Student Theses, Dissertations and Capstones

Document Type

Thesis - NSU Access Only

Degree Name

Master of Science (M.S.) in Dentistry

Copyright Statement

All rights reserved. This publication is intended for use solely by faculty, students, and staff of Nova Southeastern University. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, now known or later developed, including but not limited to photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author or the publisher.

Department

College of Dental Medicine

First Advisor

Niranjan Joshi

Date of original Performance / Presentation

January 2024

Publication Date / Copyright Date

1-1-2024

Abstract

Objective: The study will quantify the shades of the specimens and shade guide, L*a*b* values, and compare their differences, ΔE*, between Vita Easyshade with the established Vita Classic shade guide for the zirconia specimens. Background: Achieving optimal aesthetics in dental restorations requires meticulous shade selection and verification. With the recent advancements in digital dentistry and the increasing use of zirconia as a restorative material, it is important to investigate the shade matching accuracy between conventional shade guides, such as the Vita Classic Shade Guide, and the final zirconia full contour crowns. This research aims to comprehensively investigate the shade compatibility between Vita Classic Shade Guide and the final zirconia full contour crowns. The incorporation of Vita Easyshade allows for a quantitative assessment of the L*a*b* values, which can be used to calculate the color difference, ΔE*. This will provide a detailed insight into color parameters in prosthodontic applications. Methods: A digital spectrophotometer was used to obtain the L*a*b* values from milled zirconia specimens. The same device was used to obtain L*a*b* values from Vita Classical shade tabs (A1, A2, B1, and C1). A custom-made positioning mold was fabricated. The position mold encompassed the specimen position matrix. This matrix was used for the seating of the specimens and provided a pink-colored background, ensuring the same lighting environment each time. ΔE* values were obtained from the L*a*b* values and statistical analysis was done. Results: The Two-way ANOVA analysis revealed that both the shade (P < 0.001) and the interaction between shade and thickness (P < 0.001) had a significant effect on ΔE*. The effect size for Shade was both large and significant (Estimate: 0.95, CI: [0.94, 1.00]), indicating a significant effect on ΔE*. However, Thickness appeared to have no effect on ΔE* individually, yet the interaction between Shade and Thickness yielded a significant effect with a moderate effect size (Estimate: 0.63, CI: [0.58, 1.00]). Conclusion: The study highlights the significant impact of shade and the relationship that thickness has to shade perception as relation to ΔE*. Shade has a great influence, with substantial variations observed, while thickness alone did not significantly affect ΔE*. However, its impact is overshadowed by the interaction effect with the shade. These findings emphasize the importance of considering both shade and thickness simultaneously when assessing the final shade of zirconia prostheses.

Disciplines

Dentistry

Keywords

Crown; Shade; Spectrophotometer; vita; Zirconia

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