Textured Intaglio Micropores Improve the Properties of 3D-Printed Zirconia Crowns

Monolithic zirconia crowns fabricated using computer-aided design and computer-aided manufacturing (CAD-CAM) via subtractive manufacturing (SM) exhibit limited bonding properties compared with other ceramics. Traditional methods such as air abrasion can improve bonding but may negatively affect the mechanical stability of zirconia. Nanoparticle jetting (NPJ), an emerging 3-dimensional-printing technology for zirconia restorations, offers the potential to create intricate structures, such as porous surfaces, with high precision. This study aimed to demonstrate that NPJ-manufactured monolithic zirconia crowns with an intaglio porous design can enhance bonding properties while maintaining mechanical strength. Standard NPJ zirconia crowns and commercially available SM zirconia crowns (SZC) were used as control groups. The surface roughness, fracture load, 2-body wear, and shear bond strength (SBS) were evaluated. The NPJ intaglio porous crowns (NIPC) with an intaglio porous design exhibited satisfactory and comparable fracture strength to SZC (within 1-mm occlusal thickness). Although the NIPC retained a relatively high original surface roughness, it demonstrated similar occlusal surface roughness, 2-body wear, and aging resistance to SZC after thorough polishing. Furthermore, the NIPC showed significantly superior intaglio surface roughness and SBS compared with conventionally air-abraded zirconia. Overall, this study successfully demonstrated the potential of NIPC as a viable restorative option, offering robust bonding and reliable mechanical properties.