Mean ΔE Research Articles

Combined Effects of Different Bracket Bonding Adhesives and Different Resin Removal Methods on Enamel Discoloration: A Preliminary Study.

This study aimed to investigate the effects of 3 orthodontic bracket adhesives and 3 resin removal methods on enamel discoloration. Ninety metal orthodontic brackets were bonded to 90 intact human premolars, using 3 adhesives (total etch composite (Transbond), self-etch composite (OptiBond), and light-curedresin-modified glass ionomer cement (RMGI, Fuji); n = 3 × 30). Each "bracket bonding" group (n = 30) was randomly divided into three subgroups of 10 specimens each, each with a different method of remnant resin removal (using only tungsten carbide burs; using tungsten carbide burs plus Sof-Lex polisher discs; using tungsten carbide burs and Stainbuster burs; n = 3 × 30). After bracket debonding and coffee staining (at 37°C for one week), the color change parameters (Δa, Δb, ΔL, and ΔE) were measured and then analyzed statistically (α = 0.05). All 9 mean ΔE values were significantly greater than 3.7 and 1.0 (P values ≤0.002, t-test). The effects of composites and resin removal methods on the ΔE parameter (and their interaction) were significant (P values ≤0.008, two-way ANOVA). There were significant pairwise comparisons between total etch (Transbond) and each of the other composites (P values ≤0.008, Tukey). Nonetheless, the difference between self-etch (OptiBond) and RMGI (Fuji) was not significant (P=0.967). There were significant pairwise comparisons between the ΔE parameter of group "Bur + Stainbuster" and ΔE of each of the other methods (both P values ≤0.017). All 9 pairs of adhesives and resin removal techniques will cause quite visible discolorations. Still, self-etch composites or RMGI might be recommended over total etch composites. Moreover, using Stainbuster burs together with tungsten carbide burs is recommended to reduce discoloration. However, the coloration caused by each composite type can change drastically given the following adhesive removal technique used.

Color stability of three commercial resin cements after accelerated aging.

This study aimed to assess the color stability of resin cements subjected to xenon radiation and evaluate their color change (ΔE) during time. In this in vitro experimental study, 15 specimens (8 mm in diameter and 2 mm in height) were made from a light-cured resin cement (Choice 2, Bisco, USA) and two dual-cured resin cements (Panavia F2 and V5, Kuraray Co, Ltd, Osaka, Japan). For assessment of color change, ΔE parameters were measured immediately (ΔE1) and 24 h (ΔE2) after polymerization using XRiteCi64 spectrophotometer. Next, they were subjected to xenon lamp radiation (122 h at 35C° and 22% humidity in off mode and 95% in light mode). Then, their color change was measured again (ΔE3). The mean ΔE and standard deviation of all specimens were calculated, and data analysis was done using analysis of variance and Tukey's honestly significant difference. L* values had a tendency to decrease and Panavia F2 and Choice 2 had the highest change after accelerated aging. The comparison of Δa and Δb showed no significant difference between cements except Δa in Panavia F2. All the values were clinically acceptable (ΔE >3.3). The lowest Δ E1 was for Panavia V5 and the highest Δ E1 was measured for Panavia F2. After accelerated aging, there was no significant difference between Panavia V5 and choice 2 (P > 0/05). Following polymerization and under xenon radiation, ΔE of all the specimens was clinically acceptable.

In vitro evaluation of the color stability and surface roughness of a new composite flow.

The aim of this study was to evaluate the color stability and the surface roughness of a bulk-fill composite flow (SDR® Plus) by comparison to an ORMOCER-based composite (Ceram.x® Universal SphereTEC™) in order to confirm the validity of using SDR® Plus in the anterior region and to allow the prediction of its long-term results. 35 composite specimens of the same shade (A2), thickness (2mm) and shape of both types of composite were prepared. The specimens were cured and polished according to the manufacturer's instructions. The initial shade of the specimens was measured using a calibrated EasyShade spectrophotometer. The initial surface roughness of the specimens was measured by AFM. Afterwards, the specimens were subjected to an accelerated aging procedure through thermo-cycling, a coffee stain challenge and brushing to simulate two years in the oral environment. The shade and surface roughness of the specimens were measured again after the accelerated aging procedure. The mean ΔE was significantly larger than 3.368 in Ceram.x® group (-p-value<0.001) and SDR® Plus group (-p-value<0.001). The mean surface roughness has significantly increased for both groups after aging with no significant difference between the two groups. It however remained clinically acceptable. SDR® Plus and Ceram.x® showed similar surface roughness when subjected to the same testing conditions. Concerning the color stability, both composites displayed noticeable discoloration, with higher ΔE values registered for Ceram.x®. Key words:Composite resins, spectrophotometry, atomic force microscopy, dental material, resin-based material.

Effect of In-Office Bleaching Agents on Three Different Esthetic Restorative Materials: An In Vitro Study

Objective: The purpose of this study was to evaluate the effect of two hydrogen peroxide concentrations, commonly used in In-Office bleaching, on the surface roughness and color change of different esthetic restorative materials. Materials and Methods: Sixty disc samples (10 mm in diameter and 2 mm in thickness) of the different restorative materials used were constructed following the manufacturers’ instructions. Samples were classified into three main groups (n=20) according to the type of restorative material: Group1: Microhybrid composite Filtek P90 Silorane, Group 2: IPS emax Press and Group 3: Vitadur Alpha porcelain. Each of the three groups was divided into two subgroups (n=10) (a and b) according to the type of bleaching agent used (Opalesence Xtra Boost 35% hydrogen peroxide (HP) and Zoom 2 25% HP respectively). Samples of subgroups were further divided into two equal divisions (n=5) according to the type of test performed (Roughness testing and Color assessment). Each sample was assessed for surface roughness and color change before bleaching so that each sample served as its own control. Surface roughness was examined using Environmental scanning electronic microscope (ESEM). Color measurements were made with spectrophotometer using CIELAB color scale. One sample from each subgroup was examined to confirm their crystalline phase before and after bleaching using X-Ray Diffraction. Results were statistically analyzed. Results: Significant differences in Ra values were observed between the unbleached and bleached samples, as well as between subgroups treated with Opalesence Xtra Boost and those treated with Zoom 2. The two bleaching agents had statistically significant effect on the color of restorative materials (P&lt;0.05). Moreover, the color change was found to be significantly higher for the restorative materials treated with Opalesence Xtra Boost compared to Zoom 2, regarding their mean ΔE values. Conclusion: Highly concentrated in-office bleaching systems adversely affected the surface roughness and color of Filtek P90 Silorane, IPS e-max Press and Vitadur Alpha porcelain.

Does Age Have a Role in Color and Whiteness Variations After Dehydration and Rehydration in Maxillary Anterior Teeth? An In Vivo Study.

To determine the influence of in vivo dehydration and rehydration on color and whiteness variations in maxillary anterior teeth of younger, middle-aged, and older individuals. The spectrophotometric shade of maxillary anterior teeth from younger (20 to 30 years, n=20), middle-aged (50 to 60 years, n=20) and older (65 to 80 years, n=20) participants were assessed at baseline and every 10 minutes for 30 minutes after rubber dam isolation (dehydration). The teeth were then allowed to rehydrate, and shade values were assessed every 10 minutes for 30 minutes, after 24 hours, and after 48 hours. Data were collected as International Commission on Illumination (CIE) L*a*b* color coordinates. Color differences (ΔE*ab) and whiteness differences (ΔWID) were evaluated. Statistical analysis was performed using one-way analysis of variance with the Tukey Honest Significant Difference test. The color and whiteness changes of maxillary anterior teeth in older individuals after dehydration for 30 minutes were significantly lower than that of younger and middle-aged individuals. In younger participants, after 10 minutes of dehydration, mean ΔE*ab values of maxillary anterior teeth were above the acceptability threshold (AT), while mean ΔWID values were above AT only in maxillary canines. In middle-aged participants, mean ΔE*ab values were above AT, and mean ΔWID values were above the perceptibility threshold (PT) and below AT after 10 minutes of dehydration. In older participants, mean ΔE*ab values were above PT and below AT at 20 minutes of dehydration, while mean ΔWID values were above PT at 10 minutes of dehydration, and both were above AT at 30 minutes of dehydration. The mean ΔE*ab values were above AT after 20 minutes of rehydration in younger and middle-aged participants, while they were below AT in older participants after 10 minutes of rehydration. Mean ΔWID values were below AT for older participants after 20 minutes of rehydration. All mean ΔWID values were below AT and above PT after 30 minutes of rehydration except central incisors of younger participants. After 24 hours of rehydration, mean ΔE*ab and mean ΔWID values of participants in all age groups were below AT. After 48 hours of rehydration, mean ΔE*ab and ΔWID values of participants in all age groups were below PT except mean ΔE*ab values of canines and mean ΔWID values of central incisors in younger participants. L*, a*, and b* values were significantly different between age groups at 30 minutes of dehydration and after 48 hours of rehydration (p<0.05). Color and whiteness changes due to dehydration were less pronounced in older participants. Dehydration for 10 minutes in most maxillary anterior teeth of younger and middle-aged participants led to perceptible and clinically unacceptable color and whiteness changes. Maxillary anterior teeth of older participants showed color and whiteness changes that were perceptible at 10 minutes of dehydration but clinically acceptable up to 30 minutes of dehydration. After 30 minutes of dehydration, a 10- and 20-minute rehydration was needed, respectively, for color and whiteness changes to be clinically acceptable in maxillary anterior teeth of older individuals, while a 30-minute rehydration was recommended for the middle aged group and for maxillary laterals and canines of the younger group. Color and whiteness changes in most maxillary anterior teeth were imperceptible only after 48 hours of rehydration.

Evaluation of Color Difference and Translucency of Modified PEEK Restorations Veneered with Different Veneering Materials Before and After Thermal Cycling

The aim of this study was to investigate the effect of different PEEK veneering materials, as well as thermocycling on the color difference (ΔE) and the translucency parameter (TP) of modified PEEK veneered restorations. Materials and Methods: Thirty-disc shaped specimens of veneered BioHPP (1.5 mm X 12 mm) were randomly divided into three groups (n=10) based on the type of the veneering material. Group (A): Discs veneered with CAD milled Lithium Disilicate, group (B): Discs veneered with pre-cured milled composite, and group (C): Discs veneered with conventional light cured composite. CIELab values were calculated for all specimens over white and black backgrounds using a laboratory spectrophotometer and then (ΔE) and (TP) were calculated. Specimens were subjected to thermal cycling, after which the same procedure for calculating (ΔE) and (TP) was repeated. Results: Repeated measures ANOVA showed that both the veneering material, and thermocycling had a statistically significant effect on mean ΔE, and on (TP) (P-value). Conclusions: All veneering techniques rendered an amount of color difference that was clinically unacceptable, as well as displaying much lower translucency levels than that of natural enamel and dentine

12- months color stability of direct resin composite veneers in anterior teeth: Clinical trial

Background: This clinical trial aims to evaluate the color changes of direct resin composite veneer (DCV) restorations based on spectrophotometric analysis of 4 different types of resin composites between the baseline immediately after polishing and after one year of follow-up. Materials and methods: 28 patients were assessed for eligibility for participation, aged between 18 and 38 years old, who indicated for DCV restorations in anterior maxillary teeth were considered for participation in this study. In total, 25 patients who met the inclusion criteria were selected (6 males and 19 females, mean age: 20.9 at the time of restoration placement), and 3 patients were excluded. Participants were divided into four groups based on the type of composite resin used for restorations. Group 1 nanohybrid Ips Empress direct (Ivoclar Vivadent)](IPS) (13 restorations/6 patients), group 2 microfilled [Essentia (GC cooperation Japan)](ES) (14 restorations / 7 patients), group 3 supra-nano filled [ Estelite ∑ Quick (Tokuyama, Tokyo, Japan)](EQ) (17 restorations / 7 patients) and group 4 nanofill [Filtek Ultimate (3M ESPE)](FU) (13 restorations / 5 patients). Baseline Color measurements were performed with a spectrophotometer immediately after finishing and polishing (baseline), and after one year of recall, color change (ΔE) from baseline values and after one year of follow-up of DCVs were calculated according to CIELab color coordinates. For this, a silicone mold was fabricated for each patient and used as a guide for each measurement to standardize the site of the readings. Statistical analysis of the data was applied using the Kruskal-Wallis test with Dunn-Bonferroni posthoc test after controlling the distribution of data in terms of normality with the Shapiro Wilk test. Results: At the end of one year,25 participants(57restorations) were followed up. The mean ΔE of IPS, EQ, and FU composites were higher than the ES composite resin, but there was no statically significant difference between all types of composites (P&gt; 0.05). There was no statistically significant difference in the mean ΔL* between any types of composite resin (p&gt; 0.05). There was a significant change in Δa* and Δb* after a one-year recall for all the types of DCV restorations (p &lt; 0.05). Conclusion: After one year of follow-up, the spectrophotometer measurements of direct resin composite veneer restorations, it was concluded no difference between the mean ΔE of ES, IPS, FU, and EQ resin composite. ES (Microfilled hybrid) showed a lower mean ΔE value compared to the other groups. All groups of resin composite showed color changes within clinically acceptable levels after a one-year follow-up.

Incorporation of Green Capping Agents to Reduce Silver-Mediated Dentine Staining

Silver diammine fluoride (SDF) is known as a noninvasive, cost-effective, safe, and simple method of dental caries treatment. However, staining and discoloration seem inseparable with SDF and continue as a cosmetic concern. Research is ongoing to overcome these issues, for example, by using glutathione (G) or potassium iodide among others. Therefore, the study aimed to investigate the effects of incorporating different concentrations of capping agents on SDF chemistry and SDF-mediated tooth staining at different time points. Tannic acid (TA), gallic acid (GA), carboxymethyl chitosan (CM), and G at different concentrations (5, 10, and 15% w/v) were incorporated in 30% SDF. FTIR and UV-Vis spectroscopies of the prepared solutions was performed to evaluate chemical changes. Time-dependent color changes (ΔE) in bovine dentine specimens (6 × 6 × 1 ± 0.25 mm³) were measured spectrophotometrically at application/washup, 1 and 3 h, after 1, 2, 4, 7, and 14 days. Results showed suppression of FTIR peaks at 3,358 cm⁻¹ and 1,215 cm⁻¹ in capping agent-modified SDF indicative of a successful capping effect of the silver ions, which was corroborated by UV-Vis blueshift of ∼∆32 nm. The capping effect on SDF increased proportionally with the concentrations of TA, GA, CM, and G used. A more pronounced tooth staining reduction however was shown more in TA- and G- rather than in GA- and CM-modified SDF. At day 14, SDF showed the highest mean ΔE(50.14 ± 2.14), while 15% TA showed the lowest ΔE(30.14 ± 0.81). In conclusion, capping agent incorporation significantly reduced SDF-mediated tooth staining. This reduction in staining is more dependent on the respective capping agent functional groups than concentrations per se. The potential of capping agents to minimize tooth staining of SDF was TA>G>CM>GA.

Impact of masking hypomineralization opacities in anterior teeth on the esthetic perception of children and parents: A randomized controlled clinical trial

Objectives: The aim of this study was to evaluate the impact of treating demarcated opacities in anterior teeth on the esthetic perception of children and their parents. Additionally, the masking effect was evaluated quantitively and qualitatively. Methods: Thirty-nine patients, 8–18 years-old, presenting white-creamy opacity in permanent incisors were randomly allocated to test or control group. Test received resin infiltration and control received a placebo. The questionnaire Child's and Parent's Questionnaire about Teeth Appearance was used. The masking effect was quantitatively analyzed using the Lab System to calculate the color difference (ΔE) between the opacity and the surrounding enamel in Photoshop. Fisher's, Chi-square, Wilcoxon, Mann-Whitney tests and Spearman's correlation were applied to data analysis. Results: In the test group, a significant impact on physical and psychological domains in parents' and in social domain in parents’ and children's perception was observed (p<0.05). Significant difference in ΔE between test and control groups was seen from 15 min of application onwards (p<0.05). After treatment, the mean ΔE was 4.07 (SD=3.07) in the test and 7.35 (SD=3.54) in the control group (p<0.01). One month later, the mean ΔE was 4.22 (SD=2.96) in the test and 6.06 (SD=2.52) in the control group (p<0.01). Total masking was seen only in the test group (p<0.01). Conclusion: Aesthetic treatment of hypomineralization opacities in anterior teeth with resin infiltration impacted positively on parents and children. Resin infiltration reduced the color difference between opacities and sound enamel significantly after an application time of at least fifteen minutes.Clinical significance: Opacities in anterior teeth impact the self-image of children and parents negatively. This study demonstrated that 15 min resin infiltration can mask opacities in permanent incisors and recover social wellbeing. This minimally invasive approach can be offered to MIH children who report dissatisfaction with their incisors.

Clinical assessment of color stability and patient satisfaction for polished versus glazed lithium disilicate glass ceramic restorations

Aim: To evaluate clinically the color stability and patient satisfaction of polished versus glazed lithium disilicate glass ceramic restorations. Methodology: Twenty full coverage crowns were fabricated from IPS e. max press in the posterior area. The patients were randomly divided into two equal groups according to the applied crown surface treatment. Group 1 (control group) 10 glazed crowns and Group 2 (intervention group) 10 polished crowns. ΔE was measured using Vita easyshade and patient satisfaction was evaluated through Visual Analogue Scale (VAS), immediately after cementation and every two months for one year. Data were analyzed using two-way ANOVA and t-test. P ≤ 0.05 was considered statistically significant. Results: The results showed that the polishing technique had a statistically significant mean ΔE than glazing but both were clinically acceptable. Regarding the follow up period results showed that time had no statistically significant effect on mean ΔE values. There was also no statistically significant difference in patient satisfaction within each technique and at the different follow up times. Conclusion: Although polishing showed higher color change than glazing, it was clinically acceptable. Therefor polishing can be recommended as an alternative to glazing for IPS e.max crowns.

Tooth Color Change and Erosion: Hydrogen Peroxide Versus Non-peroxide Whitening Strips.

The study evaluated the efficacy and potential erosion of non-peroxide strips compared to hydrogen peroxide (HP) whitening strips (WSs). Color evaluation samples (N=64) were distributed into four groups and treated according to manufacturer's directions. NC: Negative control treated with water; BT: Non-peroxide Brilliant Dissolving Strips; FM: Non-peroxide Fancymay Teeth WSs; WS: Crest 3D Brilliance HP White Strips. A contact-type spectrophotometer was used to measure color at baseline (T1), 1-day posttreatment (T2), and 1-week posttreatment (T3). Teeth were cut to a rectangular block for micro-CT erosion assessment. The samples (N=30) were divided into five groups. In addition to the four groups for color assessment, a positive control (PC) treated with 0.25% citric acid was added. The samples were scanned, reconstructed, and measured for erosion depth using a micro-CT analysis program software. Kruskal-Wallis test was used to determine differences in color change and erosion depth among the groups. Tests of hypotheses were two-sided with an alpha level of 0.05. The mean ΔE*ab at 1-day/1-week posttreatment were 2.4/2.5, 2.8/2.9, 2.8/3.2, and 8.6/11.0 for NC, BT, FM, and WS, respectively. There was a statistically significant difference for ΔE*ab at 1-day and 1-week posttreatment (p<0.001). Group WS had the highest color change, while the other three groups did not differ from each other (p>0.05). Mean erosion depths in microns were 0.52, 0.58, 0.42, 0.49, and 29.55 for NC, BT, FM, WS, and PC, respectively. There was a statistically significant difference among the groups (p=0.004). Group PC had the greatest erosion, while the other groups had negligible erosion that did not differ from each other (p>0.05). Peroxide WSs had superior whitening efficacy compared to non-peroxide strips. None of the tested products compromised tooth structure integrity through enamel erosion.

Susceptibility of repigmentation of enamel surface to red wine and brandy staining after 35% hydrogen peroxide bleaching

Aim and objectives: To investigate the susceptibility of enamel surface for repigmentation by red wine and brandy stains after 35% hydrogen peroxide bleaching. Methodology: 40 freshly extracted human permanent maxillary central incisor teeth were collected for the study. Incisors were stored in 0.1% thymol solution and were used within 1 month of extraction. The teeth were cleaned with ultrasonic scaler, polished with pumice paste. The samples were than divided into two groups of 20 incisors teeth each. Both groups of 20 teeth each were than bleached using 35% hydrogen Peroxide as per the manufacturer’s instructions, i.e. 15 minutes three times a day, every alternate day for four days. Group 1 were than immersed in 200 ml of red wine and group 2 were immersed in 200 ml of brandy for 15 minutes, 6 hours, 1 week and 1 month each. Advance spectrophotometer was used to measure the color shade of the teeth pre bleaching, after 15 minutes, after 6 hours, after 1 week and after 1 month of red wine and brandy immersion. The colour differences (ΔE) at each time interval were calculated accordingly. Results: Spectrometer analysis showed mean ΔE values ± standard deviation of group 1 and group 2 at different time intervals. Color change due to repigmentation was lowest for group 1 teeth from baseline to 15 minutes time interval. Mean ΔE value ± standard deviation was 4.04045±1.308029. However color change value was highest in group 2 teeth at 1 week to 1 month time interval and was 13.45717±1.098210. Group 2 teeth had higher ΔE value than group 1 at any point of time interval. Conclusions: It was concluded that low pH values causes more repigmentation of bleached enamel surface as it was found more with brandy in comparison to red wine. The bleaching treatment with 35% hydrogen peroxide enabled the teeth to become clearer; nevertheless, the intake of food and beverages containing colorants or an acidic pH can negatively affect the effectiveness of bleaching.

Effect of finishing protocols and staining solutions on color stability of dental resin composites.

ObjectiveThe objective of this study was to evaluate the effect of finishing protocol and exposure to staining solutions on color stability of dental resin composites.Materials and MethodsA nanofill and microhybrid composite, three finishing protocols (mylar, Soflex disc, and white polishing stone) and four staining solutions (tea, red wine, khat extract—two concentrations, control—distilled water) were evaluated. A digital spectrophotometer was used for color change (ΔE) measurements employing the CIE‐Lab‐color system. Paired/independent‐sample t test and two‐way analysis of variance (ANOVA) followed by Tukey's honestly significant difference posthoc test were used for inferential statistics at α = .05.Results Soflex finish was associated with least staining and comparable color stability for the two materials in tea and red wine. In Khat 2, microhybrid composite had statistically significant better color stability than nanofill for Soflex finish (14 days t = 3.270, p = .011). For microhybrid composite, mylar resulted in highest mean ΔE, whereas Soflex recorded the least in all staining solutions. For nanofill composite, white stone resulted in highest mean ΔE, whereas Soflex demonstrated the least mean ΔE in all staining solutions, except red wine where mylar demonstrated the least mean ΔE. For mylar finish, nanofill demonstrated statistically significant better color stability than microhybrid in both red wine (14 days t = 4.902, p = .001) and Khat 1 (14 days t = 3.252, p = .012). For stone finish, microhybrid demonstrated statistically significant better color stability than nanofill in all staining solutions (14 days t ≥ 4.785, p ≤ .001). Two‐way ANOVA showed a statistically significant difference in mean ΔE between and within specimens (F = 42.658, p < .001). All staining solutions caused clinically unacceptable discoloration for mylar and white stone finish. For Soflex finish, red wine produced clinically unacceptable color difference beyond 48 h.ConclusionThere was a difference in color stability of resin composites depending on filler type, further influenced by finishing protocol. Soflex disc finish results in better color stability than mylar and white stone in both microhybrid and nanofill composites.Clinical significanceEsthetic dental restorations such as resin composites are routine in contemporary restorative practice. Color stability of composites may be influenced by surface finish, dependent on the filler type, and consumption of chromogenic substances such as khat. To prolong their service, selection of suitable finishing protocols is an important consideration.

Effect of aging on color stability and bond strength of dual-cured resin cement with amine or amine-free self-initiators.

This study aimed to evaluate the effect of aging on the color stability and bond strengths of dual-cured resin cements containing amine or amine-free self-initiators. Three dual-cured and one light-cured resin cements were used. The covered (by lithium disilicate ceramic disks) and uncovered groups (n=10) were included. Color measurements were tested after 24 h, 10,000 and 20,000 thermal cycles (TCs). Micro-shear bond strengths (µSBS) were tested after 24 h, 10,000 and 20,000 TCs, and failure modes were analyzed (n=14). Two-way ANOVA and Tukey's test were implemented for color difference (ΔE*ab) and µSBS (α=0.05). The mean ΔE*ab difference was significant among groups (p<0.001). The lowest ΔE*ab values were obtained for dual-cured resin cement with amine-free self-initiators dual-cured cement after aging in all dual-cured resin cements, and the µSBS of the dual-cured resin cements on ceramic was significantly higher than that of the light-cured ones after aging (p<0.001).

The minimum thickness of a multilayer ceramic restoration required for masking dark background

Masking dark tooth structure or darkness of oral cavity with ceramic restorations is an important concern. The aim of this study was to determine the minimum thickness of a multilayer all-ceramic restoration (IPS-emax Press) required for a proper masking in these situations. In this experimental in vitro study, 36 multilayer ceramic disks of IPS e.max Press (IvoclarVivadent, Schaan, Liechtenstein) with the diameter of 13 mm were prepared and allocated in six groups of different core/veneer thicknesses: 0.4/0.4 mm (G1), 0.5/0.5 mm (G2), 0.6/0.6 mm (G3), 0.8/0.7 mm (G4), 1.0/0.8 mm (G5), and 1.1/0.9 mm (G6). For backgrounds, the standard black tile of spectrophotometer (B) was used to stimulate the darkness of oral cavity, and an opaque ceramic (OC) of IPS-emax Press (OC) was fabricated to determine the masking ability. CIELAB values of all disks on B and OC backgrounds were measured, and ΔE was calculated between two backings. One-way ANOVA and post hoc tukey test were used to analyze the data. ΔE ≤3.3 and P < 0.05 were considered, respectively, as the clinically acceptable limit and the level of statistical significancy. The mean ΔE between B and OC of groups 4 (2.83 ± 0.80) and 5 (1.46 ± 0.36) were within the range of the clinically acceptable color difference (ΔE ≤3.3); thus these groups could properly mask the black background. A trend was existed in the results as by increasing the thickness, ΔE was decreased. A thickness of 1.5 mm of a multilayer ceramic restoration (IPS e.max Press) is required to mask a dark discoloration.

Influence of zirconia/glass veneer thickness and implant abutment material on the final shade of implant restorations.

The aim of this study was to investigate the combined effect of ceramic material, ceramic thickness, and implant abutment background to the final color of restorations. This was a comparative in vitro study. Three different types of monolithic and porcelain-veneered zirconia disc-shaped specimens (Prettau Anterior, VITA YZ ST, and VITA YZ HT) were prepared in A3 shade with two different thicknesses (1 mm and 1.5 mm) (n = 10). Each zirconia material was made of 4-mm thickness as a control specimen of each monolithic zirconia type, and 4-mm thick veneering ceramic (VITA VM9 Base Dentine) was made as a control for veneered zirconia groups. Three simulated implant abutments were fabricated from titanium, white-shaded and yellow-shaded zirconia. The zirconia specimens were placed on different abutment backgrounds, and the color difference (ΔE) between experimental and control specimens was measured. The three-way ANOVA and the Scheffé test were used for data analysis (α = 0.05). The mean ΔE values between two thicknesses were significantly different in every background for all zirconia materials. The ΔE values of zirconia specimens on yellow zirconia were lower than those of other abutments. The clinically acceptable ΔE value (ΔE <3) was found in some monolithic zirconia specimens on white-shaded and yellow-shaded abutments, while the ΔE value is approximately 3 or less in all 1.5-mm thick porcelain-veneered zirconia groups. Different zirconia materials on implant abutments affected the final color of restorations. To achieve satisfactory color, the minimum thickness of zirconia restorations should be at least 1.5 mm on yellow zirconia abutment.

Effect of Conventional and Electronic Cigarettes Smoking on the Color Stability and Translucency of Tooth Colored Restorative Materials: An In Vitro Analysis

This in vitro study compared the effects of conventional and electronic cigarettes on the aesthetics (color stability and translucency) of two types of composite resins: micro and nano-hybrid. Methods: A total of 120 specimens from two different composite materials Filtek Z250 XT (Nano-hybrid, 3M) and Filtek Z250 (Micro-hybrid, 3M) were divided into four groups (n = 30); shade A2 was used. The samples were exposed to conventional and electronic cigarette smoke via a custom made chamber device. The color values and measurements were recorded using a spectrophotometer before and after the exposure. The color and translucency were evaluated using the three-dimensional CIE Lab. Results: There was a significant change in the color (ΔE) and the translucency parameter (TP) in all of the specimens exposed to electronic cigarettes and conventional cigarettes. The results showed that the highest ΔE mean is for the nano-hybrid composite exposed to conventional cigarettes with 1.74 ΔE while the same material is 0.64 under the electronic cigarettes and the difference is significant with (p &lt; 0.05). The micro-hybrid composite data showed less changes in color under both exposures with 0.85 ΔE mean under the conventional cigarette smoke and 0.48 under the electronic cigarette smoke with (p &lt; 0.004). Conclusions: The conventional cigarette smoke has more effect on the color stability of the composite resins than electronic cigarettes. From a clinical point of view, the effect of smoke exposure on the tested specimens’ color, for the time duration to which the specimens were exposed, were moderate (ΔE &lt; 2). The micro-hybrid composites showed better color stability as compared to the nano-hybrid composites.

Influence of Different Beverages on the Color Stability of Nanocomposite Denture Base Materials.

Background The effect of beverages on nanocomposite denture base materials is neglected. Therefore, this study aimed to investigate the influence of different beverages (coffee, tea, cola, and mineral water) on the color stability of nanoparticles-modified denture base materials (DBMs). Materials and Methods A total of 280 specimens (n = 10/group) were prepared from heat-polymerized acrylic resin modified with different concentrations (3% and 7%) of zirconium dioxide (nano-ZrO2), titanium dioxide (nano-TiO2), and silicon dioxide (nano-SiO2) nanoparticles, while 0% was taken as a control. Color change (∆E) of the specimens was evaluated after simulating 6-month immersion time in four commonly used beverages, coffee, tea, cola, and mineral water, as experimental groups. Color stability was measured using a spectrophotometer, and then values were converted to National Bureau of Standards units (NBS units). The one-way ANOVA test was applied to compare color change (ΔE) results followed by Bonferroni's post hoc test (α = 0.05). Results The results showed that the heat-polymerized acrylic resin modified with different types of nanoparticles showed lower color changes after being immersed in beverage solutions compared to the unmodified group (P < 0.001), so the color stability of heat-polymerized acrylic resin was significantly enhanced by the addition of several nanoparticles; nano-ZrO2 showed the lowest ΔE followed by nano-TiO2 and then nano-SiO2. Regardless of the filler type, 3% concentration showed lower mean ΔE than 7% concentration. Regarding the beverage solutions, the greatest color change was found in the coffee group followed by tea and cola, while water showed the least changes. Conclusion Modification of heat-polymerized acrylic resin with certain amounts of nano-ZrO2, nano-TiO2, and nano-SiO2 may be useful in improving color stability.

Color Match of Composite Resin and Remaining Tooth Structure over a Period of 28 Days Using Spectrophotometer-A Randomized Clinical Trial.

The tooth and the composite restoration can undergo a change in color after the restorative procedure over time. The purpose of this randomized clinical trial was to evaluate the color difference (ΔE) of two types of composite resins and remaining tooth structure over a period of 28 days. A total of 40 teeth in 30 patients with Class IV caries or EllisClass II fracture in maxillary incisors were randomized into two groups based on the type of composite resin used for restoration: IPS Empress (n=20 teeth) and Filtek Z250 (n=20 teeth). Shade selection was done using a spectrophotometer. Restorations were performed using an anatomical layering technique, and finishing and polishing was done after 48 hours. Baseline spectrophotometer color values for the remaining tooth structure were measured before isolation and for composite restorations, 10 minutes after light cure. Further color evaluations using a spectrophotometer for the remaining tooth structure and composite restorations were done at 48 hours (both before and immediately after finishing and polishing), 7days, 14 days, and 28 days, and color difference (ΔE) from baseline values for remaining tooth structure and restorations and ΔE between remaining tooth structure and restorations were calculated. Descriptive statistics including mean, standard deviation, and frequencies were computed. Mann-Whitney U test was done to compare spectrophotometer values. There was a significant reduction in mean color difference (ΔE) from baseline values for both tooth (p<0.05) and composite restoration (p<0.05) at all evaluation periods in both groups. Filtek Z250 showed significantly lower mean ΔE between the tooth and the composite resin restoration than IPS Empress at 48 hours (before and after finishing and polishing), 7 days and 14 days (p<0.05). At the 28 day recall, mean ΔE value of IPS Empress restorations to tooth structure was 3.5, while the mean ΔE value of Filtek Z250 restorations to tooth structure was 3.6, which was not statistically different (p>0.05). The remaining tooth structure as well as the composite restorations showed color changes at all evaluation periods, compared to baseline values in both the composite resin groups. Filtek Z250 exhibited less ΔE with remaining tooth structure at 48 hours, 7 days, and 14 days, when compared to IPS Empress. The composite restorations of both the groups reached clinically acceptable color match (mean ΔE<3.7) with the remaining tooth structure 28 days after the procedure.

Texture and Color Enhancement Imaging Increases Color Changes and Improves Visibility for Squamous Cell Carcinoma Suspicious Lesions in the Pharynx and Esophagus.

Texture and color enhancement imaging (TXI) has been developed as an image-enhanced endoscopy technology. TXI mode2 enhances texture and brightness, and TXI mode1 also enhances color. This study aims to assess the color differences in squamous cell carcinoma (SCC) suspicious lesions in the pharynx and esophagus using white light imaging (WLI), TXI mode1, TXI mode2, and narrow-band imaging (NBI). A total of 59 SCC suspicious lesions from 30 patients were analyzed. The color differences (ΔE) between the lesion and the surrounding mucosa were calculated for each modality. The color value was assessed using the Commission Internationale d’Eclairage L*a*b* color space. The visibility of the lesion in each modality was evaluated and compared to that in the WLI by six endoscopists. The mean ΔE values in the WLI, TXI mode1, TXI mode2, and NBI were 11.6; 18.6; 14.3; and 17.2, respectively, and the ΔE values of TXI mode1, TXI mode2, and NBI were significantly higher than those of the WLI (p < 0.001). No lesions had worse visibility, and 62.5% (37/59) had improved visibility, as assessed by more than half of the endoscopists in TXI mode1. TXI mode1 can enhance color changes and improve the visibility of SCC suspicious lesions in the pharynx and esophagus, compared to WLI.