Abstract Objective To investigate the effect of zirconia (Zr) surface treatment with different femtosecond laser (FS) wavelengths on the shear bond strength (SBS) of metal brackets to multilayer zirconia. Methods A total of sixty-four zirconia disc-shaped samples were randomly divided into four equal groups ( n = 16). Airborne- particle abrasion (APA) utilizing 50 μm alumina particles (Al 2 O 3 ) was applied to the first group, while the other three groups were treated with FS laser light at wavelengths of 385 nm, 800 nm, and 870 nm, respectively. Orthodontic metal brackets were bonded at the center of zirconia samples using universal bond and light-cured resin cement. Specimens were tested for SBS with a universal testing machine in occlusogingival direction at a crosshead speed of 0.5 mm/min until fracture. The adhesive remnant index (ARI) was registered, and surfaces were observed under stereomicroscope. Scanning electron microscopy (SEM) was utilized to analyze and compare the morphology of treated and untreated zirconia surface samples. Results The APA group showed the greatest SBS value (17.23 ± 2.02 MPa), with no significant difference from the FS with 800 nm group (15.07 ± 3.42 MPa) or the FS with 870 nm group (13.01 ± 2.74 MPa). The FS 385 nm group showed significantly the lowest SBS value (8.07 ± 1.26 MPa) with P = 0.0001. Conclusions The femtosecond laser irradiation at 800 nm and 870 nm achieved comparable shear bond strength (SBS) to airborne-particle abrasion (APA), indicating its potential as an alternative zirconia conditioning method, although it did not surpass APA. Its effectiveness was highly dependent on the selected wavelength parameters.
Shalaby et al. (Tue,) studied this question.
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