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Online ISSN 1827-174X
Xediek Consani R. L. 1, Lacerda Vieira M. 1, Ferraz Mesquita M. 1, Coelho Sinhoreti M. A. 2, Danil Guiraldo R. 3, Arruda Nóbilo M. A. 1
1 Department of Prosthodontics and Periodontics, Piracicaba Dental School, State University of Campinas, Piracicaba, Brazil;
2 Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, Brazil;
3 Department of Restorative Dentistry, University of North Parana, Londrina, Brazil
AIM: This study verified the effect of polymerizing cycles on the linear dimensional change, hardness and impact strength of denture acrylic resins.
METHODS: One hundred and twenty samples (N.=10) each for the Classico and Vipi acrylic resins were made according to the manufacturers’ instructions. The polymerization cycles were: 1- water bath at 74 ºC for 9 hr; 2- water bath at 74ºC for 8 hr and temperature increased to 100 ºC for 1 hr; 3- water bath at 74 ºC for 2 hr and temperature increased to 100 ºC for 1 hr; and 4- water bath at 120ºC and 60 pounds pressure for 1 hr. Samples were deflasked after flask cooling and submitted to finishing. Linear distances between referential points in the samples were measured at deflasking and after water storage for 7 and 30 days with a comparator microscope with an accuracy of 0.0005 mm. Knoop hardness test was accomplished in a durometer with a load of 25 gf for 10 sec and an average of three indentations was considered for the sample hardness. Impact strength (kgf/cm2) was measured by the Charpy system with load of 40 kpcm. Data were submitted to ANOVA and Tukey’s test (5%).
RESULTS: Dimensional changes in the A-B and A-C distances, hardness values and impact strength for Classico and Vipi resins were differently influenced by the polymerization cycles, when deflasking and water storage for 7 and 30 days were considered.
CONCLUSION: Linear dimensional change, hardness and impact strength of denture acrylic resins were differently affected by the polymerization cycles.