Advisor(s)

Nathaniel Lawson

Committee Member(s)

Amjad Javed
Daniel Givan
Ramakiran Chavali
Ramtin Zadeh

Document Type

Thesis

Date of Award

6-1-2026

Degree Name

Master of Science in Dentistry (MSDent)

School

School of Dentistry

Department

Dentistry

Abstract

Statement of Problem: Additive manufacturing has emerged as an alternative to conventional milling for zirconia-based dental restorations because of its potential to reduce material waste and increase design flexibility. However, whether 3D-printed zirconia can provide optical and structural properties comparable with those of conventionally milled zirconia for esthetic applications remains unclear. Purpose: The purpose of this in vitro study was to compare the optical properties of 3D-printed zirconia and conventionally milled 3Y, 4Y, and 5Y zirconia, as measured by translucency and fluorescence, and to evaluate their structural characteristics, as measured by density, porosity, phase composition, and surface morphology. Materials and Methods: Four groups were evaluated: 3D-printed 3Y zirconia, milled 3Y zirconia, milled 4Y zirconia, and milled 5Y zirconia. A sample size calculation performed with G*Power identified a required total sample size of 100 specimens (25 per group). Disc-shaped specimens measuring 14 mm in diameter and 1.0 ± 0.05 mm in thickness were fabricated. Translucency was measured spectrophotometrically over white and black backgrounds. Fluorescence was analyzed with a spectrofluorometer at 365-nm excitation and 400- to 600-nm emission. Density and apparent porosity were determined by the Archimedes principle. Phase composition was assessed with X-ray diffraction, and surface morphology was evaluated with scanning electron microscopy. Results: Translucency differed significantly among groups (P<.001). Milled 5Y zirconia showed the highest translucency parameter (10.20 ± 0.21), followed by milled 4Y zirconia (8.98 ± 0.31), milled 3Y zirconia (8.22 ± 0.35), and 3D-printed 3Y zirconia (2.50 ± 0.88). Fluorescence peak wavelength differed significantly (P<.001), with 3D-printed 3Y zirconia showing a red-shifted peak at 462.2 ± 11.7 nm compared with the milled groups (432.9 to 441.2 nm). Fluorescence intensity and emission area were not significantly different. Printed 3Y zirconia demonstrated lower density, higher porosity, and more visible surface defects than the milled groups. Conclusion: Both fabrication technique and yttria content influenced the optical and structural behavior of zirconia. Conventionally milled zirconia, particularly 5Y zirconia, demonstrated superior optical performance, whereas 3D-printed 3Y zirconia showed reduced translucency and less favorable structural features. Clinical Implications: Current printable 3Y zirconia may be less suitable for highly esthetic restorations, whereas conventionally milled higher-yttria zirconia may be preferred when improved optical integration is required.

Keywords

additive manufacturing;fluorescence;porosity;translucency;yttria content;zirconia

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