Degree of conversion in denture base materials for varied polymerization techniques

New processing techniques for denture base acrylic resins have been introdu ced which have not comparatively quantified the residual monomer content. W hile proper processing keeps the residual monomer in a tolerable range for most patients, tissue irritation and reaction due to potentially higher res idual monomer in these alternative techniques could be a clinical concern. Decreased degree of conversion may influence physical properties as well as biocompatibility. This investigation evaluated the residual monomer conten t of acrylic resins cured by three different polymerization modes. Material s (polymerization system) evaluated were: Lucitone 199(R) (conventional pro cess), Accelar 20(R) (rapid boil-out), and Acron MC(R) (microwave). Fourier transform infrared spectrometry (FTIR) was employed to determine the degre e of conversion. All curing methods produced similar results (Lucitone 199( R) = 92.7% (0.21), Acron MC(R) = 92.6% (0.57), Accelar 20(R) = 90.9%(0.73). Conversion for Accelar 20(R) (rapid boil-out technique), though statistica lly different (P < 0.05, ANOVA) from the other two materials and polymeriza tion techniques, was only slightly less. It is unlikely that the rapid boil -out technique would induce more adverse tissue responses than the other te chniques included in this study.