Effect of Laser Surface Texturing Using a Surface Transition Machine on Bonding Strength to Zirconia Ceramic

The purpose of this study was to evaluate the effect of zirconia surface treatment using laser surface texturing performed with a Surface Transition Machine (STM). Zirconia specimens were fabricated in two shapes: 40 cylindrical specimens and square specimens. These were divided into two groups: the sandblasting group and the STM treatment group. Each group was bonded with either resin cement (Duo-Link) or resin-modified glass ionomer (RMGI) cement (RelyX Luting 2) after Z-Prime Plus primer application. The shear bond strength was measured using a universal testing machine, and the surface characteristics were analyzed using scanning electron microscopy and high-performance 3D digital microscopy. The group bonded with resin cement after STM treatment (48.4 ± 10.4 MPa) exhibited the highest shear bond strength, whereas the group bonded with RMGI cement after sandblasting (8.1 ± 1.5 MPa) exhibited the lowest. The STM treatment group showed significantly higher shear bond strength than the sandblasted group, and the Duo-Link group demonstrated significantly higher bond strength than the RelyX Luting 2 group. Surface observations showed that the STM treatment group exhibited rough surfaces and regularly patterned retentive structures. The surface roughness (Sa) was also significantly higher in the STM treatment group (13.3 ± 1.5 μm) than in the sandblasting group (7.08 ± 0.4 μm). In conclusion, STM treatment effectively improved the shear bond strength between zirconia and cement, particularly providing the highest bond strength when used with resin cement.