Influencia do tipo de carregamento sobre a resistencia da união ao cisalhamento da interface dentina-resina

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

The purpose of this study was to compare the influence of the orthodontic looped wire, stainless steel tape, and chisel-shaped rod systems used in shear bond tests to verify the dentin-resin interface bond strength. 48 human teeth divided in 3 groups were used. The roots were seccioned and the dental crowns embedded in cold acrylic resin cure. The teeth were previously ground to obtain a smooth and plain surface, that was delimited with adhesive tape containing a 4 mm diameter hole. The limitted area of dentin was treated with Scotchbond Multi-Purpose Plus adhesive system (3M) in accordance with manufacturer s instructions. Following this step, a metallic split die with 4 mm in diameter and 5 mm in height was placed over the conditionated dentin, and Z 100 composite resin (3M Dental Products, St. Paul, MN) was placed in three increments. Each increment was light cured by Visilux 2 light cure unit (3M Dental products, St. Paul, MN), for 40 seconds. The specimens were stored at 37°e and 100% relative humidity for 24 hours. Half specimens of each group was submitted to ,500 thermic cycles with baths at 5°e and 60° C, interspersed with baths at 37°C. Afterwards, the specimens were submitted to shear bond tests in an Otto Wolpert universal testing machine operated at a cross-head speed of 6 mm/min. After the failure, representative specimens from each group were examined by scanning electron microscopy. The results were submitted to variance analysis and Tukey s test at 5% significance level. It follows that small variation in test methods give different shear bond strenght values. The debonding values depend on the complex combination of stresses produced during the loading of the specimens. The electronphotomicrographs showed that to the stainless steel tape system, the failures were always cohesive in adhesive. With orthodontic-looped wire, the failures more usual were cohesive in composite. In case of chisel shaped rod system, the failures were mixed (cohesive in adhesive and composite )

ASSUNTO(S)

dentina adesivos dentarios cisalhamento materiais dentarios

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