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® 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 (α=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).