Effect of surface treatment on the retention of implant-supported zirconia restorations over short abutments

Abstract

The retention of cement-retained implant-supported restorations can be affected by the height of the abutments. The purpose of this study was to evaluate the effects of the surface treatment on the retention of implant-supported zirconia restorations over short abutments. Eighty solid abutments reduced to 3 mm in height and their corresponding fixture replicas were embedded vertically in autopolymerizing acrylic resin blocks. Eighty zirconia copings (Cercon) with an occlusal loop were fabricated and divided into 2 groups (n=40). One group was airborne-particle abraded with 110 μm aluminium oxide and the other group was treated with silica coating (Rocatec System). Each group was then divided into 4 subgroups (n=10). The subgroups received either no treatment (control) or were treated with silane (Clearfil Porcelain Bond Activator+SE Primer), acid etching followed by silane, or ceramic primer (Clearfil). All copings were luted with a self-adhesive luting agent (Clearfil SA). After 1 week of conditioning in artificial saliva and thermal cycling (5000 cycles, 5°C-55°C), the removal force of the copings were tested with a universal testing machine at a 5 mm/min crosshead speed. The dislodgment force and failure mode were recorded. Two-way ANOVA and the Tukey honestly significant difference and the Fisher exact tests were used for data analysis (α=.05). The highest retentive values were obtained for airborne-particle abrasion--ceramic primer (228.84 N) and silica coating--ceramic primer (230.37 N), which were not significantly different from silica coating alone (216.26 N; P=.95) or a combination of airborne-particle abrasion followed by silanation (211.67 N; P=.87). The failure mode was primarily adhesive and cement principally remained on the copings. Within the limitations of this study, ceramic primer that contains adhesive phosphate monomer significantly improved the retention of zirconia ceramic restorations. Silicoating as a mechanical treatment provided greater retention for zirconia copings than airborne-particle abrasion when a resin-luting agent was used.