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Impact of Fabrication Techniques and Polishing Procedures on Surface Roughness of Denture Base Resins
Published on: January 17, 2025
Effect of polymerization cycles on the linear dimensional change, hardness and impact strength of denture base
R L Xediek Consani1, M Lacerda Vieira, M Ferraz Mesquita
1Department of Prosthodontics and Periodontics, Piracicaba Dental School, State University of Campinas, Brazil. rconsani@fop.unicamp.br
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.
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