The enhanced shear bond strength of resin cement to zirconia with ordered conical spots through the CO₂ laser process

In this study, a new shear bonding system was created that uses a CO2 laser to form a pattern of conical spots on a zirconia prosthesis surface to improve mechanical interlocking. Four types of zirconia substrates were employed, which underwent particle abrasion after being polished, machined, spotted, and spot-particle abraded. The surface roughness of each substrate was measured via scanning electron microscopy and X-ray diffraction (XRD). A shear bond strength test was performed with the zirconia-based material and a composite resin assuming abutment construction. XRD did not indicate that forming spots caused a phase transformation in zirconia with respect to machined zirconia. The shear bond strength was approximately twice that of the machined samples and approximately 2.3 times that of the samples that underwent particle and spot-particle abrasion. Surface modification by spotting improved the mechanical fitting force. However, no significant difference was observed between particle abrasion and spot-particle abrasion.