[A basic study on visible light cured resins for denture bases. 1. Mechanical properties]

Denture base resins: comparison study of color stability

Several denture base resins have been recently introduced that provide easier or faster processing. Although these materials have adequate strength properties, the color stability is also of interest. This study evaluated the color stability of five denture base acrylic resins and one denture base repair resin. The samples were subjected to conditions of accelerated aging to test color stability. Five samples of each material were processed and aged for 100 and 300 hours. The color stability was quantitatively measured using the Minolta Chroma Meter II. Color measurements were made before weathering and at 100 and 300 hours the color difference delta E was calculated for all samples. At 300 hours the color change of the materials was significantly different at p less than 0.01. It was found that: (1) the color of Lucitone Hy-pro and Acron was least affected by conditions of accelerated aging; (2) Triad, Accelar 20, and Perm demonstrated noticeable color changes; and (3) Compak-20 had an appreciable color change and was the least color-stable of the materials tested.

Adaptation of acrylic resin dentures as influenced by the activation mode of polymerization

With the advent of newer methods of activation of the polymerization of denture base resins, there is a need to compare dentures constructed using various modes of activation such as heat, light, and microwave energy. This study compares the dimensional accuracy of a conventional heat-activated acrylic resin poly (methyl methacrylate) with a new pour resin, a visible light-activated resin, and microwave-activated acrylic resin, all polymerized for denture bases. All groups showed a processing contraction; the poorest-fitting group was processed in a brass flask and a water bath at 70-100 C, using a heat-activated resin (Acron); the relatively new light-activated resin (Triad) produced dentures of intermediate accuracy, as did Acupac 20, when either heat- or microwave-activated. The two best-fitting groups were prepared from an autopolymerizing resin (PERform) and the microwave-activated resin (Acron MC).