Influencia do tempo de armazenagem inicial na resistencia a tração de cimentos resinosos unidos a dentina

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

The objective of this study was to evaluate the effect of the initial storage time in tensile strength of three resin cements bonded to dentin. Sixty bovine teeth were used. The teeth were embedded, polished with silicon carbide papers of 220 and 600 grit and cleaned on ultra-sonic. They were divided in 3 groups of 20 samples each: Group I was fixed with Rely X cement; Group II, Enforce and Group III, Dual Cement. The samples of each group were lutted with the above materials according to each manufacturer s instructions. Half of the samples were tested after 30 minutes, and the other half, after 24 hours. The teeth were embedded to the pairs and positioned in adie stamp, with the surfaces face-to-face to each other and in contact for the adhesive procedure with the resin cement. The resin was photocured for 160 seconds and each specimen was them stored for 30 minutes or 24 hours at 37° C and 100% of relative humidity. With the aid of a metallic die stamp the samples were submitted to the tensile test in machine of universal test INSTRON I (model 4411) at speed of 1 mm/min. The results were submitted to the variance analysis and to Tukey s test (5%). The obtained averages were the following (SD): Group I, 30 minutes = 2,53 (+0,49) MPa; 24 hours = 2,90 (+1,12) MPa; Group II, 30 minutes = 1,65 (+0,46) MPa, 24 hours = 1,94 (+0,43) MPa; Group III, 30 minutes = 4,24 (+1,26) MPa; 24 hours = 6,14 (+01,80) MPa. After the tensile strength test, the surfaces of one of the tested samples were analyzed under SEM in order to determine the prevalence of the fracture pattern in the interface. Based upon the results obtained and discussed on this study can conclude that the mean values of tensile strength for groups I and groups II Obtained with the samples tested on the period of 30 mino did not differ statistically from those tested 24 h., except for group III that differ statistically. The Mean values of tensile strength of groups I, II e III were statistically different among them. Comparing time and values obtained, it is possible to verify a direct proportionality between time and strength, what means that a longer time is necessary to allow the polymerization process to occur in a satisfactory way

ASSUNTO(S)

materiais dentarios adesivos dentarios

ACESSO AO ARTIGO

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