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

2005; Elsevier BV; Volume: 93; Issue: 2 Linguagem: Inglês

10.1016/j.prosdent.2004.10.024

1097-6841

Shigemi Ishikawa‐Nagai, Kanji Ishibashi, Osamu Tsuruta, Hans‐Peter Weber,

Cultural Heritage Materials Analysis

Statement of problemTo 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.PurposeThis 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 methodsThe 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.ResultsThe 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.ConclusionThe 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. 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. 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. 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. 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. 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.