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Bond strength of a dentin bonding system using two techniques of polymerization: visible-light and argon laser
Alessandra Cassoni1, Michel Nicolau Youssef, Igor Prokopowitsch
1Department of Restorative Dentistry, University of São Paulo, São Paulo, Brazil. acassoni@osite.com.br
Objective:
The aim of this work was to study one dentin-bonding system associated with posterior teeth restorative composite resin by means of tensile bond strength tests varying the technique of polymerization: visible light and argon laser.
Background Data:
Previous studies have demonstrated the ability of the argon laser to polymerize light-activated materials.
Methods:
Sixty specimens were prepared by grinding the labial surface of bovine teeth embedded in acrylic resin. The dentin bonding system used was Single Bond (3M), which has a poliacenoic acid copolimer, associated with a posterior teeth restorative composite resin (Filtek P60, 3M). The bonding sites were treated according to the instruction of the manufacturers. The 60 teeth, duly embedded and ground, were assigned to four groups with 15 teeth each: group 1, the adhesive was light cured during 10 sec with visible light (Curing Light, 3M) with power density of 410 mW/cm2 and the composite resin was light cured during 20 sec with visible light; group 2, the adhesive and the composite resin were cured during 10 seconds with argon laser with 150 mW of power; group 3, the adhesive and the composite resin were cured during 10 sec with argon laser with 200 mW of power; and group 4, the adhesive and the composite resin were cured during 10 sec with argon laser with 250 mW of power. The composite resin was light cured in layers of 1 mm of thickness until the model of teflon with 3 mm in height was completely filled.
Results:
The tensile bond strength test was performed in a Mini-Instron (model 4442) and the results for group 1 were 19.75 MPa (+/-4.65), group 2 were 16.09 MPa (+/-7.27), group 3 were 11.56 MPa (+/-4.50), and group 4 were 11.90 MPa (+/-5.78).
Conclusions:
One can conclude that the tensile bond strength promoted by the polymerization with visible light presented greater tensile bond strength than the polymerization with argon laser with 200 mW and 250 mW, but there was no significant difference between visible light and argon laser with 150 mW. There was no significant difference between argon laser with 150 mW and argon laser with 200 mW or 250 mW.