Shear bond strength of an experimental composite bracket

The in vitro shear bond strength of MZ100 brackets (an experimental composite bracket developed by the Dental Biomaterial Laboratory at Boston University) and the effect of different treatment methods on these brackets were evaluated. As the bonding substrates, 80 VitablocsA (R) Mark II (Vident, Brea, CA, USA) were chosen. Three treatment methods were employed on 60 MZ100 bracket bases (20 brackets per treatment): silane coupling agent (Porcelain Primer; Ormco, Orange, CA, USA), sandblasting (Basic Professional Model Sandblaster; Renfert GmbH, Germany), and non-treatment. Two different orthodontic adhesives were also used: Blugloo (TM) (Ormco, Orange, CA, USA) and Enlight (TM) (Ormco, Orange, CA, USA). Twenty metal brackets were used as controls. Shear bond strength tests were performed after sample preparation and bracket bonding. The mean shear bond strength of non-treated MZ100 brackets bonded with Enlight (TM) had the lowest value (7.9 MPa), while that of sandblasted MZ100 brackets bonded with Blugloo (TM) showed the highest value (17.9 MPa). The mean shear bond strength of non-treated MZ100 brackets was significantly lower than that of the other groups (p < 0.05). The mean shear bond strength of sandblasted MZ100 brackets bonded with Blugloo (TM) was significantly higher than that of those bonded with Enlight (TM) (p < 0.05). With the exception of the silane-Blugloo (TM) group, the treated MZ100 brackets demonstrated shear bond strengths that did not significantly differ from metal brackets. The use of sandblasting and silane coupling agent significantly increases the shear bond strength of the MZ100 brackets to values resembling those of metal brackets.