Shear bond strength of ceramic brackets bonded to glazed lithium disilicate using different bonding protocols

Objectives: To evaluate the shear bond strength (SBS) of ceramic brackets to lithium disilicate using different bonding protocols. Materials and methods: Forty five lithium disilicate discs were embedded into acrylic resin. and randomly assigned to three equal groups (n=15), according to bonding protocol into: (A)Air abrasion with 50μm aluminum oxide particles + Assure Plus, (B) air abrasion with 50μm aluminum oxide particles + silane + Assure Plus (C) air abrasion with 50μm aluminum oxide particles + hydrofluoric acid etching + silane + Transbond XT Primer. Ceramic brackets were then bonded to the lithium disilicate discs using light curecomposite resin. Following thermocycling (500 cycles, 5° 55° C), shear bond strength(SBS) testing was performed with a universal testing machine. After bracket debonding Failure mode and Adhesive Remnant Index were assessed under a stereomicroscope. Results: No significant differences were found among the three groups regarding SBS, Group B showed the highest SBS values. Most specimens in Group B and Group C showed a failure at the bracket adhesive interface. Specimens in Group A showed a mixed cohesive-adhesive failure pattern Conclusion: All 3 groups exhibited shear bond strengths within the clinically acceptable level, samples recieving Air abrasion + Assure plus only displayed better debonding characteristic.