimen.Analysis of variance and LSD multiple comparison test were applied. It was found that cement type, storage time, and medium pH exerted statistically significant (p<0.001) effects on solubility. Among the tested cement types, zinc phosphate cement (Adhesor Carbofine) presented the highest solubility. In terms of medium pH, the cements seemed to be most stable in the medium with pH 7.

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Heat and surface treatments influenced the mechanical properties of zirconia ceramic. The biaxial flexural strength and crystalline phase of materials decreased after heat treatments.