Comparative in Vitro Analysis of Milled vs. 3D-Printed Zirconia for Emergency Dental Splints: The Effect of Printing Angle on Optical Properties.

Moghadas, Elham; Najari, Nazila; Tahmassebi, Elahe

doi:10.30491/tm.2026.574907.1920

Comparative in Vitro Analysis of Milled vs. 3D-Printed Zirconia for Emergency Dental Splints: The Effect of Printing Angle on Optical Properties.

Document Type : Original Article

Authors

Elham Moghadas ¹^{, 2}

Nazila Najari ³

Elahe Tahmassebi ¹

¹ Research Center for Prevention of Oral and Dental Diseases, Baqiyatallah University of Medical Sciences, Tehran, Iran

² Department of prosthodontics, School of dentistry, Baqiyatallah University of medical sciences, Tehran, Iran

³ Specialist in Prosthodontics, Private office

10.30491/tm.2026.574907.1920

Abstract

Introduction: To evaluate the optical properties of zirconia fabricated via milling and 3D printing for urgent dental restoration in trauma and reconstructive care, focusing on the impact of printing orientation—a critical parameter for point-of-care, patient-specific manufacturing.
Method: In this in vitro study, eighty zirconia specimens were fabricated using four methods relevant to digital workflows: conventional milling (control) and digital light processing (DLP) 3D printing at 0°, 45°, and 90° build orientations (n = 20 per group). Key aesthetic parameters—translucency parameter (TP) and surface gloss—were measured using a spectrophotometer and glossmeter, respectively, both before and after simulated clinical aging (10,000 thermocycles).
Result: Translucency was not significantly affected by fabrication method or aging (p > 0.05). In contrast, surface gloss was significantly reduced by thermocycling in all groups (p < 0.001) and was dependent on the manufacturing technique (p = 0.019). Milled zirconia demonstrated the highest gloss. Among 3D-printed specimens, the 0° orientation yielded significantly higher gloss than the 45° or 90° orientations.
Conclusion: For aesthetic dental restoration in trauma care, 3D-printed zirconia can match the translucency stability of milled standards. However, its surface gloss is inferior and highly sensitive to printing angle. To integrate efficient, patient-specific 3D printing into emergency digital workflows, protocols must be optimized—favoring lower print angles (e.g., 0°)—to minimize post-processing and expedite the delivery of definitive, aesthetically satisfactory restorations.

Keywords

3D Printing

Gloss

Milling

Optical Properties

Zirconia

Subjects