[Determination of residual monomer content in Acropars samples by Fourrier Transform Infrared method]

Acrylic resins possess many desirable properties, but it is possible that the denture bases contain residual monomer, which may cause some side effects such as hypersensitivity of oral tissues and altered characteristics of acrylic resin. The purpose of this study was to measure the residual monomer in heat cure Acropars[R] acrylic resin and comparison of these results with ISO standard. This study was an experimental research which was performed according to ISO 1567 standard. At first, five solutions of MMA monomer in MIBT, as the solvent, were produced with concentrations of 0.1, 0.2, 0.3, 0.4 and 0.5 weight percents for which Fourier Transform Infrared [FTIR] spectra were obtained. The calibration curves were then prepared based on these five known samples. As unknown samples, four disks of Acropars acrylic resin with diameter of 50 mm and thickness of 3 mm were provided and were dissolved in MIBT. After the swelling of samples and therefore the releasing of monomer in the solvent, the solutions were characterized by FTIR analysis. Concentration of monomer in solution was assessed by calibration curves. Data were statistically analyzed using t-student test [alpha=0.05]. The average level of residual monomer in Acropars samples was 0.428 weight percent. The level of residual monomer in Acropars samples met the requirements of ISO standard. The difference between the mean concentration of Acropars residual monomer and ISO standard was positively significant [p<0.05]

effect of surface coating on softness of two kinds of tissue conditioners

One of the limitations of tissue conditioners [TC] is gradual hardening of the material in a short time period after insertion in the mouth, due to the loss of their viscoelastic properties. The aim of this study was to determine the softness of two different tissue conditioners with and without the Monopoly coating. In this experimental study, Acropars and Viscogel tissue conditioners were examined. Ten samples of each tissue conditioner were prepared, using 3x20 mm [hxd] aluminum cylindrical molds. Half of the samples in each group were coated with Monopoly coating. Samples were kept in a water bath at 37 degree C and the hardness of their surfaces was measured [in Shore-A] after 1, 3, 7, 14, and 28 days. The results were analyzed using t-test, Multivariant ANOVA and Tucky posthoc test. There were significant differences in hardness [P < 0.05], comparing, the coated and uncoated Acropars [p=0.000], the coated and uncoated Viscogel [p=0.000], the coated Acropars and uncoated Viscogel [p=0.000], the coated Acropars and coated Viscogel [p=0.036], and the uncoated Acropars and coated Viscogel [p=0.000] samples. It was found that the hardness of all of the samples increased with time. For both tissue conditioners, the hardness of samples with coating was higher than of those without coating. This indicates that the Monopoly coating does not protect the softness of these two tissue conditioners