Assessment of the color stability of two silicone elastomers for maxillofacial prostheses upon exposure to cold beverages.

PURPOSE: This study investigated the color stability of different commercially available silicone materials for facial prostheses upon exposure to everyday beverages. It was hypothesized that the beverages would not alter the color of the silicone under conditions simulating daily exposure. METHODS: Sixty specimens were fabricated using two materials - VST-50 and Silfy - and exposed to commercially available cold mineral water, tea, or coffee. Specimen color was evaluated on days 1 and 15. The color was measured with a spectrophotometer based on CIELab system and color differences were calculated as ΔE. Statistical analysis was performed using the Kruskal-Wallis test and Mann-Whitney U test. RESULTS: The mean ΔE values after 15 days of exposure to mineral water, cold green tea, and coffee were 1.016, 3.480, and 3.636 for VST-50 and 0.440, 0.798, and 1.425 for Silfy, respectively. Both materials showed significant differences in color, and VST-50 showed a greater color change than Silfy, especially for coffee. CONCLUSION: Pigmented silicone elastomers have low color stability, leading to an overall color change in silicone prostheses when exposed to pigmented beverages. Color changes in such prostheses can be mitigated by selecting materials with better color stability to extend their longevity.

Assessment of relative translucency and resultant color of contemporary resin-matrix ceramics indicated for laminate veneers and full crowns.

Background and Aims: Evaluation of the optical properties of restorative materials is an important parameter for identifying clinical success. The aim of this study was to compare the translucency of contemporary resin-matrix ceramics (RMCs) and to evaluate the effect of cement shade on the final color of RMCs indicated for laminate veneers and full crowns. Materials and Methods: A hundred A2 shade RMC specimens were fabricated by using Mazic Duro (MD), CAMouflage NOW (CN), KZR-CAD HR2 (KZR), Grandio Block (GB), and Brilliant Crios (BC) at 0.7-mm and 1.5-mm thicknesses (n = 10). A2 shade composite resin was used for the foundation structure. Twenty resin-cement specimens were prepared from A2 and translucent shades at 0.1-mm thickness. Interchangeably, the foundation-cement-resin matrix ceramic assemblies were created with optical gel. The color coordinates were recorded using a spectrophotometer. After calculating translucency parameter (TP00) and color difference (ΔE00) values, data were analyzed statistically (P = 0.05). Results: TP00 values were influenced by RMC type and thickness. TP00 values of RMCs can be listed in descending order as MD>GB = CN>BC=KZR. ΔE00 values were significantly influenced by all parameters and their interactions. MD exhibited higher ΔE00 values among tested RMCs. The effect of A2 cement was not perceived visually while TR cement demonstrated visually perceptible but clinically acceptable values for both laminate veneers and full crowns. As the material thickness decreased, the TP00 and ΔE00 values increased in all RMCs. Conclusions: Clinicians should carefully prefer cement shade and RMC material by contemplating their impact on the optical properties particularly when the restoration is thin.

An In-Vitro Assessment of Operator Accuracy and Inter-Operator Agreement in Recording Shade and Shade Characteristics.

Color assessment remains a challenging aspect of esthetic dentistry. This study aimed to evaluate inter-operator agreement and accuracy in assessing shade parameters and to investigate the effect of different clinical backgrounds of the operators under different lighting conditions. Three veneers with a single shade (VITA VM7, shade 2M2: VITA Zahnfabrik, Bad Säckingen) and different shade characteristics (lustre, translucency and opacity) were assessed by 24 operators with different backgrounds using natural and color-corrected light (Trueshade, Interempresas Media, S.L.U. - Grupo Nova Àgora, Spain). Shade assessment accuracy was only 5.5% using natural light and 9.7% using Trueshade. The majority of operators identified value and hue correctly, although chroma was mostly identified incorrectly. The most accurate assessments were recorded by technicians, and translucency was the characteristic to be least accurately recorded. Inter-operator agreement of shade was better with Trueshade compared without Trueshade, although group agreements of shade characteristics were higher without Trueshade for lustre and opacity, but not for translucency. Operators showed limited agreement and poor accuracy in assessing shade and shade characteristics and the clinical background had an effect on shade selection. Technicians were more reliable in shade assessment. Trueshade could be a promising tool to improve shade assessment outcomes.

Comparing the effectiveness of shade measurement by intraoral scanner, digital spectrophotometer, and visual shade assessment.

OBJECTIVE: Trios3 (3Shape, Denmark) intraoral scanner is complete with a tooth shade measurement function, but there is limited information about its efficacy. This in vivo study aimed to evaluate this function in relation to visual and spectrophotometric shade determination. MATERIALS AND METHODS: Ten dental students from Semmelweis University determined tooth shade for 10 volunteers using Vita A1-D4 (VC) and Vita Linearguide 3D-Master (LG) guides, Vita Easyshade spectrophotometer (ES) and Trios 3 intraoral scanner (TR). First and last patient was always the same (Patient R). Intrapersonal repeatability was calculated. Four selected shades of each tooth were presented to student, supervisor, and patient to select best match. Selection percentages were calculated. The supervisor's best match was the reference (∆E00 ). RESULTS: Median ∆E00 of Patient R: TR 1.09; VC 1.5; ES 2.35; LG 3.1. The percentages of best match: VC 16.7%.; TR 21.64%; ES 26.58%; LG 34.08%. Median ∆E00 of students' and supervisor's best match: LG 2.73; ES 4.29; TR 4.29; VC 16.35. TR was the most repeatable. The most "best-match shade tabs" were selected using LG. VC shade tabs was the least consistent with the examined teeth. CONCLUSIONS: TR can be used for shade selection with a 3D-Master tooth color system with visual verification. CLINICAL SIGNIFICANCE: Correct tooth shade determination is one of the most important step in making esthetic restorations. New shade matching systems have been developed to surpass the visual method of shade determination. There are new intraoral scanners with built-in shade measurement functions. Digital shade determination methods are more independent from the environmental circumstances, and with intraoral scanners, it is easy to measure the tooth shade by taking a digital impression at the same time. These new devices may be a reliable alternative method for shade selection with visual verification.

Assessment of a smartphone-based software application as a potential digital tool in tooth shade selection: a prospective clinical study.

OBJECTIVE: To determine the reliability of a newly developed software application (Shadent) in natural tooth shade selection. METHOD AND MATERIALS: A smartphone device with the self-developed Shadent software (patent no. 201841046815, Intellectual Property of India) recorded tooth shades of the maxillary right central incisor and canine for 250 volunteers. A prospective, clinical, double-blind trial was conducted. The shade match obtained under the standardized condition from Shadent software was compared with the visual method and spectrophotometer. The digital recordings were captured by two master's candidates, while the visual shade match was evaluated by four master's candidates and one faculty member from the Department of Prosthodontics. Crosstab analysis assessed the relationship between the visual method of shade selection, a spectrophotometer, and the Shadent software. Cohen kappa was used to measure the agreement between the methods. RESULTS: A kappa coefficient of 0.59 was observed between the visual assessment and the Shadent software, with an agreement percentage of 64.6%. A kappa coefficient of 0.65 was observed between the spectrophotometer and the Shadent software with an agreement of 69.3%. The software also had a better Cohen kappa agreement with the maxillary central incisor than the maxillary canine. CONCLUSIONS: Shadent's reliability was comparable with the visual and spectrophotometric methods and offered repeatability with standardized light intensity.

Assessment of the Change in Color of Maxillofacial Silicone after Curing Using a Mobile Phone Colorimeter Application.

AIM: To evaluate the change in color of the maxillofacial silicone after curing using a mobile phone colorimeter application. MATERIALS AND METHODS: A two-piece metal mold was fabricated. Twenty five samples were made using M511, maxillofacial silicone. A jig was prepared to hold the mobile phone at a fix distance from the samples. The color was measured for each sample in terms of HSV (hue, saturation, value) with the mobile phone colorimeter application after manipulation and after polymerization of the samples. Data were statistically analyzed using the Student's paired t test and the software used in the analysis was SPSS 22.0 version. RESULTS: The mean difference of hue was 1.32 ± 2.71, with p value 0.053. Mean differences in saturation was 0.72 ± 2.01, with p value 0.066. Mean differences in value were 2.16 ± 3.11, with a p value 0.002. The measure of value showed statistically significant differences (p < 0.05). CONCLUSION: There was a significant change in the value of the color of the maxillofacial silicone after polymerization. CLINICAL SIGNIFICANCE: Increasing the value of the color by 2-3% at the time of manipulation of the maxillofacial silicone with the use of a mobile phone colorimeter application can help the clinician to reproduce the same color in the final prosthesis after curing to achieve a predictable esthetic outcome for a facial prosthesis.

Dental prophylaxis influence in tooth color assessment-Clinical study.

OBJECTIVE: To evaluate dental prophylaxis influence in tooth color assessment with the use of different methods. MATERIALS AND METHODS: Volunteers were consecutively recruited and screened according to appropriate inclusion/exclusion criteria. Each participant's upper right central incisive and canine color was measured before and after dental prophylaxis with a one-week interval. Tooth color assessment was performed by calibrated operators and the patient using a VITA Classical shade guide and by spectrophotometric methods with a proper device (SpectroShade). Color was reported as mean with SD of Commission Internationale De l'Eclairage (CIE) L*a*b* values, ΔEab and ΔE00 . One-way analysis of variance and Tukey post hoc were performed to assess differences between methods and paired t test for assessing differences in tooth color coordinates after dental prophylaxis. Values of P < .05 were taken as significant. RESULTS: Fifty patients were included. Self-assessed dental prophylaxis effects equated to a significantly different mean ΔE00 value of 2.3 ± 1.7 (P < .01), when compared to the calibrated operator reported 0.8 ± 1.1 and the spectrophotometer 1.0 ± 0.5. Half of volunteer's ΔE00 values surpassed the acceptability threshold, when compared to 28% from investigator and 10% from spectrophotometer. CONCLUSION: Performing a dental prophylaxis did have an influence in tooth color perception with a higher self-perceived effect in the patient assessment. CLINICAL SIGNIFICANCE: The results of this study suggest that performing professional dental prophylaxis presented a perceived effect in tooth color regardless of the method used being that patients precepted whiter and less yellowish teeth. Since extrinsic stain is considered as one of the factors that could influence tooth color assessment, performing professional dental prophylaxis prior to composite or ceramic color selection in anterior teeth restorations could consequently increase treatment predictability.

Dental color assessment through TTB exercises.

Aim.To verify the impact of taking the Toothguide Training Box (TTB) exercise in improving the individual ability to correctly determine dental color. Material and method.A prospective study was conducted on the 5th year dental students. The participants were required to carry out 3 distinct steps: visual color determination for sample tabs out of the 3DMaster shade guide, the TTB exercise and another color determination after training completion. Results.The sample included 60 students (19M/ 41F) with a mean age of 24, which made 360 color determinations of 6 shade tabs before and after TTB exercise. 32,5% (n=117) of the color determinations were incorrect in both moments, and the value was incorrectly determined just in 11% of them. Students found 3L1.5 and 3M2 colors as the hardest to determine. The results suggested that a single TTB training exercise did not have a high positive influence on the individual capacity to correctly determine the color for tabs out of the shade guide. Conclusions.While there is no evidence of an immediate positive impact of the TTB exercise in evaluating and determining different color variations for sample key elements, through repeat exercises, the individual perception can be improved and thus the correct determination of dental color and its correct codification can be increased. ABBREVIATIONS: TTB = Tooth Training Box, CIE = Commission internationale de l'éclairage, L = lightness, C = chroma, H = hue.

Online colour training system for dental students: a comprehensive assessment of different training protocols.

The purpose of this study was to evaluate the training effect and to determine the optimal training protocol for a recently developed online colour training system. Seventy students participated in the evaluation. They first completed a baseline test with shade guides (SGT) and the training system (TST), and then trained with one of the three system training methods (Basic colour training for group E1, Vitapan Classical for E2, and Vitapan 3D-Master for E3) or shade guides (group C1) for 4 days. The control group (C2) received no training. The same test was performed after training and they finally completed a questionnaire. The correct matches after training increased in three experimental groups and group C1. Among experimental groups, the greatest improvement of correct matching number was achieved by group E3 (4·00 ± 1·88 in SGT, 4·29 ± 2·73 in TST), followed by E2 (2·29 ± 2·73 in SGT, 3·50 ± 3·03 in TST) and E1 (2·00 ± 2·60 in SGT, 1·93 ± 2·96 in TST). The difference between E3 and E1 was statistically significant (P = 0·036 in SGT, 0·026 in TST). The total average training time was shorter in group E2 (15·39 ± 4·22 min) and E3 (17·63 ± 5·22 min), with no significant difference between them. Subjective evaluations revealed that self-confidence in colour matching were improved greater in group C1 and E3. In conclusion, all tested sections of the system effectively improved students' colour-matching ability. Among system training methods, Vitapan 3D-Master showed the best performance; it enabled greater shade-matching improvement, it saved time and was superior in subjective evaluations.

Purpose of esthetic risk assessment in prosthetic rehabilitations with gingiva-shade ceramics.

Esthetic predictability and the possibility to reduce the need for more aggressive surgical interventions have been two strong reasons for the growing acceptance of gingiva shade ceramics in dental treatments. However this type of rehabilitation also has several esthetic constraints. The aim of this paper is to present an assessment system that may serve as a clinician's guideline to clearly identify the risk factors influencing the esthetic result of gum-shade ceramics and, in the end, to grade these clinical situations as high, medium or low esthetic risk. Over several years of clinical experience, the authors have identified different factors that influence the achievement of satisfactory esthetic results using gumshade ceramics: smile line, extension of the prosthetic rehabilitation, anatomical area, vertical and horizontal transition between the prosthesis and the natural gingiva, contact surface, framework material, and color. In conclusion, despite the great applicability of gingiva-shade ceramics in the resolution of clinical cases involving complex architecture of the hard and soft tissues, this procedure should not be considered one free of esthetic risk. There are different factors that should be evaluated when considering the esthetic results with gingiva-shade ceramics.

Implementation of a laboratory quality assurance program: the Louisville experience.

Remakes, or the refabrication of dental prostheses, can occur as a result of inherent inaccuracies in both clinical and laboratory procedures. Because dental schools manage large numbers of predoctoral dental students with limited familiarity and expertise as related to clinical prosthodontic techniques, it is likely these schools will experience an elevated incidence of laboratory remakes and their ramifications. The University of Louisville School of Dentistry, not unlike other dental schools, has experienced remakes associated with both fixed and removable prosthodontic procedures. Limitations in faculty standardization and variable enforcement of established preclinical protocols have been identified as variables associated with the high percentage of remakes documented. The purpose of this study was to introduce the implementation of a new multidepartmental quality assurance program designed to increase consistency and quality in both information provided to commercial dental laboratories and the prostheses returned. The program has shown to be advantageous in terms of cost-effectiveness and treatment outcomes. A statistically significant decrease in remake percentages has been recorded from inception of this program in December 2010 until December 2012. Furthermore, this program has resulted in more consistent communication between the dental school and commercial dental laboratories, among faculty members, and between faculty and students.

In vitro and in vivo assessment of titanium surface modification for coloring the backplate of the Boston keratoprosthesis.

PURPOSE: Recent use of a titanium (Ti) backplate has improved the design and biocompatibility of the Boston Keratoprosthesis (BKpro). Titanium's shiny metallic appearance, however, makes the cosmetic outcome less favorable. The purpose of this study was to develop and test a coloring surface modification of Ti. METHODS: Ti coloring was achieved using electrochemical anodization. Color assessment included scanning electron microscopy, atomic force microscopy (AFM), x-ray diffraction crystallography (XRD), and Fourier transform infrared spectroscopy (FTIR). Biocompatibility assessment of Ti disks included in vitro proliferation and cytotoxicity in coculture with human corneal limbal epithelial (HCLE) cells, primary human corneal fibroblasts, and immortalized human corneal endothelial cells (HCEnCs), and in vivo intralamellar implantation in rabbit corneas. Histologic appearance (hematoxylin-eosin and trichrome staining) and presence of cell inflammation (CD45), apoptosis (TUNEL), and corneal neovascularization (CD31) were evaluated 27 and 53 days post implantation. RESULTS: Blue and brown coloration of Ti was achieved. Analysis showed the presence of a nanoporous oxide surface with no chemical change of the modified Ti surface. In vitro assessment showed no significant differences in cell proliferation and cytotoxicity between anodized and nonanodized Ti (P > 0.05; ANOVA for all cell types). Analysis of corneal tissues harboring the Ti disks showed normal cellular appearance, and lack of CD45, TUNEL, and CD31-positive cells. CONCLUSIONS: A biocompatible Ti backplate coloring was achieved by electrochemical anodization. In vitro and in vivo results suggest that the anodized Ti is equally biocompatible and as safe as the standard nonanodized Ti. The color modification of the BKpro may improve the cosmesis and acceptance of the BKpro by patients.

Spectrophotometric assessment of peri-implant mucosa after restoration with zirconia abutments veneered with fluorescent ceramic: a controlled, retrospective clinical study.

OBJECTIVES: The purpose of this study was to investigate the optical appearance of the soft tissue labial to dental implants restored with fluorescent ceramic-veneered zircona abutments. It was hypothesized that the tested abutment design leads to an increased brightness in the marginal peri-implant tissue, which does not differ from that of natural teeth. Moreover, a reduction of the color difference that has been reported from other abutment materials was expected. MATERIALS AND METHODS: A total of 12 patients with single titanium implants in the maxillary anterior region were recruited. All implants (N = 12) were restored with zirconia abutments veneered with fluorescent ceramic and full-ceramic crowns. Color measurements of the peri-implant mucosa at the test sites were made of the facial aspect of the teeth using a Spectroshade-spectrophotometer. The gingiva of a contralateral or adjacent natural tooth served as a control. Color data (CIE-L*a*b* color coordinates) were obtained in five incremental areas of 1 × 2 mm in both test and control sites. ∆E-values were calculated from the ΔL*, Δa* and Δb* values for each patient. RESULTS: Data acquisition from the test site demonstrated lower mean values of L*, a* and b* than the control site. Statistical significance between the test site and control site was reached in the L* values only in the second of the five incremental areas (P < 0.05, Wilcoxon test). However, discrepancies in a*- and b*-values reached a statistically significant difference in the incremental areas 1, 2 and 4, and in b* in area 5 (P < 0.05, Wilcoxon test). Medians of the ∆E-values in all five increments were found to be higher than the clinical perceptual threshold of 3.7. However, considering the original data, five individual patients did not reach the threshold in increment 1 and 2, two in increment 3 and three in increment 4. None of the patients showed lower ∆E-values than the perceptual threshold of 3.7 in increment 5, which had the largest distance from the gingival margin. CONCLUSION: The tested abutment design leads to a peri-implant soft tissue color that, in the critical marginal area, in five of 12 patients did not statistically differ from the tissue of the gingiva of natural teeth. Particularly, the brightness of the peri-implant soft-tissue seemed to be more adapted to the natural situation using a fluorescent abutment design.

Assessment of perceptibility and acceptability of color difference of denture teeth.

OBJECTIVES: To assess the color difference values that represent the perceptibility and acceptability thresholds of denture teeth. METHODS: Eighteen interchangeable right upper central incisors denture teeth were selected to have color difference values from representative left upper central incisor denture tooth in a range of 0.4-11.4 ΔE* units measured with a spectrophotometer (CM 2600d, Minolta Konica, Japan). These teeth were placed in an artificial dental arch in a phantom head. Under controlled conditions, a total of 80 observers divided into 4 groups (technicians, nurses, dentists and researchers) were asked to report the perceptibility and acceptability of each of the color difference values. The findings was then analysed using logistic regression for determining the perceptible and acceptable thresholds of dental color differences. RESULTS: The determined color difference values at which 50% of all observers could detect a color difference (50:50 probability) was 1.9 ΔE* units with a 95% confidence interval and ranged from 1.7 ΔE* units to 2.1 ΔE* units. The determined color difference value at which 50% of all observes preferred to replace the tooth because of unacceptable color difference (50:50 probability) was 4.2 with a 95% confidence interval that ranged from 3.9 ΔE* units to 4.7 ΔE* units. CONCLUSIONS: Within the limitation of this study, the following conclusions were made: 1. The mean color perceptibility threshold was significantly lower than the mean color acceptability threshold. 2. Significant differences between different observers groups were noticed in determination of perceptibility and acceptability of color differences. The technicians groups displayed lower perceptibility and acceptability limits than the dental nurses and non-dental observers. CLINICAL SIGNIFICANCE: When shade matching artificial denture teeth to natural teeth, 50:50 perceptibility (1.9 ΔE* units) and acceptability (4.2 ΔE* units) thresholds are used to compare color difference values. The technicians group displayed lower perceptibility and acceptability limits than other observers.

Simulation of color perception of layered dental composites using optical properties to evaluate the benefit of esthetic layer preparation technique.

OBJECTIVES: Esthetic restorations require that dental restorative materials have similar optical properties to teeth. To improve the color perception, the inhomogeneous morphology of the native tooth can be imitated by layering two optically different restorative materials. However until now the benefit of this method has not been satisfactorily demonstrated. METHODS: The optical parameters, absorption coefficient µ(a), scattering coefficient µ(s), anisotropy factor g and effective scattering coefficient µ'(s), were determined for the enamel and dentin material of the restorative material systems Artemis(®) and Herculite XRV(®). This was carried out for each material system in the wavelength range between 400 and 700nm using integrating sphere measurements followed by inverse Monte Carlo simulations. RESULTS: Using the optical parameters and a forward Monte Carlo simulation, the color perception of layered samples could be predicted with a sufficient degree of accuracy. The total color impression was shown to be dependent on the sample thickness and the transparency/translucency of the single layers of enamel and dentin materials. CONCLUSION: The study demonstrated that the use of two materials is well-suited for the restoration of front teeth with their relatively high proportion of enamel. This study will continue further with the compilation of a data pool of optical parameters which will enable the application of calculation models to optimize the optical approximation of the natural tooth.

[Clinical assessment of acceptability of shade mismatch of infiltrated alumina ceramic crowns].

PURPOSE: To measure and evaluate the acceptability of shade mismatch of infiltrated alumina ceramic crowns directly in clinic. METHODS: Ten cases with restoration of hot casting alumina ceramic crown were collected in clinic. L*, a*, b*, C, H, ΔE values of hot casting alumina ceramic crowns and corresponding natural teeth in natural light were surveyed and calculated, then analyzed with CIE1976L*a*b* color system, digital photography and Photoshop CS2. All statistical analyses and calculations were completed in paired t test with SAS6.12 software package. RESULTS: In cervical 1/3 region, significant statistical difference in lightness, a*, hue angle parameter value between alumina all-ceramic crown and natural tooth (P<0.01) was found; in middle 1/3 region, significant difference in a*, b*, saturation parameter value (P<0.01) existed; in incisory 1/3 region, the parameters had no significant difference (P>0.05). To parameter ΔE, there was significant difference in every region, but it was in the acceptable range. CONCLUSIONS: The acceptability of shade mismatch is about 6 ΔE units, we can analyse the color difference between the restoration and natural teeth directly in clinic through symmetry of central incisor.

Estimating costs for shade matching and shade corrections of fixed partial dentures for dental technicians in Germany: a pilot investigation.

AIMS: To evaluate the additional operating expenses caused by shade matching by dental technicians in the dental practice and by color changes of fixed partial dentures. METHODS: A questionnaire was handed out to visitors of the 2010 ADT dental technician congress in Germany. Thirty-one completed questionnaires were evaluated. RESULTS: Mean costs caused by shade matching and shade correction per month were 1269$ (SD = 1278$; n = 25) and per unit of FPD 9.32$ (SD = 8.89$). CONCLUSIONS: An improvement of shade matching, shade communication and reproduction should be made in order to minimize the considerable economic damage for dental laboratories.

Development of digital shade guides for color assessment using a digital camera with ring flashes.

Digital photographs taken with cameras and ring flashes are commonly used for dental documentation. We hypothesized that different illuminants and camera's white balance setups shall influence color rendering of digital images and affect the effectiveness of color matching using digital images. Fifteen ceramic disks of different shades were fabricated and photographed with a digital camera in both automatic white balance (AWB) and custom white balance (CWB) under either light-emitting diode (LED) or electronic ring flash. The Commission Internationale d'Éclairage L*a*b* parameters of the captured images were derived from Photoshop software and served as digital shade guides. We found significantly high correlation coefficients (r² > 0.96) between the respective spectrophotometer standards and those shade guides generated in CWB setups. Moreover, the accuracy of color matching of another set of ceramic disks using digital shade guides, which was verified by ten operators, improved from 67% in AWB to 93% in CWB under LED illuminants. Probably, because of the inconsistent performance of the flashlight and specular reflection, the digital images captured under electronic ring flash in both white balance setups revealed less reliable and relative low-matching ability. In conclusion, the reliability of color matching with digital images is much influenced by the illuminants and camera's white balance setups, while digital shade guides derived under LED illuminants with CWB demonstrate applicable potential in the fields of color assessments.

Assessment of color fidelity of several composite resins compared to their Vita Classical shade registration.

This study compared the color fidelity of different composite resins with their registration in the Vita Classical Shade Guide. Using a prefabricated Teflon mold, 120 specimens were divided into four groups (n = 30), according to the resin tested. Three subgroups (n = 10) were prepared for each resin group; these subgroups tested enamel shade, dentin shade, and enamel and dentin shade. Three measurements were performed to verify whether the tooth shade matched that of the Vita Classical Shade Guide. The color was evaluated and the shade variations were calculated. The data were submitted to a three-way ANOVA test (time, color match, and composite type), followed by Tukey's test. It was concluded that all composite resins showed color differences in relation to the Vita Classical Shade Guide.

Photometric assessment of tooth color using commonly available software.

It would be expedient to develop a simple digital procedure for matching shade guides to teeth for dental restorations. It was hypothesized that precise and objective L*a*b* measurements could be performed on photographic images of teeth and shade guides using commonly available photo software. Tooth shade guide tabs, shaped like computer-generated posterior crowns, were used for color matching. Digital photographs were obtained of the vestibular surface of the tooth and the neighboring shade guide. Sections of the tooth and shade guide on the photograph were cropped and analyzed in Photoshop CS2. The precision error of the measurements was expressed as the coefficient of variation in percent. The effects of tolerance setting and number of measurements and analysts were evaluated. The difference in color was calculated as the DeltaE L*a*b*. The precision errors of the L*a*b* measurements with a tolerance setting of 6 pixels were better than 1.3%. There was no significant difference between one and five repeated measurements or between the measurements and the precision errors of two analysts. Color differences (DeltaE) between repeated measurements were below 0.5 units, thus reproducible and visually identical. DeltaE L*a*b* calculations were expedient for matching a particular color guide tab to the neighboring tooth. The color coordinates L*a*b* of teeth and shade guides can be calculated with a precision error of only 1.3%, using readily available software. A tolerance setting of 6 pixels is optimal and only one measurement and one analyst are necessary for objective and precise measurements. The described digital L*a*b* measurements on a photograph offer the dentist and the ceramist a simple, precise, and objective tool for matching tooth and shade guide.