Effects of different frequencies of Er:YAG laser on the bonding properties of zirconia ceramic

The effects of Er:YAG laser with different frequencies on zirconia ceramic's bonding properties were studied. In total, 42 Y-TZP (yttrium-stabilized tetragonal zirconia polycrystals, UPCERA ST) with 3 mmx3 mmx2 mm divided into 6 groups (n=7): control (C), sandblasting (SB), and Er:YAG laser (A1-A4), which the frequencies correspond to 5 Hz, 10 Hz, 15 Hz, and 20 Hz, IPS e.max Press ceramics were B. Scanning electron microscope (SEM) images were recorded. The ceramics were bonded to enamel from extracted teeth. After being constantly stored at 37 ? for 24 h, the shear test was performed with a universal testing machine. Stereomicroscope evaluated fracture modes. Stereomicroscope evaluated fracture modes. Data were analyzed by SPSS26.0 statistical software; the standard was P=0.05. (1) The SEM showed the surface of A1-A4 became rough compared with C. (2) The shear test showed that the highest bonding strength for B was 13.15 +/- 2.97 MPa, followed by SB was 7.78 +/- 0.97 MPa, and A2 was 7.13 +/- 0.75 MPa. However, there was no significant difference between SB and A2 (P>0.05). Fracture modes of C were the interface fracture of Y-TZP and resin adhesive; most of A1-A4 and SB also were interface fracture, a few mixed fractures, and cohesion fracture of resin adhesive; B were all mixed fracture. Er:YAG laser with 10 Hz could be used as an alternative to sandblasting with Al2O3 for surface modification of Y-TZP to increase the bonding strength.