Flexural strength of acrylic resins polymerized by different cycles

Author(s)

Débora Barros Barbosa ^[1] ; Raphael Freitas de Souza ^[2] ; Ana Carolina Pero ^[3] ; Juliê Marra ^[4] ; Marco Antonio Compagnoni ^[5]

Affiliation

^[1] UNESP. Dental School of Araçatuba. Department of Dental Materials and Prosthodontics - Brasil

^[2] USP. Dental School of Ribeirão Preto. Department of Dental Materials and Prosthodontics - Brasil

^[3] UNESP. Dental School of Araraquara. Department of Dental Materials and Prosthodontics - Brasil

^[4] UNESP. Dental School of Araraquara. Department of Dental Materials and Prosthodontics - Brasil

^[5] UNESP. Dental School of Araraquara. Department of Dental Materials and Prosthodontics - Brasil

• Document type: Journal article
• Source: Journal of Applied Oral Science; v. 15, n. 5, p. 424-428, 2007-10-00.

Abstract

Despite the large number of studies addressing the effect of microwave polymerization on the properties of acrylic resin, this method has received limited clinical acceptance. This study evaluated the influence of microwave polymerization on the flexural strength of a denture base resin. A conventional heat-polymerized (Clássico), a microwave-polymerized (Onda-Cryl) and a autopolymerizing acrylic (Jet) resins were used. Five groups were established, according to polymerization cycles: A, B and C (Onda-Cryl, short cycle - 500W/3 min, long - 90W/13 min + 500W/90 sec, and manufacturing microwave cycle - 320W/3 min + 0W/3 min + 720W/3 min); T (Clássico, water bath cycle - 74ºC/9h) and Q (Jet, press chamber cycle - 50ºC/15 min at 2 bar). Ten specimens (65 x 10 x 3.3mm) were prepared for each cycle. The flexural strength of the five groups was measured using a three-point bending test at a cross-head speed of 5 mm/min. Flexural strength values were analyzed by one-way ANOVA and the Tukey's test was performed to identify the groups that were significantly different at 5% level. The microwave-polymerized groups showed the highest means (p<0.05) for flexural strength (MPa) (A = 106.97 ± 5.31; B = 107.57 ± 3.99; C = 109.63 ± 5.19), and there were no significant differences among them. The heat-polymerized group (T) showed the lowest flexural strength means (84.40 ± 1.68), and differ significantly from all groups. The specimens of a microwavable denture base resin could be polymerized by different microwave cycles without risk of decreasing the flexural strength. (AU)