Abstract
The purpose of this study was to investigate the influence of the thermal cycling test on the adhesion of the resin on the ground primary enamel which was etched with different etching times.
Labial surfaces of 50 extracted and frozen bovine mandibular primary incisors were used. The etchant used in this study was 37% phospholic acid gel and the etching times were 0,10,20,30 and 60 seconds. All of the specimens were washed with an air water spra y after etching. The bonding agent and composite resin used in this study (Silux group) were Scotch Bond and Silux (3M Co. ). After thermal cycling tests consisting of water baths with 10,000 temparature cycles between 60°C and 4°C, shear bond strengths on the ground enamel were measured. The results of this study were compared with the previous results of the Silux nonthermal cycled group and the PCA thermal cycled group. In the PCA groups, Photo Bond and Photo Clearfil A (Kuraray Co. ) were used.
The following conclusions were obtained.
1) The etching time which showed the highest bond strength was 60 seconds (63.61±19.64MPa).
2) The bond strength without etching was significantly lower than those with 20,30 and 60 seconds of etching time.
3) The bond strength with 10 seconds of etching time was significantly lower than those with 20,30 and 60 seconds of etching time.
4) In the 10 and 20 second etching groups of the Silux groups, the bond strengths of the thermal cycled group were significantly lower than those of the nonthermal cycled group.
5) In the 10 and 30 second etching groups of the Silux thermal cycled group and the PCA thermal cycled group, the bond strengths of the PCA group were significantly higher than those of the Silux group.
