Effect of silica-containing glass–ceramic liner treatment on zirconia coping retention

Zirconia prostheses show a high rate of retention loss, and more information is needed regarding the treatment of the intaglios of zirconia prostheses to improve the bond strength between zirconia and resin cement.The purpose of this in vitro study was to evaluate the retention of titanium abutments and zirconia prostheses treated with silica-containing glass-ceramic liners. The effect of the abutment convergence angle on retention force was also examined.Titanium abutments and zirconia copings (n=90) were fabricated with 3 different convergence angles (6, 12, and 24 degrees). Specimens were divided into 2 groups according to surface treatment: an airborne-particle-abraded control group and a group that was coated with a silica-containing glass-ceramic liner after airborne-particle abrasion (liner group). The thickness of the liner was measured, and the inner spacing of the zirconia coping was modified in the liner group. The coping was cemented, and the retention was evaluated with a tensile bond strength test by using a universal testing machine. Retention was analyzed by using a 2-way analysis of variance. Modes of failure were evaluated by examining the fracture surface. Elemental analysis of the interface was also performed.The liner group showed a significantly higher retention force for the zirconia prosthesis (P.05). Regardless of surface treatment, the retention force at a convergence angle of 6 degrees was higher than that at 24 degrees (P.05). The control group showed mostly adhesive type failures, whereas the liner group exhibited mostly mixed type failures.Silica-containing glass-ceramic liner treatment increased the retention compared with airborne-particle abrasion treatment alone. Tensile bond strength increased with decreasing abutment convergence angle.