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Published on: December 15, 2015
Influence of microwave polymerization method and thickness on porosity of acrylic resin
Ana Carolina Pero1, Débora Barros Barbosa1, Juliê Marra1
1Graduate Student, Department of Dental Materials and Prosthodontics, Araraquara Dental School, São Paulo State University, Araraquara, São Paulo, BrazilAssistant Professor, Department of Dental Materials and Prosthodontics, Araçatuba Dental School, São Paulo State University, Araçatuba, São Paulo, BrazilAssociate Professor, Department of Chemistry, São Carlos Federal University, São Carlos, BrazilAssociate Professor, Department of Dental Materials and Prosthodontics, Araraquara Dental School, São Paulo State University, Araraquara, São Paulo, Brazil.
Purpose:
This study evaluated the influence of polymerization cycle and thickness of maxillary complete denture bases on the porosity of acrylic resin.
Materials And Methods:
Two heat-activated denture base resins--one conventional (Clássico) and one designed for microwave polymerization (Onda-Cryl)--were used. Four groups were established, according to polymerization cycles: A (Onda-Cryl, short microwave cycle), B (Onda-Cryl, long microwave cycle), C (Onda-Cryl, manufacturing microwave cycle), and T (Clássico, water bath). Porosity was evaluated for different thicknesses (2.0, 3.5, and 5.0 mm; thicknesses I, II, and III, respectively) by measurement of the specimen volume before and after its immersion in water. The percent porosity data were submitted to Kruskal-Wallis for comparison among the groups.
Results:
The Kruskal-Wallis test detected that the combinations of the different cycles and thicknesses showed significant differences, and the mean ranks of percent porosity showed differences only in the thinnest (2.0 mm) microwave-polymerized specimens (A = 53.55, B = 40.80, and C = 90.70). Thickness did not affect the results for cycle T (I = 96.15, II = 70.20, and III = 82.70), because porosity values were similar in the three thicknesses.
Conclusions:
Microwave polymerization cycles and the specimen thickness of acrylic resin influenced porosity. Porosity differences were not observed in the polymerized resin bases in the water bath cycle for any thickness.
