Avaliação das resistencias a fratura e a fadiga de tres sistemas de ceramica dental

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

The aims of this paper was to investigate the influencia of fatigue, on the fracture strength of In ceram, OPC¿ and IPS Empress in both wet and dry environments, luted with zinc phosphate and glass ionomer cements. Fifty two crowns shapes with 8mm in diameter and 8.5mm height were fabricated for each ceramic system. After glazing, the crown shapes were cemented onto identical brass dies with zinc phosphate and glass ionomer cements. After, the specimens were then stored in distilled water at room temperature for 24 hours before testing. For each ceramic system luted with zinc phosphate and glass ionomer cement, ten specimens were tested for fracture strength without fatiguing at a crosshead speed of 1.0 mm per minute. The second group was submitted to a fatigue for 10,000 cycles, with minimum and maximum load of 20 and 300 N applied with the force profile in the form of a sine wave at 1 HZ, and fracture test in wet (8 specimens for each kind of ceramics and cement) and third group in a dry (8 specimens for each kind of ceramics and cement) environment; using a an Instron testing machine. The results were statistically analysed using a Mann-Whitney. The results indicated that (1) - the fracture strength for In ceram using luted zinc phosphate and glass ionomer was significantly stronger than OPC¿ and IPS Empress (p<0.05); (2) - when fatigued in a dry environment, In ceram crown shapes, luted with glass ionomer, were significantly stronger than OPC¿ and IPS Empress (p<0.05). The same statistical differences were found when fatigued in a wet environment; (3) - for luted with zinc phosphate, when fatigued in a dry environment, In ceram and OPC¿ were significantly stronger than IPS Empress (p<0.05); (4) - fatinguing and fracture testing showed a significant decrease in the frature strength for In ceram e IPS Empress in wet environment and no difference was found in dry environment. No difference was found for OPC¿; (5) -the strength of the three ceramic systems, luted with zinc phosphate, decreased significantly after fatiguing in both dry and wet environments, compared with non fatigued. No difference was found between fatiguing in dry and wet environments

ASSUNTO(S)

fadiga cimento ceramica

ACESSO AO ARTIGO

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