Characterization of an Experimental PMMA Polymerized with Two Techniques

Objectives: The purpose of this study was to evaluate and compare the particle size (PZ), transverse deflection (TD) and flexural modulus (FE) of an experimental PMMA polymerized with two techniques (obtained by suspension polymerization) with commercial heat-polymerized (Lucitone 199) and microwave-polymerized (Acron MC) PMMA used for denture bases.

Methods: The PZ for each PMMA was obtained by SEM. TD test was measured according to ADA Specification 12; ten samples (n=60) were polymerized using different techniques: Group 1: Lucitone (water bath), Group 2: Acron (microwave), Group 3: Experimental (water bath), Group 4: Experimental (microwave), Group 5: Lucitone (microwave), Group 6: Acron (water bath). FE was calculated using: FE=FL3/4bh3d. Commercial and experimental PMMA thermal behavior at 10ºC/min in nitrogen atmosphere from 20 to 600ºC, was compared by thermogravimetrical analysis (TGA).

Results: The data analyzed with ANOVA and Tukeyxs test (P>0.05) showed no statistical significative difference among properties. PZ of Lucitone, Acron and experimental PMMA were 55, 85 and 48 µm. TGA showed that all PMMA decomposed at 145, 332, 380 and 400ºC. TD values at 34 and 49 N (in mm) and FE (in GPA), were: Group 1 (1.6, 3.1, 2.5); Group 2 (1.5, 2.9, 2.5); Group 3 (1.7, 3.5, 2.0); Group 4 (1.8, 3.1, 1.6); Group 5 (1.5, 1.8, 2.8); Group 6 (1.4, 3.0, 2.3).

Conclusions: The values obtained from experimental PMMA are similar to commercial acrylic resins and fulfill ADA Specification 12. These results allow offering an acrylic resin that polymerize with two techniques for denture bases.