The influence of some different factors on the accuracy of shade selection

Comparison of different illumination intensities of mobile units for tooth color differentiation: An in vitro study

STATEMENT OF PROBLEM

Visual color determination in clinics or dental offices should take place under reproducible environmental conditions. To reduce false tooth color measurements, daylight and illumination lamps (5000-7500 K) have been recommended. Those can be used either as stationary or mobile handheld illumination units. However, depending on the manufacturer, the handheld lights use different illuminance brightness, and whether the choice of unit affects shade selection is unclear.

PURPOSE

The purpose of this in vitro study was to determine whether the mobile handheld light-emitting diode (LED) lighting unit shows a significantly better result in visual color determination than the conventional reference lighting unit.

MATERIAL AND METHODS

Trained preclinical dental students (N=23) with a mean ±standard deviation age of 24 ±5 years participated in the study. Two color differentiation lamps (Smile lite 1620lx and Dialite Color 4450lx) (SL and DC) were each placed at a 15-cm distance to determine the color of the shade tabs (templates, N=10) with the VITA Linear Guide 3D Master in a double-blinded study. According to the manufacturer's recommendation, polarization filters were used with the Smile lite lamp.

RESULTS

Of N=220 shade determinations each, 31.8% (SL) and 33.2% (DC) were correct; the median (ΔE00) and interquartile range were 0.96 (±3.32) for SL and 1.35 (±3.28) for DC. The differences between the groups were not statistically significant (P=.67).

CONCLUSIONS

The results show that the use of the mobile LED illumination unit did not improve color determination compared with the reference illumination. The different illumination intensities of 980 lux (SL) with a polarizing filter or 1500 lux (DC) did not have a positive effect.

Analysis of shade-matching ability in dental students: a comparative study under clinical and correcting light conditions

BACKGROUND

Selecting the ideal tooth shade is essential to the success of aesthetic dental restorations. Students' cognitive abilities are involved in the multifaceted and intricate process of shade matching. Hence, the present study aimed to assess and compare the shade-matching ability of undergraduate dental students in various years of dental education under clinical and correcting light.

METHODS

This comparative cross-sectional study was instigated amongst male 4th, 5th, and 6th-year students of the dental complex of King Faisal University, Kingdom of Saudi Arabia. A total of 72 male dental students assessed the shade under clinical (fluorescent light) and correcting light (handheld Dental Base Light) by using VITA Classical shade guides. Statistical analysis was done using SPSS version 23 (Armonk, NY, USA). The Chi-square test was used to evaluate the association between correct and incorrect shade matching under correcting and clinical light.

RESULTS

Out of 72 male students, 22(30.6%) were from the 4th year, 26(36.1%) were from the 5th year, and 24(33.3%) were from the 6th year, with a mean age of 22.92 ± 1.01 years. The majority of the 6th-year students selected shade of anterior tooth # 11 correctly under clinical and correcting light, and 3(12.5%) students selected incorrectly under clinical and correcting light, with a statistically significant association among them (p = 0.004). As far as the shade selection of the posterior tooth is concerned, a statistically significant difference was observed under clinical light among all clinical students (p = 0.008).

CONCLUSION

The clinical performance of dental students in shade matching improved with advancing years of dental education. Additionally, the shade matching ability of all groups of dental students was superior under correcting light compared to conditions under clinical light.

Comparison of different digital shade selection methodologies in terms of accuracy

PURPOSE

This study aims to evaluate the accuracy of different shade selection techniques and determine the matching success of crown restorations fabricated using digital shade selection techniques.

MATERIALS AND METHODS

Teeth numbers 11 and 21 were prepared on a typodont model. For the #11 tooth, six different crowns were fabricated with randomly selected colors and set as the target crowns. The following four test groups were established: Group C, where the visual shade selection was performed using the Vita 3D Master Shade Guide and the group served as the control; Group Ph, where the shade selection was performed under the guidance of dental photography; Group S, where the shade selection was performed by measuring the target tooth color using a spectrophotometer; and Group I, where the shade selection was performed by scanning the test specimens and target crowns using an intraoral scanner. Based on the test groups, 24 crowns were fabricated using different shade selection techniques. The ΔE values were calculated according to the CIEDE2000 (2:1:1) formula. The collected data were analyzed by means of a one-way analysis of variance.

RESULTS

For the four test groups (Groups C, Ph, S, and I), the following mean ΔE values were obtained: 2.74, 3.62, 2.13, and 3.5, respectively. No significant differences were found among the test groups.

CONCLUSION

Although there was no statistically significant difference among the shade selection techniques, Group S had relatively lower ΔE values. Moreover, according to the test results, the spectrophotometer shade selection technique may provide more successful clinical results.

Effect of Ceramic Thickness and Technician Variability on the Shade Duplication of Dental Ceramo-Metallic Restorations

Ceramic thickness and technicians' manipulative variables are critical factors affecting the resultant shade of dental ceramo-metallic restorations. This study investigated the effect of the following variables on shade duplication of ceramo-metallic specimens: (a) ceramic thickness; (b) differences between several technicians (inter-technician variability); and (c) the ability of each technician to repeat the resultant shade (intra-technician variability). Ninety ceramo-metallic specimens were prepared and divided into three main groups (n = 30/gp) according to the different technicians who built up the veneering ceramic of the specimens. Each group was further subdivided into three subgroups (n = 10/subgroup) according to the thickness of the ceramic (1, 1.5, and 2 mm built over a 0.5 mm-thick metal substructure). Three different technicians were asked to follow the same protocol as regards the same ceramic batch (Shade 3M2, Vita VM13, Zahnfabrik, Germany), firing temperature, and number of firing cycles. Meanwhile, each technician followed his own protocol with regard to other ceramic manipulative variables. The duplicated shades of the specimens were investigated using the Vita Easyshade spectrophotometer by using the verify shade mode. Color difference (∆E) values were calculated between the target shade (3M2) and the duplicated shades of the specimens automatically by the Vita Easyshade spectrophotometer (Vita, Zahnfabrik, Germany). The effect of ceramic thickness and inter- and intra-technician variability on the duplication of the target shade was investigated. The results showed that the effect of ceramic thickness on the duplicated shades depended on inter-technician variability. High inter-technician variability (∆E = 2-6.4) was noticed in contrast to low intra-technician variability (∆E = 0.2-1.5). It could be concluded that proper shade-duplication of ceramo-metallic restoration was a cumulative technique intimately related to manipulative variables and ceramic thickness.

Accuracy of tooth color determination by dental students using daylight-calibrated dental operatory lighting sources

STATEMENT OF PROBLEM

Lighting conditions are an essential factor for accurately determining tooth color. However, the ideal lighting conditions for determining tooth shade are rarely met and are difficult to quantify. While the use of a standardized daylight lamp D55 can improve accuracy, its high cost limits its use in dental offices. The use of modern operatory treatment units for tooth color determination is promising, as they now allow for the adjustment of light source settings such as color temperature and intensity. However, studies are needed to determine whether they provide accurate color determination.

PURPOSE

The purpose of this study was to assess the accuracy of visual tooth shade determinations under the adjusted light sources of 2 different dental treatment units in comparison with a standardized daylight lamp D55.

MATERIAL AND METHODS

Dental treatment units from 2 manufacturers KaVoLUX 540 LED (LK) and LEDview Plus (LDS) were tested. The light sources of these units were adjusted to match daylight conditions. A daylight lamp (Dialite Color 7; Eickhorst & Co. KG) was used as a control (D55). A total of 49 participants (median age of 25 years, 30 women) underwent the Ishihara screening and received standardized training calibration. A total of 2205 clinical visual tooth shade determinations were performed with the Toothguide Training Box using the Vita 3D-Master shade guide under the 3 different lighting types. Each participant had 15 color determinations made under each of the 3 light settings. Color differences were analyzed by using the Kruskal-Wallis, Wilcoxon rank-sum, and chi-squared tests (α=.05).

RESULTS

The type of lighting used for tooth shade determination had no significant effect on the accuracy of selected shade based on the ΔE00 metric (P=.133). Perfect matches were achieved in 50.8% of the cases under LK, 49.8% under LDS, and 53.6% under D55 light, with no significant difference among percentages (P=.315). Although there was a significant difference in time elapsed for shade determination by light type (P=.004), this difference was not clinically relevant (20.8 seconds for LK, 23.9 seconds for LDS, 21.9 seconds for D55).

CONCLUSIONS

The accuracy of color determination for both examined dental operatory lamps was found to be comparable with that of the standard D55 daylight lamp when adjusted to specific settings.

Degree of Standardisation in Ceramic Gingival Systems

No gingival shade guide exists that can be used as a 'gold standard' in gingival shade selection. This research, therefore, aimed to determine whether comparable results in subjective gingival shade selection can be achieved using basic gingival colours produced by distinct manufacturers. It also aimed to explore how coverage of the colour space is affected by mixing these basic colours to create additional shades. To achieve these objectives, the basic gingival colours of three ceramic systems (Heraceram, Kulzer, Madrid, Spain; Vita VM9, Vita Zahnfabrik, Bad Säckingen, Germany; IPS Style, Ivoclar, Schaan, Liechtenstein) were analysed. The colour systems were expanded by creating porcelain gingival samples, whose colours were obtained by mixing the basic colours, altering each mixture by increments of 10%, and respecting the numerical order used by manufacturers to identify the colours. The colour coordinates of the basic and additional colours were recorded using spectrophotometry, and the intra- and inter-system colour differences were calculated using the Euclidean (ΔEab) and CIEDE2000 (ΔE00) formulae. None of the basic colours in the three systems, despite their similar nomenclature, were found to be interchangeable (the colour differences exceeded the gingival acceptability threshold: ΔE00 2.9 units). The expanded gingival colour systems, with mixtures altered by 10% increments, notably increased the gingival colour space covered by the original systems. The authors concluded that there are clear differences between the basic gingival colours produced by distinct manufacturers using the same nomenclature. Ceramic samples produced by mixing basic gingival colours are a resource with the potential to improve subjective gingival shade matching.

Coverage error and shade-match accuracy in three ceramic gingival systems

STATEMENT OF PROBLEM

Research into the coverage error (CE) of gingival systems that have been expanded by using ceramic specimens created by mixing basic colors is lacking.

PURPOSE

The purpose of this in vitro study was to compare the CEs of 3 ceramic gingival color systems that have been expanded with basic-color mixtures from a sample of 360 White participants and to classify the participants according to the accuracy of the shade match achieved with each system.

MATERIAL AND METHODS

L*a*b* color coordinates were recorded in 3 zones of attached gingiva for 360 White participants with healthy gingival tissue (187 men and 173 women). The CEs were calculated for 3 ceramic gingival systems that had been expanded with specimens obtained by mixing the basic colors in consecutive order, the color percentages in each mixture having been altered by 10% increments. The systems were Heraceram (Kulzer GmbH) (n=51); Vita VM9 (Vita-Zahnfabrik) (n=41); and IPS Style (Ivoclar AG) (n=41). The participants were classified into 3 groups according to how well the selected shade matched their gingival color (excellent, acceptable, or poor). The data were analyzed using a 1-way ANOVA with a randomized block design and the homogeneity of proportions test (α=.05).

RESULTS

Statistically significant differences were found between the CEs of the 3 expanded gingival systems in the 3 zones where gingival color was measured (P<.001). The expanded Heraceram system had the smallest CE (ΔE00: minimum 2.66 in the middle zone and maximum 2.95 at the mucogingival line). In the 3 gingival zones, the expanded IPS Style system produced the largest percentage of participants with a poor shade match (ΔE00: minimum 71.4% at the mucogingival line and maximum 75.8% at the free gingival margin), while the expanded Heraceram system had the lowest percentage of participants with a poor shade match (ΔE00: minimum 33.3% in the middle zone and maximum 41.7% at the mucogingival line).

CONCLUSIONS

The CEs calculated for the expanded Vita VM9 and IPS Style ceramic gingival color systems exceeded the clinical acceptability thresholds in the 3 zones examined. According to the ΔE00 formula, the gingival color of at least 33% of participants matched poorly with the expanded systems studied.

Clinical Tooth Color Matching: In Vivo Comparisons of Digital Photocolorimetric and Spectrophotometric Analyses

OBJECTIVE

This study aimed to compare the tooth color matching of two dental colorimetric methods: the spectrophotometric analysis (SPM) and the standardized digital photocolorimetric analysis (DPC).

METHODS

The color of 60 maxillary central incisors of 30 volunteers (22.5 ± 7.6 years) was analyzed. In the DPC method, tooth photographs were standardized with the eLABor_aid protocol, processed with Adobe Photoshop Lightroom software, and the values of L*, a*, and b* were obtained with a Digital Color Meter software. For the SPM, L*, a*, and b* were measured directly with a handheld spectrophotometer. Data were submitted to paired t-test and Pearson correlation test (α=0.05). Mean color difference between the two methods was calculated with CIELAB formula.

RESULTS

All color coordinates revealed different values when comparing DPC to SPM in the same tooth (p<0.0001). Mean color difference (ΔEab) between SPM and DPC was 11.5 ±3.1. A positive correlation was observed for L* (R2=0.73,p<0.0001), a* (R2=0.31, p=0.017), and b* (R2=0.83, p<0.0001).

CONCLUSIONS

Even though the color coordinate values were different in both methods, they were correlated, revealing that the DPC is a viable alternative to determine the tooth color matching.

Comparison of Shade Matching Ability among Dental Students under Different Lighting Conditions: A Cross-Sectional Study

Successful esthetic dentistry to meet patient satisfaction and produce a progressive impact on someone's personality cannot be succeeded without proper shade selection, both for direct or indirect restoration of dentition. The accurate shade selection is one of the most interesting phases of restoring the natural look of teeth. In clinical practices, dental students should be aware of the various light sources used for shade selection. The purpose of this research is to compare the shade matching ability of clinical and non-clinical students under clinical and correcting light. This comparative cross-sectional study was instigated amongst clinical and non-clinical students of the dental complex of King Faisal University, Kingdom of Saudi Arabia, after obtaining ethical approval from the Research Ethics Committee with reference number (KFU-REC-2022-MAR-EA000518). A total of 102 students assessed the shade under clinical (fluorescent light) and correcting light (handheld Dental Base Light) by using VITA Classical shade guides. Statistical analysis was done using SPSS version 23 (Armonk, NY, USA). The Chi-square test and t-test were used to evaluate the association between shade matching scores under correcting and clinical light. Out of 102 students, 41 (40.2%) were non-clinical and 61 (59.8%) were clinical, with a mean age of 21.66 ± 1.397 years. Shade matching scores were found significantly higher (p < 0.001) with the light-correcting device (2.29 ± 1.26) as compared to clinical light (1 ± 1.11) for non-clinical students. Similarly, clinical students also had significantly better (p < 0.001) shade matching with the light-correcting device (4.01 ± 1.34) in comparison to clinical light (2.47 ± 1.25). This study concluded that the shade matching scores under correcting light was significantly better than the results obtained by dental operatory light. Furthermore, it was also evidenced that clinical students' skills in matching shades were significantly improved under a correcting light source as compared to non-clinical students.

Repeatability of dental shade by digital spectrophotometry in current, former, and never smokers

Cigarette smoking contributes to poor oral health and dental discoloration. Therefore, stopping smoking may translate into measurable amelioration of dental shade indices. We compared dental shade parameters by digital spectrophotometry among current, former, and never smokers and verified their repeatability at 7 and 30 days. Dental shade parameters (CIE L*a*b* and corresponding whiteness index for dentistry-WID) were measured in current, former, and never smokers with a digital spectrophotometer (Vita Easyshade V) on three separate study visits: at baseline (day 0), at day 7, and day 30. Dental shade parameters were analyzed in 18 current, 18 former, and 20 never smokers. The repeatability of shade parameters was consistent in current, former, and never smokers. L*, a*, b*, and WID show significant short and long-term repeatability (p < 0.0001, by regression analyses). The mean (± SD) WID score of 13.42 (± 4.9) in current smokers was significantly lower compared to the WID score of 20.38 (± 5.3) in never smokers (p = 0.001). No significant differences were observed between current and former smokers and between former smokers and former smokers. Dental shade measurements by digital spectrophotometry were highly reproducible and showed that teeth whiteness of current smokers is substantially inferior compared to never smokers. Objective discrimination of dental shade can be a valuable regulatory science endpoint for investigating oral hygiene and dental aesthetics of consumer care products, smoking cessation medications, and tar-free tobacco products (e-cigarettes, heated tobacco products, oral nicotine products) for cigarette substitution.

Clinical trial registration: the study was not registered in ClinicalTrials.gov considering that it is a pilot study, parts of a larger project with ID: NCT04649645

Impact of Smokeless Tobacco on the Color Stability of Zirconia, Zirconia-Reinforced Lithium Silicate and Feldspathic CAD/CAM Restorative Materials: An In-Vitro Study

WHO estimates that the global number of tobacco users exceeds 1.3 billion people. Few studies have examined the effect of locally made smokeless tobacco (ST) products on the color changes of material used in dental prosthetics. Bearing the recent advances in CAD/CAM ceramic restorations material in mind, this study aimed to assess ST influence on mean color change (∆E*) values among selected CAD/CAM ceramic types: multilayer zirconia (Ceramill Zolid PS), zirconia-reinforced lithium silicate ceramic (Vita Suprinity), and feldspathic (Vita TriLuxe) restorative materials. The color changes of the ceramics were compared to VITA classical and VITA 3D-MASTER shade guides. Sixty CAD/CAM ceramic specimens (20 samples each) were fabricated from Ceramill Zolid PS, Vita TriLuxe Forte, and VITA Suprinity. Specimens were prepared and divided into two groups according to the ST type and immersed for two weeks. Basic VITA classical and VITA 3D-MASTER colors were recorded at a baseline of one week and two weeks. The highest ∆E* values were recorded in the black ST for Vita Suprinity (4.77) in the first week, followed by Vita TriLuxe (4.07) in the second week. For white ST, Vita TriLuxe (4.87), and Vita Suprinity (4.42) showed extensive color change after two weeks and one week, respectively. The color change was least in zirconia for black and white ST after one week. CAD/CAM ceramic materials showed no significant difference after 1 and 2 weeks for the tested ST types. The effects of ST on CAD/CAM ceramic material (∆E* values) were high but did not reach clinically unacceptable values. Zirconia showed the least amount of color change among all the tested materials.

Visual and digital tooth shade selection methods, related effective factors and conditions, and their accuracy and precision: A literature review

OBJECTIVE

Despite developments of dental shade selection methods, shade selection is still a challenge affecting esthetic outcomes. The purpose of this review was to discuss visual and digital shade taking methods, related effective factors and conditions, and their accuracy and precision to find out the most accurate, precise shade selection method available in dentistry.

OVERVIEW

The key terms of accuracy, background, ceramic, color, colorimeter, color analysis, color science, color measurement, color measuring instrument, color matching, composite resin, dental/tooth shade guide, digital camera, esthetics, imaging, imaging application/program/ software, intraoral scanner, light source, photography, precision, shade, shade matching/ determination/prediction/reproduction/selection, shade taking device, spectrophotometer, spectrophotometry, tooth color measurement, tooth color/shade, and visual perception were used separately and jointly to detect related English-language articles published between January 1, 1985, and January 1, 2021. Electronic/non-electronic searches of Google Scholar/PubMed/Scopus/Web of Science were accomplished. Consequently, 249 articles were considered. Accordingly, the digital methods show higher accuracy and precision compared to the visual methods while requiring to be enhanced regarding accuracy to achieve ideal shade taking results.

CONCLUSIONS

Dental spectrophotometers provide the highest overall accuracy and precision among different shade selection methods while needing clinical setting to control related effective factors/conditions and technological improvement to perform optimally.

CLINICAL SIGNIFICANCE

Different factors can affect the accuracy and precision of tooth shade selection methods and devices. The understanding of these effective factors may lead to a standard shade taking protocol using accurate, precise methods and devices.

Color perceptibility and validity of silicon carbide-based protective coatings for dental ceramics

STATEMENT OF PROBLEM

A silicon carbide (SiC) protective coating has been developed for dental ceramics, but whether the coated ceramics can match the classical VITA shades is unclear.

PURPOSE

The purpose of this observational in vitro study was to evaluate the color adaptability of SiC-coated dental ceramics by testing the hypotheses that SiC-coated disks can be fabricated to match standard tooth shades and have a perceptible color match rate of at least 50% for disks with a color difference (ΔE)<2.0. The effects of ΔE, shade hue, shade value, observer sex, years of experience, profession, and shade guide orientation on color perception were studied.

MATERIAL AND METHODS

SiC-coated disks were fabricated to color match (ΔE_ab<3.3) all 16 VITA classical shades. Uncoated disks of each VITA shade were used as the reference materials to determine whether the SiC-coated disks were color matched to the classical VITA shade guide. Three ΔE formulas (76, 94, and 2000) were applied and compared. Participants (N=120) with an average of 22 years of experience included dental school students, dental faculty members, and dental assistants. Pseudoisochromatic plate and the Farnsworth D-15 Panel test for assessing color deficiency and color blindness were administered. Participants then attempted to match SiC-coated disks to standard shade guides arranged by value or hue. All spectrophotometer readings and color matching were conducted in a light booth with standardized daylight illumination. Statistical analysis used the Fisher's exact test to determine factors associated with improved matching performance (α=.05).

RESULTS

A significant difference in color match rate was found between disks with ΔE<2.0 (63.9%) and ΔE≥2.0 (41.7%) (P<.001). Arranging shade by value (72.2%) instead of hue (67.2%) produced better color matching (P<.001). Sex (P=.430), profession (P=.708), and years of experience (P=.902) had no significant influence on color matching.

CONCLUSIONS

SiC-coated disks were successfully fabricated to match all VITA classical shades, and clinical visual color matching results confirmed that ΔE was a useful metric in optimizing color matching for the SiC-coated dental ceramics.

Prevalence of Color Vision Deficiency among Dental Practitioners and its Effect on Shade Matching Ability

Objective:

Shade selection is a crucial step in achieving aesthetically-pleasing restorations, and it is affected by the dentist’s ability to match the shade of the patient’s teeth. Color Deficiency Disease (CVD) has been thought to be a potential factor affecting color perception. The study aims to find the prevalence of CVD between dentists and dental students and to evaluate its effect on shade matching ability.

Methods:

A sample of 319 dentists and dental students in the College of Dentistry at Ajman University, Ajman, UAE was examined with the Ishihara test to find the prevalence of CVD. Then participants with CVD were tested for shade matching ability, and were compared to participants with normal color vision with the same gender and qualification level. They were asked to match 10 random composite samples with different shades to a custom shade guide made from the same composite material. A score was calculated, representing the number of correct answers they achieved.

Results:

The results showed that 8 out of 143 males (5.6%) had CVD, and 0 out of 176 females had CVD. There was no significant difference in the score of shade matching test between participants with CVD and participants with normal color vision (p=0.075).

Conclusion:

Males showed a higher prevalence of color vision deficiency than females. CVD had no significant effect on shade matching ability.

Spectrophotometric Evaluation of Shade Selection with Digital and Visual Methods

Aim

The main purpose of the study was to learn the possible shade differences between human eye and the digital method with spectrophotometric methods.

Materials and Methods

Fifty dental students of age groups 18-25 with maxillary right central incisor after undergoing oral prophylaxis were included in this study. Before undergoing shade selection, standardization protocol was followed. The shade of the right maxillary central incisor was determined by using the following methods: visual, spectrophotometer, and digital photography. The shades obtained by both spectrophotometer and visual methods are compared and similarly L*, a*, and b* values obtained by both spectrophotometer and digital methods are compared. Finally these comparisons are subjected to statistical analysis.

Results

Z and P values of digital and spectrophotometric methods were found to be statistically significant. Tooth shade selected between spectrophotometric and visual method was analyzed by using chi-square test, which shows highly significant value.

Conclusion

It was concluded that the digital photography can be used as one of the reliable methods for shade selection in a clinical setup.

In-office bleaching with low/medium vs. high concentrate hydrogen peroxide: A systematic review and meta-analysis

OBJECTIVE

To answer the following research question: "Dolow/medium hydrogen peroxide (HP) concentrations used for in-office bleaching in patients with permanent dentition have similar color change and bleaching sensitivity (BS) to high HP concentrations?"

DATA

Randomized controlled trials that compared low/medium vs. high concentrate HP were included. The risk of bias (RoB) was evaluated using the Cochrane Collaboration tool. Meta-analyses were conducted for color change (ΔE*ab, ΔSGU/SGU), risk, and intensity of BS, using the random-effects model. Heterogeneity was assessed with the Cochrane Q test, I² statistics, and prediction interval. The GRADE assessed the certainty of the evidence.

SOURCES

Search was performed in PubMed, Cochrane Library, BBO, LILACS, Scopus, Web of Science and grey literature on 15th September 2018 (updated on 13th May 2020).

STUDY SELECTION

25 studies remained. Five were at low RoB; thirteen were at unclear RoB, and seven were at high RoB. The risk of having BS was, on average, 33 % lower (RR = 0.67; 95 % CI 0.51 to 0.86) for low/medium concentrate HP than high HP. No significant difference in color change was detected among groups, except from the subgroup low vs. high HP for the immediate color change, but this difference is not clinically relevant. The certainty of evidence for color change was low and very low, and moderate for the BS.

CONCLUSIONS

Low and medium hydrogen peroxide concentrate products for in-office bleaching have lower risk and intensity of bleaching sensitivity than the high concentrate hydrogen peroxide group, with no difference in color change efficacy.

CLINICAL SIGNIFICANCE

The use of low concentrate hydrogen peroxide products may produce the same color change efficacy with the bonus of having lower risk and intensity of bleaching sensitivity. However, the ideal concentration at which this occurs is yet unknown and deserves further investigations. No funding. PROSPERO CRD42018108266.

Impact of the ambient light illuminance conditions on the shade matching capabilities of an intraoral scanner

PURPOSE

To compare the shade matching capabilities between an intraoral scanner (IOS) and a spectrophotometer under different ambient light illuminance conditions.

MATERIAL AND METHODS

The shade of three teeth of a patient was obtained using an IOS (IOS group) (TRIOS 3; 3Shape) and a spectrophotometer (DS group) (EasyShade V; Vita Zahnfabrik) at 4 ambient illuminances: 10000-, 1000-, 500-, and 0-lx. Ten shade measurements were documented using Vita Classical and 3D-Master guides per tooth at each lighting condition. Data was analyzed using the Kruskal-Wallis and Mann Whitney U tests (α = .05).

RESULTS

Significant shade discrepancies were obtained between the groups in different lighting conditions (P < .05). The IOS group presented significant shade discrepancies in different lighting conditions when evaluated using either shade guide, with lower variation under the 0-lx condition. However, the DS group did not present significant shade discrepancies among the different lighting conditions with either shade guide, except for the maxillary lateral incisor measured under 10 000-lx condition using the 3D-Master guide.

CONCLUSIONS

Lighting conditions influenced the shade matching competency of an IOS. The IOS tested obtained high variation in the different lighting conditions evaluated and provided a lower shade value than the spectrophotometer. The spectrophotometer revealed high consistency amongst the various lighting conditions evaluated.

CLINICAL IMPLICATIONS

Ambient light illuminance conditions can impact the shade matching capabilities of IOSs. The results of this investigation suggest the use of a supplementary instrumental method for assessment of tooth shade.

Is there an association between Perceptual Ability Test scores and color vision acuity?

OBJECTIVE

The purpose of this study was to determine if there is an association between Perceptual Ability Test (PAT) results and color vision deficiency (CVD).

METHODS

Three consecutive classes of first-year dental students (n = 291) voluntarily participated in the study. The Farnsworth-Munsell 100 Hue Color Vision test (FM-100) was administered to students beneath a Macbeth Judge II viewing booth that provided ideal lighting conditions to ascertain CVD. Results of FM-100 test were recorded as total error scores (TES). Color acuity was scored as superior (TES 0-16), average (TES 20-100), or poor (TES > 100). Additional information of age, sex, ethnicity, and time to complete the FM-100 was obtained. Multiple linear regression was used to determine the association between PAT and CVD while adjusting for age, sex, ethnicity, and time to complete the FM-100 test.

RESULTS

TES ranged from 0-244. There were 132 students with superior color acuity, 161 with average, and eight with poor acuity. Females performed better than males on the FM-100 test. Time to complete the FM-100 test ranged from 3:40 minutes to 25:12 minutes. There was a strong relationship between PAT scores and CVD (P = 0.0003). A 1-unit increase in PAT scores was found to result in a 9% decrease in TES; indicating that students with higher PAT scores are less likely to have CVD.

CONCLUSION

The PAT may be a preliminary screening instrument to identify students who may have CVD. The FM-100 test can then confirm the presence of CVD. Students with CVD may desire to improve dental shade matching skills through targeted training and education.

Evaluation of accuracy of shade selection using two spectrophotometer systems: Vita Easyshade and Degudent Shadepilot

Objective:

The aim of this in vitro study was to evaluate the accuracy of shade matching using two spectrophotometric devices.

Materials and Methods:

Thirteen patients who require a full coverage restoration for one of their maxillary central incisors were selected while the adjacent central incisor was intact. 3 same frameworks were constructed for each tooth using computer-aided design and computer-aided manufacturing technology. Shade matching was performed using Vita Easyshade spectrophotometer, Shadepilot spectrophotometer, and Vitapan classical shade guide for the first, second, and third crown subsequently. After application, firing, and glazing of the porcelain, the color was evaluated and scored by five inspectors.

Results:

Both spectrophotometric systems showed significantly better results than visual method (P < 0.05) while there were no significant differences between Vita Easyshade and Shadepilot spectrophotometers (P < 0.05).

Conclusion:

Spectrophotometers are a good substitute for visual color selection methods.

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

Background

Dental shade guides are used before restorative and prosthodontic procedures for the evaluation of tooth color. The spectral coverage of the specific shaded guide and a clinician's experience in shade matching are the two most important factors for a clinically viable shade match of the restoration to the given tooth. Repeated disinfection of the shade guide with disinfectant lead to a clinically significant difference of the shade to be matched, finally resulting in a clinically unacceptable prosthesis. The purpose of this study is to evaluate the effects of disinfection on various shade tabs of VITA 3D Master Shade guide after being subjected to 2 years of simulated disinfection with 70% isopropyl alcohol.

Methodology

Two sets of VITA 3-D Master Shade Guides were used. One set of each shade guide was assessed after simulated use and surface disinfection with 70% isopropyl alcohol (test group), while the other full set was subjected to cleansing with distilled water (control group). Spectrophotometer was used to measure each of the shade tabs. Readings were recorded at regular intervals of 120, 240, 360, 480, 600, 720, 840, and 960 disinfection cycles. The ΔE values obtained were used to examine the color difference.

Results

There was a significant difference in terms of ΔE between the shade tabs of control and test groups of VITA 3D Master shade guides after 960 cycles of disinfection. The change in mean ΔE was more in the test specimens in the shade tabs of VITA 3D Master Shade Guide tabs than the control specimens. These results are of statistical significance, but they might not be of any clinical significance.

Conclusion

There was a statistically significant but clinically nonsignificant color change in the shade tabs of VITA 3D Master shade guides after 2 years of simulated use and disinfection with 70% isopropyl alcohol.

A Digital Shade-Matching Device for Dental Color Determination Using the Support Vector Machine Algorithm

In this study, we developed a digital shade-matching device for dental color determination using the support vector machine (SVM) algorithm. Shade-matching was performed using shade tabs. For the hardware, the typically used intraoral camera was modified to apply the cross-polarization scheme and block the light from outside, which can lead to shade-matching errors. For reliable experiments, a precise robot arm with ±0.1 mm position repeatability and a specially designed jig to fix the position of the VITA 3D-master (3D) shade tabs were used. For consistent color performance, color calibration was performed with five standard colors having color values as the mean color values of the five shade tabs of the 3D. By using the SVM algorithm, hyperplanes and support vectors for 3D shade tabs were obtained with a database organized using five developed devices. Subsequently, shade matching was performed by measuring 3D shade tabs, as opposed to real teeth, with three additional devices. On average, more than 90% matching accuracy and a less than 1% failure rate were achieved with all devices for 10 measurements. In addition, we compared the classification algorithm with other classification algorithms, such as logistic regression, random forest, and k-nearest neighbors, using the leave-pair-out cross-validation method to verify the classification performance of the SVM algorithm. Our proposed scheme can be an optimum solution for the quantitative measurement of tooth color with high accuracy.

Evaluation of the repeatability and matching accuracy between two identical intraoral spectrophotometers: an in vivo and in vitro study

PURPOSE

The purpose of this study was to evaluate the repeatability and matching accuracy between two identical intraoral spectrophotometers.

MATERIALS AND METHODS

The maxillary right central incisor, canine, and mandibular left central incisor of each of 30 patients were measured using 2 identical intraoral spectrophotometers with different serial numbers (EasyShade V). The color of each shade tab from 3 shade guides (VITA 3D-Master) was also determined with both devices. All measurements were performed by a single operator. Statistical analyses were performed to verify the repeatability, accuracy, and the differences between the devices with paired t-tests, one-way ANOVA, and intra-class correlation coefficients (ICCs) (α=.05).

RESULTS

A high level of measurement repeatability (ICC>0.90) among L^*, a^*, and b^* color components was observed within and between devices (P<.001). Intra-device matching agreement rates were 80.00% and 81.11%, respectively, while inter-device matching agreement rate was 51.85%. ANOVA revealed no significant different color values within each device, while paired t-test provided significant different color values between both devices. The CIEDE2000 color differences between both devices were 2.28±1.61 ΔE₀₀ for in-vivo readings. Regarding the clinical matching accuracy of both devices, ΔE₀₀ values between teeth and matching shade tabs were 3.05±1.19 and 2.86±1.02, respectively.

CONCLUSION

Although two EasyShade V devices with different serial numbers show high repeatability of CIE L^*, a^*, and b^* measurements, they could provide different color values and shade for the same tooth.

Analysis of Shade Matching in Natural Dentitions Using Intraoral Digital Spectrophotometer in LED and Filtered LED Light Sources

PURPOSE

To evaluate the shade matching capabilities in natural dentitions using Vita Toothguide 3D-Master and an intraoral digital spectrophotometer (Vita Easyshade Advance 4.0) in various light sources.

MATERIALS AND METHODS

Participants between 20 and 40 years old with natural, unrestored right maxillary central incisors, no history of bleaching, orthodontic treatment, or malocclusion and no rotations were included. According to their shades, subjects were randomly selected and grouped into A1, A2, and A3. A total of 100 participants (50 male and 50 female) in each group were chosen for this study. Shade selection was made between 10 am and 2 pm for all light sources. The same examiner selected the shade of natural teeth with Vita Toothguide 3D-Master under natural light within 2 minutes. Once the Vita Toothguide 3D-Masterwas matched with the maxillary right central incisor, the L*, a*, and b* values, chroma, and hue were recorded with Vita Easyshade Advance 4.0 by placing it on the shade tab under the same light source. The values were statistically analyzed using one-way ANOVA and Tukey's HSD post hoc test with SPSS v22.0 software.

RESULTS

The mean ∆E*_ab values for shades A1, A2, and A3 for groups 1, 2, and 3 were statistically significantly different from each other (p < 0.001).

CONCLUSION

The intraoral digital spectrophotometer showed statistically significant differences in shade matching compared to Vita Toothguide 3D-Master. Incandescent light showed more accurate shade matching than the filtered LED, LED, and daylight.

A Study on Possibility of Clinical Application for Color Measurements of Shade Guides Using an Intraoral Digital Scanner

PURPOSE

To assess if color measurement with intraoral scanner correlates with digital colorimeter and to evaluate the possibility of application of a digital scanner for shade selection.

MATERIALS AND METHODS

The L*a*b* values of the five shade tabs (A1, A2, A3, A3.5, and A4) were obtained with an intraoral scanner (TRIOS Pod) and a colorimeter (ShadeEye). Both devices were calibrated according to the manufacturer's instructions before measurements. Color measurement values were compared with paired t-test, and a Pearson's correlation analysis was performed to evaluate the relationship of two methods.

RESULTS

The L*a*b* values of the colorimeter were significantly different from those of the digital scanner (p < 0.001). The L* and b* values of both methods were strongly correlated with each other (both p < 0.05). The device repeatability in both methods were reported to be excellent (p < 0.05). Within the limitations of this study, color measurements with digital intraoral scanners and computer-assisted image analysis were in accordance with those of the colorimeter with respect to L* and b* values; however, all the coordinates of shade tabs were significantly different between two methods.

CONCLUSIONS

The digital intraoral scanner may not be used as the primary method of color selection in clinical practices, considering significant differences in color parameters with colorimeter. The scanner's capability in shade selection should be further evaluated.

A Single-Blind Randomized Trial About the Effect of Hydrogen Peroxide Concentration on Light-Activated Bleaching

Objective: To compare the bleaching efficacy and tooth sensitivity (TS) of two hydrogen peroxide (HP) concentrations (20% and 35%) used for in-office bleaching associated or not with a light-emitting diode (LED)/laser light activation.

Method: Seventy-seven patients with a right maxillary canine darker than A3 were selected for this single-blind randomized trial. The participants were distributed in four groups: bleaching with 35% HP, 35% HP + LED/laser, 20% HP, and 20% HP + LED/laser. The anterior teeth were bleached in two sessions, using a 35% or 20% HP gel with a one-week interval. Each session had three applications of 15 minutes. For the light-activated groups, the LED/laser energy (Whitening Laser Light Plus, DMC) was employed according to the manufacturer's instructions. The color change was evaluated by subjective and objective methods. Participants recorded TS with five-point verbal and visual analog scales. Color change in ΔE was evaluated by analysis of variance and Tukey tests (α=0.05) and in ΔSGU with Kruskall-Wallis and Dunn test. The absolute risk of TS and TS intensity were evaluated by Fisher exact test and Kruskall-Wallis test, respectively (α=0.05).

Results: All groups achieved the same level of whitening, except for the 20% HP group, which showed the lowest degree of whitening in the subjective analysis. The use of light did not increase the absolute risk or intensity of TS. No significant difference among groups was observed when color changes were assessed with the spectrophotometer.

Conclusion: According to the value-oriented shade guide, the use of LED/laser light activation was able to increase the degree of whitening of the 20% HP group, but this association was not useful for the 35% HP gel. The spectrophotometer, however, did not detect significant differences among groups.

Effects of the type and thickness of ceramic, substrate, and cement on the optical color of a lithium disilicate ceramic

STATEMENT OF PROBLEM

Reproducing the characteristics of natural teeth in ceramic crowns remains a complex and difficult process.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of the substrate, cement, type, and thickness of the ceramic on the resulting color of a lithium disilicate ceramic.

MATERIAL AND METHODS

Forty ceramic disks were prepared from IPS e.max Press LT (low translucency) and HO (high opacity) in 2 different thicknesses (1.5 and 2 mm). The LT groups were composed of monolithic ceramic disks, and the HO groups were composed of disks fabricated with a 0.5-mm thickness combined with a 1- or 1.5-mm veneering ceramic thickness. Disks made of composite resin (R) and alloy (A) were used as substrate structures. The resin cement used was Variolink II. Color was measured with a spectrophotometer and expressed in CIELAB coordinates. Color differences (ΔE) were calculated. The data were analyzed with ANOVA and the Tukey HSD test (α=.05).

RESULTS

When the ΔE of ceramic disks with both substrates, with and without cement, were compared, the lowest value (3) was obtained for ceramic HO with a 2-mm thickness/alloy substrate/without cement; the highest value (10) was obtained for ceramic LT with a1.5-mm thickness/alloy substrate/with cement. This difference was statistically significant. When the effect of cement on the ΔE of ceramics in both substrates was compared, the lowest value (1.1) occurred with ceramic HO with a 1.5-mm thickness/resin substrate, and the highest was observed for ceramic LT with a 1.5-mm thickness/alloy substrate (6.4). This difference was statistically significant.

CONCLUSIONS

The substrate color, type and thickness of ceramic, and presence of the cement significantly influenced the resulting optical color. The ΔE values of cemented HO ceramics were lower than that of the LT ceramic.

Prevalence of Tooth Shade and its Correlation with Skin Colour - A Cross-sectional Study

INTRODUCTION

Aesthetics has become an important issue in modern society. Tooth shade is one of the factors in determining aesthetics. Studies have revealed that tooth shade is influenced by age, gender, eye colour, skin colour and other factors.

AIM

The present study was aimed to assess the prevalence of tooth shade and its correlation with skin colour.

MATERIALS AND METHODS

A total of 300 subjects aged 18-20 years were evaluated for tooth shade using Vitapan - 3D shade guide. Anterior teeth were checked under natural light and facial skin colour by Lakme liquid foundation make up as a shade guide. Data was analysed using chi square test and spearman's correlation.

RESULTS

Out of 300 students, 114 (38.00%) had A2 tooth shade; the least prevalent tooth shade among Chitradurga population was C1 (4.00%). There was a positive correlation between tooth shade and skin colour which was found to be statistically significant (p <0.05).

CONCLUSION

The most prevalent tooth shade among Chitradurga population was A2 and least was C1. There was a significant correlation between tooth shade and skin colour with lighter skin tone subjects having lighter tooth shade hence skin colour can be used as a guide for shade selection.

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

AIM

There is limited and inconsistent information on some factors affecting visual shade selection. The aim of this study was to evaluate the influence of shade guide type and professional experience on shade-matching results.

MATERIALS AND METHODS

Thirty Dental students (DS), 30 General dentists (GDs) and 30 Dental specialists (S) participated in this study. The participants were asked to match six target tabs using two dental shade guides: Vitapan Classical (VC) and Vitapan 3D-Master (3D). An intraoral spectrophotometer was used for color measurement of target tabs and selected tabs. The color difference (ΔE) values between the target tab and selected tab were calculated. Data were analyzed using analysis of variance (ANOVA) and paired f-test (α = 0.05). Results of the first five best matches for each target tab were expressed as ΔE1 to ΔE5. Differences in the mean values of ΔE1 to ΔE5 between VC and 3D were compared using descriptive statistics.

RESULTS

There were no significant differences among the three participating groups in ΔE values when the 3D was used (p = 0.389). However, significant differences were found with VC (p < 0.001). The ΔE values achieved from the 3D were significantly lower than those from VC for DS and S (p = 0.001 and p < 0.001, respectively). For each of the first five best matches, the mean ΔE values from the 3D were smaller than the corresponding values of VC.

CONCLUSION

The type of dental shade guide affected the shade-matching results. The level of experience was not found to be an influential factor in shade matching when 3D-Master shade guide was used.

CLINICAL SIGNIFICANCE

Compared with Vitapan Classical shade guide, use of the Vitapan 3D-Master shade guide improves shade-matching results.

KEYWORDS

Color, Experience, Gender, Selection, Shade, Visual. How to cite this article: Nakhaei M, Ghanbarzadeh J, Amirinejad S, Alavi S, Rajatihaghi H. The Influence of Dental Shade Guides and Experience on the Accuracy of Shade Matching. J Contemp Dent Pract 2016;17(1):22-26. Source of support: This study was supported by a grant (No. 920903) from the Vice Chancellor for Research of Mashhad University of Medical Sciences. The results presented here are based on undergraduate thesis (No. 2686) submitted to Mashhad School of Dentistry and Dental Research Center.

CONFLICT OF INTEREST

None.

Factors involved in the spectrophotometric measurement of soft tissue: A clinical study of interrater and intrarater reliability

STATEMENT OF PROBLEM

The reliability of spectrophotometric measurements of gingival color has not been tested.

PURPOSE

The purpose of this study was to evaluate the repeatability and reproducibility of gingival color measurements with a digital spectrophotometer. Measurement error was estimated by determining the interrater agreement and by repeating measurements in different illumination environments with and without contact of the device with the gingiva.

MATERIAL AND METHODS

Two trained examiners measured the gingival shade around 30 central incisors with a spectrophotometer with and without external illumination and with and without contact of the device with the gingiva. Color data obtained (CIELab color coordinates; L*, c*, h*, a*, b*) were analyzed with the intraclass correlation coefficient (ICC) and the Student t test for paired samples.

RESULTS

Mean L*, c*, a*, and b* values differed significantly between measurements made with and without contact of the device with the tissue, but no difference was found in h* values. An ICC of >0.9 was obtained for interrater and intrarater agreements in all cases. Shade measurements did not differ between the presence and absence of stable ambient light.

CONCLUSIONS

The repeatability and reproducibility of soft tissue shade measurements were almost perfect (ICC >0.9) under the examination conditions tested. The measurements were affected by pressure but not by ambient light.

Evaluation of Novel Microabrasion Paste as a Dental Bleaching Material and Effects on Enamel Surface

PURPOSE

Dental fluorosis is an enamel dysplasia that can cause serious aesthetic and psychological problems. An examination of the literature shows that the microabrasion method is the most effective way to treat fluorosis. This study aimed to produce a prototype microabrasion paste for the treatment of fluorosis stains and to examine the effects of the paste on tooth structure and color in vitro.

MATERIAL AND METHODS

Forty extracted upper incisor teeth were used in this study. The teeth were divided into four treatment groups: a prototype microabrasion paste group (N = 10), an Opalustre paste group (N = 10), a 37% phosphoric acid gel group (N = 10), and a distilled water (control) group (N = 10). Following treatment, all specimens in each of the four groups were examined by scanning electron microscopy for changes in their surface enamel. Changes in tooth color changes of the 1st and 2nd groups were measured before and after treatment by a VITA Easyshade Advance spectrophotometer.

RESULTS

In scanning electron microscopy evaluations, significant differences were not observed between the 1st and 2nd groups. Differences in three color-measuring coordinates between the 1st and 2nd were also not statistically significant (p > 0.05).

CONCLUSIONS

The study demonstrated that the prototype paste is a viable treatment option for dental fluorosis.

CLINICAL SIGNIFICANCE

The findings in this study demonstrated that the tested prototype microabrasion paste is extremely harmless, minimally invasive agent, and able to improve the color, shine and chrome values of the teeth.

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.

Shade matching performance of dental students with three various lighting conditions

AIM

To evaluate the ability of dental students to match shades under three various light conditions.

MATERIALS AND METHODS

Sixty senior dental students participated in this study. All students were tested for color deficiency using Ishahara's tests. Nine classical vita shade tabs were randomly selected and their identification codes were concealed. The students were asked to match these 9 selected items by using a complete vita shade guide under three various light conditions (natural light, clinical light, and correcting light source). The chosen shade tabs were recorded and the correct matches were counted. Scores were calculated by adding the number of correct matches.

RESULTS

The mean values of correct match scores with natural light, clinical light and correcting light source were 4.82, 4.75 and 6.82, respectively. There was no significant difference in correct matches scores between men and women, nor among various vita A, B, C and D shades.

CONCLUSION

The students showed a better performance in shade matching under the correcting light source than natural light and clinical light. Gender had no effect on shade matching selection and there was no difference in shade matching ability among vita A, B, C, D shades.

CLINICAL SIGNIFICANCE

Shade matching performance is significantly improved with correcting light source.

Effect of Gender, Experience, and Value on Color Perception

Statement of the Problem

Precise shade matching can be one of the most difficult tasks for the dentist and some variables may influence the process of shade comparison.

Purpose of the Study

This study tested the differences in shade perception between genders, the influence of the observer's clinical experience, and the value of ceramics in correct shade selection.

Material and Methods

A total of 45 women and 54 men compared 16 pairs of ceramic disks according to shades. The χ2 and Fisher exact tests were used to analyze the results, adopting 5% as the level of statistical significance. An analysis of risk was also performed to evaluate the variables.

Results

The results indicated that there were statistical differences among gender, clinical experience, and shades in discriminating ceramics.

Conclusions

Men and observers with more clinical experience were more successful in discriminating shades, although darker shades were selected more correctly than the lighter ones.

Color management of the cervical region using different framework materials

BACKGROUND

  Color-matching of the cervical area between natural teeth and different crown prostheses is a common clinical problem.

PURPOSE

  The purpose of this study was to compare the color of the cervical region of five commercially available crown systems to an extracted natural tooth and to each other.

MATERIALS AND METHODS

  The color of the cervical region of an extracted maxillary incisor was measured by means of a colorimeter (ShadeVision, X-Rite). Fifty master dies were fabricated, divided into five groups (N=10) according to the framework material; group 1: high-noble gold alloy, group 2: same as group 1 but treated with gold paste material, group 3: precious reinforced alloy, group 4: white zirconium oxide substructure (Lava 3M ESPE), and group 5: shaded zirconium oxide (Lava). A direct comparison of L*, a*, and b* parameters was accomplished between the control natural tooth and the five crown systems, and the mean color differences (ΔE) was calculated. The data were statistically analyzed with one-way analysis of variance and post hoc multiple comparison (α=0.05).

RESULTS

  Compared to the natural tooth, the mean color differences (ΔE) values were clinically unacceptable for all groups (ΔE > 3.7). The detected color differences, among different porcelain systems, were not visually perceptible (ΔE < 3.7).

CONCLUSIONS

  Within the limitations of this study, the cervical color of an extracted natural tooth could not be duplicated using different crowns systems.

CLINICAL SIGNIFICANCE

Color-matching of the cervical region of different crown systems with natural tooth remains a difficult task.