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Color Consistency of Zirconium Oxide CEREC Crowns Milled at Different Thicknesses

Alali, Talal and Engelmeieir, Robert and Kunkel, Thomas and Shah, Nilesh and stoffer, warn (2021) Color Consistency of Zirconium Oxide CEREC Crowns Milled at Different Thicknesses. Master's Thesis, University of Pittsburgh. (Unpublished)

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Purpose: The purpose of this study was to evaluate the color of full-contour zirconia CEREC restorations milled at different material thicknesses which could aid dental practitioners in planning full-contour ceramic restorations.
Method and materials: Two sample crown preparations were made of an individual biogeneric copy of a left maxillary central incisor on a model scanned by means of Sirona CEREC Omnicam. One sample was prepared at a reduction of 1 mm, while the other was prepared at a 2mm reduction. A total of 60 CEREC Ivoclar ZirCad LT blocks were used to create 10 Samples of monochromic Zirconia crowns milled at 1 mm and 2 mm thicknesses in each of Vita classic shades A1, B2, and C2. The optimal thickness of 1 mm was chosen for the control groups Based on manufacturer recommendations and optimal thickness of 2 mm was chosen for the test groups. Sample crowns were sintered by means of a Sirona SpeedFire oven. No additive coloring or glaze was applied. A Canon 80D digital camera equipped with a Canon MR-14EXII ring flash and a polarized filter was used to photograph all test and control group specimens. The photographs were developed via digital software, Photoshop CC 2019. The CIE L*a*b* color values were measured.
Results: CIE L*a*b* data for all samples was recorded and statistically analyzed using a two sample t-test, STATA.SE v16. There was a statistically significant difference (P<0.05) in L* values when test groups (2mm) were compared with the control groups (1mm) for shades A1, B2, and C2 with P<0.00. ΔE for shades A1, B2 and C2 groups were 3.64, 3.67, and 4.55 respectively which is higher than the clinically acceptable threshold 3.3.
Conclusion: An increase in the thickness of Zirconia from 1mm to 2mm demonstrated a ∆E >3.3 in all test groups which is detectable by untrained observers. As the thickness if Zirconia increased from 1mm to 2 mm, L* decreased in all test groups. Vita Classic shade C-2 demonstrated a more dramatic decrease in L* than shade A-1 and B-2 following the Zirconia thickness change from 1mm to 2mm.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Alali, Talaldr.talali@gmail.comtaa82
Engelmeieir, Robertrle14@pitt.edurle14
Kunkel, Thomastck14@pitt.edutck14
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairEngelmeieir, Robertrle14@pitt.edurle14
Committee MemberKunkel, Thomastck14@pitt.edutck14
Committee MemberShah, Nileshnhs3@pitt.edunhs3
Committee MemberStoffer,
Date: 7 January 2021
Date Type: Publication
Defense Date: 26 October 2020
Approval Date: 7 January 2021
Submission Date: 6 November 2020
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 40
Institution: University of Pittsburgh
Schools and Programs: School of Dental Medicine > Dental Science
Degree: MDS - Master of Dental Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: zirconia thickness color
Date Deposited: 07 Jan 2021 22:49
Last Modified: 07 Jan 2021 22:49


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