Significant Differences In ΔE Research Articles

Remineralization of post-orthodontic white spot lesions with a fluoride varnish and a self-assembling P 11 - 4 peptides: a prospective in-vivo-study.

The objective was to evaluate the remineralization effects of fluoride varnish (Clinpro White varnish), self-assembling peptide (Curodont™ Repair) and their combined use on WSL after orthodontic treatment. Thirty-two subjects, aged of 10-18 (mean age 13.91 ± 2.92) with 107 post-orthodontic WSL were included in the study. Subjects were divided into four groups as control, tricalcium phosphate (TCP) containing fluoride varnish (Clinpro White varnish) group, self-assembling P11-4 peptides (Curodont™ Repair) group and combined application of the two products. At the beginning, each subjects' caries risk profile was assessed by evaluating diet cariogenicity, plaque index, gingival bleeding index and stimulated salivary flow rate. Before the application of the remineralization agents, WSL baseline demineralization values were determined with QLF Inspektor™ Pro, laser fluorescence using DIAGNOdent and color values were measured by Vita EasyShade. Remineralization data were obtained by measuring ΔF, ΔQ, and lesion area with QLF. The aesthetic improvement after the remineralization process was evaluated with a spectrophotometer at six weeks, three and six months. No statistically significant differences were found between the groups in terms of criteria determining patients' caries risk profiles, DIAGNOdent data, and plaque index scores (p > 0.05). Intra-group evaluation following remineralization revealed statistically significant increases in ΔF and ΔQ with a decrease in lesion area for the fluoride varnish group at six months, for the peptide group at three months, and for the combined application group at three and six months (p < 0.05). In inter-group comparisons, ΔF and ΔQ values were found to be statistically significant only in the fluoride group at six months compared to the other groups (p < 0.05). While the L* value decreased significantly in all groups at six months, a statistically significant difference in ΔE* values was observed only in the control group between three and six months. Fluoride varnish with TCP showed highest remineralization at 6 months, and the remineralization was positively affected in the short term (three months) after the use of self-assembling P11-4 peptides and their combined application. Remineralization obtained after single application of agents tested in six months in-vivo showed parallel results. In an attempt to trigger subsurface remineralization, the combined use of fluoride with self-assembling peptides as biomimetic remineralization agent needs further evaluation.

Color stability and marginal adaptation of ceramic veneers cemented using different composite resins.

The purpose of this study was to compare the color stability and marginal adaption of lithium disilicate veneers before and after thermocycling using various resin composite materials employed as cement. Laminate veneer preparation was done on an acrylic tooth according to standardized procedures. The veneer preparations were duplicated into twenty-one dies. The veneers were fabricated from lithium disilicate using the CEREC in Lab system. According to the cement type, the twenty-one die specimens were randomly divided into three equal groups: group I, with light cured adhesive resin cement (N.=7), group II, with flowable light cured composite, and group III, with preheated nano filled composite. The cemented specimens underwent 5000 thermocycling cycles. Color was assessed using a reflective spectrophotometer. The vertical marginal gap, following cementation and thermocycling, was measured using a digital microscope. One-way ANOVA followed by Tukey's post-hoc test was used to statistically assess the data. After thermocycling, there was no statistically significant difference in ΔE among cement type groups for color stability (P=0.369). However, the preheated composite showed the lowest ΔE mean values. Within adhesive resin cement and flowable composite groups, marginal gap means values recorded after thermocycling were significantly higher than those after cementation (P=0.013 and P<0.001, respectively). Although preheated composite cement showed the highest marginal discrepancy, it would be the best choice regarding color stability.

Color Changes in Artificially Induced Incipient Caries after Photodynamic Therapy with Different Concentrations of Methylene Blue and Toluidine Blue and Irrigation with Water and Hypochlorite.

The aim of this study was to assess the color changes in artificially induced incipient caries after photodynamic therapy (PDT) using different concentrations of methylene blue and toluidine blue, along with irrigation using water and hypochlorite. Forty-two sound human premolar teeth were used to create two artificial incipient carious lesions. One lesion was placed on the buccal surface and the other on the lingual surface. The color of these artificial incipient carious surfaces was determined using the CIE L ∗ a ∗ b ∗ color system. The teeth were then randomly assigned to 12 groups (n = 7) based on the PDT method. These methods included methylene blue with concentrations of 50, 100, and 150 µg/mL, followed by water irrigation, methylene blue with concentrations of 50, 100, and 150 µg/mL, followed by hypochlorite solution irrigation, toluidine blue with concentrations of 50, 100, and 150 µg/mL, followed by water irrigation, and toluidine blue with concentrations of 50, 100, and 150 µg/mL, followed by hypochlorite solution irrigation. The teeth underwent a colorimetry procedure again, and the resulting color changes were calculated. A three-way ANOVA was performed to analyze the effects of laser wavelength, concentration of the light-absorbing material, and irrigation solution on ΔE. The results showed that the color changes caused by toluidine blue photosensitizer at a concentration of 100 µg/mL, with both water and hypochlorite irrigation, were not noticeable to the naked eye (ΔEwater = 3.04, ΔEhypochlorite = 2.00). However, in the other study groups, the color changes were perceptible (ΔE > 3.3). There were no significant differences in ΔE between different concentrations of methylene blue and toluidine blue when using either water or hypochlorite irrigation (P > 0.05). A significant difference was observed between methylene blue and toluidine blue at a concentration of 100 µg/mL with water irrigation (P=0.006). Additionally, a significant difference was found between methylene blue and toluidine blue at a concentration of 100 µg/mL with hypochlorite irrigation (P=0.049). However, no significant differences were observed between methylene blue and toluidine blue at other concentrations with either water or hypochlorite irrigation (P > 0.05). In conclusion, tooth color in teeth with incipient caries did not change significantly after PDT using toluidine blue (the photosensitizer) at a concentration of 100 µg/mL with either water or 1% hypochlorite solution irrigation for 5 s.

Effects of 35% Versus 10% Carbamide Peroxide At-Home Bleaching Agents with or without MI Paste Plus on Enamel Properties

This study compared the effects of 35% with 10% carbamide peroxide (CP) home used bleaching agents on enamel color change, microhardness, and surface changes in association with MI paste plus (CPP -ACPF). Forty buccal and lingual enamel samples from twenty human third molars were prepared and divided into four groups (n=10). The groups were bleached for two weeks according to different bleaching regimens as follow; G1 bleached with 10%CP, G2 bleached with 35%CP, G3 bleached with a mixture of 10%CP and MI paste plus, and G4 bleached with a mixture of 35%CP and MI paste plus. Color change was recorded with a colorimeter before and after bleaching and total color differences (ΔE*) was calculated. Vickers microhardness test was recorded for all the samples before and after treatment. One sample from each group was evaluated for surface changes by scan electron microscopy (SEM). The data were analyzed with repeated measure of variance and student's t-test at p&lt;0.05. No significant difference in ΔE* was recorded among the four groups (p&gt;0.05). Significant reduction in enamel microhardness was only recorded for G2 (p=0.003). SEM for G3 and G4 showed obvious mineral deposition. Similar teeth color whitening can be resulted after two weeks of bleaching with both 10%CP and 35%CP when used as recommended by the manufacturer with and without the addition of MI paste plus. Using 35%CP decreased enamel microhardness significantly, whereas MI paste plus when mixed with both bleaching agents could compensate for the microhardness reduction.

Impact of glazing on wear, fracture load, and optical properties of a new fully crystallized lithium disilicate ceramic material

ObjectivesLithium disilicate (LDS) based glass ceramics are indispensable materials in the field of prosthetic dentistry due to their strength and excellent esthetics. Recently, novel fully crystallized LDS for the milling process have been introduced to the market, requiring only chairside polishing before delivery. Since limited data is available about subjecting this material to glazing, this study aimed to evaluate the wear properties, fracture resistance, and optical properties of the newly introduced fully crystallized LDS after glazing. MethodsLithium disilicate glass-ceramics (fully crystallized (LiSiCAD) and partially crystallized types (EmaxCAD), of shade A3, were used in the present study. The fully crystallized specimens were subjected to a glazing firing cycle in a furnace (LiSiCAD-G) and compared to a polished fully crystallized counterpart (LiSiCAD-P, negative control) and a glazed partially crystallized LDS (EmaxCAD, positive control). Rectangular-shaped ceramic specimens (n = 10, 12 × 6.5 × 1.5 mm) and enamel antagonists were used to test the wear resistance in a specially designed wear machine built at the Department of Oral Technology, University of Bonn, Germany. The volumetric enamel loss of antagonists was measured by means of overlapping virtual 3D models derived from micro-CT scans for the teeth before and after the wear test. The weight loss of ceramic specimens in milligrams was measured after 100,000 and 200,000 wear cycles. A spectrophotometer was used to calculate the CIELAB color parameters of the ceramic specimens against black and white backgrounds to measure the translucency. Fracture resistance was also assessed after thermodynamic fatigue using a universal testing machine until fracture at a 1 mm/min crosshead speed. Statistical analysis was performed using one-way ANOVA and the significance level was set at α = 0.05. ResultsEmaxCAD and LisiCAD-G groups showed significantly higher mean ceramic weight loss after 100,000 cycles (2 ± 0.3 mg and 1.93 ± 0.2 mg, respectively) than LisiCAD-P group (0.78 ± 0.19 mg). Glazed LiSiCAD specimens demonstrated significantly higher ΔE values from shade A3 compared to polished LiSiCAD. There was no significant difference in ΔE between LiSiCAD-G and EmaxCAD. For fracture resistance, no significant difference was observed between LiSiCAD-G and LiSiCAD-P before or after aging. ConclusionsThe glazed fully crystallized LDS was superior to the partially crystallized one with regard to wear resistance but showed more color changes than the polished fully crystallized one. Furthermore, polishing of fully crystallized LDS could still be considered a better option than glazing when aesthetics is a primary prerequisite.

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.

Evaluating changes in the color and luminosity of dental enamel after orthodontic treatment: A clinical study.

The aims of this clinical study were to evaluate the Color change - ΔE (based on spectrophotometry and visual analysis) and luminosity - L* (based on spectrophotometry) of dental enamel surface (after orthodontic treatment) around the area where orthodontic brackets were fixed, based on different cementing materials such as a resin (R group) and resin-modified glass ionomer cement (RMGIC group). The split-mouth study initially comprised 14 patients. Orthodontic brackets were fixed to the upper central incisors with resin or RMGIC. The color of the buccal surface of each tooth was measured through spectrophotometry and visual examination before the bracket-fixation process. Four individuals were excluded during the follow-up; thus 10 patients were evaluated (n=10). Brackets were removed after 12 months of orthodontic treatment, tooth color measurement and visual examination were performed again, and Adhesive Remaining Index (ARI) was also measured. ΔE and L* results were subjected to Student's t-test and by repeated-measures analysis of variance, respectively (α=0.05). ARI data were analyzed in percentages. There was statistically significant difference in ΔE between groups; the R group showed statistically higher values of L* after orthodontic treatment. ARI of 2 and 3 prevailed in the RMGIC group, whereas the R group presented 0 and 1. After orthodontic treatment, the RMGIC group presented smaller changes in ΔE, and the increase in the white scale was observed on the enamel surface around the area where brackets were fixed in the R group. The visual analysis did not show color change on the evaluated teeth.

Comparison of bleaching effects when applied to white-spot lesions before or after resin infiltration: An in vitro study

BackgroundThe purpose of this study was to compare color alterations (ΔE) of white-spot lesions (WSLs) bleached before versus after resin infiltration (RI). MethodsUsing the facial surfaces of bovine maxillary incisors, WSLs were created and the teeth were allocated into 2 groups (n = 45/group): bleach then RI (B-RI group) and RI then bleach (RI-B group). To determine ΔE, Commission Internationale de l’Eclairage L∗ a∗ b∗ (L∗ represents lightness, ranging from black to white [0-100]; a∗ represents green to red chromaticity [–150-+100]; and b∗ represents blue to yellow chromaticity [–100-+150]) measurements were obtained at baseline, after WSL formation, and after RI and bleaching. Representative specimens were evaluated by means of scanning electron microscopy. Statistical analyses included the Mann-Whitney U and Wilcoxon signed rank tests (P ≤ .0016) and repeated measures analysis of variance (P ≤ .05). ResultsNo differences in ΔE were found comparing B-RI with RI-B groups or when the B-RI group was compared with bleached enamel. A statistically significant difference was found when the RI-B group was compared with bleached enamel (ΔE, 0.81; P < .001), but the difference was deemed not clinically significant. Scanning electron microscopy revealed that bleaching after RI increased surface roughness of the resin. ConclusionsThere were no clinically significant differences in ΔE of WSLs when bleach was applied before or after RI; however, applying bleaching agent after RI roughened the surface of the resin material. Practical ImplicationsResults indicate that ΔE were not clinically significantly different between WSLs bleached before versus after RI, although it is best to sequence bleaching before RI therapy, as bleaching after RI roughened the restoration’s surface.

Variations in the Shades of Contemporary Dental Ceramics: An In Vitro Analysis

Background: To identify and compare the shade variations of various commonly used esthetic dental ceramics by calculating their total-color-difference (ΔE) and translucency parameter (TP) using a spectrophotometer. Methods: In total, 165 disc specimens from three shades (A1, B1, and C1) of five ceramic materials (N = 55/shade; n = 11/ceramic material group) were prepared (Metal-ceramic (MC), IPS e.max press (Emax-P), IPS e.max layer (Emax-L), Layered Zirconia (Zr-L) and Monolithic zirconia (Zr-M)). With a spectrophotometer, the L* a* b* values were obtained. Total color differences (ΔE = [(ΔL*)2 + (Δa*)2 + (Δb*)2]1/2) and translucency parameter (TP = [(L*B − L*W)2 + (a*B − a*W)2 + (b*B – b*W)2]1/2) were calculated. The statistical tests included ANOVA and Post hoc Tukey’s analysis (p &lt; 0.05). Results: Significant differences (p = 0.000) were found between the groups for ΔE. Highest ΔE (A1) were found for Zr-L (80.18 ± 20) and lowest for Zr-M (62.97 ± 1.28). For B1, highest ΔE values were noted for MC (76.85 + 0.78) and lowest for the Emax-L (62.13 ± 1.49). For C1, highest ΔE values were found for the MC group (73.96 ± 0 67) and lowest for Emax-P (55.09 ± 1.76). Translucency variations between tested ceramics were revealed (p &lt; 0.05). Highest TP values (A1) were found for Emax-L (2.99 ± 1.64) and lowest for Zr-L (0.35 ± 0.16). For B1, highest TP values were noted for Emax-P (3.50 ± 1.74) and lowest for MC (0.57 ± 0.40). For C1, highest TP values were found for Emax-P (4.46 ± 2.42) and lowest for MC (0.58 ± 0 48). Conclusions: Significant differences in ΔE and TP were found for tested ceramic groups. The color differences of the tested materials varied according to clinical acceptability, even with the selection of same color/shade. The color/shades of the various dental ceramics do not match with the vita shade guide tabs, to which they are compared most often. Shade differences are present between different lots of ceramic materials from the same or different brands.

THE ABILITY OF COFFEE TO STAIN NANOHYBRID COMPOSITE RESINS

INTRODUCTION: One of the main causes of composite replacement is its discoloration after prolonged exposure to the oral environment. In an effort to fulfill the patient esthetic desire, harmonize composite material have been introduced with limited studies regarding its esthetic properties and color stability.OBJECTIVES: To study the effect of coffee on the color stability of two nanohybrid composites with different monomers.MATERIALS AND METHODS: The resin composites tested were Venus diamond and Harmonize. A custom made disk-shaped mold (4mm thickness x 8 mm diameter) used to prepare 12 composite specimens. They were divided into 2 groups (n=6) according to the resin based composite that was used as follow: Group A restored with Urethane dimethacrylate based composite (Venus diamond, Heraeus Kulzer) and Group B restored with Bisphenol A diglycidil dimethacrylate based composite (Harmonize, Kerr). The specimens were finished using (Multi fluted tungsten carbide finishing bur for fifteen seconds) followed by polishing using (HiLuster, Kerr) polishing system. After that, the specimens were immersed in coffee solution for 7 days. Color difference ΔE was calculated before and after immersion of specimens for 48 hours and after 7 days using spectrophotometer (VITA easy shade).RESULTS: Mann Whitney U test showed significant difference in ΔE among composite restorative materials (p < 0.05). Venus diamond composite resin was found to be more stain-resistant than Harmonize composite resin after both 48 hours and 7 days.CONCLUSION: Different monomer compositions, immersion time and solution may have direct effect on the color stability of nanohybrid restorative materials.

Comparison between nanohybrid filler and submicron composite resin shade on color changes after polymerization

Background: Initial color determination of composite resins before polymerization is crucial to achieve an esthetic result that mimics the original tooth color. A filler particle size and composition affect the color change of the composite resin after polymerization despite the improvement in the chemical composition and filler of the composite resin. Objective: The effects of nanohybrid filler and submicron composite resin shade on color changes after polymerization were determined. Methods: Disc-shaped composite resin samples (diameter and thickness of 12 mm and 2 mm, respectively) were categorized into six groups, with each group containing 10 plates, according to the shade and type of filler (nanohybrid UD1, UD2, UD3; submicron OA1, OA2, OA3). Digital photographs were taken before and after polymerization. The changes in color (ΔE*ab values) were determined using software via eLABor_aid. Result: Only the Micerium EHRi UD1 composite resin group exhibited ΔE*ab < 3.3. The independent t-test revealed significant differences in the ΔE*ab (P < 0.05) between the nanohybrid and submicron composite resins in all shade groups (A1, A2, and A3). One-way analysis of variance revealed significant differences in ΔE*ab (P < 0.05) among A1, A2, and A3 between the nanohybrid and submicron composite resin groups. Tukey’s post hoc test revealed significant differences in ΔE*ab (P < 0.05) for the Micerium EHRi UD1 group compared with those of the UD2 and UD3 groups, as well as in the case of the Tokuyama Palfique OA1 group compared with those of the OA2 and OA3 groups. Conclusion: Nanohybrid filler and submicron composite resin shade affected color changes after polymerization. Compared to the darker color groups, brighter shades (UD1 and OA1) exhibited a lower-intensity color change.

Effect of a wear-resistant resin coat on the color stability of a resin-modified glass ionomer restorative material.

The purpose of this in vitro study was to evaluate the effect of the Equia Forte Coat on the color stability of Equia Forte Fil. Sixty discs of Equia Forte Fil were randomly divided into two groups. One group of 30 samples was treated with Equia Forte Coat according to the manufacturer's directions. The other 30 discs were not coated. All discs were continuously soaked in cola for 7 consecutive days. The color changes in the Equia Forte Fil samples were determined using a colorimeter. The color difference (△E) was calculated using the Commission Internationale de l'Eclairage L*a*b* coordinates. There was a significant difference in ΔE between the two groups (P < 0.0001). The group with Equia Forte Coat had significantly less color change than the group without the Equia Forte Coat. The application of the Equia Forte Coat significantly improved the color stability of Equia Forte Fil.

Effectiveness of Whitening Strips Use Compared With Supervised Dental Bleaching: A Systematic Review and Meta-analysis.

Bleaching performed at home while under the supervision of a dentist provides greater color alteration compared with whitening strips when evaluated with a spectrophotometer, although the color alteration was undetectable by unaided human eyes. Objective: A systematic review and meta-analysis were performed to answer the following research question: Does the use of whitening strips (WS) lead to an equivalent color change compared with supervised dental bleaching in patients with permanent dentition?Methods: A search was performed on August 10, 2017 (updated on March 22, 2019), in PubMed, the Brazilian Library in Dentistry, Latin American and Caribbean Health Sciences Literature database, Cochrane Library, Scopus, Web of Science, and SIGLE, without restrictions regarding date or language. Abstracts from the International Association for Dental Research, unpublished and ongoing trial registries, dissertations, and theses were also searched. Only randomized clinical trials (parallel or split mouth) in patients with permanent dentition that compared WS with dentist-supervised dental bleaching performed at home (AH) or in office (IO) were included. The risk of bias (RoB) was evaluated using the Cochrane Collaboration tool. A meta-analysis with subgroup analysis (low and high peroxide concentration) was conducted for color change ΔE* (spectrophotometer) and ΔSGU (shade guide units), risk and intensity of tooth sensitivity (TS), gingival irritation (GI), and patient satisfaction using a random effects model. Heterogeneity was assessed with the Cochrane Q test and I2 statistics. GRADE (Grading of Recommendations, Assessment, Development and Evaluation) was used to assess the quality of the evidence.Results: After the removal of duplicates, followed by title and abstract screening, 20 studies remained. Only two studies were considered to have a low RoB; 11 had a high RoB, and seven had an unclear RoB. For WS versus IO, data were not available for the meta-analysis. For WS versus AH bleaching, a significant difference in ΔE* favoring the AH group was observed (standardized mean difference [SMD] = -0.50, 95% confidence interval [CI] -0.79 to 0.21), but the risk (risk ratio = 0.78, 95% CI 0.65 to 0.93) and intensity of TS (SMD = -0.30, 95% CI -0.56 to -0.04) were lower in the WS group. Color change in ΔSGU, risk and intensity of GI, and patient satisfaction were not significantly different between groups (p>0.20). The quality of evidence for ΔE*, risk and intensity of TS, and intensity of GI were graded as moderate.Conclusion: Although the risk and intensity of TS were lower in the WS group, dentist-supervised at-home bleaching led to a better color change when measured with a spectrophotometer, although the color alteration was undetectable by unaided human eyes.

Clinical Efficacy of Four In-Office Vital Tooth Bleaching Products with Different Concentrations of Hydrogen Peroxide: A Randomized, Quadruple-Blind Clinical Trial

Background: Dental bleaching has become an everyday procedure for treating teeth presenting discoloration, as a therapy on its own or as a part of restorative dentistry. The most widely used bleaching products available for vital teeth are hydrogen peroxide and carbamide peroxide, marketed as a range of products adapted to different treatment modes. The purpose of the study was to evaluate the clinical whitening efficacy of four high-concentration bleaching products for vital teeth applied in single in-office sessions. Methods: This clinical trial included 40 patients divided into four groups according to the concentration of the hydrogen peroxide-based (HP) product used (Group 1: HP 35%; Group 2: HP 37.5%; Group 3: HP 38%; Group 4: HP 40%). Each patient received one in-office whitening treatment of maxillary and mandibular anterior teeth (incisors, canines, and premolars), making a total of 791 teeth. The color changes produced in central incisors and canines were measured. Results: All groups underwent significant color changes from initial to final evaluations for color parameters L*, a*, and b*. No significant differences between the four groups were found for either the L* or a* parameters. Analysis of the b* parameter found significant differences between the HP 38% group and the HP 35% group. No significant differences in ΔE were found between the four groups (ANOVA p = 0.174). HP 38% obtained the highest ΔE (4.63), while HP 40% obtained 4.01. Conclusions: A single in-office whitening session, regardless of the bleaching product used, modifies tooth color effectively. All four products achieved increases in the L* parameter and significant reductions in parameters a* and b*. The ΔE did not show significant differences between the four groups. In-office whitening with high concentration hydrogen-peroxide-based products was found to be an effective treatment for moderate and severe dental discoloration.

The effects of repetitive firing processes on the optical, thermal, and phase formation changes of zirconia

PURPOSEThe aim of this study was to investigate the effect of different numbers of heat treatments applied to superstructure porcelain on optical, thermal, and phase formation properties of zirconia.MATERIALS AND METHODSForty zirconia specimens were prepared in the form of rectangular prism. Specimens were divided into four groups (n = 10) according to the number of firing at heating values of porcelain. Color differences and translucency parameter were measured, and X-ray diffraction (XRD) analysis and differential scanning calorimetry (DSC) were performed. Data were analyzed with analysis of variance (ANOVA).RESULTSThere were no statistically significant differences in ΔE, TP, L, a, and b value changes of the zirconia specimens as a result of repetitive firing processes (P>.05).CONCLUSIONAlthough additional firing processes up to 4 increase peak density in thermal analysis, additional firing processes up to 4 times can be applied safely as they do not result in a change in color and phase character of zircon frameworks.

Influence of simulated gastric juice on surface characteristics of CAD-CAM monolithic materials

Statement of problemHow the surfaces of monolithic esthetic restorations behave in the presence of acidic substances is unclear. PurposeThe purpose of this in vitro study was to evaluate the effect of simulated gastric juice on roughness, morphology, microhardness, substance loss, and color change of computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic materials. Material and methodsDisks from Lava Ultimate, VITA ENAMIC, IPS e.max CAD, and VITA SUPRINITY were analyzed for roughness, morphology, and microhardness by using a confocal microscope, scanning electron microscope (SEM), and Vickers hardness tester. Substance loss was determined by weighing the specimens on an analytical balance, and color change (ΔE) was assessed by using a spectrophotometer based on the CIELab parameters. All analyses were carried out before and after acid exposure. ResultsAcid exposure significantly decreased the roughness, having a very high effect size on this property. The material was highly decisive in determining the microhardness, presenting the following order: VITA SUPRINITY>IPS e.max CAD>VITA ENAMIC>Lava Ultimate. The mass was not significantly affected by the acidic challenge. No significant difference in ΔE was found between Lava Ultimate and VITA ENAMIC and between IPS e.max CAD and VITA SUPRINITY. Lava Ultimate showed a higher ΔE than IPS e.max CAD and VITA SUPRINITY, whereas VITA ENAMIC exhibited higher ΔE only when compared with VITA SUPRINITY. All materials presented ΔE<1. ConclusionsThe simulated gastric juice significantly influenced the roughness of all the evaluated materials and promoted a color change classified as clinically undetectable in all materials.

Effect of lights with various wavelengths on bleaching by 30% hydrogen peroxide.

The objective of this study was to evaluate the bleaching effect of light sources with various wavelengths using 30% hydrogen peroxide (HP) in vitro. The hematoporphyrin-stained paper was bleached with HP and irradiated for 10min using LED light sources with 265, 310, 365, 405, or 450nm respectively. In control group, HP was applied for 10min without light irradiation. The bleaching procedure was repeated two times. The L*a*b* values of the samples before bleaching and after each bleaching step were measured using a colorimeter. Color changes of specimens were then calculated and statistically analyzed. There was an interaction between light sources and time of irradiation in the color change (p < 0.05). Time and light sources significantly affected ΔE and ΔL (p < 0.05). The light source of 256nm showed the highest bleaching effect over time followed by that of 310nm, which were statistically different from other groups (p < 0.001). The 365nm, 450nm groups, and control group showed low bleaching effect visually with no significant differences in ΔE and ΔL (p > 0.05). It was concluded that the wavelengths of the light sources affected the bleaching by HP. The 310-nm light can be a potential source for bleaching.

Teeth whitening with 6% hydrogen peroxide and its impact on quality of life: 2years of follow-up.

This study aimed to evaluate color longevity after 2years of whitening gel (6% hydrogen peroxide (HP), blue LED/infrared laser activation system) in comparison to a control 35% concentration in a split-mouth study and investigate the long-term effect on quality of life (QOL).Thirty-one patients were treated. Whitening using 6% or 35% HP gel was performed on half of the upper jaw in each patient. The color was measured at baseline and 1week, 1month, 1 and 2years after treatment using the Easyshade Vita spectrophotometer and the Vita Bleached and Vita Classical Shade Guides organized by value. During 2years of follow-up, color was evaluated before and after dental prophylaxis. Oral Health of Impact Profile (OHIP 14) and Psychosocial Impact Dental Aesthetics Questionnaire (PIDAQ) surveys measured QOL. Nineteen patients were evaluated at the 2-year follow-up. Significant differences in ΔE were measured between the two groups at all time points (p < 0.05). No significant differences in ΔSGU were observed at any time point (p > 0.05). The positive effect of bleaching on QOL was maintained in patients treated with a low concentration of the whitening gel. The two compounds remained effective after 2years. An objective color difference was found between the groups, but no difference was observed in subjective reports. The positive effect on QOL remained after 2years of follow-up in this cohort of patients.ClinicalTrials.gov identifier NCT02353611.

Colorimetric evaluation of white spot lesions following external bleaching with fluoridation: An in-vitro study.

ObjectiveThis study was performed to investigate the effects of external tooth bleaching with flouridation on the appearance of white spot lesions (WSLs) in vitro.MethodsIn total, 125 bracket-bonded bovine incisor enamel blocks with artificial WSLs were randomly divided into a control group and four treatment groups (home bleaching, home bleaching + fluoridation, in-office bleaching, and in-office bleaching + fluoridation). A spectroradiometer (SR) and digital images (DIs) were used to evaluate colorimetric parameters (Commission Internationale l'Eclairage L*a*b*) for all specimens. Color measurements were obtained before WSL formation (T1), after WSL formation (T2), and after completion of the external tooth bleaching treatment (T3).ResultsThe SR-based color change after bleaching was significantly greater in the treatment groups than in the control group (p < 0.05). SR-based lightness (L*) and red-green (a*) values were significantly higher at T2 than at T1 (p < 0.001), with no significant changes in yellow-blue (b*) values. At T3, SR-based L* values had increased while a* and b* values had decreased in the treatment groups (p < 0.001). The DI-based color difference between the sound enamel and WSL areas (ΔE*DI) increased significantly from T1 to T2 in all groups (p < 0.001) and significantly decreased from T2 to T3 in the treatment groups (p < 0.001). No significant differences in ΔE*DI at T3 were shown between the four treatment groups (p > 0.05).ConclusionsThe findings of this study suggested that external tooth bleaching with fluoridation can alleviate the conspicuity of WSLs.

An in vivo spectrophotometric evaluation of Vivera® and Essix® clear thermoplastic retainer discolouration

Abstract Aim To assess the in vivo colour alterations of two different clear thermoplastic retainers. Methods Thirty patients were randomly allocated into two Groups (N = 15) following the completion of active orthodontic treatment. Group 1 received Vivera® and Group 2 Essix® C+ thermoplastic retainers. Each patient was provided with two fabricated retainers (one for use and the other to serve as a control). The CIELAB parameters of the patients’ upper central incisors were measured with a SpectroShade™ spectrophotometer immediately after retainer placement (T0) and again after 15 days (T1), one month (T2) and three months (T3). The measurements were also performed on teeth without the retainer in place. ΔE differences were calculated. Methods ΔE changes from T0 to Tp T2 or T3 showed no statistically significant differences between Groups 1 and 2 within any combination of measurements or teeth. ΔEļŢ3-Ţ0ļ changes for used retainers were 1.55 times higher than control appliances (p = 0.002) and 1.44 times higher than for teeth-only (p = 0.004). For used retainers, changes between T3 and T0 were 1.56 times higher than between T and T0 and 1.47 higher than between T2 and T0 (p &lt; 0.001). There were no statistically significant differences in ΔE between teeth 11 and 21. Results Used retainers exhibited greater colour change than control appliances or teeth-only readings, and increased commensurate with the duration of use. Vivera® and Essix® retainers exhibited similar colour stability. All differences observed were considered clinically acceptable (ΔE &lt; 3.7), although prolonged use could cause clinically significant colour changes.