Effect of different surface conditioning methods and low pH solutions on the shear bond strength of orthodontic brackets to newly introduced CAD/CAM materials.

AIM

To evaluate the shear bond strength (SBS) of ceramic and metallic orthodontic brackets bonded to lithium disilicate ceramics or hybrid ceramics and subjected to different surface conditioning treatments.

MATERIALS AND METHODS

In total, 300 specimens were fabricated from GC LiSi (lithium disilicate) and GC Cerasmart (hybrid) ceramic blocks. The specimens were divided into four groups according to the following surface treatments: hydrofluoric acid (HF); sandblasting with 50 μm aluminum oxide; Monobond Etch and Prime; and erbium-doped yttrium aluminum garnet (Er-YAG) laser. Metal (Victory Series) and ceramic (Clarity) brackets were bonded using an orthodontic adhesive resin (Transbond XT; 3M Unitek, CA, USA). The specimens were then stored in three different mediums (artificial saliva, mouth rinse, and gastric juice) and thermocycled. An SBS test was performed after 1 week. The surface morphology was examined after the conditioning treatments using a scanning electron microscope. Data were analyzed using analysis of variance, -test, and Duncan test.

RESULTS

The SBS data revealed that the type of computer-aided design/computer-aided manufacturing (CAD/CAM) block and surface conditioning method significantly affected the SBS. The highest SBS was recorded (10.112 MPa) for the HF-treated hybrid ceramic blocks stored in the saliva medium, while the lowest SBS (1.862 MPa) was reported for the Er-YAG laser-treated lithium disilicate ceramic blocks stored in the gastric juice medium. GC Cerasmart exhibited better bond strength than that of GC LiSi; however, no significant difference was observed between the ceramic and metal brackets.

CONCLUSION

The CAD/CAM material, surface conditioning method, and medium affect the SBS.