Porcelain Shade Research Articles

A Clinical Comparison Between New and Conventional Methods for Quantification of Intended and Fabricated Dental Porcelain Color

Introduction: The accurate selection of dental porcelain shades is crucial for achieving natural-looking and aesthetically pleasing restorations. This study aimed to compare the effectiveness of various shade selection methods, including visual assessment, spectrophotometry, and intraoral scanning. Aims and Objectives: This study aims to improve the accuracy of shade selection in prosthodontics. To achieve this, it will compare digital, intraoral, and visual methods, identify factors influencing shade selection, develop educational guidelines for dentists, and minimize color discrepancies between chosen and final shades. Methods: A diverse group of 37 participants with 111 shades of teeth were involved. Three shade selection methods were employed: visual assessment using a shade guide, spectrophotometry with the VITA Easyshade Compact, and intraoral scanning with the Medit i700. The accuracy of each method was determined by comparing the selected shade to the fabricated porcelain restoration. Results: While digital methods (spectrophotometry and intraoral scanning) simplified the shade selection process, visual assessment, especially when performed by experienced dentists, consistently demonstrated higher accuracy. Factors such as lighting conditions and individual variations in color perception influenced the reliability of visual assessment. Discussion: The study emphasizes the importance of a comprehensive approach to shade selection, combining both visual and digital methods. Digital tools offer objective measurements, while visual assessment captures subtle nuances in color and ensures patient satisfaction. Conclusion: The optimal shade selection method depends on the specific clinical situation and the dentist's expertise. By incorporating both visual and digital techniques, dental professionals can enhance the accuracy and reliability of shade selection, ultimately leading to more natural-looking and aesthetically pleasing dental restorations.

Spectrophotometric comparison of two porcelain systems, VMK master and VM13 with the VITA 3D-master shade guide (An in vitro study)

Accurate shade matching of metal-ceramic restorations with natural teeth is one of the most challenging aspects of dental restorations and esthetic dentistry. The aim of this study was to evaluate of the color parameters of two types of porcelain systems VMK Master and VM13 porcelain with VITA 3D-master shade guide. In this in vitro study a total of 56 metal discs (10 mm diameter and 2 mm thickness) were fabricated. Each of the disks was veneered with porcelain (Vita Zahnfabrik, Bad Sackingen, Germany) of the VITA shade. The discs were randomly divided into four groups (2M2 and 3M2 from VM13, 2M2 and 3M2 from VMK master) of 14 (n = 14). The spectrophotometer was used for taking color measurements based on the numerical color data of the CIELAB color system. Data analysis was performed by t-test (P < 0.05). Comparison of color parameters in different porcelain showed that the type of porcelain caused a significant difference in color parameters (L, a, and b) (P < 0.05). The degree of translucency (L*) or glaze of VMK porcelains was higher than VM13, but the parameters a* and b* were higher in VM13 porcelains than VMK (P < 0.05). Furthermore, the color difference of two porcelain in 2M2 (1.63 ± 0.84) and 3M2 (1.71 ± 0.96) shades was within the acceptable clinical limit. Considering the total color difference (ΔE), there were no significant differences between the ΔE values produced by any of shades (P > 0.05). In the present study, the spectrophotometric analysis revealed that the porcelain shade type causes a change in the color parameters, but the color difference between two porcelains VMK and VM13 is within the acceptable range of clinical color. Therefore, both porcelain systems with 2M2 and 3M2 shades are suitable for enhancing the results of restorative dentistry.

The effect of repeating firing cycle on the shade of porcelain fused to metal, all-ceramic and zircona restorations

BackgroundCeramic have a long history in fixed prosthodontics for achieving optimal esthetics and various materials have been used to improve ceramic color. However, there is a lack of information on how color is affected by fabrication procedures.PurposeThe purpose of this study was to evaluate the effects of repeating firings cycle on the color of porcelain fused to metal (PFM), Empress II and Zirconium based restoration.Materials and methodsThirty disc-shaped of 10 mm in width and 1.5 mm in thickness divided into three groups (n = 10) shade A3, were fabricated each groups of PFM, Empress and Zirconia respectively. Repeated firings were performed for the specimens and color differences (ΔE) were determined using a spectrophotometer, repeated measures analysis of variance was used to analyze the data (number of firings, color). The Tukey's post-hoc test was used for pair-wise. Comparisons between the groups when analysis of variance test is significant.ResultsThe repeated firing cycles on the ceramic discs has resulted in, Empress II showed the highest decrease in L* value with Empress II followed by zirconia and PFM showed the lowest decreased in L* value. Empress and zirconia both showed the statically significantly highest mean (Δa) values. PFM showed the statistically significantly lowest mean (Δa) Empress showed the statistically significantly highest mean (Δb). There was no statistically significantly lowest mean (Δb) value. Empress showed the statistically significantly highest mean (ΔE). Zirconia showed statistically significantly lower mean (ΔE). PFM showed the statistically significantly lowest mean (ΔE).ConclusionEmpress II was highly affected by repeated firing than zirconia-based restoration, and PFM.

The effect of repetitive firings on the color of an alumina ceramic system with varying ceramic shade and thickness.

The color of all-ceramic restorations is one of the main criteria to achieve esthetical success. Many factors such as ceramic thickness, condensation techniques, firing temperature, and numbers can affect the final color of restoration. The purpose of this study was to investigate the color changes in alumina-based ceramic system according to ceramic shade and thickness during the multiple firings. Sixty disc-shaped specimens with two different veneering porcelain shades (A1 or A3), and with three different ceramic thicknesses (0.5, 1, or 1.5 mm), were fabricated from an alumina-based ceramic system. Multiple firings (3, 5, 7, or 9 firings) were performed, and color changes (ΔE00 ) were determined using a spectrophotometer. Repeated-measures ANOVA were used to analyze the data. The Duncan test was used for multiple comparisons (α = .05). The L*a*b* values of the specimens were affected by the number of firings (3, 5, 7, or 9), veneering ceramic shades (A1 or A3) and veneering ceramic thicknesses (0.5, 1, or 1.5 mm). Significant interactions were present between the number of firings, veneering ceramic shade, and veneering ceramic thickness for L* (p < .001), a* (p < .001), and b* (p < .001) values. No statistically significant color change was observed between 3rd and 9th firings. Veneering ceramic shade, veneering ceramic thickness, and number of firings should be carefully considered to obtain an acceptable color match of the definitive restorations.

Management of alveolar defect with one-piece implant and index of gingival porcelain shade selection in a North Indian Youth

Esthetics is a prime demand for patients who seek anterior replacement of missing teeth. Resorption of the alveolar bone of the edentulous area occurs if left untreated for a long time. It further leads to thinning of the labial cortical plate in the maxillary arch. Few other reasons for narrowing of the alveolar crest are anatomic such as congenitally missing teeth and pathologic, that is dental trauma from tooth avulsion. Nowadays, patients always look for a fixed alternative for the restoration of missing teeth. Other than a conventional fixed partial denture, dental implants are the first choice of treatment. It is one of the difficult tasks for the clinician as well as the dental technician to meet the expectation of the patient when the ridge defect is present in the edentulous area. Extensively invasive procedures such as guided bone regeneration for correction of alveolar defects lead to prolong treatment time and induce psychological trauma to the patient.

Color masking measurement for ceramic coating of titanium used for dental implants

Statement of problemPoor implant placement or thin gingival tissue and progressive bone resorption may lead to the dark metal color showing through the peri-implant soft tissue. Whether the dark color can be adequately masked is unclear. PurposeThe purpose of this in vitro study was to test the color masking effect of porcelain applied on titanium used in fabricating the polished collar of tissue level implants. Material and methodsType 4 commercially pure titanium disks and 5 porcelain dentin shades (A2, A3, B2, C2, and D3) were used. Ten titanium disk specimens per porcelain shade were airborne-particle abraded and ultrasonically cleaned. Porcelain was condensed directly on the specimens, fired, and finished (1200 grit SiC paper). The color (L*a*b* values) of the polished specimens was measured with a reflective spectrophotometer. The specimens were then ground and polished in 0.1 mm increments. Color was measured and ΔE values were calculated at each increment until the thickness at which the ΔE was greater than 3.3 was identified. The data (n=10) were statistically analyzed by ANOVA and the Tukey multiple-comparison test (α=.05). ResultsFor ceramic thicknesses greater or equal to 0.5 mm for the A2, A3, B2, and C2 shades, the ΔE was less than 3.3. This value was 0.4 mm for the D3 shade. ConclusionsThe minimum ceramic thickness required to mask the underlying titanium color is 0.5 mm for all shades except D3, which only needs 0.4 mm. L* decreased with thickness increase. Redness and yellowness increased with thickness increase.

COLOR MASKING MEASUREMENT FOR CERAMIC COATING OF TITANIUM USED IN DENTAL IMPLANTS

Statement of problem: The dark metal color showing through the periimplant soft tissue as a result of poor implant placement or thin gingiva and progressive bone resorption is a common problem in implant dentistry. Purpose: The purpose of this study was to test the color masking effect of porcelain applied on titanium used in fabricating the polished collar of tissue level implants to solve this problem.Material and Methods: Type 4 commercially pure titanium disks and five porcelain dentin shades (A2, A3, B2, C2, and D3) were used. Ten titanium disk specimens per porcelain shade were air abraded and ultrasonically cleaned. Porcelain was condensed directly on the specimens, then fired and finished (1200 grit SiC paper). The color (L*a*b* values) of the polished specimens were measured using reflective spectrophotometer. The specimens were then ground and polished in 0.1 mm increments. Color was measured and ΔE values were calculated at each increment until the thickness at which the color coordinates start to change. ΔE greater than 3.3 was considered as a significant color mismatch detectable by the human eye. The data (n=10) was statistically analyzed by ANOVA/Tukey test at the 95% confidence level (α = .05).Results: ΔE was less than 3.3 as long as the ceramic thickness was ≥ 0.5 mm for A2, A3, B2, and C2 shades. For D3, ΔE was less than 3.3 as long as the ceramic thickness was ≥ 0.4 mm.Conclusions: The minimum ceramic thickness required to block the underlying titanium color is 0.5 mm for all shades except D3 which only needs 0.4 mm ceramic thickness. L* decreased with thickness increase. Redness a* and yellowness b*increased with thickness increase.

Comparison of Shade of Ceramic with Three Different Zirconia Substructures using Spectrophotometer

This study assessed how changing the Zirconia (Zr) substructure affected the color samples after they have been overlaid by the same shade of veneering ceramic. Three commercial Zr materials were tested in this study: Prettau(®) Zirconia (ZirKonZahn, Italy), Cercon (Dentsply, Germany) and InCoris ZI (Sirona, Germany). For each system, 15 disk-shaped specimens (10 × 1 mm) were fabricated. Three shades of A1, A2 and A3.5 of porcelain (IPS e.MaxCeram, IvoclarVivadent, USA) were used for layering the specimens. Five specimens from each type of Zr were layered with same shade of ceramic. Color measurements were recorderd by a spectrophotometer Color-Eye(®) 7000A (X-Rite, Grand Rapids, MI). Mean values of L, a, b color coordinates and ΔE were recorded and comparisons were made. Differences in the ΔE were recorded for the same porcelain shade with different Zr substructures and affected the color of the specimens (p < 0.01, ANOVA). The maximum difference between the ΔE values for the A1, A2 and A3.5 shades with three types of Zr substructures was found to be 1.59, 1.69 and 1.45 respectively. Multiple comparisons of the ΔE with PostHoc Tukey test revealed a statistically significant difference (p < 0.05) between the three types of Zr, except between Type 2 Zr and Type 3 Zr for the Shade A1. The mean values of L, a, b and ΔE for the Prettau(®) Zirconia substructure were found to be the least among the three types. The brand of Zr used influences the final color of the all ceramic Zr based restorations and this has clinical significance.

The effect of chemical disinfectants on the color of a porcelain shade guide.

To evaluate the effect of long term utilization of chemical disinfectants on the color of porcelain shade guides. three chemical disinfectants were used in this study: Minuten spray, Lysol ICQuaternary Disinfectant Cleaner (QDC), and Lysol IC Ready to Use Disinfectant Cleaner (RDC). Simulation of disinfecting cycles for one year, two years, and three years were done on Vita 3D master shade guide. Color differences were determined by visual inspection and analyzing ΔE. ΔE values were significantly below the perceptible (ΔE=1) and the clinically acceptable (ΔE=3.7) thresholds. Simulated utilization of Minuten Spray, Lysol IC (QDC), and Lysol (RDC) disinfectants for up to three years didn't cause a clinically significant difference in the color of VITA Toothguide 3D-Master Shade Guide.

Assessing the accuracy of computer color matching with a new dental porcelain shade system

In a previous study, a novel computer color matching system for dental ceramic restoration was developed, and 21 new shades were established. Theoretically, a natural tooth color can be accurately reproduced by combining 2 or 3 ceramic mixtures from the database of 21 new shades. The purpose of this study was to test the use of these shades in conjunction with the computer color matching system to determine their ability to accurately reproduce the body color of 29 shade tabs from a shade guide (VITAPAN 3D-Master). Disks of 21 reference shades were prepared with porcelain (Cerabien CZR) and polished to 1.0 mm thickness. A spectrophotometer was used to measure the reflectance values from 380 to 780 nm for each disk; the scattering coefficient and absorption coefficient were determined. By using the reflectance values and the scattering and absorption coefficients, the computer color matching program generated porcelain prescriptions incorporating proportions from the 21 reference shades to reproduce the shade tabs. Disks were fabricated from the prescriptions, polished to 1.0 mm thickness, then placed over a zirconia core plate and measured with the spectrophotometer. The color differences (ΔE*) between the shade tabs and the corresponding ceramic disks were calculated. Statistical analysis was performed with the 1-sample t test. The ΔE* values between computer color matching specimens and the target shade tabs varied from 0.5 to 1.9, with an average ΔE* of 1.3, which was significantly less than the clinically detectable ΔE* threshold of 1.6 (P<.001). The computer color matching system with the established 21 new shades is accurate and effective for reproducing tooth shades.

Effect of the framework material on the final color of all-ceramic restorations

OBJECTIVES: to evaluate the effect of the type of ceramic framework material on the final color of all-ceramic restorations. The hypotheses tested were: (1) the final color of the restoration is different than the porcelain shade selected initially to veneer the framework and (2) different framework materials result in different colors of all-ceramic restorations. METHODS: Steel models simulating abutment teeth were used to design all-ceramic fixed partial dentures (FPDs). The FPDs were produced using three different framework materials (n=8): (YZ) yttria partially stabilized tetragonal zirconia polycrystal (LAVA, 3M); (IZ) glass-infiltrated alumina/zirconia (Vita In-Ceram Zirconia); (AL) polycrystalline alumina (Vita In-Ceram AL). Each framework was veneered with the recommended porcelain, VM9 for YZ and VM7 for IZ and AL groups (Vita). The porcelain shade used was 2M2. A uniform thickness of 1.2 mm of porcelain was applied around the retainers. The color difference (ΔE) and lightness difference (ΔL) between the selected porcelain shade (2M2) and the color of the final restoration were obtained using a clinical spectrophotometer (VITA Easyshade). Statistical analysis was performed using One-Way ANOVA and Tukey’s test (α=0.05). RESULTS: The ΔE mean values, standard deviation and statistical ranking for the experimental groups were: (YZ) 2.38 ± 0.44b; (IZ) 2.92 ± 0.67ab; (AL) 3.43 ± 0.84a. AL group showed the highest ΔE and ΔL mean values. IZ showed an intermediate ΔE value and statistically similar to AL and YZ groups. There was no significant difference between ΔL values for YZ and IZ groups. CONCLUSION: Although the color difference between all experimental groups and the porcelain shade selected to veneer the restorations could be visually detected (ΔE&gt;1.0), only AL showed a difference above the clinical threshold (ΔE&gt;3.0). Thus, the first study hypothesis was partially accepted. In addition, the type of framework ceramic influenced the final restoration color, accepting the second study hypothesis.

To evaluate the variation in shade by a spectrophotometer of porcelain fused to metal samples with respect to repeated firing and variation in lot of ceramic – An in-vitro study

Shade matching is an integral part of esthetic dentistry. Thus, this study was done to compare the variation in shade of standardized porcelain fused to metal samples after 5th, 7th and 9th firing with no repeated firing (control group) using a spectrophotometer. It also compared the variation in shade by changing the lot of ceramic of same dentinal shade. For the study 120 samples were made in the form of discs and subdivided into four groups for the required grouping. All the samples were gauged by Vernier caliper. Layering was done of the samples for wash opaque, shade opaque and lastly ceramic layer of dentine. 1st firing was wash opaque firing, 2nd firing – shade opaque, 3rd firing – 1st dentine build up, 4th firing – 2nd dentine build up and 5th firing – autoglaze. Any firing after this was considered as repeated firing. The results were calculated by using ANOVA test and ‘F test.’ Thus, within the limitations of this study it was concluded that repeated firing did not significantly affect the shade of porcelain fused to metal samples and secondly variation in batch showed a statistical significant change but within the acceptable limits of an individual's color perception.

Effect of resin cement and ceramic thickness on final color of laminate veneers: An in vitro study

Different shades of resin cements may adversely affect the final color of translucent restorations, especially thin laminates. The purpose of this study was to determine the effect of different types and shades of resin cement and different thicknesses and shades of IPS Empress Esthetic ceramics on the final color of laminate restorations. A total of 392 disks were made with A1, A3, EO, and ET shades of IPS Empress Esthetic with 0.5-mm and 1-mm thicknesses. Two dual-polymerizable and 2 light-polymerizable resin cement systems from different manufacturers (a total of 13 shades) were selected for cementation (n=7). Similarly, with porcelain ingot shades A1 and A3, opaque and translucent shades were selected from the Rely X Veneer and Maxcem Elite cement systems. For the opaque and translucent shades of the Variolink II resin cement system, the highest and lowest (+3 and -3) and medium (0) shades of Variolink Veneer cement were included in the study. Color changes in the porcelain substructures after cementation were examined with a colorimeter, and color differences (ΔE) were calculated. The results were analyzed with Wilcoxon signed-ranks and Kruskal-Wallis tests (α=.05). The results indicated that the color of porcelain disks changed significantly after cementation (P<.001). Most of the color changes appeared after cementation with Variolink-3 Veneer in all porcelain shades. The smallest color change was obtained from Variolink II Tr in the EO shade of porcelain. The colors of the same shades of different resin cement systems were found at different coordinates in the CIE L*a*b* system. The final color difference (ΔE) of cemented veneers decreased when ceramic thickness increased. The type and shade of resin cement and the thickness and shade of the ceramic all influenced the resulting optical color of laminate restorations.

Developing a custom dental porcelain shade system for computer color matching

ObjectivesThis study aims to update the computer color matching method by generating a new ceramic shade system that covers the entire spectrum of natural tooth color and has an efficient design. MethodsFirst, the color map of 176 maxillary natural incisors and two commercially available and commonly used shade guide systems (Vitapan classic and 3D master) were drawn. Then, 15 shades of layered disks (NW-0: neutral white-0, A1, A2, A3, A4, B1, B4, C4, and D4, and six modifiers; white, pink, grey, blue, cervical-1 and cervical-2, Cerabien ZR) were plotted on the tooth color distribution map. Ultimately, 12 target shades were selected around the perimeter of the natural tooth color space, and nine different shades were selected within the cluster. By trial and error informed by known formulations published previously, the formulations of Cerabien ZR porcelain powders necessary to achieve these 21 target shades in thickness of 1.0mm layered on zirconia substrate were then determined and ceramic disks were fabricated. ResultsColor distribution L*–C* and a*–b* maps showed that new 21 shade system covers a slightly broader range than the natural tooth distribution, and its distribution is larger than the 3D Master shade's range. ConclusionsIn the present study, a 21 custom dental porcelain shade system was developed with a 1.0mm porcelain thickness overlying a zirconia substrate, which can be incorporated into the computer color matching system. This new shade system has homogeneity with 3D Master, and has a slightly wider color distribution than that of natural teeth.

A Clinical Study to Correlate Maxillary Anterior Natural Teeth with that of the Commercially Available Acrylic and Porcelain Shade Guides

The success of the dental treatment as perceived by our patients is often preferentially evaluated on the appearance of the restoration. Usually visual determination is unreliable and inconsistent, complicated by the inability of the shade guide to cover the entire dental color range and also there is lack of logical order of arrangement of the tabs. Hence a clinical study is planned to perform visual shade selection in standardized conditions to correlate the shades of maxillary anterior natural teeth in adult subjects of Davengere district origin to one acrylic and three porcelain shade guides commercially available in India.

The effect of repeated firings on the color of an alumina ceramic system with two different veneering porcelain shades

Possible sources of processing variables in porcelain firing include thickness and color of the opaque; thickness, color, and translucency of the body and enamel layers; firing temperature; and number of firings. The purpose of this in vitro study was to investigate the color changes of an alumina ceramic system veneered with different veneering porcelain shades and fired different numbers of times. Twenty disc-shaped ceramic specimens (10 mm in diameter, with a core thickness of 1 mm), with 2 different veneering porcelain shades (A1, A3), were fabricated from an alumina ceramic system (Turkom-Cera) (n=10). Repeated firings (3, 5, 7, or 9 firings) were performed, and color differences (ΔE) were determined using a spectrophotometer. Repeated-measures ANOVA was used to analyze the data (number of firings, veneering porcelain color). The Duncan test and paired 2-tailed tests were used for multiple comparisons (α=.05). The L*a*b* values of the ceramic system were affected by the number of firings (3, 5, 7, or 9) (P<.005) and veneering porcelain shade (P<.001). Significant interactions were present between the number of firings and the veneering porcelain shade for L* (P=.002), a* (P=.001), and b* (P=.001) values. A1 shade specimens maintained their L* value independent of the number of firings, whereas A3 shade specimens became lighter after an increased number of firings. For both A1 and A3 veneering porcelain shades, the a* value decreased after repeated firings, which resulted in less reddish specimens, and the b* value decreased after repeated firings, which resulted in less yellowish specimens. Imperceptible (ΔE<1.6) and clinically acceptable color changes (ΔE<3.7) were demonstrated by the alumina ceramic system tested.

The influence of opaque application methods on the bond strength and final shade of PFM restorations

Objectives The aim of this study is to compare the influence of the opaque application method on the adhesion and final shade of porcelain-fused-to-metal restorations. Methods Four samples ( n = 12) were cast in a NiCrMo alloy and opaqued using three application methods: aerosol-spray (one application), aerosol-spray (two applications), paste and powder–liquid prior to veneering with dentine porcelain to a thickness of 1.0 mm to mimic the clinical thickness of porcelain-fused-to-metal crowns. The porcelain to metal adhesion was determined by measuring the interfacial fracture toughness or strain energy release rate with a four-point bending configuration developed by Charalambides et al., 13 at a loading rate of 0.05 mm min −1 in kerosene. The resultant porcelain shade was measured with a spectrophotometer under daylight. Values of L*, a* and b* were used to calculate the total color difference Δ E with different equations CIELAB, CMC(1:1), CIE94, and CIEDE2000. The resulting values were also compared with a reference unbonded sample made from the same dentine porcelain used to veneer the porcelain-fused-to-metal specimens. Results The application technique of the opaque did not influence the adhesion between the porcelain and metal. All the application methods demonstrated brittle cracking behaviour through the opaque layer. No visible color differences were found between the applications methods in the final shade of the porcelain. Significance The application method in terms of bond strength and final porcelain shade is not a factor in choosing which method to use in the dental laboratory.

The effect of repeated firings on the color of an all-ceramic system with two different veneering porcelain shades

Color matching between a restoration and natural teeth is a common clinical problem. Despite careful shade selection, color of the restoration may be affected by fabrication procedures. The purpose of this study was to determine the color changes of an all-ceramic restoration with 2 different veneering porcelain shades after repeated firings. Twenty disc-shaped ceramic specimens, 4 mm in diameter with a 1-mm core thickness and 2 different veneering porcelain shades (A1, A3), were fabricated from a zirconia-based porcelain (DC-Zirkon) (n=10). Repeated firings (3, 5, 7, or 9 firings) were performed for the specimens, and color differences (DeltaE) were determined using a spectrophotometer. Repeated measures ANOVA was used to analyze the data (number of firings, veneering porcelain color). The Tukey HSD test and paired 2-tailed tests were performed for multiple comparisons (alpha=.05). The L*a*b* values of the ceramic system were affected by the number of firings (3, 5, 7, or 9) (P<.001) and the veneering porcelain shade (P<.001). Significant interactions were present between the number of firings and veneering porcelain shade for L* (P=.003) and b* (P=.042) values, but not for the a* value (P=.82). An increase in the number of firings of the specimens with both A1 and A3 veneering porcelain shades produced an increase in the L* value, resulting in lighter specimens (P<.001). For both A1 and A3 veneering porcelain shades, the a* value decreased after repeated firings, which resulted in more green specimens (P=.002). The b* value did not change after repeated firings (P=.09) for the A1 veneering porcelain shade; however, it increased for the A3 veneering porcelain shade, which resulted in more yellow specimens (P=.001). The color of the all-ceramic specimens with different veneering porcelain shades is influenced by repeated firings. However, color changes that occurred are clinically acceptable.

New shade guide for tooth whitening monitoring: Visual assessment

Shade guides currently used to monitor tooth bleaching lack logical order, uniform color distribution, and light shade tabs, thus, limiting the design of bleaching studies and diminishing the validity of obtained results. The purpose of this study was to perform a visual evaluation of a new shade guide designed primarily for monitoring tooth whitening and to compare this shade guide with 2 commercial shade guides. Tab arrangement of 3 shade guides (prototype of new VITA Bleachedguide 3D-Master (BG), value scale of Vitapan Classical (VC), and color-ordered Trubyte Bioform porcelain shade guide (TB)) was evaluated. The tabs from each shade guide, one at a time, were scattered and visually reordered from the lightest to the darkest by 15 observers under controlled conditions of a viewing booth. Visual ranking was compared to manufacturer-suggested ranking. Interobserver repeatability was compared using the Mann-Whitney U test (alpha=.05). All observers responded to a questionnaire grading the 3 shade guides using a Likert scale (1, strongly disagree, to 5, strongly agree). The Kolmogorov-Smirnov z-test (alpha=.05) was used to process the results obtained in the questionnaire Visually determined BG order was found to be identical to the order given by the manufacturer. This was not the case with the 2 other products: visual and manufacturers' order were identical for 7 of 16 VC tabs and 9 of 24 TB tabs. Interobserver repeatability for BG was significantly higher (P<.001) as compared to corresponding values recorded for VC and TB, whereas no statistically significant difference in interobserver repeatability between VC and TB was observed. Visually determined lightest to darkest order was identical to the suggested manufacturer order only for VITA Bleachedguide 3D-Master. The same shade guide was also superior based on the scores given in the questionnaire. These findings support the use of the new VITA Bleachedguide 3D-Master for monitoring tooth whitening.

New Shade Guide for Evaluation of Tooth Whitening—Colorimetric Study

Available shade guides lack colorimetric uniformity, which compromises the validity of visual evaluation of tooth whitening efficacy. The objective of this study was to perform a colorimetric analysis of a new shade guide designed primarily for the visual evaluation of tooth whitening efficacy and to compare this shade guide with two commercial shade guides. Color ranges and color distribution of three shade guides (prototype of the new Vita Bleachedguide 3D-Master [BG, Vita Zahnfabrik, Bad Säckingen, Germany], value scale of Vitapan Classical [VC, Vita], and color-ordered Trubyte Bioform porcelain shade guide [TB, Dentsply International, York, PA, USA]) were analyzed (N=3). A circular area (d=1.7 mm) on the middle of the labial surface of the tab, excluding the cervical portion, was measured with a spectroradiometer (D65, 2). Whiteness and yellowness indices were computed. Data were analyzed by analysis of variance and Fisher's PLSD test at a 0.05 level of significance. The range of color difference (DeltaE*) from the lightest to the darkest tab was 33.8 (BG), 17.1 (VC), and 23.2 (TB). Mean values of DeltaE* among pairs of adjacent tabs were 3.0 (BG), 4.2 (VC), and 3.3 (TB). BG exhibited the highest R2 values between color coordinate pairs and between whiteness and yellowness indices with the respective color coordinates. BG exhibited the widest color range and had the most consistent color distribution as compared with the two commercial products. Extension of the lightness range of BG toward higher L* values (bleach shades) was confirmed. A dental shade guide that is colorimetrically uniform might increase the reliability of visual comparisons of tooth whitening efficacy, whereas the inclusion of realistic bleaching shades in the shade guide will complement contemporary esthetic dentistry.