Using the 3D Shade System in Color Matching Comparison: Easy Shade System vs. Visual Methods
Dental News Volume XIX, Number I, March, 2012
by Dr. Wael Abdulla, Dr. Waleed AlYaseen, Dr. Abdulaziz Sadeq
The prevalence of color defective vision in male dentists was found by Barna et al. to be 14%8, by Moser et al. to be 9.9%,9 and by McMaugh to be 8.2%.10 The prevalence of color defective vision in male dentists, being as much as 14%, supports the conclusions of different studies that every dentist as well as dental students along with dental auxiliaries should be tested for color deficient vision as well as their shade matching abilities be evaluated for accuracy.8,11,12 The ability to consistently match shades accurately can help reduce the number of unsatisfactory results which could lead to costly remakes.
Previous authors have recommended that dental students, dentists and auxiliaries be tested for color discrimination.9,11-13 The Farnsworth 100-Hue test has been used in dental research studies as a screening test to rule out defective color vision subjects.14
The 100-Hue test is a sensitive and accurate test that is used widely and is considered the standard by which most other color discrimination tests are measured.15-17 The Easyshade is a relatively new system. The standard for clinical shade matching has always been the human eye. The machine will be analyzed for effectiveness as well as compared to specific operator’s abilities whose effectiveness in color analysis has been determined by using a simple color screening test. Hamad et al.18 stated that the use of the Vitapan 3D-Master shade guide significantly improved intrarater repeatability among general practitioners when compared with the Vita Lumin Vacuum shade guide (P_.0001). This improvement could be attributable to the color science information gained by the general practitioners after they used the organized and scientific approach associated with the Vitapan 3D-Master shade guide. This study will compare the results using the 3D Vita shade guide with the results using the Vita classic shade guide when using the Easyshade system.
Materials and Methods
The Vita-Vita test17 was used to identify two visual shade evaluators with a predetermined superior shade matching ability. The individuals were the evaluators to whom the Vita Easy Shade’s accuracy was compared. Expert observers were chosen to participate in the vita easy shade matching study. The Vita Easy Shade machine was used on 40 subjects to measure the central region of each subject’s left maxillary central incisor. Protocol consisted of mandating virgin non restored teeth without any gross signs of developmental intrinsic staining. The two visual evaluators selected a shade from the same area of the left maxillary central incisor for all subjects. The visual evaluators were instructed to focus only on the central portion of the tooth.
The evaluators analyzed the tooth first, and then the tooth was scanned by the machine. If the evaluators disagreed amongst the shade chosen, they were asked to retake the shade and come to a consensus of one shade. The machine tip was placed on the middle third of the tooth for shade analysis. The Vita Easyshade (Vita Zahnfabrik) is an intramural dental spectrophotometer that provides CIE L*a*b* values in specific modes. This shade taking device (Vita Easyshade) comprises a base unit, a handpiece, and a fiberoptic cable assembly. There are 3 measuring modes: tooth, shade tab, and restoration. The appropriate mode must be selected prior to measuring, and data reported are mode specific. The accuracy of the Vita Easy Shade was based on the comparison of the results obtained compared to the shade chosen using the visual evaluation method. All readings on the Vita easy shade instrument were made by the same operator for consistency. Statistical analysis included comparison of the correct matches of the Vita Easy Shade to the standard matching technique the visual observers using a standard t-test. A 95% confidence interval was used in comparative analysis.
Shade matching to adjacent teeth is one of the most difficult and important aspects of an esthetically successful restoration. The Vita Easy Shade system is a relatively new handheld device that uses electronic optical measurements of teeth. While the standard method for clinical shade matching is the human eye, different visual evaluators are able to match shades more or less effectively depending on multiple variables. This is why the Vita- Vita test was used to choose the best visual evaluators available. Also, shade matching was performed under similar conditions as well as during the same time of day. It was considered a “match” if the visual evaluator’s choice matched the machines’ reading.
The results showed that the machine was accurate 97.5% of the time. However, at a 95% confi dence interval one can be certain that 95% of the time the machine will not perform below 92.7% matches the visual method. One can only infer that this machine is not absolutely reliable, but considerably accurate and should be used as an adjunctive shade matching method.
As more dentists realize the importance of a scientifi c approach to color matching in dentistry, manufacturers will continue to research and develop better digital equipment. Currently, the Vita Easy Shade instrument in combination with the 3D vita shade guide shows superiority in color matching and determination when compared to the Vita classic shade. Nevertheless, this machine is not a replacement for traditional methods. However, it is a defi nite adjunct to visual shade matching. The final question, regardless of which system used, visual or electronic, is “Does it match?” The final evaluation system for success or failure will be the patients’ and their peers’ visual methods. The art of dentistry will always rely on individual observation and interpretation, and adjunctive electronic instruments can only enhance this process and attempt make it more reliable.
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