Monitoring the polymerization process of acrylic resins.

Four groups of autopolymerizing acrylic resins used for various purposes in current dental practice were investigated by monitoring their temperature changes during the polymerization process. Resins were compared in terms of characteristic parameters (such as the time interval needed to reach mechanical stability and the maximum temperature generated during the polymerization process) and interpretations were made of such temporal temperature profiles.

Determination of ammonia using carbon dioxide laser photoacoustic spectroscopy compared with conventional spectrophotometry.

The potential of carbon dioxide laser photoacoustic spectroscopy and the traditional Indophenol Blue colorimetric method for detecting gaseous ammonia have been compared. The results obtained with the two independent techniques are comparable in the range of concentrations studied.

A novel approach to the distortion assessment of denture impression trays.

A novel method to treat and interpret distortion of denture impression trays has been proposed. When compared with the conventional method this approach, based on the general least squares principle, offers a significant advantage since the displacement for each individual point can be traced providing more profound insight into the character of the overall deformation itself. The method was applied to study dental impression trays manufactured of self-curing acrylic. The results indicate the existence of a large degree of individuality and non-uniform behaviour of a specific tray material. The method developed here can be applied to specimens of any arbitrary size and shape and it is not limited by the number of the reference points.