Days Of Bleaching Research Articles

Excessive Dental Bleaching with 22% Carbamide Peroxide Combined with Erosive and Abrasive Challenges: New Insights into the Morphology and Surface Properties of Enamel.

This study aimed to evaluate the effects of 22% carbamide peroxide combined with an erosive challenge and simulated brushing on enamel. Bovine incisor teeth were divided into G1, tooth bleaching; G2, tooth bleaching + erosive challenge; and G3, tooth bleaching + erosive challenge + simulated brushing, and evaluated at T0, before any intervention; T1, 14 days after the proposed treatments; and T2, 28 days after the proposed treatments. Tooth bleaching was performed daily for 1 h for 28 days. The microhardness, surface roughness, mass variation, and ultrastructure were analyzed at T0, T1, and T2. Two-way analysis of variance for repeated measures was performed and Tukey's post hoc test (α = 5%) was used. The surface roughness increased in groups G2 and G3 as a function of time, whereas microhardness and mass measurements demonstrated a significant reduction for groups associated with challenges. Ultrastructural evaluation indicated a loss of the aprismatic layer and exposure of the enamel prisms in all groups after 14 days of bleaching, with more pronounced results in G2 and G3 after 28 days. In conclusion, abrasive and erosive challenges potentiated the deleterious effects of tooth whitening on microhardness, ultramorphology, and mass, without affecting the roughness of dental enamel.

H2O2 gel bleaching induces cytotoxicity and pain conduction in dental pulp stem cells via intracellular reactive oxygen species on enamel/dentin disc.

Bleaching is widely accepted for improving the appearance of discolored teeth; however, patient compliance is affected by bleaching-related complications, especially bleaching sensitivity. This study aimed to investigate the role of reactive oxygen species (ROS) in cytotoxicity and pain conduction activated by experimental tooth bleaching. Dental pulp stem cells with or without N-acetyl-L-cysteine (NAC), an ROS scavenger, were cultured on the dentin side of the enamel/dentin disc. Subsequently, 15% (90 min) and 40% (30 min) bleaching gels were painted on the enamel surface. Cell viability, intracellular ROS, Ca2+, adenosine triphosphate (ATP), and extracellular ATP levels were evaluated using the Cell Counting Kit-8 assay, 2',7'-dichlorodihydrofluorescein diacetate, CellROX, fura-3AM fluorescence assay, and ATP measurement kit. The rat incisor model was used to evaluate in vivo effects after 0, 1, 3, 7, and 30 days of bleaching. Changes in gene and protein expression of interleukin 6 (IL-6), tumor necrosis factor-alpha (TNFα), transient receptor potential ankyrin 1 (TRPA1), and Pannexin1 (PANX1) in dental pulp stem cells and pulp tissue were detected through RT-PCR, western blotting, and immunofluorescence. The bleaching gel suppressed dental pulp stem cell viability and extracellular ATP levels and increased intracellular ROS, Ca2+, and intracellular ATP levels. The mRNA and protein expression of IL-6, TNFα, TRPA1, and PANX1 were up-regulated in vitro and in vivo. Furthermore, the 40% gel had a stronger effect than the 15% gel, and NAC ameliorated the gel effects. Our findings suggest that bleaching gels induce cytotoxicity and pain conduction in dental pulp stem cells via intracellular ROS, which may provide a potential therapeutic target for alleviating tooth bleaching nociception.

Titanium dioxide nanotubes incorporated into bleaching agents: physicochemical characterization and enamel color change.

Titanium dioxide nanotubes are nanostructures that can accelerate the oxidation reaction of bleaching procedures and promote a more effective whitening effect. Objective This study evaluated physicochemical properties of bleaching agents incorporated with titanium dioxide (TiO2) nanotubes, and the effects on tooth color change at different periods.Methodology 40 premolars were treated according to the following groups (n=10): CP - 10% carbamide peroxide (1 hour daily/21 days); CPN - CP incorporated into TiO2; HP - 40% hydrogen peroxide (three 40-minute sessions/7 days apart); HPN - HP incorporated into TiO2. Color shade was evaluated at five different periods (baseline, after 7, 14 and 21 days of bleaching, and 7 days after end of treatment) according to Vita Classical, CIELab and CIEDE2000 scales. Mean particle size (P), polydispersity (PO) and zeta potential (ZP) were evaluated using dynamic light scattering. Data on the different variables were analyzed by mixed model tests for measures repeated in time (ZP e L*), generalized linear models for measures repeated in time (P, PO, Vita Classical and b*), and Friedman and Mann-Whitney tests (a* and color change/ΔE and ΔE00).Results CP and CPN presented higher P, higher PO and lower ZP than HP and HPN (p≤0.05). All groups showed a significant decrease in Vita Classical color scores after 7 days of bleaching (p<0.05), and HPN presented a greater significant reduction than the other groups. L* increased in TiO2 presence, in all groups, without any differences (p>0.05) in bleaching time. A significant reduction occurred in the a* and b* values for all the groups, and HPN presented lower a* and b* values (p<0.05) than CPN. ΔE was clinically noticeable after 7 days, in all groups, and all groups resulted in a perceptible color change according to ΔE00.Conclusion TiO2 did not influence physicochemical properties of the bleaching agents. HPN presented more effective tooth bleaching than CPN.

Comparison and evaluation of color stability and flexural strength of various provisional restorative materials after bleaching: An in vitro study

Aims: The purpose of this in vitro study was to evaluate and compare the effect of bleaching (16% carbamide peroxide) on color stability and flexural strength of DPI Self-Cure Tooth Moulding Powder, Protemp 4, and Revotek LC. Materials and Methods: Disc-shaped 10 samples were prepared for each of the materials DPI Tooth Moulding Powder, Protemp 4, and Revotek LC with a dimension of 10-mm diameter and 4-mm height. Similarly for flexural strength, 30 rectangular samples with a dimension of 25mm × 2mm × 2mm were made for each material. All the disc-shaped samples were dipped in bleaching agent and ΔE values were recorded before bleaching after 7 and 14 days of bleaching using spectrophotometer. For flexural strength, 10 rectangular samples of each material were kept in bleaching agent for 7 days and 10 samples were kept for 14 days. Remaining 10 without bleaching acted a control group. The data were subjected to repeated measures analysis of variance test. Result: No statistically significant difference was observed between the mean values of color change before bleaching and after 14 days of bleaching for all three materials. But statistically significant difference was observed in mean values of color change among the three materials (P < 0.001). For flexural strength, statistically significant difference was observed between the mean values of flexural strength before bleaching and after 14 days of bleaching for DPI (P = 0.007) and Revotek LC (P = 0.026). Conclusion: All the three materials showed noticeable color change after 7 and 14 days of bleaching when compared with color of specimen before bleaching. Maximum color change was observed in Protemp 4 and least color change was observed in Revotek LC. Flexural strength was significantly different among the material as well as there were significant changes in flexural strength of each material after bleaching.

Clinical Evaluation of 10% Hydrogen Peroxide on Tooth Sensitivity and Effectiveness in at Home Dental Bleaching

The purpose of this study was to evaluate the dental effect and sensitivity of at-home dental bleaching with 10% hydrogen peroxide (H2O2). Twenty volunteers with A2 or darker central incisors were selected for this study. Was used 10% H2O2 for thirty minutes twice a day, for two weeks. Shade evaluation was assessed visually by the value-oriented shade guide Vita Classical shade guide, Vita Bleachedguide 3D-MASTER and by the Easyshade spectrophotometer at baseline, during bleaching (first and second weeks), and post-bleaching (one month). The perceptions of sensitivity were recorded by the patients through the numerical rating scale (0 to 4) and 0 to 10 visual analog scales daily. Data from the shade guide units was subjected to a one way repeated measures (RM) analysis of variance (ANOVA) test (a = 5%). The overall AE, absolute risk and intensity of tooth sensitivity were calculated as well as the 95% confidence interval. The absolute risk of tooth sensitivity was 65% and the intensity was mild. Data from ASGU and AE after 1 month of bleaching for H2O2 10% showed significant whitening, 4 units for Vita Classical, 5 units for Vita Bleachedguide and 9.7 units for spectrophotometer. At-home bleaching using 10% hydrogen peroxide is effective in 14 days of bleaching. The most common adverse events were mild tooth sensitivity, and no subjects discontinued use early because of a treatment-related adverse event. At-home dental bleaching with 10% hydrogen peroxide gel reduces the time of use of the tray, maintaining the effectiveness with low intensity of dental sensitivity. Brazilian clinical trials registry (REBEC) RBR-45xmzj.

Evaluation of the Efficacy and Color Stability of Two Different At-Home Bleaching Systems on Teeth of Different Shades: A Randomized Controlled Clinical Trial.

This randomized controlled clinical trial compared the bleaching efficacy of two different at-home bleaching systems on teeth of different shades and their color stability after a 6-month follow-up. Ninety-two patients (777 teeth) were randomly divided into three groups: (a) negative control, (b) patients treated with a custom-made tray containing 10% carbamide peroxide (10% CP/PF) (Opalescence PF), and (c) patients treated with a pre-loaded tray containing 6% hydrogen peroxide (6% HP/Go) (Opalescence Go). Teeth in all groups were divided into three sub-groups according to the VITA Classic Shade Guide: light (A1-C1), medium dark (C2-B3), and dark (A3.5-C4). Bleaching systems were performed in accordance with manufacturers' instructions for 14 days. The color values were measured at the baseline, 10 days and 14 days of bleaching, 2 weeks, and 6 months after bleaching. Three-way ANOVA and Mann-Whitney U tests were used for statistical analysis (α = 0.05). Irrespective of original shade, both bleaching groups showed significantly higher ΔE* values than the control groups, and the ΔE* values were significantly higher in the 10% CP/PF groups than those in the 6% HP/Go groups (p < 0.05). In both bleaching systems, the dark teeth showed higher ΔE* values than the light teeth (p < 0.05). The ΔE* values decreased significantly only in the 10% CP/PF groups after 6 months (p < 0.05). Both bleaching agents produced a bleaching effect, but 10% CP/PF was more effective. A pre-loaded tray system may be used for dental bleaching, but it is still less effective than conventional a 10% carbamide peroxide system, irrespective of the initial shade. (J Esthet Restor Dent 29:325-338, 2017).

Comparative Effects of Turmeric, Coffee, and Chewable Tobacco on the Color Stability of Tooth-colored Restorative Materials

Objective: To compare the staining intensity of turmeric and chewable tobacco with that of coffee and to investigate the impact of staining status on the bleaching efficacy of discolored restorative materials. Study Design: A total of 72 specimens from two types of dental composites (nanocomposite, and microhybrid composite) and two types of glass ionomer cements (conventional glass ionomers, and resin-modified glass ionomers) were immersed in different staining media including turmeric, coffee, and chewable tobacco (3 Hour/day). The color changes were measured at 15th, 30th, and 45th days of staining according to the CIELAB system. The discolored specimens were then bleached using a 10% carbamide peroxide solution (2×30 min daily) and the color changes were quantified after 7 and 14 days of bleaching. The obtained data were further analysed using ANOVA with complementary Tukey's test (p<0.05). Results and Conclusion: Chewable tobacco displayed the most overall staining effect on the selected materials, followed by coffee and turmeric. Nanocomposites showed the highest vulnerability to color change due to the exposure to coffee and turmeric, while the highest color change by chewable tobacco was observed in the resin-modified glass ionomers. In contrast, the conventional glass ionomers were least stained in all staining solutions. Carbamide peroxide also exhibited more bleaching effect on nanocomposites compared to other selected restorative materials. Clinical Significance: Conventional glass ionomers and microhybrid composites are more suitable compared to resin-modified glass ionomers and nanocomposites for utilization in places where esthetic longevity is the prime concern (anterior teeth and premolars in smile line) and patient has high intake of coffee, turmeric, or chewable tobacco.

Effect of dental bleaching after bracket bonding and debonding using three different adhesive systems

To evaluate the influence of bonding and debonding of orthodontic brackets on dental in-home bleaching, taking into account three different adhesive systems. Forty-four bovine incisors were divided into four groups according to the primer system used for orthodontic bracket bonding. Following the debonding of orthodontic brackets, the teeth were stored in staining solution for 96 hours. Then, teeth were whitened using 10% carbamide peroxide for two weeks at a 6-hour-a-day regime. Standardized digital photographs were taken at the following intervals: T₀ (initial); T₁ (after debonding); T₂ (after pigmentation); T₃, T₄ and T₅ representing 1, 7, and 14 days of bleaching. Repeatability and stability tests were carried out to check the method accuracy. Images were analyzed using Adobe Photoshop 7.0 software considering (L*a*b*) color coordinate values and a modified color difference total (ΔE'). The results of this study (ANOVA and Tukey; p < 0.01) demonstrated that after 7 days of bleaching, experimental groups showed significantly less teeth whitening compared to the control group. However, there were no significant color differences between the groups after 14 days, according to values of lightness (L*). Regardless of the adhesive primer system applied, bonding and debonding of orthodontic brackets alters the outcome of tooth whitening in the first 7 days of bleaching, however it has no influence on the whitening of the dental structure after 14 days of in-home dental bleaching with 10% carbamide peroxide.

Clinical evaluation of 4% hydrogen peroxide bleaching in mandibular teeth

Introduction: Bleaching agents have been constantly introduced into market; however, the efficacy of new hydrogen peroxides still needs to be evaluated. Objective: The aim of this study was to evaluate in vivo the effectiveness of 4% hydrogen peroxide bleaching agent in color change, bleaching maintenance, tooth sensitivity, and patients’ satisfaction. Material and methods: Forty subjects were selected, lower bleaching trays were constructed, and the patients were instructed to apply 4% hydrogen peroxide bleaching agent at home. Shade measurements of the mandibular anterior teeth were carried out with a spectrophotometer and Vita Classical shade guide (VITA) at the following moments: baseline, 14 days, after patients’ satisfaction, and after 90 days. In addition, tooth sensitivity was evaluated using a visual analogue scale (VAS) at the first 14 days. Shade measurements were submitted to repeated measures ANOVA with Bonferroni adjustment and level of significance set at 5%. Results: Statistically significant differences were found for mandibular tooth shade after at-home bleaching (p &lt; 0.001). After 14 days of bleaching, 90% of the subjects were not pleased with the achieved bleaching; however, after 27 days most of the patients reported to be satisfied. Tooth sensitivity was reported to range from 1.01 in a scale from 0-10. Conclusion: At-home bleaching using 4% hydrogen peroxide is effective in lower teeth with reduced tooth sensitivity.

Avaliação de Técnicas de Clareamento de Consultório com e sem o Uso de Luz (Laser/Led)

Current research compared two dental bleaching techniques with regard to bleaching and to dental sensitivity degrees. Ten volunteers, involved in the process according to inclusion and exclusion criteria, received a bleaching application of the upper and lower dental arch. Gel from hydrogen peroxide 35% (Whiteness HPMaxx - FGM) was applied by LED (Ultrablue Lazer System IV - DMC Equipments) to the patient’s right side. Three successive applications were carried out every 15 min, totaling 45 min. Bleaching gel Calcium Blue 35% (FGM) was applied to the left superior and inferior dental arches of the patient and kept on the vestibular surfaces during 45 min without any light source. Color scale classical Vita - VITAPAN® and digital images was employed for color evaluation prior to bleaching and after seven days. VAS questionnaire was used to measure sensitiveness prior to bleaching and after seven days of bleaching. Statistical analysis did not reveal any significant color difference between the groups, with or without the light activation of the bleaching gel. Sensitiveness was similar to both groups. Results show that bleaching techniques with or without light provided similar results with regard to bleaching. Patients considered sensitiveness as slight or nil and showed that the method is safe with regard to post-bleaching sensitiveness.

Tooth whitening with hydrogen/carbamide peroxides in association with a CPP‐ACP paste at different proportions

Different enhanced peroxide formulations have been developed to overcome mineral loss during tooth whitening. This study investigated the impact on tooth whitening from combining a CPP-ACP paste with home peroxide agents at several proportions. Ninety bovine incisors were randomly allocated into nine groups (n = 10) and exposed to 7.5% hydrogen peroxide (HP), 16% carbamide peroxide (CP), a CPP-ACP paste (Tooth Mousse/MI Paste, GC Corporation, Tokyo, Japan) and blends of HP/CP:MI at three proportions (1:1, 2:1 and 1:2). Tooth whitening was performed for 14 days and its effectiveness was measured by a spectrophotometer utilizing the CIE L*a*b* system (ΔE, ΔL*, Δa* and Δb*). Colour readings were measured at baseline (T0), 7 days of bleaching (T7), 14 days of bleaching (T14) and 7 days after the end of bleaching (T21). Data were analysed by two-way ANOVA for paired averages followed by the Tukey's test and Pearson's correlation at 5%. Although CP produced the greatest colour change (ΔE), all whitening protocols were considered to be effective regardless of the CPP-ACP presence. In general, greater changes in ΔE, ΔL*, Δa* and Δb* were detected at T14, with T21 exhibiting similar results to those at T7. A greater number of strong correlations with ΔE values was found for a* (11/15). Within the limitations of this study, the results indicate that the CPP-ACP paste did not affect tooth whitening efficacy.

Comparison of Effectiveness of Two 10% Carbamide Peroxide Tooth‐Bleaching Systems Using Spectrophotometric Measurements

The purpose of this study was to compare the color changes achieved with two commonly used bleaching systems on the basis of a spectrophotometric analysis. Two commercially available 10% carbamide peroxide bleaching systems were used by a total of 48 individuals. Subjects who had intact natural maxillary anterior teeth void of any restorations or decay that had not been subjected to any prior bleaching were included. Opalescence 10% PF (Ultradent Products Inc., South Jordan, UT, USA) was used by 23 patients for 14 days, whereas Nite White Excel (Discus Dental, Culver City, CA, USA) was applied by 25 patients for the same duration. Tooth colors for the middle one-third region of maxillary central incisors and canines were measured with a spectrophotometer prior to bleaching and after 14 days of bleaching. Color difference deltaE and color coordinates L* (lightness), a* (redness), and b* (yellowness) of CIELAB color system (developed by the Commission Internationale de l'Eclairage) were calculated. Mean deltaE values for Opalescence ranged from 5.03 to 8.92 and from 5.84 to 9.61 for Nite White. The most significant factor of the color change was b* followed by L* and a*. L* values were higher after bleaching, whereas values for both a* and b* decreased. There were no significant differences between the two systems examined (p < .05).

Bleaching effect of carbamide peroxide gel on discolored nonvital teeth

The bleaching of discolored nonvital teeth is conservative treatment that satisfy the cosmetic desire. The most common method for this treatment, walking bleaching, is using 30% hydrogen peroxide and sodium perborate. Many alternatives are suggested for preventing the external cervical root resorption that is the common complication of the nonvital teeth bleaching with 30% hydrogen peroxide The same extent of oxidation reactions as that resulted by the bleaching with the application of 30% hydrogen peroxide and sodium perborate can also be acquired more safely by materials that contain 10% carbamide peroxide, used primarily for the bleaching of vital teeth. Therefore, this study was performed to evaluate the efficacy of 10% and 15% carbamide peroxide bleaching gel in nonvatal teeth bleaching. The internal bleaching of intentionally discolored teeth was performed in vitro with 10% carbamide peroxide (Group 1), 15% carbamide peroxide (Group 2), mixture of distilled water and sodium perborate (Group 3), and mixture of 30% hydrogen peroxide and sodium perborate (Group 4). The bleaching materials were refreshed following 3, 6, 9 and 12 days. To evaluate the bleaching effect, the color change of the crowns was measured at 1, 2, 3, 4, 7 and 15 days of bleaching using the colorimeter. The results were as follows：1. L and E values were increased with time in all bleaching agents (p and E value among bleaching agents. 3. E value higher than 3 was shown after 3 days of bleaching with 10% carbamide peroxide gel, 1 day with 15% carbamide poroxide gel, 4 days with mixture sodium perborate and distilled water and 4 days with mixture sodium perborate and 30% hydrogen peroride, respectively. These results revealed that the use of 10% and 15% carbamide peroxide bleaching gel in non-vital teeth bleaching is as effective as mixture of distilled water and sodium perborate and mixture of 30% hydrogen peroxide and sodium perborate. Accordingly, carbamide peroxide could be used clinically to bleach discolored non-vital teeth.