RESUMO
PURPOSE: This study evaluated the bonding strength of direct relining resin to Co-Cr denture base material according to surface treatment and immersion time. MATERIALS AND METHODS: In this study, Co-Cr alloy was used in hexagon shape. Each specimen was cut in flat surface, and sandblasted with 110 microm Al2O3 for 1 minute. 54 specimens were divided into 3 groups; group A-control group, group B-applied with surface primer A, group C-applied with surface primer B. Self curing direct resin was used for this study. Each group was subdivided into another 3 groups according to the immersion time. After the wetting storage, shear bond strength of the specimens were measured with universal testing machine. The data were analyzed using two-way analysis of variance and Tukey post hoc method. RESULTS: In experiment of sandblasting specimens, surface roughness of the alloy was the highest after 1 minute sandblasting. In experiment of testing shear bond strength, bonding strength was lowered on group B, C, A. There were significant differences between 3 groups. According to period, Bonding strength was the highest on 0 week storage group, and the weakest on 2 week storage group. But there were no significant differences between 3 periods. According to group and period, bonding strength of all group were lowered according to immersion time but there were no significant differences on group B and group C, but there was significant difference according to immersion time on group A. CONCLUSION: It is useful to sandblast and adopt metal primers when relining Co-Cr metal base dentures in chair-side.