College of Dental Medicine Student Theses, Dissertations and Capstones

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Dentistry

Department

College of Dental Medicine

First Advisor

Singer, Richard

Publication Date / Copyright Date

2014

Publisher

Nova Southeastern University. College of Dental Medicine.

Abstract

Introduction: Dentistry has changed significantly during the last two decades. Patients are more aware and demanding of the latest technologies available in restorative dentistry. The purpose of this study was to determine any possible changes on the surface roughness, gloss and color change of CAD-CAM milled porcelain veneers following repeated milling times, before and after a glazing process. Methods: A Teflon disk-shaped mold was used as a cast to take a digital impression (BlueCam) in order to fabricate cylindrical-shaped specimens. A total of one hundred (N=100) specimens porcelain veneers using Empress CAD (I10) block, were milled using the CAD/CAM CEREC-SIRONA system. The specimens representing the 1 st , 5th , 10th , 15th , 18th and 20th milling times were evaluated to determine any statistical differences regards surface roughness, gloss and color-change. Subsequently, all milled specimens representing the 1 st , 5th , 10th , 15th , 18th and 20th received a standard surface glaze and surface properties (roughness, gloss and color) were re-measured. Results: There was a statistically significant difference in roughness (Pre-glazing) between test groups at different milling times with a determined p value of 0.027. Regard roughness (Pre and Post-glazing) a statistically significant difference was found between test groups on different milling times, which present a p value of 0.18. A statistically significant difference was found in gloss (Pre and Post glazing) between test groups on different milling times. A significantly higher score after glossing, which present a p = 0.791.There was a significant difference found between samples with the same milling time, (Pre and Post the glazing process). The ΔE range between (2.5021 to 3.0418), which is considered to be detectable only by a skilled person and is clinically acceptable. Also, after perform the SEM evaluation of the burs used after 20 milling times, it showed some lost particles leaving some void on the bur surface. Conclusions: There was a statistically significant change in the surface roughness on porcelain veneers processed by CAD/CAM using the same set of burs prior to the glazing process. There was no statistical difference in porcelain surface roughness between samples of the groups Pre-Glazing. Porcelain gloss was altered significantly between groups Pre and Post-Glazing at all milling times. Porcelain Color-shade, value, and hue were significantly altered after the glazing process. There seem to be a considerable change in the physical and optical characteristics (surface roughness, gloss and color-change) after the glazing process, and this likely has a meaningful impact on the clinical aesthetic qualities of the final restoration.

Disciplines

Dental Materials | Dentistry

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