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Digital image color analysis compared to direct CIE colorimeter assessment under different ambient conditions


Knösel, M; Attin, R; Jung, K; Brunner, E; Kubein-Meesenburg, D; Attin, T (2009). Digital image color analysis compared to direct CIE colorimeter assessment under different ambient conditions. American Journal of Dentistry, 22(2):67-72.

Abstract

Abstract: Purposes: To evaluate the concordance and repeatability of two in-vivo methods for dental color
assessment and to clarify the influence of different ambient light conditions and subject´s head position on the assessed color variables.
Methods: Color assessments were performed by two examiners
on sixteen arbitrarily selected subjects under two different, standardized conditions of illumination and at two different standardized head angulations. CIE (L*a*b*) data for upper and lower central incisors were recorded in two different ways: (1) by an intra-oral contact dental colorimeter and (2) by processing digital images for performing color calculation using AdobePhotoshop™ software. The influence of the different ambient conditions on both methods, as well as the concordance of measurements were analyzed statistically using several mixed linear models.
Results: Ambient light as a single factor had no significant influence on maxillary L*, a* and b* values, but it did have an effect on mandible assessments. Head angulation variation resulted in significant L* value differences using the photo method. The operator had a significant influence on values a* and b* for the photo method and on a* values for the colorimeter method. In fully lit ambient condition, the operator had a significant influence on the segregated L*, a*, and b* values. With dimmed lights, head angulation became significant, but not the operator. Evaluation of segregated L* values was error prone in both methods. Comparing both methods, ΔE values did not exceed 2.85 units, indicating that color differences between methods and recorded under varying ambient conditions are well below the sensitivity of the naked eye.

Abstract: Purposes: To evaluate the concordance and repeatability of two in-vivo methods for dental color
assessment and to clarify the influence of different ambient light conditions and subject´s head position on the assessed color variables.
Methods: Color assessments were performed by two examiners
on sixteen arbitrarily selected subjects under two different, standardized conditions of illumination and at two different standardized head angulations. CIE (L*a*b*) data for upper and lower central incisors were recorded in two different ways: (1) by an intra-oral contact dental colorimeter and (2) by processing digital images for performing color calculation using AdobePhotoshop™ software. The influence of the different ambient conditions on both methods, as well as the concordance of measurements were analyzed statistically using several mixed linear models.
Results: Ambient light as a single factor had no significant influence on maxillary L*, a* and b* values, but it did have an effect on mandible assessments. Head angulation variation resulted in significant L* value differences using the photo method. The operator had a significant influence on values a* and b* for the photo method and on a* values for the colorimeter method. In fully lit ambient condition, the operator had a significant influence on the segregated L*, a*, and b* values. With dimmed lights, head angulation became significant, but not the operator. Evaluation of segregated L* values was error prone in both methods. Comparing both methods, ΔE values did not exceed 2.85 units, indicating that color differences between methods and recorded under varying ambient conditions are well below the sensitivity of the naked eye.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Center for Dental Medicine > Clinic for Preventive Dentistry, Periodontology and Cariology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:April 2009
Deposited On:20 Jul 2009 15:28
Last Modified:05 Apr 2016 13:18
Publisher:Mosher & Linder
ISSN:0894-8275
Related URLs:http://www.amjdent.com/Archive/2009/April%202009%20Issue.html (Publisher)
Permanent URL: https://doi.org/10.5167/uzh-19786

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