Dental Shade Guides Research Articles

MANUAL METHOD FOR GINGIVAL SHADE SELECTION- A LITERATURE REVIEW

Objective- The purpose of the article is to present a narrative review of the literature related to the different shade guides available for dental practitioners. Materials And Methods- A literature search was performed in the online databases – PubMed, Science Direct, Medline and Google Scholar with the following When fabricating a restoration, patient satisfaction with the shade match is essential. The patients level of satisfaction may not be the same as that of the dental practitioner. Esthetic expectations have dramatically increased in the last few years. Color and shade determination are generally considered difficult in dental practice. Most prostheses fail esthetically owing to improper shade selection. A good understanding of color shade guides is essential for precise shade matching, but the paucity of dental practitioners knowledge of color science because of the numerous available shade guides creates a challenge. This comprehensive review states information on shade selection, different shade guides, and shade matching devices commonly used in dental practice. Dental shade guides are a set of colour standards mimicking the colour of tissues, which dentists aim to restore – tooth structures, gingival tissues or facial structures in facial prosthodontics - skin, mucosa, eyes etc. They can be systematized based on the following principles – fabrication process, the material of manufacturing or restoration and according to the tissues, which are restored. Conclusion: To provide an esthetic restoration to the patient, the dentist must have a full understanding of the science of color and color perception. Matching the correct shade satisfies both the dentist and patient and gives a pleasing appearance to the patient.

Three-dimensional representation of the Vita Toothguide 3D-Master: An in vivo clinical study.

The Vita Toothguide 3D-Master (Vita Zahnfabrik) is considered the dental shade guide in which the three dimensions of color - lightness, hue, and chroma - are most well-ordered in the CIELAB color space. No research has yet explored how well the Vita Toothguide 3D-Master is ordered in the 3D color space by recording color coordinates in vivo. To evaluate the spatial color distribution of the Vita Toothguide 3D-Master's lightness, chroma, and hue groups and its 26 physical shade tabs. The dental color (L*, C*, h°, a*, and b* color coordinates) of a healthy maxillary central incisor was recorded for 1361 participants (aged between 18 and 89 years) using a Vita Easyshade Compact spectrophotometer (Vita Zahnfabrik). The R 2.7.2. statistics program was used to create the visual representations. The five lightness levels are those that are best distributed in the color space, in relation to the L* coordinates, followed by the chroma group and, finally, the hue group. The 5M1, 5M2, and 5M3 physical shade tabs are situated at a greater distance apart from the other tabs in the color space. The Vita Toothguide 3D-Master's 26 physical shade tabs are satisfactorily distributed in three-dimensional space, although strict mathematical criteria are not followed. The natural dental shades that fall lower on the lightness scale are the most poorly represented by the physical shade tabs. Darker teeth are poorly represented by the Vita Toothguide 3D-Master's physical shade tabs. The spatial distribution of dental shade guides needs to be improved to ensure they provide homogeneous coverage of the entire chromatic spectrum corresponding to natural teeth. This would help reduce the errors inherent to the subjective visual color selection process.

Visual and instrumental coverage error of two dental shade guides: an in vivo study

ObjectivesThis study aims to evaluate in vivo the color agreement between natural teeth and dental shade guides by means of visual and instrumental coverage error (mathrm{CE}) index.Materials and methodsThe color of the middle third of 735 incisors was visually determined by two evaluators using the Vita Classical (VC) and Vita 3D Master (V3DM) shade guides. The color match between the natural tooth and the shade tab was rated as poor (P), good (G), or optimum (O) by each observer. CIE color coordinates of the target teeth and shade tabs of VC and V3DM were instrumentally measured using a clinical spectrophotometer. Visual ({mathrm{CE}}_{mathrm{V}}) and instrumental ({mathrm{CE}}_{mathrm{I}}) coverage error indexes were computed using CIELAB and CIEDE2000 metrics for both shade guides. For {mathrm{CE}}_{mathrm{V}} calculation, only the concordant inter-observer determination on tooth shade rated as O–O or O–G was used. The results were evaluated using perceptibility (PT, {mathrm{Delta E}}_{mathrm{ab}}^{*}= 1.2, {mathrm{Delta E}}_{00}= 0.8) and acceptability (AT, {mathrm{Delta E}}_{mathrm{ab}}^{*}= 2.7, {mathrm{Delta E}}_{00}= 1.8) color thresholds for dentistry.ResultsVC and V3DM exhibited {mathrm{CE}}_{mathrm{I}} (2.5, 3.2, and 3.2, 2.7 CIELAB units; 1.9, 2.3, and 2.8, 2.4 CIEDE2000 units, respectively, for O–O and O–G match) and {mathrm{CE}}_{mathrm{V}} (4.7, 4.8, and 4.1, 4.6 CIELAB units; 3.3, 3.4, and 3.4, 3.6 CIEDE2000 units, respectively, for O–O and O–G match) values greater than 50:50% AT for both color difference formulas. {mathrm{CE}}_{mathrm{I}} contributes more than 50% (53.2–82.4% range) to the {mathrm{CE}}_{mathrm{V}} value. This contribution depends on the shade guide used and the quality of the visual rating.ConclusionsThe evaluated shade guides exhibited visual coverage errors above acceptability thresholds, largely due to the contribution of the instrumental coverage error to the visual coverage error.Clinical relevanceIt necessary to further improve commercially available dental shade guides to facilitate achievement of satisfactory esthetics results in clinical practice.

Assessment of coverage error for two common commercial dental shade guides using a spectrophotometric method

AbstractThe purpose of this study was to assess the coverage error and the coverage error percentage for two common commercial dental shade guides named VITA classical A1‐D4 shade guide and VITA Toothguide 3D‐MASTER. Totally, 197 dental students with intact maxillary anterior teeth were randomly selected to participate in the study. CIELAB values of the teeth were measured with a spectrophotometer. The teeth matched shades were selected by using the spectrophotometer. ∆E00 and ∆E*ab color differences between the matched shades and the teeth shades were calculated. The mean ∆E00 and ∆E*ab values represented the coverage errors for the shade guides. The coverage error values were compared with the thresholds for perceptibility and acceptability using 1‐sample t test (α = 0.05). To calculate the coverage error percentages for the shade guides, a color matching error for the shade guides was considered when the color difference value was greater than the thresholds. For VITA classical shade guide, the coverage error was 3.0 ± 1.2 (∆E00) and 3.3 ± 1.3(∆E*ab) while the coverage error percentages ranged between 63.6% and 99.4%. For VITA 3D‐MASTER guide, the coverage error was 2.5 ± 1.3 (∆E00) and 2.9 ± 1.5 (∆E*ab) while the coverage error percentages ranged between 44.5% and 96.9%. Overall, the teeth were more reddish than their matched shades of the shade guides. Using these shade guides may cause inaccurate shade determination in the population studied due to their high coverage error and coverage error percentage values.

Can identical dental shade guides be used interchangeably?

To determine if identical dental shade guides can be used interchangeably considering their precision. Twenty Vita classical (VC) and Vita 3D-Master (VM) shade guides were subjected to spectrophotometric measurements and their CIELab values were measured in three shade tab regions: incisal, middle, and cervical and also in total. The mean L*, a*, and b* values for analogous shade tabs were calculated to identify CIELab values for typical shades. ∆E00 color differences between a typical shade and its analogous shade tabs were measured. ∆E00 values were compared with perceptibility (∆E00 = 0.8) and acceptability (∆E00 = 1.8) thresholds using one-sample t test (α= 0.05). An error was considered when the ∆E00 value was greater than the threshold. Subsequently, the shade guides' precision scores were calculated. Mean ∆E00 values ranged between 0.3 and 0.5 for VC tabs and between 0.3 and 0.6 for VM tabs. Precision scores for both shade guides ranged from 83.3% to 100%, considering the perceptibility threshold. Regarding the acceptability threshold, precision scores for VC ranged from 93.3% to 100%, while the precision scores for VM were 100%. Owing to high precision of VC and VM, identical dental shade guides can be used interchangeably. Using identical dental shade guides interchangeably may affect the color results of restorative treatments. This study identified high levels of precision for identical shade tabs of Vita classical and Vita 3D-Master across different batches. Thus, similar dental shade guides can be used interchangeably.

Preparation and Performance Evaluation of Duotone 3D-Printed Polyetheretherketone as Oral Prosthetic Materials: A Proof-of-Concept Study.

Literature has reported the successful use of 3D printed polyetheretherketone (PEEK) to fabricate human body implants and oral prostheses. However, the current 3D printed PEEK (brown color) cannot mimic the vivid color of oral tissues and thus cannot meet the esthetical need for dental application. Therefore, titanium dioxide (TiO2) and ferric oxide (Fe2O3) were incorporated into PEEK to prepare a series of tooth-color and gingival-color PEEK composites in this study. Through color measurements and mechanical tests, the color value and mechanical performance of the 3D printed PEEK composites were evaluated. In addition, duotone PEEK specimens were printed by a double nozzle with an interface between tooth-color and gingival-color parts. The mechanical performance of duotone PEEK with two different interfaces (horizontal and vertical) was investigated. With the addition of TiO2 and Fe2O3, the colors of 3D printed PEEK composites become closer to that of dental shade guides. 3D printed PEEK composites generally demonstrated superior tensile and flexural properties and hence have great potential in the dental application. In addition, duotone 3D printed PEEK with a horizontal interfacial orientation presented better mechanical performance than that with a vertical one.

CIEL*a*b* values in vita classical and vita 3d master by two dental spectrophotometers.

To compare the CIE L*a*b* values of two different dental shade guides using two shade-matching spectrophotometers. SpectroShade Micro (MHT) and Easyshade (VITA Zahnfabrik) were tested. One calibrated operator performed 30 measurements of each tab from three batches of two guides, VITA Classical (VC) and VITA 3D-Master (VM). Receiver operating characteristic (ROC) curves and intraclass coefficients (ICC) between the different batches were calculated. Results were given as mean and SD of the L*a*b* values and the respective color differences according to the CIEDE 2000 formula (ΔE00) for each of the shade tabs in the two spectrophotometers, then analyzed with independent student t test (α = .05). A total of 1,440 and 2,610 measurements for VC and VM, respectively, were performed per spectrophotometer. There were statistically significant differences between the two devices for all L*a*b* values, with the exception of: L* for 3R1.5; a* for 2R1.5, 3L1.5, 2L2.5, 3M2, 3L2.5, 4L1.5, and 4L2.5; and b* for D3, 1M2, and 3M2. When assessing the same shade guide, differences in ΔE00 were detected between devices above the acceptability threshold (ΔE00 ≥ 1.8) for all shade tabs except for VC (C1, C2, D3, A3.5, C3, and A4) and VM (4M1, 3R2.5, 4L2.5, and 4M3). The overall mean of the inter-device ΔE00 was 2.2 ± 1.0 for VC and 2.5 ± 1.0 for VM. The two dental spectrophotometers presented high ICC and ROC values, which validates their indication as auxiliary tools. However, there are discrepancies in the hues D (VC) and R (VM) with interdevice variability when evaluated for the L*a*b* component.

Two years survivability of VITA 3D master shade matching guides after disinfection with isopropyl alcohol: An in vitro study.

Background:Dental shade guides are used before restorative and prosthodontic procedures for the evaluation of tooth color. The spectral coverage of the specific shaded guide and a clinician's experience in shade matching are the two most important factors for a clinically viable shade match of the restoration to the given tooth. Repeated disinfection of the shade guide with disinfectant lead to a clinically significant difference of the shade to be matched, finally resulting in a clinically unacceptable prosthesis. The purpose of this study is to evaluate the effects of disinfection on various shade tabs of VITA 3D Master Shade guide after being subjected to 2 years of simulated disinfection with 70% isopropyl alcohol.Methodology:Two sets of VITA 3-D Master Shade Guides were used. One set of each shade guide was assessed after simulated use and surface disinfection with 70% isopropyl alcohol (test group), while the other full set was subjected to cleansing with distilled water (control group). Spectrophotometer was used to measure each of the shade tabs. Readings were recorded at regular intervals of 120, 240, 360, 480, 600, 720, 840, and 960 disinfection cycles. The ΔE values obtained were used to examine the color difference.Results:There was a significant difference in terms of ΔE between the shade tabs of control and test groups of VITA 3D Master shade guides after 960 cycles of disinfection. The change in mean ΔE was more in the test specimens in the shade tabs of VITA 3D Master Shade Guide tabs than the control specimens. These results are of statistical significance, but they might not be of any clinical significance.Conclusion:There was a statistically significant but clinically nonsignificant color change in the shade tabs of VITA 3D Master shade guides after 2 years of simulated use and disinfection with 70% isopropyl alcohol.

Assessment of Color Changes in Vita 3D-Master Shade Guide after Sterilization and Disinfection

Purpose:Dental shade guides are commonly used for color determination and should be disinfected and sterilized. The purpose of this study was to evaluate the color change of Vita 3D Master shade tabs after disinfection and sterilization. Material and methods:Overall, 98 samples (shade tabs) were randomly selected from 14 new, unused Vita 3D sets, including the following shades: 2M1, 3L1.5, 3M1, 3M2, 3M3, 3R1.5 and 4M1. In each set, values of 2, 3 and 4, chroma of 1, 2 and 3 and hue were selected for the comparison of different shades. All tabs were measured using the Vita Easyshade device at baseline. The first group was disinfected with Deconex and the second group was sterilized by autoclaving in a simulated annual application. All the tabs were measured again using the same device. This process was repeated to simulate 2 and 3 years of usage. Statistical analysis was conducted by repeated measures analysis of variance (ANOVA) and independent t-test and paired sample t-test. Results:In the disinfected group, we observed significant differences in value and chroma in all periods (p˂0.001). However, hue showed no significant difference after the first year of simulated treatment (p=0.527), though it was significantly different in the second and third simulations (p˂0.001). In the sterilized group, all variables showed a significant difference for each year (p˂0.05). Considering total color difference (ΔE), there was a significant difference between the two groups in the first, second and third simulated years; ΔE increased in the sterilized group more than in the disinfected samples (p˂0.001). Conclusions: The color change of shade tabs was significant both after disinfection by a chemical solution and by sterilization through autoclaving. However, although disinfectants may not have a clinically important effect, sterilization should be considered as an interfering factor during color-matching procedure.

The Influence of Dental Shade Guides and Experience on the Accuracy of Shade Matching.

There is limited and inconsistent information on some factors affecting visual shade selection. The aim of this study was to evaluate the influence of shade guide type and professional experience on shade-matching results. Thirty Dental students (DS), 30 General dentists (GDs) and 30 Dental specialists (S) participated in this study. The participants were asked to match six target tabs using two dental shade guides: Vitapan Classical (VC) and Vitapan 3D-Master (3D). An intraoral spectrophotometer was used for color measurement of target tabs and selected tabs. The color difference (ΔE) values between the target tab and selected tab were calculated. Data were analyzed using analysis of variance (ANOVA) and paired f-test (α = 0.05). Results of the first five best matches for each target tab were expressed as ΔE1 to ΔE5. Differences in the mean values of ΔE1 to ΔE5 between VC and 3D were compared using descriptive statistics. There were no significant differences among the three participating groups in ΔE values when the 3D was used (p = 0.389). However, significant differences were found with VC (p < 0.001). The ΔE values achieved from the 3D were significantly lower than those from VC for DS and S (p = 0.001 and p < 0.001, respectively). For each of the first five best matches, the mean ΔE values from the 3D were smaller than the corresponding values of VC. The type of dental shade guide affected the shade-matching results. The level of experience was not found to be an influential factor in shade matching when 3D-Master shade guide was used. Compared with Vitapan Classical shade guide, use of the Vitapan 3D-Master shade guide improves shade-matching results. Color, Experience, Gender, Selection, Shade, Visual. How to cite this article: Nakhaei M, Ghanbarzadeh J, Amirinejad S, Alavi S, Rajatihaghi H. The Influence of Dental Shade Guides and Experience on the Accuracy of Shade Matching. J Contemp Dent Pract 2016;17(1):22-26. Source of support: This study was supported by a grant (No. 920903) from the Vice Chancellor for Research of Mashhad University of Medical Sciences. The results presented here are based on undergraduate thesis (No. 2686) submitted to Mashhad School of Dentistry and Dental Research Center. None.

The effect of various disinfectants on dental shade guides

Dental shade guides are used to evaluate tooth color before prosthodontic procedures and are subjected to disinfection after use. The effect of disinfection on shade guides has not been thoroughly investigated. The purpose of this study was to evaluate the effect of disinfectants on the color of shade tabs. Changes in the color (ΔE) of VITA Classical Shade Guide tabs were measured with a VITA Easyshade spectrophotometer in the CIELAB system and calculated after being subjected to Cavicide, Asepticare TB, Sporicidin, and distilled water (control) over a simulated period of 2 years. Statistical analysis was accomplished by a 2-way analysis of variance followed by the Tukey honestly significant difference (HSD) test (α=.05). A significant difference was noted in the degree of shade tab color change, depending on the type of disinfectant used (F=153.2, P<.001). No significant difference was noted in the amount of shade tab color change that occurred afterdisinfection among the different shade tabs used (F=0.611, P=.865), nor was a significant interaction noted between the type of disinfectant and the different shade tabs used (F=0.7, P=.919). Asepticare TB showed the least significant amount of change (ΔE=0.401), and Sporicidin (ΔE=0.889) and the control (ΔE=0.969) showed significantly more color change than Asepticare TB but less than Cavicide (ΔE=1.198). The average total CIELAB color difference for 50% human perceptibility is approximately 1 unit (under standardized laboratory conditions). In the oral cavity, however, an average change of 3.7 ΔE units could still allow teeth to be perceived as having the same color. Therefore, although the results are statistically significant, they may not be clinically important.

Colour discrimination of dental professionals and colour deficient laypersons

ObjectivesThe aim of the present study was to compare results of non-dental (conventional) and dental colour discrimination tests (customized, shade guide test), to evaluate influence of profession, gender and age of colour normal dentists and laboratory technicians on colour discrimination results and to evaluate results of colour deficient laypersons. MethodsA total of 36 colour normal dental professionals, all volunteers were divided into two groups consisting of 18 participants each: dentists (DDS) and laboratory technicians (CDT). In addition, a group 15 colour deficient males also volunteered (CDP).Colour discrimination was examined using Farnsworth–Munsell 100 Hue Test and total error scores (TES) were calculated. Participants performed a dentistry related colour discrimination test by matching 26 pairs of shade tabs. Shade guide scores (3DS) were calculated. These tests were performed under the controlled conditions of a viewing booth. Mean values and standard deviations were determined. ANOVA, Mann–Whitney test, t-test and Pearson's correlation coefficient (r) were used for result analysis. ResultsTES and 3DS were correlated for colour normal observers, r=0.47 (p<0.01). No statistically significant differences in TES and 3DS by profession, gender and age were recorded. TES of 159 (83) and 3DS of 6.7 (2.7) were recorded for colour deficient laypersons. Based on TES, 33% of colour deficient laypersons had average discrimination, whilst 67% had low discrimination. ConclusionsWithin the limitation of this study, it was concluded that results of non-dental and dental colour discrimination tests were correlated, and that profession (DDS/CDT), gender and age gender did not influence colour discrimination of colour normal participants. Clinical significanceAlthough colour and appearance of dental restorations are of paramount importance for the aesthetic outcome, colour vision of dental professionals is not routinely tested. This paper validates and recommends the usage of dental shade guides for a simple, affordable and understandable testing of colour vision, either as a sole test or complementing conventional (professional) tests.

Using discrete optimization for designing dental shade guides

A key criterion in the design of dental shade guides used for matching tooth color is that the shade tabs cover the natural tooth color space as completely as possible with a manageable number of tabs. Earlier studies have designed hypothetical shade guides from a given population of tooth colors described in the CIELAB system using the goal of minimizing the mean coverage error. In this study, we investigate this topic using the goal of maximizing coverage, meaning that as many measured colors as possible were within a given color difference from the nearest shade tab of the guide. We use techniques of linear discrete optimization to determine the positions of the shade tabs and consider both color difference formulas, CIELAB and CIEDE2000, in an exemplary tooth color population. We obtain coverage error and coverage figures for hypothetical shade guides of various numbers of tabs designed with the goal of either minimizing coverage error or maximizing coverage. Results show that discrete optimization and the goal of maximizing coverage could be used to improve shade guide development. The described technique could be used not only for dental shade guides development, but also for any purpose requiring coverage of as many colors as possible while keeping the number of reference colors manageable. © 2009 Wiley Periodicals, Inc. Col Res Appl, 2010

Colour compatibility between teeth and dental shade guides in Quinquagenarians and Septuagenarians

The aim of this investigation was to determine colour compatibility between dental shade guides, namely, VITA Classical (VC) and VITA 3D-Master (3D), and human teeth in quinquagenarians and septuagenarians. Tooth colour, described in terms of L*a*b* values of the middle third of facial tooth surface of 1391 teeth, was measured using VITA Easyshade in 195 subjects (48% female). These were compared with the colours (L*a*b* values) of the shade tabs of VC and 3D. The mean coverage error and the percentage of tooth colours being within a given colour difference (DeltaE(ab)) from the tabs of VC and 3D were calculated. For comparison, hypothetical, optimized, population-specific shade guides were additionally calculated based on discrete optimization techniques for optimizing coverage. Mean coverage error was DeltaE(ab) = 3.51 for VC and DeltaE(ab) = 2.96 for 3D. Coverage of tooth colours by the tabs of VC and 3D within DeltaE(ab) = 2 was 23% and 24%, respectively, (DeltaE(ab) </= 2 as clinically acceptable match). The hypothetical guides performed better and would only need seven to eight tabs to reach the same results as VC and 3D. Both guides had a mean coverage error that was too high and coverage that was too low according to an acceptable colour difference of tooth colour for these subjects. The optimized hypothetical, population-specific guides performed better indicating the possibility for improvement in colour compatibility of the guides with tooth colour in future shade guide development, allowing acceptable shade matching for most of the patients in clinical routine.

COLOR IN DENTISTRY: IMPROVING THE ODDS OF CORRECT SHADE SELECTION

This Critical Appraisal focuses on how well dental shade guides correspond to the color range and distribution of natural teeth. In other words, we will discuss “chances” of shade guides to match shades of human teeth and demonstrate alternatives.

Performance assessment of dental shade guides

Objectives The goal of this study was to evaluate influence of different shade guides and respective shade matching methods on shade matching results and to analyze user satisfaction with these products and methods. Methods Eighty-eight pre-doctoral dental students completed the study. The color of four target shade tabs was matched using Toothguide 3D-Master (TG), Vitapan Classical (VC), and the prototype of Linearguide 3D-Master (LG). Shade matching was performed using color-corrected light source and 0/45° optical geometry. An intra-oral spectrophotometer was used for color measurements of target tabs and shade guide tabs. Results for the first 10 best matching shade guide tabs were expressed as ranks (best match – 10 points to 10th match – 1 point). Participants also performed subjective evaluation of three shade guides/tab arrangements. Descriptive statistics were calculated. T-test and Wilcoxon signed rank test were used for statistical analysis of the data ( α = 0.05). Results The best shade matching results were achieved using LG, followed by VC and TG, and the ranks were 9.1 ± 1.2, 8.8 ± 1.9 and 8.4 ± 2.8. Differences in Δ E* values for the first 10 matches between TG/LG (4.5 ± 1.8) and VC (6.2 ± 2.2) were found to be statistically significant ( p < 0.001). Subjective evaluation revealed significant advantage of LG compared to TG and VC. Conclusions Linearguide 3D-Master enabled better shade matching results compared to Toothguide 3D-Master ( p < 0.05). Both 3D-Master shade guides exhibited significantly smaller Δ E* values for the first 10 matches compared to Vitapan Classical ( p < 0.001). Linearguide 3D-Master was superior in a subjective evaluation compared to Toothguide 3D-Master and Vitapan Classical ( p < 0.001).

Clinical performance of a newly developed spectrophotometric system on tooth color reproduction

Matching a natural maxillary central incisor to a metal ceramic crown is one of the most difficult challenges in clinical dentistry due to the limitations of dental shade guides and the subjectivity of perceptual evaluation. The purpose of this study was to assess the clinical effectiveness of a spectrophotometric shade-matching system on tooth color reproduction. Two metal ceramic crowns were fabricated for a maxillary central incisor for 36 patients using 2 shade-matching techniques. The first technique was conventional visual matching using 3 shade guide systems, and the second was an instrument-based color-matching technique using a new spectrophotometric system. Color difference (DeltaE) values between the contralateral natural tooth and each of the 2 crowns were calculated in the cervical, middle, and incisal regions. The DeltaE values were compared using a Student's t test (alpha=.05). Three calibrated examiners evaluated the color match by ranking it from 1 to 10 (10 = perfect match; 1 = no match; < or =8, accepted; > or =7, rejected). McNemar's test was used to calculate the odds ratio of accepting restorations fabricated using a spectrophotometric system to conventional methods. Results revealed that the mean DeltaE values of crowns matched with the spectrophotometer were significantly lower than those using a conventional technique (P<.001). The odds ratio of 12.5 was calculated, indicating that conventionally matched crowns were more likely to be rejected than those matched using the spectrophotometer (P<.001). In this clinical study, crowns fabricated using a dedicated spectrophotometer had a significantly better color match and a lower rate of rejection due to shade mismatch compared to crowns fabricated with a conventional shade-matching method.

Optimization of Tooth Color and Shade Guide Design

One critical prerequisite for dental shade guides is to match the color range and distribution of human teeth. The purpose of this study was to design computer models for dental shade guides and compare them with an existing shade guide. A targeted coverage error for a newly developed shade guide was DeltaE(ab) < 2 with a corresponding CIE2000 value. A total of 1064 teeth were evaluated in vivo using an intra-oral spectrophotometer. Shade guide models were designed using different methods for representation of the data set, hierarchical clustering, and nonlinear constrained optimization. Coverage error was calculated for both CIELAB and CIE2000 values. Recorded values were compared with coverage error of Vitapan Classical (VC) shade guide. Wilcoxon signed-rank test for paired samples and linear regression were used in statistical analysis. Coverage error of VC was 4.1 (SD 1.8), ranging from 0.5 to 11.5 DeltaE(ab). Group A shades had the best match for human teeth (43.9%) followed by Groups C (24.1%), B (20.4%), and D (11.7%) shades, respectively. CIELAB coverage error of the newly designed 24-tab shade guide using clustering and optimization was 2.05 (0.95) and 1.96 (0.92), respectively. Corresponding CIE2000 coverage error values were 1.43 (0.68) and 1.40 (0.65), respectively. A significant difference between results obtained using clustering and optimization was determined. CIELAB color differences were greater, but highly correlated as compared with their CIE2000 counterparts (DeltaE(00)= 0.64 x DeltaE(76)+ 0.13, r > 0.99). This study demonstrated that, compared with existing shade guides, future shade guides can provide either (a) similar coverage of tooth color with fewer tabs, thus simplifying shade matching procedure, or (b) better coverage of tooth color with a similar number of tabs, in both cases increasing the chances of satisfactory matches and, consequently, better esthetics. Both clustering and optimization enabled better representation of tooth color as compared with an existing dental shade guide. Optimization outperformed clustering and is therefore recommended as a method of choice for representation of tooth color and designing of dental shade guides.

Designing visually optimal shade guides

Dental shade guides do not provide a broad coverage of tooth colors. There is a need for shade guides that can provide closer color matches. The purpose of this study was to propose and assess a visually optimal shade guide for tooth color matching. With the use of a spectrophotometric approach, the color distribution (L*a*b*) of 150 extracted human teeth and 3 commercially available shade guides (Vita Lumin V, Trubyte Bioform Color Order Shade Guide, and Vitapan 3D-Master Shade System) was measured. With the use of a hierarchical clustering approach, a series of shade guides was designed with a varying number of tabs. The average error (DeltaE) between colors from each shade guide and the extracted teeth was computed. The proposed visually optimal shade guide had the smallest average error of all guides tested. The new guide achieved lower error with fewer shade tabs than the 3 commercial systems evaluated. Within the limitations of this study, it was demonstrated that a hierarchical clustering technique can be used to design a visually optimal shade guide for a given population with a flexible degree of control over the mean error and number of tabs.

Dental color standards: shade tab arrangement.

The aim of this study was to analyze the shade tab arrangement of two popular dental shade guides, suggest possible improvements, and propose clinical guidelines. Data were recorded using a colorimeter set to standard illuminant source C and CIE L*a*b* system. The manufacturers' shade tab arrangement as well as the possible improvements in the arrangement of shade tabs of Vitapan Classical and Vitapan 3-D Master (Vita Zahnfabrik, Bad Säckingen, Germany) shade guides were examined by regression analysis. Certain shortcomings in the manufacturers' arrangement of both color standards were observed. The Vitapan 3-D Master arrangement was more consistent, but with a decrease in lightness, tab saturation decreased as well in four of its five groups. When Vitapan Classical and Vitapan 3-D Master tabs were arranged according to deltaE* in relation to the lightest tab, r2 was 0.98 and 0.96, respectively. After dividing the total deltaE* range into four equal segments for the newly established Vitapan Classical guide, r2 was 0.91, 0.95, 0.68, and 0.94, respectively. Corresponding r2 values for Vitapan 3-D Master were 0.96, 0.94, 0.90, 0.94, and 1.0. Total color difference in relation to the lightest tab, followed by the tab division into an adequate number of groups, is recommended as a possible and universally applicable mode of tab arrangement in dental color standards.