Influence emerged by termal changes in the flexural strength of heat polymerized acrylics used for denture bases, with and without metallic inserts. In vitro study
Keywords:
Dental Prosthesis, Acrylic Resins, ProsthodonticsAbstract
Objective: The aim of this study was to determine if the different temperature changes affect in the flexural strength of the heat-cured acrylic for the base of dentures with and without metallic inserts by means of thermal cycling and flexion tests. Materials and Methods: Eighty samples were prepared of a heat-cure acrylic Veracril® marque according to the specification no. Nº12 de la American Dental Association (ADA) (10×65×25 mm); Four groups of 20 burettes were formed, each being Group 1: samples without realizing thermo cycling and without metallic insert. Group 2 for samples submitted to thermo cycling and without metallic insert. Group 3 for samples without thermo cycling and metallic insert in this structure. Group 4 samples submitted to thermo cycling and with metallic insert. 1000 thermal cycles were realized by means of a manual procedure of 2 minutes by every thermal cycle, corresponding 1 minute in temperature of 5 ± 2 oC and 1 minute to 55 ± 2 oC to a cycle. The flexural resistance was evaluated by a test of three points at a speed of 1mm/min. The statistical analysis was through the Student t-test with a level of significance of 5%. Results: The mean flexural resistance was 73.51, 65.65, 71.14 and 73.08 MPa. For the groups 1,2,3 and 4 respectively. It was observed that G1 was greater than G2 (p = 0.002) and G3 with G4 did not obtain values with significant statistical difference (p = 0.554). Conclusion: The thermal changes as aging processes of the material negatively influence the flexural resistance of the samples which in their structure did not have a metallic insert improving the resistance of the material.
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