Abstract
Aims
The objective of the present study was to evaluate the effect of three different surface treatment protocols on the shear bond strength (SBS) of metal brackets to Vita Enamic® and Lava™ Ultimate CAD/CAM hybrid ceramics.
Methods
A total of 60 crowns were milled and divided into one of three etching groups which used 9.6% hydrofluoric acid, 35% phosphoric acid and 50 μ aluminum oxide microetching. The surface morphology of the ceramic was observed after each etching treatment using a scanning electron microscope to characterise the etched surface. Lower left first molar tubes (Ormco™) were bonded with light-cure composite, stored in artificial saliva for one week and subsequently thermocycled. The SBS test was performed using an Instron 5566 machine. Adhesive Remnant Index (ARI) scores were also assigned to determine the mode of bond failure. Data were analysed using an Independent Sample t-test.
Results
The SBS of all groups, except the HFA Enamic® group, were significantly lower than the mean SBS of the enamel control group (8.8 MPa). The mean shear bond strength values of Enamic® were significantly higher than those of Lava™ Ultimate (p-values < 0.05).
Conclusions
Statistically, only Enamic® treated with HFA exhibited sufficient SBS when compared with the enamel control. Adhesive failures between the bracket base and adhesive were the predominant mode of failure in all groups except in the PA Lava™ Ultimate group.