Retention of zirconia copings on zirconia implant abutments cemented with provisional luting agents.

The purpose of this study is to measure and compare the retentive force of zirconia-based all-ceramic crowns cemented on zirconia abutments using five provisional luting agents. In addition, the effect of sandblasting and thermocycling on the retentive force was evaluated. Two hundred zirconia abutments and copings were fabricated (Procera system; Nobel Biocare) and divided into five groups. Hy bond temporary cement hard (Hard), Hy bond temporary cement soft (Soft), experimental temporary cement (New), Tempbond NE (Temp) and Freegenool temporary pack (Pack) were used according to the manufacturers' instructions. Each group was divided into two groups, one with and one without sandblasting. Furthermore, thermocycling up to 2000 cycles was conducted on half of each group. After 24 h and thermocycling, the retentive force was measured using a universal testing machine. The data were subjected to analysis of variance, and comparisons of the means were performed with a Games-Howell test at a level of 95%. As a result, Hard showed the highest retentive force, sandblasting was effective for improving the durability, and no effect of sandblasting was detected in the others. New showed stability of the retentive force even after thermocycling. The retentive force of Temp and Pack decreased significantly after thermocycling even with sandblasting. The retentive forces were different from the provisional cement and sandblasting, and Temp and Pack may not be appropriate for the retention of single-tooth zirconia abutments and coping restorations.