Short-pulse direct laser writing of 3Y-TZP zirconia: a superior surface modification strategy for enhanced resin bonding and adhesion durability

The clinical success of zirconia-based restorations relies on surface modifications that enhance adhesion without compromising material integrity. This study evaluates Direct Laser Writing (DLW) as a non-contact, contamination-free alternative to conventional grit-blasting methods (alumina particle abrasion [SB] and silica-coated alumina treatment [SC]. Surface roughness (R_a), wettability, surface free energy (SFE), phase transformation, and shear bond strength (SBS) were assessed. Zirconia specimens (N = 40) underwent DLW at two distinct parameters (DLW35, DLW10) or conventional grit-blasting (SB, SC). Surface characterization included roughness measurements, contact angle analysis, and SFE calculation (Owens-Wendt method). Phase transformation was quantified using X-ray diffraction (XRD). SBS tests between zirconia and resin-matrix cement were performed under water storage and thermocycled conditions. Results showed DLW provided controlled, uniform roughness comparable to grit-blasting without inducing mechanical damage or contamination. DLW-treated surfaces exhibited significantly better wettability and higher SFE. SBS values were statistically similar across all groups, indicating stable adhesion performance under both dry and thermocycled conditions. DLW preserved the tetragonal zirconia phase substantially better (DLW35: 93 %, DLW10: 85 %) compared to grit-blasted surfaces (SB: 76 %, SC: 68 %), minimizing residual stress and microstructural damage. The study concludes DLW is a superior zirconia surface treatment, offering precise control, contamination-free surfaces, enhanced wettability, and maintained microstructural integrity, making it ideal for dental, maxillofacial, and orthopedic applications.