Shear Bond Strength of Metal Orthodontic Brackets to Different All Ceramic Materials

Objectives: The aim of the present study is to evaluate and compare the shear bond strength of metal orthodontic brackets to different types of all ceramic materials after different surface conditioning methods.
Methods: Sixty square shaped ceramic blocks were prepared and glazed using two types of all ceramic materials (IPS e. max and VITA SUPRINITY® PC) (n=30). Ceramic blocks from each material were divided into three groups (n=10) according to the following surface preparation: G1: Surface etching with 9.6% hydrofluoric acid (HFA) for 2 mins; G2: Surface roughening with Soflex finishing discs; G3: Surface roughening with Soflex finishing discs and etching wit HFA. Metal orthodontic brackets were bonded to the prepared surfaces of ceramic blocks using light Cure orthodontic adhesive. Prepared samples were subjected to 2000 thermocycling cycles (5-50 ⁰ C) before testing of the adhesive interphase. Shear bond strength (SBS) was evaluated using Instron universal testing machine.
Results: Surface preparation with Soflex discs and HFA of both ceramic materials used in the present study, resulted in a significant increase in SBS to metal orthodontic brackets when compared to other experimental groups (p<0.05). However, VITA Suprinity ceramic surfaces prepared with Soflex discs only showed the lowest SBS compared to other surface preparation methods.
Conclusions: Surface preparation of all ceramic materials with Soflex discs and hydrofluoric acid combination, produced the highest shear bond strength to metallic orthodontic brackets.