Rade Paravina

To develop a customized CIELAB-based whiteness index for dentistry that accurately correlates to perception of tooth whiteness. Four psychophysical experiments (PE1-4) were conducted by three panels of observers (OP1-3) under diffuse/0° observation/measuring conditions and under typical clinical viewing conditions. Nine whiteness indices (WI, Z%, WIC, WIO, W31, W64, W, WLAB, W*), two yellowness indices (YID1925, YIE313) and tint of white in the CIELAB color system (T) were compared with regard to their ability to measure the perceived whiteness of human teeth. Determination coefficient (R(2)) and '% wrong decision' (%WD) method were used as direct measures of the quality of the indices for whiteness perception in dentistry. CIELAB-based whiteness index (WID=0.511L* -2.324a* -1.100b*) was developed through optimization from the data obtained in PE1. The proposed WID performed better than all the CIELAB and CIE1931 XYZ-based indices under laboratory and clinical conditions (only WIO was comparable to WID in PE2 and PE4). The validation experiments under laboratory and typical clinical conditions revealed that the proposed index WID outperformed previous indices, being the only CIELAB-based index developed for evaluation of whiteness in dentistry.

The aim of this study is to compile a comprehensive database on color range and color distribution of healthy human gingiva by age, gender and ethnicity. Spectral reflection of keratinized gingiva at upper central incisors was measured by spectroradiometer and converted into CIELAB values. Lightness range (ΔL*) for all groups together was 26.8. Corresponding a* (green-red) and b* (blue-yellow) ranges (Δa* and Δb*) were 18.3 and 13.0. Significant differences (p < 0.05) were recorded by age for L* and a* coordinates, by gender for b* coordinate, and by ethnicity for L*, a* and b* coordinates. R(2)-values between color coordinates were 0.01 (L*/a*), 0.03 (L*/b*), and 0.12 (a*/b*). The smallest color differences were recorded between age groups 46-60 and 60 + (ΔE* = 0.9), and between Caucasians and Hispanics (ΔE* = 1.1). Color difference by gender was 1.3. When total L*a*b* ranges were divided into four equal segments, 51.7% of subjects had L* value within the third segment (from lig...

The aim of this study was to analyze color parameters and color compatibility of two randomly chosen Vita shade guides, as well as to propose possible clinical guidelines. Data were recorded using a colorimeter set to standard illuminant source C and the CIE L*a*b* system. A custom adapter system, which allowed a measuring area at the middle third of the tabs, was produced. Each of 42 tabs was recorded one time each on three different days. Color distribution was examined in diagrams whose coordinates were L*a*b* and L*C*H degree color coordinate pairs. Color coordinate ranges and coverage error were examined using the corresponding equations and statistical methods. The method repeatability was approximately delta E* = 0.1. Color difference ranges of Vitapan Classical and Vitapan 3D Master were 14.3 and 19.2, respectively. Color coordinate ranges of Vitapan Classical were as follows: delta L* = 12.8; delta a* = 1.7; delta b* = 9.0; delta C* = 9.0; and delta H degree = 7.4. Corresponding values for Vitapan 3D Master were delta L* = 15.3; delta a* = 3.4; delta b* = 16.3; delta C* = 16.6; and delta H degree = 10.5. Coverage error of Vitapan 3D Master to Vitapan Classical was 1.4 +/- 0.6, while vice versa it was 2.0 +/- 1.5. Compared to Vitapan Classical, chromaticity ranges of Vitapan 3D Master were extended in the desired directions: hue was extended toward yellow-red, and saturation was extended toward more saturated tabs. Compared to Vitapan Classical, Vitapan 3D Master tabs were more uniformly spaced. The examined shade guides were found to be color compatible.

... two of the studies that dem-onstrated lower conversion values were using experimental LeD lights.4, 5 the experimental LeD light used by tarle et al.5 ... as noted previ-ously in this review, the e-Light was not used at maximum power which could have an influ-enced the results. ...

This study evaluated a newly developed visual shade-matching apparatus, Shademat Visual+, as well as the influence of tab arrangement, clinician gender, and years in practice on shade-matching quality. A group of 129 color-normal evaluators-dental students and general dentists-matched the shade of four ceramometal crowns using the Vitapan Classical shade guide. Crowns were positioned onto the upper member of an artificial head and fastened to the headrest of the dental chair or Shademat Visual+. Shade tabs were arranged according to the manufacturer's suggestion or according to deltaE* in relation to the "lightest" tab and divided into groups (alternative arrangement). The evaluators matched the shade of four ceramometal crowns both in daylight and using the Shademat Visual+ artificial light source. The color coordinates were determined using digital image analysis. Based on deltaE* values, each shade-matching result was ranked from 1 (the worst match) to 16 (the best match) points. The evaluators achieved a better result in Shademat Visual+ trials than in daylight trials (13.2 points vs 12.4 points; P < .001). For the same ceramometal crown, 12.7 points were recorded in daylight trials with the manufacturer-suggested arrangement, and 13.7 were recorded with the alternative arrangement (P< .001). Corresponding values for Shademat Visual+ trials were 13.6 points and 14.6 points, respectively (P< .001). Female-male and student-dentist evaluator differences were not significant. The Shademat Visual+ apparatus enabled better shade-matching results than daylight. The alternative tab arrangement enabled better results than the manufacturer-suggested one. Gender and years in practice did not influence shade-matching quality.

Objective: To evaluate the accelerated aging effects on color of different composite resins. Method: Shades were selected from two flowable composites, A1, A3, and White (WH), Filtek Supreme Ultra Flowable/3M ESPE (FSU); A1, A3 and Bleach (BL), Tetric EvoFlow/Ivoclar Vivadent (TEF), and A1, A3, and B1 micro-hybrid control (Filtek Z250/3M ESPE). Disc shaped specimens (10 mm X 2 mm, n=60) were polymerized using a halogen curing light (Demetron 501, Kerr/Demetron) for 40 seconds. Specimens were finished using 400-grit SiC paper and polished with a one-step polisher (PoGo, Dentsply/Caulk) for 40 seconds. Color measurements were taken at baseline (after 24 hour-storage in distilled water at 37°C) using a spectrophometer (Color-Eye 7000, GretagMacbeth) and after exposure to accelerated aging (150 kJ/m2) in a Weather-ometer (Ci35A, Atlas). Means and standard deviations were determined. The data were analyzed by analysis of variance. Fisher's PLSD intervals at a 0.05 level of significan...

Objectives To assess the color stability of high-strength acrylic resin denture teeth after exposure to red wine, coffee and artificial ageing. Methods Four different shades of acrylic resin denture teeth were selected from three manufacturers. The teeth were evaluated in two phases: Phase I, upon staining for 7 days in distilled water (control Group A), red wine (experimental Group B) and coffee (experimental Group C), and Phase II, upon artificial ageing in a Weather-Ometer for a total exposure of 150 kJ/m2 (control Group A; Phase I). Denture tooth positioning jigs were fabricated and color data recorded by means of an intra-oral spectrophotometer and expressed using the Commission Internationale d’Eclairage (CIE) L*a*b* color notation system. Means and standard deviations were determined. The staining data were analysed by three-way ANOVA, while the artificial ageing data were analysed by two-way ANOVA. Fisher's PLSD intervals were calculated at a significance level of P ≤ 0....

Objectives: To create computer models of gingival shade guides based on the initial sample of 69 participants, using Agglomerative Hierarchical Clustering and Fuzzy C Means clustering Methods: A total of 69 subjects of both genders and all ethnicities, were recruited. All subjects were age 18 or above and had healthy gingiva above upper central incisors. Spectral reflection of the keratinized gingiva 2-3 mm apical to the free gingival margin was measured using a spectroradiometer. Anonymized data were converted into CIELAB values and analyzed. Two models of gingival shade guide, each containing 1 to 10 tabs, were designed using A) Agglomerative Hierarchical Clustering (AHC), and B) Fuzzy C Means Clustering (FCM) technique. Coverage error (DE*COV) was calculated for each of model shade guides. Wilcoxon signed rank test was used to compare two clustering algorithms as related to differences in coverage errors obtained for different number of clusters. A 50:50% acceptability threshold ...

Objectives: The goal of the study was to determine the current status of the teaching of color in dental education at undergraduate level in United States (USA) and Germany (GER). Methods: A cross-sectional web-based survey, containing 27 multiple choice, multiple best and single best answers, was created. Upon receiving IRB approval, dental faculty involved in the teaching of color to undergraduate dental students in USA and GER (N=121), were administered. Statistical analysis of differences between Pre-D and Post-D was performed using Fisher's Exact Test (a=0.05). Results: A total of 49 responses were received (response rate 40.5%); There were 34 responses from USA and 15 from GER. A course on color or color in dentistry was included in the dental curriculum of 73.5 of US programs and 80% of GER programs. The number of hours dedicated to color-related topics was 4.02.4 and 3.7249 for USA and GER, respectively. The following topics were frequently taught in both countries: colo...

Objective: To evaluate the effect of polishing and accelerated aging on gloss of flowable resin composites. Method: Disc shaped specimens (D=10mm, 2-mm thick, n=5 per shade/polisher) were prepared using A1 and A3 shade of the following flowable resin composites: Tetric EvoFlow (TEF, Ivoclar Vivadent), Filtek Supreme Ultra Flowable (FSF, 3M ESPE), PermaFlo (PFL, Ultradent), and G-aenial Flo (GFL, GC). Upon removal of Mylar layer, specimens were polished using PoGo (PD, Dentsply Caulk, Milford, DE), and ProGloss (PA, Axis Dental) one-step polishers for 60 seconds. Gloss was measured using gloss-meter (Novo-curve, Rhopoint Instrumentation) before and after exposure to accelerated aging at 300 kJ/m2 (Atlas SUNTEST XXL, Atlas Material Testing Technology). Means and standard deviations were determined. The data were analyzed by analysis of variance and Fisher's PLSD intervals at a 0.05 level of significance. Result: Mean (sd) gloss before (GU,B) and after aging (G,A), and gloss retent...

Objective: To evaluate influence of thermo-cycling, staining and whitening on color (DE*), translucency parameter (TP) and gloss (GU) of two resin-ceramics. Method: Rectangular specimens (12144mm) were cut from CEREC MC XL blocks of GC Experimental (G, GC Corp.) and Lava Ultimate (L, 3M ESPE) using a diamond saw. Surfaces were ground with 400-grit SiC paper and polished for 40 seconds. Experimental conditions (n=5) were: thermo-cycling (TC), TC + coffee staining, TC + red wine staining, TC + whitening, and control. ΔE* and DTP (Color-Eye 7000 spectrophotometer) and DGU (Novo-Curve gloss-meter) were measured. Data were analyzed by analysis of variance. Fisher's PLSD test was calculated at the 0.05 level of significance. The 50:50% acceptability threshold of DE*=3.5 was used for data interpretation. Result: Table shows means and standard deviations for DE*, DTP1 and DGU. Material Parameter TC TC + Red Wine TC + Coffee TC + Whitening Control G DE* 0.4 (0.2) 0.9 (0.3) 2.1 (0.6) 0.0 ...

The aim of this prospective multicenter study was to determine 50:50% perceptibility threshold (PT) and 50:50% acceptability threshold (AT) of dental ceramic under simulated clinical settings. The spectral radiance of 63 monochromatic ceramic specimens was determined using a non-contact spectroradiometer. A total of 60 specimen pairs, divided into 3 sets of 20 specimen pairs (medium to light shades, medium to dark shades, and dark shades), were selected for psychophysical experiment. The coordinating center and seven research sites obtained the Institutional Review Board (IRB) approvals prior the beginning of the experiment. Each research site had 25 observers, divided into five groups of five observers: dentists-D, dental students-S, dental auxiliaries-A, dental technicians-T, and lay persons-L. There were 35 observers per group (five observers per group at each site ×7 sites), for a total of 175 observers. Visual color comparisons were performed using a viewing booth. Takagi-Sugen...

The purpose of this study was to evaluate the color of primary teeth. A Vita Easyshade intraoral spectrophotometer was used to determine the color of primary teeth: (1) maxillary central incisors, canines, and first molars; and (2) mandibular central incisors, canines, and first molars. A total of 604 teeth were measured. Color difference was compared to DeltaE*=2.7 (mean=50:50 replacement point). Coverage error (DeltaE*cov) was calculated. Mean L*a*b*C*ho values for primary teeth were 82.5, 0.2, 18.3, 18.4, and 89.4 respectively. The most frequently chosen shades were A1 (46%), A2 (25%), and B2 (11%). Canines had the highest lightness. Maxillary canines had the lowest a* values, whereas mandibular primary incisors had the highest a* values. Molars were the most chromatic (having the highest b* values), followed by canines and primary incisors in decreasing order. Coverage error (DeltaEcov*) of Vitapan Classical was 4.2 (+/-1.9 SD). Among primary teeth, the widest ranges, in order, ...

This study examined the average surface roughness (Ra, micron) of three packable composites and one hybrid composite cured against mylar, before and after treatment with a fine finishing diamond bur, a resin finisher followed by fine and extrafine polishing paste, two silicone-based finishing and polishing systems, fine and super-fine aluminum-oxide polishing disks, a silicon carbide-impregnated polishing brush and a surface-penetrating composite sealant. Additionally, the Ra was examined for one of the packable composites before and after treatment with a finishing carbide, prior to the finishing and polishing procedures detailed above. The finishing diamond significantly increased the Ra for all composites (ALERT, SureFil, Solitaire and Z-100). The finishing carbide used with SureFil (SureFil + C) also increased the Ra; however, it also produced surfaces up to 3.5x smoother when compared to SureFil surfaces finished with the diamond. Overall, Sof-Lex Contouring and Polishing Discs...

To determine the influence of type of polymerization light on changes in color and translucency of resin composites. 16 shades of commercial composites were analyzed. Specimens were polymerized with quartz-tungsten-halogen (QTH) and light-emitting diode (LED) polymerization light. Color of non-polymerized and polymerized composites was measured against white and black backgrounds using a spectroradiometer. Changes in color (deltaE'), translucency (deltaTP') and color parameters (deltaL', deltaC' and deltah') were calculated for each polymerization light. The differences among deltaE' values and among deltaTP' values obtained for each device were analyzed by two-way ANOVA. Multiple regression analysis was used to determine the influence of color parameters on deltaE' and deltaTP'. The results indicated that there was significant difference among the deltaE' and deltaTP' values obtained using QTH and LED light polymerization (P< 0.05). Th...

This study evaluated the time necessary for at-home whitening (HW) to match the results of an in-office (OW) treatment, side effects and patients' preferences/perceptions. The tooth color change of 20 subjects was measured using a shade guide (BSG) and spectrophotometer (ES). Color difference was calculated: delta E* = [(delta L*)2 + (delta a*ab)2 + (delta b*ab)2]1/2. The whitening treatments were randomly applied to the right or left maxillary anterior teeth, in-office, with 25% hydrogen peroxide or at-home, overnight, with 10% carbamide peroxide. The tooth color was evaluated at baseline, one day after OW, six days (five days after HW) and at 20 days (14 days after HW and 19 days OW). Subjects rated their tooth and soft tissue sensitivity (1-10 scale). The results were analyzed by two-way RM ANOVA/Tukey's and Mann-Whitney (p<0.05). At six days, the teeth that were treated with HW and OW presented delta E* = 5.2 and 6.6, respectively, delta BSG = 3, and at 20 days, they presented delta E* = 6.2 and 6.6, respectively, delta BSG = 3. Less than 40% of the subjects experienced tooth sensitivity after OW and HW. No subjects experienced tooth and gingival sensitivity at 20 days. Seventy-four percent preferred HW over OW, 63% recommended OW and 100% recommended HW. While there was a subtle difference in delta E* between HW and OW at six days, the measurement of delta E* and delta BSG agreed that five days of home whitening produced the same results as a single in-office treatment. The tissue and teeth sensitivity were mild and transient. Subjects preferred and would recommend HW over OW.

The aim of this study was to evaluate polymerization-dependent changes in the color and translucency parameter (TP) of resin composites and to compare results obtained using two color-difference metric formulae, CIELAB and CIEDE 2000. Twenty-eight shades of commercial resin composites were analyzed. Specimens (n = 5) were made as discs, 11 mm in diameter and 2-mm thick, using cylindrical molds. Data were collected before and after composite polymerization, using a spectrophotometer. In regard to in vitro color changes of composites (DeltaE*) a DeltaE76 of 3.7 or greater was considered to be an unacceptable color change. Data were analyzed by analysis of variance, and Fisher's protected least significant difference (PLSD) intervals for comparison of means were calculated at the 0.05 level of significance. Mean polymerization-dependent differences in color were DeltaE00 = 4.48 (2.11) and DeltaE76 = 5.51 (2.68). The DeltaTP00 range was 2.57, while the DeltaTP76 range was 2.89. Mean polymerization-dependent differences in translucency were DeltaTP00 = 0.84 (0.77) and DeltaTP76 = 0.87 (0.76). Analysis of variance showed significant differences among composites, shades, and their interactions (P < 0.0001; power = 1.0). Regression equations and r values for the two color-difference formulae and all evaluated TP values showed very strong correlation. In conclusion, within the limitations of this study, polymerization-dependent changes in color and translucency were highly varied. The majority of shades showed polymerization-dependent differences in color higher than the DeltaE76 = 3.7. The TP generally increased after light polymerization by light activation. The very strong correlation (r > 0.97) between the two color-difference formulae indicates that the limitations of the CIELAB system do not appear to be a problem when evaluating composites; however, recorded differences between DeltaE76 and DeltaE00 values stress the importance of data conversion.

To determine the effects of opacifiers and silicone pigments on the color stability of silicone A-2000 maxillofacial prosthetic elastomers subjected to artificial aging. Seventy-five groups (n=5) were made by various combinations (5%, 10%, and 15%) of four dry earth opacifiers (Georgia kaolin, Gk; calcined kaolin, Ck; Artskin white, Aw; titanium white dry pigment, Td); and 1 silicone pigment white (Sw) with one of 5 silicone pigments (no pigment (control), red (Pr), yellow (Py), burnt sienna (Po), and a mixture of Pr+Py+Po). A reflection spectrophotometer was used for color measurements. Color differences (DeltaE*) between baseline and after an energy exposure of 450kJ/m(2) in an artificial aging chamber were calculated. A DeltaE*=3.0 was used as 50:50% acceptability threshold in result interpretation, while DeltaE*=1.1 was used as 50:50% perceptibility threshold. Means were compared by Fisher's PLSD intervals at the 0.05 level of significance. Color differences after aging were subjected to three-way analysis of variance. Yellow ochre mixed with all opacifiers at all intervals had increased DeltaE* values significantly from 0.7-2.1 up to 3.8-10.3. When mixed groups were considered, at 5%, Gk exhibited the smallest color changes, followed by Td<Aw=Sw<Ck, respectively. At 10%, Aw<Td<Gk<Sw=Ck. At 15%, Td<Aw<Gk=Sw<Ck (< indicates p<0.0001 and = indicates p>0.05). The smallest color differences, observed for opacifier groups, were recorded for Gk at 5%, and Td and Aw at 10% and 15%. Overall, 15% Td exhibited the smallest, whereas 5% Ck exhibited the most pronounced color change after artificial aging. All DeltaE* values were below the 50:50% acceptability threshold, indicating acceptable color stability. Color differences for 10% and 15% of Aw and Td were below 50:50% perceptibility thresholds, indicating excellent color stability. Silicone pigments mixed with 10% and 15% Artskin white and titanium white dry pigment opacifiers protected silicone A-2000 from color degradation over time. Yellow silicone pigment significantly affected color stability of all opacifiers especially silicone pigment white and calcined kaolin.