Effect of surface finishing (polishing and glazing) and printing layer orientation on surface roughness of 3D-printed versus conventionally milled zirconia: A vitro comparative study

To investigate how different printing layer orientations and surface finishing techniques affect the surface topography and roughness of zirconia specimens produced via milling and 3D printing utilizing digital light processing (DLP). Fifty-six square-shaped zirconia specimens (10 mm×10 mm× 3mm) were fabricated by milling (n=14; 7 for polishing and 7 for glazing), and by DLP (n=42), with three building orientations (vertical 0°, horizontal 90°, and diagonal 45°, n=14 for each; 7 from each direction for polishing and 7 for glazing). Average surface roughness (Ra) was evaluated using profilometry, and surface topography was observed by scanning electron microscopy (SEM). In the polished specimens, the Ra values differs significantly (P