title: Effect of microwave disinfection on physical and mechanical properties of acrylic resins.
abstract: This study evaluated the effect of microwave energy on the hardness, impact strength and flexural strength of the Clássico, Onda-Cryl and QC-20 acrylic resins. Aluminum die were embedded in metallic or plastic flasks with type III dental stone, in accordance with the traditional packing technique. A mixing powder/liquid ratio was used according to the manufacturer's instructions. After polymerization in water batch at 74 degrees C for 9 h, boiling water for 20 min or microwave energy at 900 W for 10 min, the specimens were deflasked after flask cooling at room temperature, and submitted to finishing. Specimens non-disinfected and disinfected by microwave irradiation were submitted to hardness, impact and flexural strength tests. Each specimen was immersed in distilled water and disinfected in a microwave oven calibrated to 650 W for 3 min. Knoop hardness test was performed with 25 g load for 10 s, impact test was carried out using the Charpy system with 40 kpcm, and 3-point bending test with a crosshead speed of 0.5 mm/min until fracture. Data were submitted to statistical analysis by ANOVA and Tukey's test (alpha=0.05). Disinfection by microwave energy decreased the hardness of Clássico and Onda-Cryl acrylic resins, but no effect was observed on the impact and flexural strength of all tested resins.
authors.affiliation: Department of Prosthodontics and Periodontics, Dental School of Piracicaba, University of Campinas, Piracicaba, SP, Brazil. rconsani@fop.unicamp.br
authors.forename: Rafael Leonardo Xediek
authors.initials: RL
authors.lastname: Consani
authors.forename: Erica Brenoe
authors.initials: EB
authors.lastname: Vieira
authors.forename: Marcelo Ferraz
authors.initials: MF
authors.lastname: Mesquita
authors.forename: Wilson Batista
authors.initials: WB
authors.lastname: Mendes
authors.forename: João Neudenir
authors.initials: JN
authors.lastname: Arioli-Filho
mesh_terms: D000180:Acrylic Resins / Q000528:radiation effects*; D003799:Dental Stress Analysis; D004203:Disinfection / Q000379:methods*; D004866:Equipment Contamination; D006244:Hardness / Q000528:radiation effects; D008422:Materials Testing; D008872:Microwaves; D018583:Pliability / Q000528:radiation effects
chemical_list: D000180:Acrylic Resins