Reproducibility of tooth color gradation using a computer color-matching technique applied to ceramic restorations

Ishikawa-Nagai, Shigemi; Ishibashi, Kanji; Tsuruta, Osamu; Weber, Hans-Peter

doi:10.1016/j.prosdent.2004.10.024

« Previous Next »Journal of Prosthetic Dentistry
Volume 93, Issue 2 , Pages 129-137, February 2005

Reproducibility of tooth color gradation using a computer color-matching technique applied to ceramic restorations

Shigemi Ishikawa-Nagai, DDS, MSD, PhD
- Instructor, Department of Restorative Dentistry and Biomaterials Sciences, Harvard University, School of Dental Medicine
- Reprint requests to: Dr Shigemi Ishikawa-Nagai, Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, 188 Longwood Ave, Boston, MA 02115, Fax: 617-432-0901
Kanji Ishibashi, DDS, PhD
- Professor and Chairman, Department of Fixed Prosthodontics, Iwate Medical University, School of Dentistry
Osamu Tsuruta, DDS
- Postgraduate student, Department of Fixed Prosthodontics, Iwate Medical University, School of Dentistry
Hans-Peter Weber, DMD, Dr Med Dent
- Professor and Chairman, Department of Restorative Dentistry and Biomaterials Science, Harvard University, School of Dental Medicine

School of Dental Medicine, Harvard University, Boston, Mass; School of Dentistry, Iwate Medical University, Morioka, Japan

Statement of problem

To reproduce tooth color precisely, an objective methodology based on color science is required. However, perception-based techniques are still the primary method for color matching in restorative dentistry.

Purpose

This study evaluated the accuracy of reproduction of color gradation for ceramic restorations using a Computer Color Matching (CCM) technique employing a prototype program and spectrophotometric data measurements.

Materials and methods

The colors of 10 target-shade tabs of the Vitapan 3D Master shade guide were measured at 4 regions of crowns from the cervical to the incisal area using a spectrophotometer. Tooth-shaped CCM ceramic specimens (30 specimens; 3 specimens for each of 10 target-shade tabs), the same size and shape as target-shade tabs, were fabricated according to the CCM prescriptions calculated using a prototype CCM program. The colors of CCM ceramic specimens and target-shade tabs were compared in 10 incremental areas from gingival to incisal (each measuring 1 mm high × 3 mm wide). The color differences, ΔE, ΔL^∗, Δa^∗, and Δb^∗, were calculated. The color difference ΔE values were analyzed by a repeated measures analysis of variance (P<.0001). Three prosthodontists evaluated CCM specimens by perception techniques.

Results

The mean color difference (ΔE) values were clinically acceptable (below 3.6) for incremental areas 3 through 10 and unacceptable for areas 1 and 2 (gingival area). Highly significant differences in the mean of ΔE values among target-shade tabs (P<.0001), areas (P<.0001), and target-shade tab-by-area interaction effects (P<.0001) were noted. However, perceptional evaluation indicated “Definitive match” or “Approximate match” for all CCM specimens.

Conclusion

The CCM technique tested in this study utilizing 4 measurements on target-shade tabs could reproduce tooth color gradation from incisal to precervical regions with clinically acceptable results.