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.

Effect of grinding on the optical properties of monolithic zirconia.

OBJECTIVES: The purpose of this study was to analyze the color infiltration in monolithic zirconia after grinding, which plays an essential role in the color stability of restorations after occlusal adjustment. METHODS: One hundred and eight white zirconia plates (36 Dentsply Sirona-Cercon high translucency [C], 36 Zirkonzahn-Prettau [P], 36 Zirkonzahn-Prettau anterior [Pa]) were stained by infiltration with target colors Vita A2, A3.5, and A4. In a standardized experimental setup, all plates were grinded in nine successive steps (from baseline to 500 µm), and color was measured with a spectroradiometer at each grinding step. Color differences ΔE00 between initial color and after each grinding step were calculated. The data was analyzed using regression, Kruskal-Wallis test, inverse prediction, and simultaneous 95%-confidence intervals. RESULTS: Grinding had a significant effect on color stability across all zirconia types and target colors (p < 0.001). At each cut level and target color, ΔE00 means for groups C, P, and Pa were statistically different (p < 0.05). Among the three zirconia types, Pa had the lowest ΔE00 mean score for cut levels 20-100 µm for A2 and between 50 and 300 µm for A3.5 and A4. For all other cut levels, differences between Pa and P were not significant (α = 0.05). C had the largest mean ΔE00 except for A4 until 100 µm, where it was second best. CONCLUSION: Zirconia type had a significant effect on the color infiltration depth across all target colors. Pa showed the best color stability until 150 µm material reduction, whereas C presented significantly less color stability than the other two zirconia materials. CLINICAL SIGNIFICANCE: Color stability is important for minimizing the risk of restoration failure due to unacceptable color changes after grinding. Pa is less susceptible to color change and has an additional buffer of 60 µm until exceeding the color acceptability threshold. When higher flexural strength is needed, P is to be preferred.

Laboratory and clinical reliability of two spectrophotometers.

OBJECTIVE: To evaluate the repeatability, interexaminer, and interdevice reliability of two clinically applicable spectrophotometers under laboratory and clinical conditions. MATERIAL AND METHODS: For the in vitro part of the study, measurements were performed by the use of Vita Easyshade Advance 4.0 (ES-A) and the Easyshade V (ES-V) at identical positions on different shade tabs (3D-Master; Vita Zahnfabrik, Bad Säckingen, Germany). To test repeatability, one shade tab was measured 50 times by one operator. To determine interrater and interdevice agreement, two operators used both devices to perform 10 measurements on five different shade tabs. Clinical interdevice and interexaminer reliability was checked with a positioning jig used (15 participants). Measurement accuracy of both devices was evaluated for the recommended color of shade tabs. RESULTS: Repeatability of results from both Easyshades was excellent for all color components (maximum deviation between measurements was ≤0.1 units). Interrater agreement was also perfect (intraclass correlation, ICC = 1.000). Interdevice agreement was lower, but still good (ICC ≥ 0.834). In the clinical environment, interrater and interdevice agreements were similar (ICC > 0.964 and ICC > 0.873). Accuracy was satisfactory for both devices, with both observers in full agreement for nearly 80% of ratings. CONCLUSIONS: Both Easyshades produced reliable and accurate measurements and can therefore be recommended for clinical determination of tooth color. CLINICAL SIGNIFICANCE: The outcome of this study might help clinicians estimate the performance of a new digital shade determination device.

Effect of grinding adjustments on the color of monolithic zirconia.

STATEMENT OF PROBLEM: Monolithic zirconia restorations have become popular because of their excellent mechanical properties and acceptable esthetics. While the biomechanical properties of zirconia have been investigated, research into their esthetic properties is sparse. Zirconia can be colored by infiltration before sintering, although how occlusal adjustment can affect restoration color is unclear. PURPOSE: The purpose of this in vitro study was to analyze the color of differently characterized monolithic white and precolored zirconia specimens after standardized grinding. MATERIAL AND METHODS: White and precolored monolithic zirconia plates (Cercon ht) (n=36) were stained by infiltration with target colors Vita A2, A3.5, and A4. In a standardized experimental arrangement, all plates were ground in 9 steps, and the color was measured with a spectroradiometer at each step. Color differences (ΔE00) were analyzed by using regression analysis, the Kruskal-Wallis test, and the inverse prediction with confidence intervals (α=.05). RESULTS: Mechanical material removal had a significant effect on the color stability (P<.05) of both white and precolored monolithic zirconia. For each grinding step and each target color, the precolored groups had a significantly lower ΔE00 mean than the white groups (P<.05), except at the 20-µm step for groups W-A4 and P-A4 (P>.05). For target color A2, the difference was significant with P<.001 at all 9 grinding steps. For target color A3.5, the difference was significant with P=.003 at grinding level 20 µm, and P<.001 for all other grinding steps. For target color A4, the difference was not significant with P=.603 at grinding level 20 µm, whereas the difference was significant with P=.007 at grinding level 50 µm, and with P<.001 for all other grinding steps. CONCLUSIONS: Precolored zirconia had less color change after grinding than white zirconia. This study established grinding depths for white and precolored zirconia corresponding to color perceptibility and acceptability thresholds.

Color stability of individually stained monolithic zirconia following occlusal adjustment.

OBJECTIVE: To meet esthetic requirements, monolithic zirconia can be stained by color-infiltration. However, adjustments of occlusal surfaces are often necessary, leading to demasking effects if too much of the color-infiltrated layer is removed. The effect of subsequent material removal on color stability of individually stained zirconia is analyzed here. MATERIALS AND METHODS: Thirty-six white zirconia disks were divided into three groups. Standardized staining strategies for tooth colors VITA A2, A3.5, and A4 were developed and applied to the disks. Samples were grinded in nine successive steps from 20 to 500 µm. A spectroradiometer was used to measure the color differences after each step. Regression analyses were performed for color differences from baseline as a function of depth of material removal. Depth of material removal resulting in color changes surpassing the acceptability threshold of ΔE00 = 1.8 was estimated using inverse prediction. RESULTS: Up to 500 µm material removal, color difference ΔE00 changes linearly with the depth of material removal (P < 0.05). Regression analyses showed coefficients of determination (R2 ) of 0.97 (VITA A2), 0.87 (VITA A3.5), and 0.96 (VITA A4). Acceptability threshold was surpassed at 62, 87, and 92 µm, respectively. CONCLUSIONS: Discolorations occur within clinically relevant occlusal adjustments of <100 µm. The effect is more severe with lighter, less saturated tooth colors. CLINICAL SIGNIFICANCE: Staining that is resistant to occlusal adjustments and abrasion is only possible if the staining solution infiltrates sufficiently deep into the ceramic structure. This study provides for the first time in the literature numerical values that describe the thresholds of acceptability of color differences in zirconia ceramics. These values are essential because they determine the extent of possible occlusal adjustments, and thus the color stability. Further research is necessary to improve the infiltration depth of staining solutions.

Effects of staining and polishing on different types of enamel surface sealants.

OBJECTIVE: To assess surface discoloration of four enamel sealants based on different chemical compositions after exposure to artificial aging and staining solutions. Furthermore, their cleanability after polishing will be evaluated. MATERIALS AND METHODS: Selected sealants were a composite resin-based sealant with fillers (Pro Seal), a composite resin-based sealant without fillers (Light BondSealant), a resin-modified glass ionomer-based sealant (ClinproXT Varnish) and a silicon-based sealant (Protecto). Natural teeth served as medium. Immersion solutions were water, juice, tea, and turmeric. In a standardized setting, all samples were measured seven times with a spectroradiometer (Photoresearch PR670) at baseline, after thermocycling; 7 days; 2 and 4 weeks of immersion; and after finally polishing. RESULTS: Thermocycling had no significant effect on color stability. After exposure to staining solutions, all sealed surfaces showed significant color changes. Color change predominately occurred for all sealants in the first week of staining (P ≤ .01). Best resistance to staining decreased as follows: Protecto > Light Bond Sealant > ProSeal > Clinpro XT Varnish. Surface cleaning by polishing significantly reduced the color change. CONCLUSION: Sealed enamel surfaces are prone to discoloration, which is most prominent in filled composite and glass-ionomer-based sealants. Staining can be reduced by polishing; however, in this in vitro setting the original color could not be restored. CLINICAL SIGNIFICANCE: Enamel sealants might exert adverse effects in terms of discoloration. This should be taken into consideration by clinicians and patients, particularly when sealants are applied in esthetically critical areas.

Changes of tooth color in middle and old age: A longitudinal study over a decade.

OBJECTIVE: To evaluate changes in tooth color for 2 age cohorts (younger cohort, YC: 1950-1952; older cohort, OC: 1930-1932) over a mean observation period of 8 years. MATERIAL AND METHODS: Sixty-one participants with 106 upper central incisors were subjected to baseline and follow-up examinations (YC: n = 46/OC: n = 15). International Commission on Illumination color coordinates of 1 or 2 unrestored test teeth for each participant were recorded by use of a spectrophotometer (VITA Easyshade 1) during both measurement times. Changes of color coordinates during the study period were evaluated by use of generalized linear mixed models with the variable "participant" as random effect. ΔEab and E2000 color differences were calculated between baseline and follow-up. RESULTS: Significant changes in color coordinates were observed, with the exception of lightness in OC. The direction of the changes depended on the cohort. A decrease of lightness (value) was observed in YC (ΔL = 4.0; P < .001) whereas in OC chroma increased (ΔC = -3.3; P < .001). For both groups, a significant shift to more reddish tooth colors was observed. In almost all cases, color differences between baseline and follow-up exceeded the 50:50 acceptability thresholds for color differences (ΔE = 2.7) in both YC (≈90%) and OC (≈80%). CONCLUSIONS: For both quinquagenarians and septuagenarians, clinically relevant changes in tooth color were observed after a decade; these could affect the long-term success of prosthetic restorations in terms of a satisfactory color match between natural teeth and dental prostheses. In contrast with the findings of cross-sectional studies, the changes were partially age-group-specific. CLINICAL SIGNIFICANCE: Tooth color can change over a decade. When fixed dental prostheses are planned, one should consider that changes of tooth color could lead to mismatch between a restoration and adjacent teeth during the period in clinical service.

Electroplated telescopic retainers with zirconia primary crowns: 3-year results from a randomized clinical trial.

OBJECTIVE: The objective of the study was to investigate the clinical outcome for electroplated telescopic removable dental prostheses (E-RDPs) with zirconia primary crowns. MATERIALS AND METHODS: Sixty E-RDPs, with primary crowns manufactured from either cobalt-chromium alloy or zirconia, were fabricated for 56 participants. Electroplating was used to produce gold copings directly on the telescopic primary crowns. These copings were bonded intra-orally to the prosthesis framework. After 36 months, prosthesis survival and number of complications were assessed. Statistical analysis was performed by the use of Kaplan-Meier modeling and the log-rank test. RESULTS: Survival of the E-RDPs, 96.4% after 3 years, was identical in both groups. The need for aftercare was high but not significantly different: technical complications were observed for 37% and 42.9% of the prostheses for the zirconia and cobalt-chromium alloy primary crowns, respectively. Fracture of composite veneer was the most frequent complication (59.1%). The incidence of fractured abutment teeth, decementation, and endodontic problems was 7.9% in the zirconia group and 14% in the control group. The majority of abutment-level complications were treated restoratively. A significant difference was found for maximum probing depth at the abutment teeth: In the zirconia group, it decreased by 0.2 mm, whereas it increased by 0.8 mm in the control group (p = 0.04). CONCLUSIONS: After 3 years of observation, survival of zirconia E-RDPs was favorable and comparable with that of established double-crown-retained prostheses. Further studies must clarify whether there are benefits of zirconia primary crowns for periodontal health. CLINICAL RELEVANCE: Although these results encourage the use of zirconia primary crowns, more research is necessary to reduce the number of complications observed for secondary telescopic crowns, for example, failure of the veneer.

Poor dental hygiene and periodontal health in nursing home residents with dementia: an observational study.

Poor oral health conditions are well documented in the institutionalized elderly, but the literature is lacking research on relationships between dementia and periodontal health in nursing home residents. The purpose of this cohort study, therefore, was to assess whether dementia is associated with poor oral health/denture hygiene and an increased risk of periodontal disease in the institutionalized elderly. A total of 219 participants were assessed using the Mini Mental State Examination (MMSE) to determine cognitive state. According to the MMSE outcome, participants scoring ≤20 were assigned to dementia group (D) and those scoring >20 to the non-dementia group (ND), respectively. For each of the groups D and ND, Gingival Bleeding Index (GBI) and Denture Hygiene Index (DHI) linear regression models were used with the confounders age, gender, dementia, number of comorbidities and number of permanent medications. To assess the risk factors for severe periodontitis as measured by the Community Index of Periodontal Treatment Needs, a logistic regression analysis was performed. Statistical analysis revealed no significant differences of GBI as well of DHI for demented and healthy subjects (p > 0.05). Severe periodontitis was detected in 66 % of participants with dementia. The logistic regression showed a 2.9 times increased risk among demented participants (p = 0.006). Oral hygiene, denture hygiene and periodontal health are poor in nursing home residents. The severity of oral problems, primarily periodontitis, seems to be enhanced in subjects suffering from dementia. Longitudinal observations are needed to clarify the cause-reaction relationship.

Comparison of the Easyshade Compact and Advance in vitro and in vivo.

OBJECTIVE: The objective of this study was to evaluate the repeatability, inter-examiner and inter-device reliability, and accuracy of the new VITA Easyshade Advance (ES-A) spectrophotometer in comparison with the Easyshade Compact (ES-C). METHODS: For the in vitro study, six porcelain disks of random shade mixtures were fabricated from VITA ceramic powders. To analyze the repeatability of the ES-C and ES-A, readings were obtained by one examiner for one porcelain disk and one shade tab (VITA 3D-Master). Measurements were repeated by two examiners to evaluate inter-examiner reliability. To assess accuracy, porcelain disks and shade tabs were measured with the ES-C and ES-A and by means of a spectroradiometer (SR). ∆E values between the shade tabs and disks were calculated. Differences between devices were evaluated by use of univariate analysis. Reliability and accuracy of both devices were also tested in a clinical setting. The intra-class correlation coefficient (ICC) was calculated for all assessments of reliability. RESULTS: Good agreement was observed for replicate measurements (ICC > 0.9), for inter-examiner reliability of the ES-A and ES-C (ICC > 0.9), and for inter-device agreement (ICC > 0.9). Univariate analysis revealed that ∆E values for the spectrophotometers were consistent (p = 0.783); spectroradiometrically measured ∆E was comparable, but the mean value was smaller than that for the spectrophotometers (p = 0.004). Clinical inter-device agreement was acceptable to high (ICC > 0.777). The accuracy of the ES-A was higher than that of the ES-C (p = 0.001). CONCLUSION: Within the limitations of the experiment, the spectrophotometers tested enabled reliable and accurate measurement. In the clinical setting, however, the ES-A seems more accurate. CLINICAL RELEVANCE: ES-C and ES-A can be valuable tools for the determination of tooth colors. Because of their good reliability, they should especially be used for the assessment of tooth color changes over time.

Determination of VITA Classical shades with the 3D-Master shade guide.

OBJECTIVES: Because of its good matching performance the VITA 3D-Master shade guide (3D) is frequently used for determination of tooth color. Numerous composites/ceramics are, however, available in VITA Classical (VC) shades only. The objective of this study was to investigate the possibility of performing a shade match with 3D Master and converting this result via a table in a VC shade (indirect method) without this resulting in an apparent inferior shade matching in comparison with direct shade matching with the VC. METHODS: Experiments were performed with an artificial, computer-generated tooth color space. Conversion tables were generated by calculating the color difference (ΔE) between a 3D shade and the closest VC shade (simple conversion table) and with the aid of optimization procedures. Statistical differences between the direct and indirect methods and between the indirect methods were assessed by use of a U-test. RESULTS: Median ΔE was 2.38 for direct matching with the VC and 2.86 for indirect matching by use of a simple conversion table (p < 0.01). Optimized tables performed slightly better (median ΔE = 2.81). CONCLUSIONS: Within the limitations of the study, it is usually possible to determine tooth color with the 3D and convert it, via a table, into a VC shade without adding a clinically apparent error to the direct shade match with the VC.

Retrospective comparison of semipermanent and permanent cementation of implant-supported single crowns and FDPs with regard to the incidence of survival and complications.

PURPOSE: To retrospectively compare the fixation modalities semipermanent and permanent for all cemented single crowns and Fixed Dental Prostheses (FDPs) placed at the Department of Prosthodontics in the years 2002 to 2010 with regard to the incidence of survival and complications. MATERIALS AND METHODS: Two hundred forty-one patients (48.5% male, mean age 57.3 years) received 166 FDPs and 232 single crowns. A total of 50.6% of the FDPs and 54.7% of the single crowns were fixed using semipermanent cements. Aside from fixation, age, gender, type, location, and material of the suprastructures were assessed as possible factors affecting complications, namely de-cementation, chipping, framework, or abutment fracture. RESULTS: During an observation period of up to 6.6 years (mean 2.24 years; standard deviation 1.38), the survival rates were 96.4% and 100% for FDPs (semipermanent/permanent cementation), and 98.4% and 92.4% for single crowns (semipermanent/permanent). The success rates achieved, counting every complication, for the FDPs were 61.9% and 70.7% (semipermanent/permanent) and for single crowns were 75.6% and 77.1% (semipermanent/permanent). The cement used had a significant effect on loss of retention of the FDPs (p = .006), but no significant effect on the retention of the single crowns. Cementation procedure exhibited no significant impact on chipping for both FDPs and single crowns. The frequency of framework or abutment fractures was too low for further statistical analyses. CONCLUSION: Both semipermanent and permanent cementation of FDPs and single crowns resulted in high survival rates. Within the limitations of the study design, because of the amount of chairside aftercare required, implant-borne FDPs could be recommended for permanent cementation.

Evaluation of two different approaches to learning shade matching in dentistry.

STATEMENT OF THE PROBLEM: An important aspect of dental education is teaching and learning shade matching. OBJECTIVE: To assess the success of two different strategies for learning shade matching. MATERIALS AND METHODS: Seventy-one pre-clinical students (mean age 23; 33.3% men) were divided into two groups. One group (TTB) formed teams of two and they matched three pre-determined teeth on each other using the 3D-Master shade guide. After this exercise, they learned shade matching using a standardized device (Tooth Guide Training Box, TTB) by matching shade tabs in an artificial environment. The other group (GL) matched tooth color in a pre-defined clinical setting in groups of four students. After this, they matched the same teeth as before training, again in groups of two, similarly to group TTB. The reference tooth color was determined by two experienced prosthodontic clinicians. The L*a*b* values for the tabs were provided by the manufacturer and the color difference (ΔE(ab)) between the chosen tab and the reference was calculated. Linear general estimation equation models were used for statistical evaluation (p = 0.05). RESULTS: In the TTB group, the difference between ΔE(ab) values before and after training was 0.03, which was not significant (p = 0.927; 95% CI: -0.70/0.77). In the GL group, ΔE(ab) was 0.98 smaller after training, which was significant (p < 0.001; 95% CI: 0.50/1.50). CONCLUSION: The ability to match tooth color could be improved by using a group-learning approach in a clinical setting and implementation of such a training session should be considered in undergraduate and postgraduate dental education.

Three-dimensional fit of CAD/CAM-made zirconia copings.

OBJECTIVES: CAD/CAM-technologies aim for a standardized, accurate production of dental restorations out of high strength materials (zirconia). The three-dimensional internal fit of CAD/CAM-manufactured zirconia copings was evaluated in vitro to verify the realizability of this aim. METHODS: The analysis was based on ceramic master dies of prepared teeth and corresponding virtual CAD surfaces. Five copings per die were manufactured with two different CAD/CAM-technologies: milling and grinding. The internal fit was determined by a three-dimensional replica technique by optical digitization and computer-assisted analysis. RESULTS: Mean internal gaps were 134/84µm (SD 78/28) for molar and 93/69µm (SD 56/35) for premolar copings (milling/grinding) using a digitizable silicone for the replicas representing the cement space; they were statistically significant regarding tooth and CAD/CAM-system (p<0.001). SIGNIFICANCE: All zirconia copings showed an internal accuracy of fit where the gap widths ranged within the current clinical recommendations. However, there still is room for improvement and further standardization of CAD/CAM-technologies.

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

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

Metameric effect between natural teeth and the shade tabs of a shade guide.

The objective of this study was to evaluate metameric effects, that is, the dependence of the colours of teeth and shade tabs on the illuminant used. The colours of 49 teeth of 37 participants and of the corresponding shade tabs of the 3D-Master (VITA Zahnfabrik; colour match DeltaE(ab)< 2) were measured using an intra-oral spectrophotometer (VITA Easyshade). Spectral reflectance data (from 400 to 700 nm) were recorded. Commission Internationale de l'Eclairage (CIE) L*a*b* values were calculated for D65 (reference daylight), A (incandescent light), and TL84 (store/office light) as reference illuminants. A modified metamerism index (Mod-M) and hue-angle ratios were calculated to express differences between tooth and tab colour relative to the difference observed under D65 illumination. The Mod-M for teeth and tabs was greater than unity (indicating a greater colour difference relative to D65) by 57.1% for A and by 49.3% for TL84. Hue-angle ratios of teeth and tabs using the test illuminants were different from those obtained using the standard illuminant D65. If teeth and shade tab matching is conducted using daylight illumination, the colour difference may not be the same under other lighting conditions, leading to perceptible, or even unacceptable, colour differences under these conditions.

Does gender and experience influence shade matching quality?

OBJECTIVES: To evaluate the influence of gender and level of experience on shade matching quality. METHODS: A study was simultaneously performed at 15 universities located in 9 countries. A total of 614 color normal participants completed all phases of the experiment. Among them, there were 305 females and 309 males, 319 dental students and 295 dental professionals. A lecture on color matching in dentistry was given to all participants. Initial training was performed using Toothguide Trainer software (TT), while Toothguide Training Box (TTB) was used for both training and testing of participants' shade matching results. The test task was to successively match 15 shade guide tabs with the corresponding shade guide. The shade matching score for each participant was computed as a sum of color differences (SigmaDeltaE(ab)(*) score) between target tabs and selected tabs. Lower scores corresponded to better shade matching results and vice versa. Means and standard deviations were calculated. Mann-Whitney U test was used for statistical analysis of the data (alpha=0.05). RESULTS: The mean shade matching score (S.D.) for all participants was 41 (21). The score for female and male participants was 38 (20) and 44 (21), respectfully (p<0.001). The difference in scores between dental students, 42 (20), and dental professionals, 39 (21), was not statistically significant. CONCLUSION: Within the limitations of this study, females achieved significantly better shade matching results than males, indicating that gender plays an important role in shade matching. The level of experience was not found to be significant factor in shade matching.

Effect of external light conditions during matching of tooth color: an intraindividual comparison.

The aim of this study was to investigate color matching under natural daylight and daylight lamp conditions. Twenty-nine preclinical students underwent a training course and then matched randomly chosen shade tabs of Vita 3D-Master Shade Guide under both natural daylight and daylight lamp conditions. Color difference (delta Eab) between presented and selected shade tabs was calculated. Statistical differences were explored by use of multivariate analyses. Mean delta Eab was 2.5 (1.0 to 4.3) with daylight lamp and 3.4 (0.9 to 7.4) with natural daylight. The difference was statistically significant (P < .001). The use of a daylight lamp helps to standardize light conditions and significantly improve the ability to match colors.