Shade Tabs Research Articles

Facial skin color assessment and proposed skin shade guide for maxillofacial prosthesis using cluster analysis in a cohort of Indian adults

Aim: The precise estimation and replication of skin color are crucial for maxillofacial prosthesis. The study aimed to evaluate facial skin color with a colorimeter and suggest a skin shade guide and formula for color estimation. Settings and Design: An observational study conducted in the department of prosthodontics. Materials and Methods: Study was conducted on 368 individuals of Indian origin in age range of 20–45 years. The facial skin color was assessed in malar regions using SkinColorCatch colorimetric device and individual topography angle (ITA) and CIELAB L*a*b* values were noted. Statistical Analysis Used: K-means clustering was utilized to propose a shade guide for maxillofacial prosthesis with 24 skin shades. Logistic regression analysis was conducted to propose a formula to estimate skin shade of the individuals. Results: Based on cluster analysis, 368 subjects were divided into three clusters with similar characteristic as Cluster 1 with dark skin color in 88 (23.91%) subjects, Cluster 2 with medium skin color in 224 (60.87%) subjects, and Cluster 3 with light skin color in 56 (15.22%) subjects. The mean ITA and L*a*b* values for cluster 1 were −47.04° ±14.77°, 34.53 ± 4.31, 8.55 ± 2, 11.42 ± 3.7033, respectively. The mean ITA angle and L*a*b* values for Cluster 2 were 4.29° ±11.34° 51.67 ± 3.42, 8.79 ± 3.13, 21.36 ± 2.38, respectively. The mean ITA and L*a*b* values for Cluster 3 were 34.65 ± 4.29°, 62.66 ± 3.08, 6.53 ± 1.79, 17.73 ± 2.39, respectively. The proposed shade guide comprised a total of 24 different shades that were categorized into three primary colors according to three distinct clusters, each of which was further broken down into eight subclusters containing various shades within each cluster. Logistic regression analysis gave an equation as follows: Y =12.43 + 0.186X (Y = Predicted skin color, X = ITA angle). Conclusions: Twenty-four facial skin shade tabs have been proposed based on ITA angle and CIELAB values. This comprehensive approach to categorize the shades will ensure a detailed and organized system for selecting and matching colors in maxillofacial prosthesis.

Comparison of the Accuracy and Reliability of Instrumental Shade Selection Devices and Visual Shade Selection: An in Vitro Study.

New shade-matching devices are available for clinical use, but their accuracy and reliability have not been investigated. This in vitro study compared the accuracy and reliability of a shade-matching colorimeter (Optishade), a spectrophotometer (VITA Easyshade V), and visual shade matching in simulated clinical conditions. Shade matching was conducted with two digital devices; (Optishade and Vita Easyshade) and the visual shade selection method, with a new 16-tab Vita Classical shade guide. Shade tabs were placed within a gingival matrix and measurements were taken from the central area of each shade tab enclosed in a black box to simulate the oral cavity. Visual assessments were conducted independently by two examiners. For the reliability assessment, each shade tab was measured 20 times by each examiner. Accuracy was calculated as a percentage of the matching readings with the actual shade per each tab. Data were analyzed with the one-way ANOVA test (α = 0.05) and Pairwise Comparison (Bonferroni Post hoc Test) to assess accuracy. The reliability evaluation was conducted by comparison between both examiners using mean and standard deviation; by a two-tailed t-test for the independent samples for all the three groups included in the study. The shade matching accuracy of Optishade was 97.50%, Vita Easyshade 89.38%, and visual method 62.19%. Statistically, high significant difference in accuracy (p < 0.001) was found when comparing both Optishade and VITA Easyshade with the visual method. Additionally, there was statistically significant difference in accuracy (p < 0.05) when Optishade was compared to Vita Easyshade. The reliability of the Optishade was 99.6% and Vita Easy shade was 99.38%. Statistically, showed no statistically significant difference in the reliability of shade match obtained within the same group when comparing the readings of Examiner 1 and Examiner 2 (p > 0.05). The colorimeter demonstrated the highest accuracy, followed by the spectrophotometer, and the visual shade selection method. Both digital methods investigated in this study showed comparable reliability. The results of this study emphasize the clinical advantage of digital shade-matching devices over visual shade-matching. The colorimeter offers high accuracy for shade matching and should be considered to use for shade matching especially with restorations in the esthetic zone.

Comparative Evaluation of Activated and Nonactivated Microbubbles on the Efficacy of Bleaching Agents.

Intracoronal bleaching serves as a conservative option for nonvital teeth that exhibit discoloration.Hydrogen peroxide (H2O2) is frequently utilized in bleaching processes owing to its capability to produce free radicals.The main drawbacks of the currently available bleaching agents are the occurrence of cervical resorption and the multiple dental visits to achieve the desired result. Therefore, in our study, to address the limitations associated with cervical resorption and extended treatment duration for badly stained teeth, an attempt was made to incorporate a whitening agent (35% H2O2) with microbubbles. This study aimed tocompareandevaluatetheeffect ofactivated and nonactivated microbubbles on the efficacy of bleaching agents. Forty-five human central incisors were collected and divided into three groups:Group I (HP), H2O2 plain(n= 15) (Control); Group II (HPM), H2O2-infused microbubbles without ultrasonic activation (n= 15) (experimental group); and Group III (HPMU), H2O2-infused microbubbles with ultrasonic activation (n= 15) (experimental group).The crowns were artificially stained. Microbubbles containing 35% H2O2were generated using the probe sonication method.The bleaching agent H2O2 plain (0.04 mL) was syringed into the pulp chamber in group I, while H2O2-infused microbubbles (0.04 mL) were syringed into group II and group III. Group III was further activated ultrasonically. The evaluation of color shade differences was conducted using the Vita Lumin shade guide at three time points: baseline, day 7, and day 14. Data regarding color change using Vita shade were investigated for normality using theKolmogorov Smirnov test and assessed a non-normal distribution.Intergroup comparisons at each particular time interval (baseline, day 7, and day 14) were analyzed using the Kruskal-Wallis H test followed by multiple pairwise comparisons using the Adjusted Bonferroni post hoc test. Intragroup comparisons between different time intervals were analyzed using related samples from Friedman's test followed by multiple pairwise comparisons using the post hoc Dunn test. The level of statistical significance was determined at P< 0.05. There was no statistical difference in the baseline values of all three groups. Group I (HP) exhibited an average increase of three Vita Lumin shade tabs on day 7 and day 14, respectively, whereasGroup II (HPM)exhibited an average increase of six and four Vita Lumin shade tabs on day 7 and day 14, respectively, and Group III (HPMU)exhibited an average increase of 10 and 3 Vita Lumin shade tabs on day 7 and day 14, respectively. Microbubbles containing H2O2 were more efficient and faster than plain H2O2 for bleaching, and the efficacy of bleaching was enhanced when activated using ultrasonic technology.

EVALUATION OF EFFICACY OF COLOUR CORRECTED LIGHT SOURCE IN DETERMINING THE ACCURACY OF SHADE MATCHING DONE WITH A COMMONLY USED SHADE GUIDE SYSTEM BY CONVENTIONAL VISUAL METHOD AND AN INTRA ORAL SPECTROPHOTOMETER

Aim: The objective of this study was to evaluate the efficiency of colour corrected light source in shade matching and to determine accuracies and inter-rater agreement of three shade matching methods (conventional visual method, visual method using colour corrected light source and spectrophotometric method). Methodology: In the conventional visual method and the visual method using colour corrected light source, four examiners with normal colour vision matched five target control shade tabs taken from the VITAPAN 3D MasterTM shade guide, with other full set of the same shade guide. Shade matching with the colour corrected light source was done under daylight mode simulating 5500K or natural daylight. Each tab was matched three times to determine repeatability of visual examiners. In the spectrophotometric method, two independent examiners matched the control tabs with three repetitions for each tab. The data was collected and statistical analysis was performed. Results: Visual method using colour corrected light source produced more accurate results (80%) than the conventional visual method (68.3%) and spectrophotometric method (0%), thus proving the efficacy of colour corrected light source (p&lt;0.05). All three methods exhibited poor inter-rater agreement. Conclusion: The question is whether handheld light correcting devices and digital assessments are clinically useful or are they unreliable andunnecessary costly. Even though visual shade matching is subjective, it is not inferior and should not be underrated. The low accuracy value obtained for the spectrophotometer may be a misrepresentation of the machines capabilities due to its inability to measure any reading asclose to the correct value. If both analyses are combined, digital determination of the basic shade and visual determination of the effects, can provide the best possible esthetic outcome. Although human eye will be the finalarbitrator, success can best be achieved by combining traditional artistic techniques with advancements in technology, complemented with innovations in colour-related research, education, and training of dental professionals.

Effect of different instrumental techniques and clinical experience on shade matching.

Many factors can affect the aesthetics of dental restorations, including the instrumental techniques used in shade matching, and can lead to clinical failure. The aim of this study was to investigate the effectiveness of using the cross-polarization digital photograph technique and intraoral scanners for shade matching, and also evaluate the effect of the level of clinical experience on shade matching success. Color analysis was performed on the maxillary right central incisors of 10 subject models with Vita Easyshade. Intraoral scanning was performed 10 times on each model using TRIOS 3 and color analysis was performed from the same spot. Then cross-polarized and non-polarized photographs of the models were taken with standard settings using a gray reference card. Each shade tab of the Vita System 3D-Master scale was also photographed with two different polarization techniques. Four groups (n = 12), including prosthodontics faculty staff, postgraduate students in prosthodontics, undergraduate students, and dental technicians matched the shade tabs and the model photographs obtained with both techniques on a standardized computer screen. Finally, the color differences between the shade tabs and maxillary central incisors matched by observers from four different groups were recorded using a colorimeter, Classic Color Meter, in accordance with the CIELAB system and CIEDE2000 (ΔE00) values were calculated. The data were compared with the acceptability threshold of 1.80 for ΔE00. The data obtained from the observers were analyzed with IBM SPSS Statistics 26.0 Release Notes program. Independent Samples t-test was used to compare normally distributed data according to binary groups. The level of significance was 0.05. A statistically significant difference was found in the shade matching on photographs taken with different techniques in postgraduate students (p = 0.02). Also, there was a statistically significant difference in success between the groups that made shade matching based on photographs obtained with the non-polarization technique (p = 0.00). The undergraduate students achieved statistically significantly lower results than all other groups (ΔE00 = 5.57±1.07). The kappa value between the intraoral scanner and spectrophotometer results was 0.10, and this value was not statistically significant (p = 0.32). The cross-polarization technique used especially for shade matching is not superior to the non-polarization technique. Academic and clinical experience might be correlated with shade-matching success with the non-polarization technique. The clinical acceptability threshold could not be achieved in the shade matchings made on digital photographs taken with both techniques. Shade matching performed with an intraoral scanner did not yield reliable results.

Level of Agreement in Subjective Selection of Gingival Colour

Background and Objectives: Primary outcome: To assess the level of agreement between the objective and subjective methods for recording gingival colour in each area of the gingiva. Secondary outcome: To compare performance of the subjective visual method of gingival colour selection by a male observer and a female observer. Materials and Methods: A chromatic study was conducted on a total of 101 participants, in five gingival zones, from the free gingival margin to the mucogingival line, using a SpectroShade Micro spectrophotometer for the objective method and 21 ad hoc ceramic gingival shade tabs for the subjective method. A man and a woman of the same age, with the same amount of clinical experience in dentistry, selected the tab that most resembled the colour of participants’ gingiva. The “chromatic error” was then assessed by calculating the colour difference (using the Euclidean and CIEDE2000 formulae) between the CIELAB coordinates of the shade tab selected and the objective coordinates of the gingiva. The unweighted Kappa coefficient was used to calculate the level of agreement between observers. Results: For the male observer, the mean chromatic errors varied between ΔEab* 10.3 and 13.1 units, while for the female observer, the mean errors varied between ΔEab* 11.1 and 12.8: these differences were not statistically significant. Similarly, no statistically significant differences were found between the mean chromatic errors for the five gingival zones in either the male operator (p = 0.100) or the female operator (p = 0.093). The minimum level of agreement (unweighted Kappa) between the observers ranged from 0.1 to 0.4. Conclusions: Subjective selection of gingival colour was very inaccurate, by both the male observer and the female observer, for any area of the gingiva, with no differences identified between them. The level of agreement between the observers was low. These findings suggest that gingival colour should not be determined using solely subjective methods, given that the chromatic errors significantly exceeded the clinical acceptability threshold for gingiva (4.1 units for ΔEab* and 2.9 units for ΔE00). Both observers showed a tendency to select gingival shade tabs that were redder and bluer than the objective colours.

Custom-Made Composite Shade for Matching an Odd-Shaded Restoration

Objective: This case report aims to present how to fabricate a new restoration to match existing odd-shaded ones. Clinical considerations: A polycarbonate provisional crown was used to produce a cement-retained immediate load provisional restoration over an implant of tooth number #9. Using a color correcting light source, it was noticed that existing restorations had very high value with excess gray hue. XL2 of Premise composite shade tab was the closest match found, and the base shade for the custom-made restoration. Once no shade match was found in commercially available shade guides, there was a demand to produce a custom-made shade to address this case. The facial surface of the provisional crown was prepared as a veneer. Utilizing XL2 Premise composite and adding different amounts of gray color modifier, shade matching was fulfilled by mixing the composite and the color modifier. In this case, five attempts were made to achieve color match. The restoration was polished utilizing Soflex Discs. Provisional crown was in function for 12 weeks. Conclusions: By implementation of the principles of color, restorative materials and characterization kits, the new temporary restoration could match the existing ones using the technique described in this case report.

Exploring Digital Gingival Shade Matching in Students.

To study the degree of accuracy in gingival shade matching of undergraduate students using a computer application. In total, 76 undergraduate dental students' gingival shade selection abilities were evaluated using an in-house developed computer application. A total of 15 intraoral gingival photographs and 21 pink gingival color porcelain samples were used. The environmental conditions were standardized, and no time limit was set for answering in the computer application. Fourteen gingival color samples (66.6%) were not useful for representing the studied gingival shades. Not all natural gingival colors studied were represented within the 50.50% acceptability limits of the pink samples. There were no statistically significant differences between men and women in terms of "hit" percentages. The highest correlation coefficient (in absolute value) was for the L* coordinate (the darker the gingiva in the picture, the higher the hit rate for choosing the "ideal" shade tab); however, none of the linear correlation coefficients were statistically significant. Not all colors provided in the pink ceramic system were useful for subjective gingival selection. There were no statistically significant differences between male and female dental students in gingival color perception. The L* coordinate was the only one that influenced the correct perception of gingival color by dental students, and it did so more in women than in men.

Effect of Polymerization Unit, Polishing, and Coffee Thermocycling on the Color and Translucency of Additively Manufactured Resins Used for Definitive Prostheses.

To evaluate the effect of polymerization unit, polishing, and coffee thermocycling on the color and translucency of additively manufactured polyurethane-based resins with different viscosities. In addition, their color behavior was compared with the color of the shade tab throughout the fabrication steps and aging. Disk-shaped specimens (Ø10 × 2 mm) were fabricated from polyurethane-based resins with different viscosities (Tera Harz TC-80DP and C&B permanent; n = 30 per material). Baseline color coordinates were measured after cleaning. The specimens in each resin group were divided into three subgroups (n = 10 per subgroup) to be polymerized with different polymerization units (Otoflash G171 [FLN], Wash and Cure 2.0 [CLED1], and P Cure [CLED2]), polished, and subjected to coffee thermocycling. Color coordinates were remeasured after each process. Color differences (ΔE00) and relative translucency parameter (RTP) values were calculated. Data were statistically analyzed (α = .05). Time points and polymerization units affected the ΔE00 for each material (P ≤ .049). ΔE00 of each polymerization unit pair had significant differences within and among different time points within each material (P ≤ .024). ΔE00 (when compared with the shade tab) and RTP were mostly affected by polymerization units and time points within both materials (P ≤ .042). Tested polymerization units, polishing, and coffee thermocycling affected the color difference and translucency of tested resins. Color differences ranged from moderately unacceptable to extremely unacceptable, and the differences in translucency values mostly ranged from perceptible to unacceptable, according to previous thresholds. In addition, tested resin-polymerization unit pairs had unacceptable color differences when compared to the shade tab. CLED1 may enable higher color stability for tested resins.

Effect of Printing Layer Thickness on Optical Properties and Surface Roughness of 3D-Printed Resins: An In Vitro Study.

To investigate the impact of printing layer thickness on the optical properties and surface roughness of various 3D-printed resins manufactured by digital light processing (DLP) and indicated for provisional and definitive restorations. A total of 240 specimens from four different 3D-printing resins-VarseoSmile Crown Plus (Bego; VS), Crowntec (Saremco Dental; CR), GC Temp PRINT (GC Dental; TG), and NextDent C&B MFH (NextDent; ND)-were divided into four groups (n = 60 per group). Each group was further divided into three subgroups (n = 20) according to printing layer thickness (25, 50, and 100 μm). All specimens were subjected to thermocycling with coffee before measurements were taken with a spectroradiometer to calculate color differences. The Kubelka-Munk (K-M) absorption (K) and scattering coefficients (S), translucency parameters (TP), and surface roughness (Ra) values were calculated for each printing layer thickness and compared with those of the 2M2 shade tab (target). The data were analyzed using Mann-Whitney U test, the variance accounted for (VAF) coefficient by Cauchy-Schwarz, and post hoc comparisons using Tukey test (α ≤ .05). S (79% ≤ VAF ≤ 100%) and K (40.45% ≤ VAF ≤ 100%) spectral distribution depended on the wavelength. A 25-μm layer thickness resulted in no significant differences from the 2M2 shade for S (P > .230) and K (P > .200). VS showed significantly different S (P = .004) and K (P = .003) values from those of the shade tab with 50-μm layering thickness, whereas other materials did not show significant differences from the 2M2 shade for S (P > .280) and K (P > .301). The 100-μm layer thickness specimens had significantly different S and K values compared to the 2M2 shade tab (P < .004). TP values of resins with 100-μm layer thickness were significantly lower than resins in 25- and 50-μm layer thicknesses (P < .001). The Ra values of resins increased significantly with 100-μm layer thickness (P ≤ .001). All tested materials, except for VS, showed color properties similar to the target shade when 25- and 50-μm printing layer thicknesses were used. The translucency of resins tended toward an inverse relationship with printing layer thickness. The surface roughness of resins increased significantly with 100-μm layer thickness. However, all resins with a printing thickness of 25 μm showed better color properties and surface roughness.

Color reproduction trueness of 3D-printed full-color dental casts with scans derived from an intraoral scanner.

To investigate the effects of shade tab color variations (tooth-colored vs. gingiva-colored) and surface treatment (application of mineral oil) on the trueness of color reproduction from dental shade tabs to 3D-printed full-color dental casts, using digital scans obtained from an intraoral scanner. Pristine tooth-colored (with 16 shade tabs) and gingiva-colored (with five shade tabs) shade guides were digitally scanned using an intraoral scanner, and subsequently, 3D-printed replicas were created using a full-color material jetting 3D printer. Three color measurements using a contact type digital spectrophotometer were recorded, including actual shade tabs (R0), dried 3D-printed study samples (RP1 ), and study samples with mineral oil application (RP2 ), in this study to calculate color differences between the actual shade tabs and 3D-printed ones. The CIEDE2000 formula was used to calculate the color differences (color reproduction trueness) between reference shade tabs and 3D-printed full-color study samples-without and with mineral oil, ∆E00 (RP1 ), and ∆E00 (RP2 ). ∆E00 (RP1 ) and ∆E00 (RP2 ) were compared with a 50:50% accessibility threshold (AT) and a 50:50% perceptibility threshold (PT). A grading system, based on the relative ranges of AT and PT, was employed. The percentage of samples falling into each color-matching category was then recorded. The data collected were subjected to statistical analysis, utilizing a mixed model ANOVA to evaluate the effects of shade tab color and mineral oil application on color differences, α = 0.05. The application of mineral oil significantly affected the ∆E00 [F(1, 378) = 19.1, p = < 0.0001]. However, this effect was only significant for the gingiva-colored study samples; the mineral oil application significantly decreased color difference, showing ∆E00 (RP1 ) of 8.71 ± 3.78 and ∆E00 (RP2 ) of 6.55 ± 2.14 (p < 0.0001). For the tooth-colored groups, the mineral oil application did not yield any color difference, showing ∆E00 (RP1 ) of 7.05 ± 2.35 and ∆E00 (RP2 ) of 6.94 ± 2.35 (p = 0.497). In the absence of mineral oil, gingiva-colored samples revealed a significantly larger ∆E00 (RP1 ) of 8.71 ± 3.78 compared to tooth-colored samples at 7.05 ± 2.35 (p = 0.017). Conversely, mineral oil application rendered comparable ∆E00 (RP2 ) values between gingiva-colored (6.55 ± 2.14) and tooth-colored (6.94 ± 2.35) samples (p = 0.558). All 3D-printed full-color samples showed Grade 1 (extremely unacceptable mismatch) and Grade 2 (clearly unacceptable mismatch), regardless of the shades or the presence of mineral oil. Utilizing an intraoral scanner to gather digital color data, along with an MJ 3D printer, offers the potential for producing 3D-printed full-color dental casts for prosthesis characterization in the dental laboratory. While mineral oil improves the color reproduction trueness of gingiva-colored objects, all 3D-printed full-color samples exhibited unacceptable mismatches when compared to their target objects. This underscores the need for future improvement in the digital color data acquisition process and color optimization protocols in 3D printing processes.

Variación del tono más común de los dientes anteriores entre estudiantes malasios de diferentes etnias: un estudio transversal

Aim: Determination of the most common shade of anterior teeth in Malaysian students of different ethnicities. Materials and Methods: A total of 120 subjects, 40 each from different ethnicities (Malay, Chinese, and Indian) aged 18-22 years were evaluated for tooth shade using the VITA Classical shade guide. The subject was asked to sit in an up-right position with teeth at the clinician’s eye level and the subject was instructed to remove makeup or tinted eyewear which may affect the result. The procedure was done in natural daylight. The shade tabs were positioned adjacent to the maxillary central incisor and the middle 1/3rd of the facial surface was assessed by experts to determine the correct tooth shade. The data was statistically analysed. Results: The differences in tooth shade were seen among the subjects of different ethnicities. The Malay ethnicity has B1 (37%) as the most common tooth shade whereas Chinese has C1 (27%) and Indian C1 (40%). Conclusions: Under the limitation of the study, it was found that there is a relationship between tooth color and ethnic background. Malay students tend to have brighter teeth as compared to Chinese and Indian students. Keywords: Tooth; Incisor; Color; Colorimetry; Ethnicity; Malaysia.

Comparison of Shade Matching Performance of Dental Professionals and Untrained Individuals in Visual Shade Matching Method

Statement of the problem: It is unclear how the success of color selection with custom shade guides is influenced by the observer's level of color education and the type of light source. Objective: The aim of this study is to compare the color matching ability under different light sources between observers with and without color education and to investigate in which shade tabs they are more successful, using a custom-made shade guide. Materials &amp; Methods: The study included 5 prosthodontists (PD), 5 general dentists (GD), 5 dental ceramists (DC), 5 removable denture technicians (RDT), and 10 participants with no color education (NP). Using dentin powder from feldspathic dental porcelain, 2 sets of 16 shade tabs matching those in the Vita Lumin Classic shade guide were produced. The Lab values of the produced shade tabs with the same shade code were measured using a colorimeter device, and those with ΔE values below 0.1 were used for shade matching. Each participant conducted a total of 48 shade matches under 3 different light sources (tungsten-TG, fluorescent-FL, and D65). Results: It was found that the shade matching success of dental professionals in the PD, GD, RDT, and DC groups significantly differed from that of the participants in the NP group (χ² = 23.417; P&lt; 0.001). Shade matches conducted under the D65 light source were more successful than those under the TG and FL light sources, and participants were found to match shade tabs with higher saturation, such as A4 and C4, more successfully. Conclusions: Color matching performed with a custom color scale is influenced by the observer's training and the light source. As the saturation of shade tabs increases, the matching success also increases.

Comparative Evaluation of Hue Value Chroma using Cross Polarised Photography

Introduction: Digital photographs offer a wide range of colour options. They aid in increasing communication between a dentist and a technician by making the morphology, colour, and texture of the teeth easier to visualise. A polarising filter reduces reflections and glare while boosting colour saturation in an image. The aim of the study was to analyse images with and without polarised photography. Methodology: A total of 125 images of shade guidelines were collected for this study, 5 each shade tab for 5 shades (A1 to A4). We looked at the following shade guidance systems: VITA Classical (VITA Zahnfabrik) (control), IPS e. max Ceram (Ivoclar Vivadent) were photographed with a Canon EOS 60D digital camera and a 100-mm Canon Macro Lens. Ambient light, exposure (1/125, f16), ISO (100), flash (ETTL), distance, focusing (1:1), and backdrop were all standardized in the photographs. The Adobe RGB colour system was utilised since it covers nearly half of the Lab colour space. Results: Mean and standard deviation values of images with and without cross polarised photography were compared. Hue, value, chroma of the images were assessed showing no statistical difference among the images with and without cross polarised photography. Conclusion: Compared to visual and digital photographic approaches for choosing shades, the application of polarising filters had negligible effect on shade choice. When routinely practised, shade matching can improve a clinician's ability to choose the appropriate shade. Thus, knowledge and training may help someone become better at shade matching. Keywords: Hue, value, chroma, cross polarised photography, Camera, Ring flash, Micro lens.

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.

Evaluation of shade correspondence between high-translucency pre-colored zirconia and shade tab by considering the influence of cement shade and substrate materials

Statement of problemThe relation between cement color and abutment substrate material and the corresponding effect on the color accuracy of high-transparency pre-colored zirconia (HT-Zr) remains unclear. PurposeThis in-vitro study aimed to investigate the difference in color accuracy when the HT-Zr is bonded to different materials-based substrates with differently colored resin cement. Materials and methodsVita A1 shade HT-Zr with 1 mm thickness was used as the testing sample. The samples were first placed on zirconia (ZR), tooth color resin (CR), and metallic (MT) abutment substrates. Subsequently, four differently colored cements (translucent (TR), bleach, opaque, and A2 shade (A2)) were used for bonding HT-Zr onto the substrate, and the non-bonded group was used as the control group (CG). There were 15 groups in total (n = 10 per group). A digital colorimeter was used to obtain Commission Internationale de l’Eclairage (CIELab) color parameters. The translucency parameter (TP00) of the substrate and sample, as well as color difference (ΔE00) and chroma (C) between the different groups were calculated. Additionally, the ΔE00 and TP00 were compared with the moderately unacceptable match of ΔE00 = 3.6. The statistical analysis was conducted using ANOVA and Tukey HSD post-hoc test (α = 0.05). ResultsHT-Zr exhibited high translucency (TP00 = 11.02 ± 0.18), and the mean ΔE00 of the testing samples ranged between 2.18 ± 0.20 and 13.14 ± 0.31. The ZR-CG and MT-A2 groups showed the highest and lowest lightness separately. The CR-CG group exhibited the highest C, and the ΔE00 was lower than that of 3.6. The MT-TR group showed the lowest C and the highest ΔE00. The inter-group comparison revealed that the ΔE00 for different cement is mostly lower than the acceptable color match of 1.0; moreover, the ΔE00 for all the substrates, excluding the CG group, is higher than 3.6. ConclusionsThe abutment substrate materials and the cement color should be considered with caution when using HT-Zr, with the effect of abutment substrate materials being more apparent in color accuracy. HT-Zr restorations are not recommended for discolored or bleached abutments but only for natural-colored abutments to achieve the optimal color appearance.

Effect of CAD/CAM Position and Thickness of Ultra-Translucent Multilayered Zirconia on Color Aspects.

Ultra-translucent multilayered zirconia restorations fabricated using computer-aided design and computer-aided manufacturing (CAD/CAM) technology have recently gained popularity. Their esthetic appeal is crucially dependent on the color accuracy, influenced by prosthesis thickness and multilayer composition due to CAD/CAM milling positions. This study comprehensively investigated how these two factors impacted color accuracy, thereby enhancing our understanding of color outcomes. One hundred monolithic multilayer zirconia specimens with 10 × 10 mm square shape were milled in four different positions and five different thicknesses (1.0, 1.5, 2.0, 2.5, and 3.0 mm). The specimens were placed on an A3 shade resin composite substrate, and CIELAB values (L ∗, a ∗, and b ∗) were measured using a spectrophotometer. Delta E (ΔE) values were calculated to quantify the color differences between the specimens and the A3 VITA classical shade tab and compared with the perceptibility and acceptability thresholds of ΔE = 1.2 and 2.7, respectively. Pearson correlation, two-way ANOVA, and Tukey multiple comparisons (α = 0.05) were performed. The proportion of the dentin layer was positively correlated with the a ∗ and b ∗ values, while specimen thickness was positively correlated with the a ∗ value and negatively correlated with the L ∗ and b ∗ values. Significant difference in ΔE value due to different CAD/CAM positions was not observed within the same specimen thickness. Perceptible color differences were observed in specimens with thicknesses greater than 1 mm, while specimens with 1 mm thickness fell within the clinically acceptable range. Highest ΔE value was found in the specimen with 1 mm thickness. Different compositions of multilayers in the final restoration due to different CAD/CAM positions do not significantly affect the color appearance of ultra-translucent multilayer zirconia, with color only influenced by specimen thickness.

A system for reliable composite shade matching: Custom shade tabs and an intra-oral mockup.

This article introduced a systematic approach to matching composite and tooth shades to create esthetic restorations that visually integrate seamlessly with the patient's tooth and surrounding dentition. A basic explanation of color science was presented to aid the clinician in adopting this systematic approach to color matching. To demonstrate the need for custom shade guides, an objective analysis of composites from different companies was performed by recording the color coordinate values of multiple composites and then calculating CIEDE2000 color differences. Different locations on the tooth were analyzed using the same identified shade from different companies, as well as using the same composite shade applied in different thicknesses. A case report documented the clinical application of these shade matching techniques. Shade matching, particularly in the anterior esthetic region, can be challenging, which can result in patient dissatisfaction with the esthetic result. Stock shade tabs are not a reliable indicator of actual composite shades. The most predictable esthetic results were achieved by using custom shade guides as an entry point, followed by a direct composite color mockup intraorally. To consistently meet the esthetic demands of today's patients, dentists need reliable tools when selecting a composite shade for restorations. Composites with the same shade designation vary in color and shade designation cannot be relied upon for accurate shade selection. The use of custom shade guides and an intra-oral mockup can enhance the esthetic outcome.

Comparison of Composite Resin (Duo-Shade) Shade Guide with Vita Ceramic Shades Before and After Chemical and Autoclave Sterilization.

BACKGROUND This study aimed to compare a composite resin (Duo-Shade) shade guide with Vita ceramic shades before/after chemical and autoclave sterilization. MATERIAL AND METHODS Color values (L*a*b*) were recorded directly from shade tabs of prefabricated composite resin (Brilliant NG Universal Duo-Shade) and ceramic (Vita classic) shade guide with a calibrated spectrophotometer (Vita Easy Shade Advance 4.0). Seventy-two composite resin disk samples with 6 different shades (A1/B1, A2/B2, A3/D3, A3.5/B3, A4/C4, and C2/C3) (n=12 each) were divided into 2 groups (Gp) - Gp A (Autoclave) and Gp C (Chemical) (15 cycles) - to assess their influence on respective shades. Mean values calculated the color differences (ΔE) while differences in color values (L*a*b*) were graded on the National Bureau of Standards (NBS) 6-grade scale and assessed for Clinical Acceptance/Perceptible Threshold (CAT), (CPT). All differences were considered significant if the color difference ΔE was ≥3.3. RESULTS Only 2 out of 12 Shade tabs (C2C3, A4C4) of composite resin matched to Vita shade tab C2 and C4 (ΔE ≤3.3). Both groups showed notable color differences after respective sterilization protocols, with color differences in Gp A significantly higher than Gp C (DE ³3.3). Within groups, all shades in Gp A showed remarkably different color changes, with shade C2C3 and A1B1 being denoted as clinically unacceptable. CONCLUSIONS Manufacturer-provided shade guides do not match ceramic shades as claimed and chemical sterilization using 10% Deconex was associated with less color changes than with autoclave sterilization.

Influence of image file and white balance on photographic color assessment

Statement of problemHow the color parameters obtained from digital photographs may be influenced by illumination, file format, and subject color is unclear. PurposeThe purpose of this in vitro study was to evaluate color differences (ΔE00) and CIELab color coordinates among different types of file formats of dental shade tab images with and without white balance. Material and methodsDifferent shade tab colors (n=10) were photographed with a digital camera under standard conditions. The photographs were stored in RAW, JPEG, and TIFF file formats and evaluated with and without white balance (WB) adjustment by using an image software program and a gray reference card with known color coordinates. CIEDE2000 color differences between each image file format and the control group (RAW WB) were calculated, and interpreted by the visual perceptibility (PT00=0.8) and acceptability (AT00=1.8) thresholds. The ΔE00 color shift was defined according to CIEDE2000 lightness, chroma, and hue and interpreted by the following respective visual acceptability thresholds: 2.92, 2.52, and 1.90. The differences among the color coordinates were analyzed by Kruskal-Wallis and Bonferroni post hoc tests (α=.05). ResultsThe color coordinates presented statistically significant differences between the file formats and control group (P<.001). Excellent matches (ΔE00 ≤0.8) were observed on TIFF and JPEG saved from RAW-WB. Images without WB presented unacceptable mismatches (ΔE00 >5.4). ΔE00 color shift of images without WB were predominantly influenced by ΔH00, while JPEG, WB, and TIFF WB were mostly influenced by ΔC00. ConclusionsOnly compressed JPEG or TIFF files of dental shade tabs derived from original RAW WB photographs were able to achieve color differences within the limits of the 50:50% perceptibility threshold, providing excellent color matches with the RAW WB files.