ABSTRACT
Abstract Objective To evaluate the amount of methyl methacrylate (MMA) released in water from heat-cured polymethyl methacrylate (PMMA) denture base materials subjected to different cooling procedures. Methodology Disk-shaped specimens (Ø:17 mm, h:2 mm) were fabricated from Paladon 65 (PA), ProBase Hot (PB), Stellon QC-20 (QC) and Vertex Rapid Simplified (VE) denture materials using five different cooling procedures (n=3/procedure): A) Bench-cooling for 10 min and then under running water for 15 min; B) Cooling in water-bath until room temperature; C) Cooling under running water for 15 min; D) Bench-cooling, and E) Bench-cooling for 30 min and under running water for 15 min. A, B, D, E procedures were proposed by the manufacturers, while the C was selected as the fastest one. Control specimens (n=3/material) were fabricated using a long polymerization cycle and bench-cooling. After deflasking, the specimens were ground, polished and stored in individual containers with 10 ml of distilled water for seven days (37oC). The amount of water-eluted MMA was measured per container using isocratic ultra-fast liquid chromatography (UFLC). Data were analyzed using Student's and Welch's t-test (α=0.05). Results MMA values below the lower quantification limit (LoQ=5.9 ppm) were registered in B, C, E (PA); E (PB) and B, D, E (QC) procedures, whereas values below the detection limit (LoD=1.96 ppm) were registered in A, D (PA); A, B, C, D (PB); C, D, E (VE) and in all specimens of the control group. A, B (VE) and A, C (QC) procedures yielded values ranging from 6.4 to 13.2 ppm with insignificant differences in material and procedure factors (p>0.05). Conclusions The cooling procedures may affect the monomer elution from denture base materials. The Ε procedure may be considered a universal cooling procedure compared to the ones proposed by the manufacturers, with the lowest residual monomer elution in water.
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Objective: To compare the water absorption values, solubility values and monomer release amounts of six kinds of light curing composite resins and explore the influencing factors, and to elucidate their relationships with the material compositions and the immersing solvent. Methods: The water absorption and solubility values of six kinds of composite resins, including FiltekTM Z250(Z250), FiltekTM Z350 XT (Z350), Aelite LS Posterior (ALS), CLEARFIL MAJESTY Posterior (CMP), Neofil Nano (NN), and Tetnc N-Ceram (TNC), were measured according to ISO 4049-2009. The concentrations of eluted Bis-GMA and TEGDMA were tested by liquid chromatography/mass spectrometry after the specimens were immersed in 75% ethanol solution for different time (24 h, 7 d, 1 month, and 3 months). Results: The water absorption values of six kinds of composite resins were in ascending order of ALS TNC> Z250> Z350> ALS> CMP (P CMP> Z250> Z350 (P<0. 05). Conclusion: The water absorption values, solubility values and monomer release amounts of different composite resins are different, and they are related to their organic matrix compositions and the immersing solvent.
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Objective:To compare the water absorption values,solubility values and monomer release amounts of six kinds of light curing composite resins and explore the influencing factors,and to elucidate their relationships with the material compositions and the immersing solvent.Methods:The water absorption and solubility values of six kinds of composite resins,including FiltekTM Z250 (Z250),FiltekTM Z350 XT (Z350),Aelite LS Posterior (ALS),CLEARFIL MAJESTY Posterior (CMP),Neofil Nano (NN),and Tetric N-Ceram (TNC),were measured according to ISO 4049-2009.The concentrations of eluted Bis-GMA and TEGDMA were tested by liquid chromatography/mass spectrometry after the specimens were immersed in 75％ ethanol solution for different time (24 h,7 d,1 month,and 3 months).Results:The water absorption values of six kinds of composite resins were in ascending order of ALS ＜CMP ＜TNC ≈Z250 ＜NN ＜Z350,there were significant differences between groups (P＜0.05);the solubility values were Z350 ＜NN≈ALS≈CMP≈Z250 ＜TNC,there were significant differences between groups (P＜0.05).The release amounts of Bis-GMA were increased slowly with the prolongation of time (P＜0.05),while the values of ALS and CMP at 3 months were decreased (P＜0.05);the descending order ofBis-GMA release amounts at 3 months was NN＞ TNC＞ Z250＞ Z350＞ ALS＞ CMP (P＜0.05).The released TEGDMA was not found in NN and TNC.The release amounts of TEGDMA of the other four resins were increased slowly with the prolongation of time (P＜0.05),and the release amount of CMP at 3 months was decreased (P＜0.05);the order of amount at 3 months was ALS＞ CMP＞ Z250＞ Z350 (P＜0.05).Conclusion:The water absorption values,solubility values and monomer release amounts of different composite resins are different,and they are related to their organic matrix compositions and the immersing solvent.
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Aim: The aim of our study was to evaluate the amount of release of BisGMA and TEGDMA from two commercially available enamel replacement composites; Tetric N-Flow™ and G-aenial Universal Flo™ over a period of 24 hours after polymerization with a standard LED Curing Unit. Methods and Materials: Two flowable nanohybrid composite materials; Tetric N-Flow™ (Ivoclar Vivadent AG, Liechtenstein) and G-aenial Universal Flo™ (GC, India) were investigated and grouped into two groups. Ten samples from each group were prepared by inserting the material into a standardized Teflon mould of size 2x2x2 mm. Each sample was cured with a LED curing unit for 20 seconds and was stored in 2 ml of Ethanol at room temperature. After 24 hours, the samples were removed from the storage medium (ethanol) and prepared for measurements. A reverse phase HPLC unit was used to detect the release of BisGMA and TEGDMA monomers from the prepared samples. The acquired measurements were obtained after testing them in a High Liquid Performance Chromatography Unit. The data obtained was statistically analyzed and the results revealed significant amount of release of TEGDMA as well as BisGMA Results: G-aenial Universal Flo™ showed significant release of both TEGDMA as well as BisGMA as compared to Tetric N- Flow™. The increase was by 0.5 units. Conclusion: Significant amount of release of TEGDMA as well as BisGMA was seen in both the composite materials after HPLC Unit analysis. This can help in the evaluation of cytoxicity to the soft tissues in the oral environment.