Influence of illuminants on the color distribution of shade guides.

STATEMENT OF PROBLEM Although a shade tab in a shade guide is matched to a natural tooth in the order of value, hue, and chroma, there are limited data on the color distribution of currently available shade guides sorted by these 3 parameters. Furthermore, spectrophotometric color measurements of shade tabs differ depending on the standard illuminant employed. PURPOSE The purpose of this study was to determine the color distributions of 2 shade guides in value (CIE L( *)), chroma (C( *)(ab)) and hue angle (h(o)) scale relative to the standard illuminants D(65), A, and F2. MATERIAL AND METHODS Color of shade tabs (n=36) from 2 shade guides (Vita Lumin and Chromascop) were measured, and the distributions for CIE L( *), C( *)(ab) and h(o) values were compared. Color differences of shade tabs depending on the illuminant were calculated. The distributions of the ratios of CIE L( *) and C( *)(ab) values of each shade tab compared with the lowest value tab or the lowest chroma tab were determined. The data for the value, chroma, and hue angle within each shade guide were analyzed with a 2-way ANOVA with the factors of shade designation and type of illuminant (alpha=.05). Color difference caused by change of illuminant was analyzed with a 2-way ANOVA with the factors of shade designation and pair of illuminants compared (alpha=.05). The Scheffe multiple comparison test was performed as a post hoc test. RESULTS CIE L( *), C( *)(ab) and h(o) values were influenced by shade designation and type of illuminant in both shade guides. Color difference caused by change of the illuminant was influenced by the shade designation and pair of illuminants compared. The order of mean color differences of 16 Vita Lumin shade tabs by pairs of illuminants compared was as follows: DeltaE( *)(ab) (D(65)/F2) = 1.63 <DeltaE( *)(ab) (D(65)/A) = 2.22 <DeltaE( *)(ab) (A/F2) = 2.46 (P<.05). The order of mean color differences of 20 Chromascop shade tabs was as follows: DeltaE( *)(ab) (D(65)/F2) = 2.45 <DeltaE( *)(ab) (D(65)/A) = 2.71 <DeltaE( *)(ab) (A/F2) = 3.14 (P<.05). The distributions of value and chroma in both shade guides were arbitrary. CONCLUSION Color distribution of 2 shade guides varied by the illuminant, and the range of color difference for shade tabs by the illuminant was 0.80 to 4.82, which may be clinically unacceptable (DeltaE( *)(ab) > 3.7). Color distribution of 2 shade guides by the value and chroma was not logical.

[1]  R J Goodkind,et al.  Teaching of color in predoctoral and postdoctoral dental education in 1988. , 1992, The Journal of prosthetic dentistry.

[2]  Mostafa Analoui,et al.  Designing visually optimal shade guides. , 2004, The Journal of prosthetic dentistry (Print).

[3]  J. J. Bosch,et al.  Influence of window size in small-window colour measurement, particularly of teeth. , 1994, Physics in medicine and biology.

[4]  J J ten Bosch,et al.  Tooth Color and Reflectance as Related to Light Scattering and Enamel Hardness , 1995, Journal of dental research.

[5]  R J Goodkind,et al.  Three-dimensional color coordinates of natural teeth compared with three shade guides. , 1990, The Journal of prosthetic dentistry.

[6]  Yong-Keun Lee,et al.  Color difference of four esthetic restorative materials by the illuminant. , 2005, American journal of dentistry.

[7]  W M Johnston,et al.  Assessment of Appearance Match by Visual Observation and Clinical Colorimetry , 1989, Journal of dental research.

[8]  R. Paravina,et al.  Color comparison of two shade guides. , 2002, The International journal of prosthodontics.

[9]  Alexander J Hassel,et al.  Clinical effect of different shade guide systems on the tooth shades of ceramic-veneered restorations. , 2005, The International journal of prosthodontics.

[10]  William D Browning,et al.  Use of shade guides for color measurement in tooth-bleaching studies. , 2003, Journal of esthetic and restorative dentistry : official publication of the American Academy of Esthetic Dentistry ... [et al.].

[11]  Y-K Lee,et al.  Effects of colour measuring mode and light source on the colour of shade guides. , 2002, Journal of Oral Rehabilitation.

[12]  R. G. Craig.  Restorative dental materials , 1971 .

[13]  J D Preston,et al.  Current status of shade selection and color matching. , 1985, Quintessence international.

[14]  G. Polyzois,et al.  Effect of individual shades on reliability and validity of observers in colour matching. , 2004, The European journal of prosthodontics and restorative dentistry.

[15]  E Pizzamiglio,et al.  A color selection technique. , 1991, The Journal of prosthetic dentistry.

[16]  Ihab A Hammad,et al.  Intrarater repeatability of shade selections with two shade guides. , 2003, The Journal of prosthetic dentistry.

[17]  L. I. Yiming,et al.  Tooth color measurement using Chroma Meter: techniques, advantages, and disadvantages. , 2003 .

[18]  Yong-Keun Lee,et al.  Metameric effect between resin composite and dentin. , 2005, Dental materials : official publication of the Academy of Dental Materials.

[19]  T P van der Burgt,et al.  A comparison of new and conventional methods for quantification of tooth color. , 1990, The Journal of prosthetic dentistry.

[20]  Stefan J Paul,et al.  Conventional visual vs spectrophotometric shade taking for porcelain-fused-to-metal crowns: a clinical comparison. , 2004, The International journal of periodontics & restorative dentistry.

[21]  R. C. Sproull,et al.  Color matching in dentistry. Part III. Color control , 1974 .

[22]  C. Groh,et al.  Coverage errors of two shade guides. , 1991, The International journal of prosthodontics.

[23]  J M Powers,et al.  Dental color standards: shade tab arrangement. , 2001, Journal of esthetic and restorative dentistry : official publication of the American Academy of Esthetic Dentistry ... [et al.].

[24]  A Baltzer,et al.  Shading of ceramic crowns using digital tooth shade matching devices. , 2005, International journal of computerized dentistry.

[25]  I. E. Ruyter,et al.  Color stability of dental composite resin materials for crown and bridge veneers. , 1987, Dental materials : official publication of the Academy of Dental Materials.

[26]  C. Groh,et al.  One-dimensional color order system for dental shade guides. , 1989, Dental materials : official publication of the Academy of Dental Materials.

[27]  J L Nieves,et al.  Response of the human visual system to variable illuminant conditions: an analysis of opponent-colour mechanisms in colour constancy. , 2000, Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians.

[28]  R. D. Douglas,et al.  Acceptability of shade differences in metal ceramic crowns. , 1998, The Journal of prosthetic dentistry.

[29]  B. P. Pereira,et al.  Metamerism in aesthetic prostheses under three standard illuminants — TL84, D65 and F , 1999, Prosthetics and orthotics international.