Background and aims. Remineralization of incipient caries is one of the goals in dental health care. The present study aimed at comparing the effects of casein phosphopeptide-amorphous calcium phosphate complex (CPP-ACP), Remin Pro®, and 5% sodium fluoride varnish on remineralization of enamel lesions.Materials and methods. In this in vitro study, 60 enamel samples were randomly allocated to six groups of 10. After four days of immersion in demineralizing solution, microhardness of all samples was measured. Afterward, groups 1-3 underwent one-time treatment with fluoride varnish, CPP-ACP, and Remin Pro®, respectively. Microhardness of groups 4-6 was measured not only after one-month treatment with the above-mentioned materials (for eight hours a day), but also after re-exposing to the demineralizing solution. The results were analyzed by one-way analysis of variance (ANOVA), repeated measures ANOVA, and Fisher’s least significant difference (LSD) test.Results. None of the regimens could increase microhardness in groups 1-3. However, one-month treatment regimens in groups 4-6 caused a significant increase in microhardness. The greatest microhardness was detected in the group treated with CPP-ACP (P = 0.001). In addition, although microhardness reduced following re-demineralization in all three groups, the mean reduction was minimum in the CPP-ACP-treated group (P < 0.001).Conclusion. While long-term repeated application of all compounds improved microhardness, the remineralization potential of CPP-ACP was significantly higher than that of Remin Pro® and sodium fluoride varnish.
ObjectiveThe purpose of this study was to assess the effect of food-simulating liquids on the flexural strength of a methacrylate-based and a silorane-based resin composite.Materials and methodsIn this in vitro study, sixty specimens of Filtek P90 and Filtek Z350 composite were prepared in a customized mold (2 × 2 × 25 mm). The specimens of each composite were divided into five subgroups as follows: one as a control group and the other four groups included distilled water, heptane, 2% citric acid, and 50% aqueous ethanol. The specimens were stored in the solutions for one week at 37°C, and the control group was stored at room temperature for the same period of time. Then, flexural strength values were measured. The statistical analysis was performed by One-Way ANOVA, Paired T test and post hoc LSD at a significance level of 0.05.ResultsIn the control group, the mean flexural strength of Filtek P90 and Filtek Z350 were 155.1 MPa and 147.3 MPa, respectively, and there was no significant difference (P-value>0.05). The mean flexural strength of Filtek P90 and Filtek Z350 significantly decreased in ethanol (P-value <0.05). Immersion in 0.02 N citric acid and heptane had no significant effect on the flexural strength of Filtek P90 and Filtek Z350. The maximum flexural strength of Filtek P90 was in the heptane group (192.6 MPa) and minimum flexural strength was in ethanol group (92.7 MPa) the maximum flexural strength of Filtek Z350 was in the heptane group (163.2 MPa) and minimum flexural strength was in the ethanol group (104.7 MPa).ConclusionThe flexural strength of tested resin composites significantly affected by ethanol solution. The flexural strength of resin composites was not affected by other food simulating liquids.
Background: This study was designed to quantitatively compare the presence of apatite peaks on demineralized dentin to induced bio-mimetically by bioactive commercial materials. Material and Methods: Dentin slice specimens (n=6) were prepared and demineralized by by17% EDTA for 2 hours. Each disks materials (Theracal, Biodentine, CPP-ACP) were freshly prepared and was maintained in close contact with a demineralized dentin specimen immersed in PBS solution during one week. To evaluation of bioactivity, cements disks (n=6) were prepared from each material and immersed in PBS solution for one week. The bioactivity and remineralization ability was evaluated using FTIR spectroscopy and Scanning Electron Microscopy. The Ca/P ratio of the surface of dentin and cements disks were compared with one -way ANOVA, independent T test and Duncan test (α=0.05). Results: Ca/P weight ratio of Biodentine (187.5) was significantly higher than Theracal (10.10) and Theracal higher than CPP-ACP (0.37) (P=0.008). Demineralized dentin in contact with Test materials, indicated Ca and P peak after 7 days, but not showed statistically differences between the groups (P=0.08). Conclusions: The outcome revealed that bioactive cements and CPP-ACP had bioactivity capability during one week. Biodentine had higher bioactivity between others. Demineralized dentin could be remineralized with bioactive materials.
Aim: This study was conducted to evaluate the effect of ceramic thickness on the surface hardness of light-cured and dual-cured resin cements. Materials and methods: Forty disk-like specimens of the dual-cured resin cement and twenty-four specimens of the light-cured resin cement were prepared (with 6 mm diameter and 1mm thickness). The samples were light-cure d for 40 seconds through three different ceramic disks (2 mm, 3 mm and 4 mm). Control specimens from each group were directly polymerized under a Mylar strip. In the control group of the dualcured resin cement, the cement setting was realized by chemical reaction alone. After storing dry in darkness (24 hours, 37°C), the surface hardness of the specimens was measured using the Vickers microhardness test. Data were statistically analyzed using a two-way analysis of variance (ANOVA) followed by the LSD's test (p <0.05). Results: BisCem resin cement which had been dual-cured under the 4 mm thickness ceramic with the 4.3 Vickers hardness, showed minimum surface microhardness, while the light-cured resin cement which had been directly activated in the control group with the 51.8 Vickers hardness value exhibited the maximum surface microhardness. So, BisCem dual polymerized control specimens had significantly higher hardness values in comparison to the chemically polymerized and indirectly activated ones (p <0.001). Conclusion:An increase in the thickness of ceramic could decrease the hardness of the resin cement. An overlying ceramic thickness of 3 mm and above was found to adversely affect the polymerization of the LC and DC resin cement and it was considered as the clinical threshold. In addition, using only the self-cured mode in the dual-cured resin cement was not sufficient for achieving the optimum surface microhardness. clinical significant: Adequate polymerization of resin cement is essential for the optimal mechanical properties and clinical performance. It affects by increasing the thickness of ceramic restorations.
Cements with minimum shrinkage and as thin layer as possible should be used. Filling the undercut with glass ionomer cement decreases the stress. Other experimental and clinical studies must follow this research.
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