Resistência flexural de duas resinas provisórias : comparação dos testes uniaxial e biaxial

Abstract

Abstract : The aim of this in vitro study was to evaluate the flexural strength of the resin bisacrílica Systemp.c&bII (S) - Ivoclar / Vivadent AG , and methyl methacrylate resin Duralay (D) - Reliance on two types of flexural tests , in order to suggest a test pattern most appropriate to assess this mechanical property . The materials were subjected to two tests of flexural strength, one uniaxial (RFU) and another three-point biaxial (RFB) with ball load in three levels of support (B3B), after 24 hours and 30 days of the making of the body proof (CP) stored in distilled water at 37 ° C. For each type of testing were made of each material 40 CPs, 20 of these tested 24 hours after preparation and the other 20 after 30 days of storage. CPs and flexural tests were performed according to ISO 4049 and ISO 6872. The tests were conducted on an Instron 4444 machine (Chicago, IL - USA) with a crosshead speed of 0.5 mm/min until fracture. The load values obtained were related to the effective area of the test and converted into MPa. The results were tested using the Anderson- Darling normality, ANOVA for three factors at two levels each test and T. The RFU test showed statistically significant difference (p > 0.05 ) for the two periods of storage the resin Duralay. The same statistical test revealed a significant difference between the Systemp.c & b and II Duralay within 24 hours. The T test found no statistically significant difference to the results of RFB. No significant interaction of test type and type of materials, however, there was interaction between storage time and type of material and type of test. The S resin showed results similar to RF of D resin 24 hours, but was higher when after 30 days of storage, being more suitable for long periods of use of the provisional. Data collected from RFU demonstrated interaction geometry test and storage time, by raising the average RFU as opposed to the decrease in the value of RFB. However, this may not represent a good capacity test for measuring the RFU, since it is expected degradation of the resin matrix leading to the possible decrease in RF.