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Purpose: The aim of this study was to evaluate the effects of two different home bleaching agents on color stability and surface roughness of hybrid ceramics. Materials and Methods: Three dental hybrid ceramics (Lava Ultimate, Cerasmart, and Vita Enamic) and two different home bleaching agents (9.5% hydrogen peroxide and 22% carbamide peroxide) were used. Thirty specimens of each material were prepared with dimensions of 12 × 14 × 1 mm. Technical polishing kits were applied to one surface of the specimens for the surface finishing procedure. Color parameters (L*a*b*) of the specimens were measured. Three subgroups were determined: control (C), hydrogen peroxide (HP), and carbamide peroxide (CP) (n = 10 each). After the bleaching procedures, color parameters were remeasured and color differences (ΔE) were calculated. Surface roughness values of the specimens were detected with a profilometer. Surface analysis of one specimen of each group was performed with a scanning electron microscope. Data were analyzed by two-way ANOVA and Tukey honest significant difference tests. Results: There was an interaction between material and bleaching agent type (P < .05). The highest ΔE values were observed in CP groups, and the lowest ΔE values were observed in control groups. For surface roughness, there was not an interaction between material and bleaching agent type (P >.05). Material and bleaching agent factors had a significant effect on surface roughness (P < .05). The highest surface roughness values were detected in HP groups. Conclusion: Home bleaching agents caused clinically acceptable color differences on hybrid ceramic materials. Hydrogen peroxide increased the surface roughness of hybrid ceramics. [ABSTRACT FROM AUTHOR]

Recent advances in bleaching technology, such as bleaching ingredients, have accelerated the development of tooth whitening materials to change the color of natural teeth toward a lighter or whiter shade. Some bleaching materials are used for patients in combination with auxiliary medical devices to activate the bleaching materials by a light or heat source. Bleaching ingredients can be a poisonous and deleterious substance. Some bleaching materials are used in dental offices and the others at home. In clinical development of bleaching materials, appropriate evaluation of safety and efficacy is required according to the intended use. For appropriate and swift approval of the emerging bleaching materials, guideline on evaluation of dental whitening materials was discussed in a commissioned project by the Ministry of Health, Labour and Welfare of Japan for FY2021. Here, we summarize the current principles of the premarketing evaluation of the safety and efficacy. [ABSTRACT FROM AUTHOR]

The most frequently used bleaching materials are hydrogen and carbamide peroxide materials with specific concentration and techniques. The disadvantages of these materials range of sensitivity to bone inflammation and resorption processes. Therefore, it is desirable to employ alternative natural materials with little to no negative effects on the enamel, pulp and oral mucosa. This article reviews recently developing materials like papain, bromelain, chlorine dioxide, sodium chloride and sodium bicarbonate and a combination of peroxide and natural substances. In studies employing bromelain and papain in comparison to peroxide bleaching materials, the peroxide materials evolved to show better stain removal than the natural alternatives. It is worth mentioning that the concentrations of natural materials used were 20 times lesser compared to the peroxide materials. Chlorine dioxide was found to improve bleaching efficacy by virtue of the warmth that was created on application of light, leading to dryness of teeth. This material needs further research and improvement to match its conventional alternatives in efficacy. The newer alternatives considered in this line-up are sodium chloride and sodium bicarbonate. There was no slod scientific support to back this material's efficacy to conclusively compare it against peroxide materials. Finally, combination materials including lactoperoxidase along with hydrogen and carbamide peroxide showed to increase after 8 hours of contact than the system without lactoperoxidase. It can be concluded by saying that further research is required to find better alternatives to peroxide materials with better efficacy. Nanoparticles, off late, have found extensive purpose in modern day dentistry. The application of nanoparticles in bleaching is through hydroxyapatite nanoparticles. These nanoparticles concentration dependent whitening in comparison with carbamide peroxide. Recent developments including reduced graphene oxide has also been tried as an alternative to conventional bleaching methods. This material provided significant results and prove to be promising alternatives to peroxide tooth bleaching materials. This article reviews the developments and efficacy of non-peroxide bleaching materials. [ABSTRACT FROM AUTHOR]

Objectives: The development of new bleaching agents with minimum concentration of hydrogen peroxide (HP), without adverse effects, and with bleaching effectiveness, has great clinical relevance. The aim of this study was to evaluate the bleaching efficacy and cytotoxicity of a new niobium-based bleaching gel, compared to already available HP-based gels. Materials and methods: For the bleaching efficacy analysis, 40 bovine incisors were randomly divided into 4 groups according to the established bleaching protocol: control, untreated; 35HP, 35% HP bleaching gel; 6HP, 6% HP bleaching gel; NbHP, niobium gel associated with 3% HP gel. The color variation was measured in a spectrophotometer and the values of ΔL, Δa, Δb, and ΔE obtained. For the cell viability assay by MTT, MC3T3 cells were exposed to bleaching gel extracts (1:500, 1:250, 1:125 dilutions; immediately and 24 h). Statistical tests were performed (P < 0.05). Results: The color alteration for all bleaching gels was significant compared to control (P < 0.05), but the NbHP gel showed a significant ΔE than other gels, with expressive color alteration at 14 days (P < 0.05). The 35HP showed high cytotoxicity regarding control and the most groups in all periods and extracts analyzed (P < 0.05), while the NbHP showed greater cell viability than control in the immediate period, dilution of the 1:500 and superior to 6HP in the most extracts at 24 h. Conclusion: The new experimental niobium-based gel has bleaching efficacy similar to that of gels with a high concentration of HP, and it has high cytocompatibility. Clinical relevance: The use of this new generation of niobium-based whitening gel associated with a low concentration of hydrogen peroxide represents the possibility of a tooth whitening with lower dentin sensitivity. [ABSTRACT FROM AUTHOR]

Objectives: The current tooth bleaching materials are associated with adverse effect. Photodynamic method based on a novel photosensitizer alone, without combining with peroxides, is evaluated for tooth bleaching application. Materials and methods: Teeth samples were randomly divided into 3 groups with different treatment schemes, including negative control group (group A, physiological saline), experimental group (group B, ZnPc(Lys)5), and the positive control group (group C, hydrogen peroxide). Tooth color, surface microhardness, and roughness were determined at baseline, right after the first and second phase of bleaching, as well as 1 week and 1 month post-bleaching. Four samples in each group was randomly selected to evaluate the changes in surface morphology using the scanning electron microscope. Results: The color change values (ΔE) in group B (7.10 ± 1.03) and C (12.22 ± 2.35) were significantly higher than that in group A (0.93 ± 0.30, P < 0.05). Additionally, surface microhardness and roughness were significantly affected in group C, but not in the group A and B. Furthermore, the scanning electron microscope images showed no adverse effect of enamel in the group A and B while the group C demonstrated corrosive changes. Conclusions: ZnPc(Lys)5 had a satisfactory bleaching effect and is promising to be a new type of tooth bleaching agent. Clinical relevance: The current tooth bleaching materials give a satisfactory clinical outcome and long-term stability, but associated with some adverse reactions. Photosenstizer ZnPc(Lys)5 eliminated the main side effects observed in hydrogen peroxide-based agents on the enamel, and also had a satisfactory bleaching effect and provide a novel selective bleaching scheme for clinical use. [ABSTRACT FROM AUTHOR]

Purpose: To assess the influence of adhesive restorations on hydrogen peroxide (H2O2) diffusion through enamel and dentin and its cytotoxicity to pulp (MDPC-23) cells. Materials and Methods: Sound and resin-restored enamel/dentin disks were stored in water for 24 h or 6 months and adapted to artificial pulp chambers. Bleaching gels with 20% or 35% H2O2 were applied to the enamel surface for 45 min, and a culture medium in direct contact with the dentin surface (extract) was applied for 1 h to the MDPC-23 cells. Cell metabolism (MTT assay) and cell morphology (SEM) were assessed. The amount of H2O2 in the extracts was also quantified (peroxidase/leuco-crystal violet reaction). Results: A significant reduction in cell metabolism was observed between the group bleached with the 35% gel and the control group (sound, nonbleached) (p < 0.05). The H2O2 diffusion was directly related to its concentration in the bleaching gel. The variables "presence of restoration" and "time of water storage" did not significantly influence H2O2 diffusion or cell metabolism for either of the bleaching gels (p > 0.05). All bleached groups presented alterations in cell morphology related to the concentration of H2O2 in the bleaching gel. Conclusion: The reduction in cell metabolism and the changes in cell morphology were H2O2-concentration dependent, having no relationship with the presence of either new or aged adhesive restorations on teeth subjected to bleaching therapies. [ABSTRACT FROM AUTHOR]

Background: Bleaching methods have been developed using peroxide compounds as bleaching material. The process of bleaching agent such as hydrogen peroxide works by forming unpaired electrons or what is called Reactive Oxygen Species (ROS). Purpose: to determine the effect of cocoa bean extract containing theobromine in inhibiting the decrease in microhardness that occurs after the application of bleaching material. Methods: This type of research is experimental laboratories using the Experimental Pre and Posttest Only Group Design. The sample of this study was 27 bovine incisive tooth enamel taken from the abattoir. The data obtained were analyzed by repaired ANOVA test and continued with Turkey's HSD test. Result: The value of the average difference in enamel surface hardness between the control and treatment concentrations of 15% was 10.99; between the control group and the extract of the cocoa beans (Theobroma cacao) concentration of 25% is equal to 31.94. Conclusion: this research is the extract of cocoa (Theobroma cacao) concentrations of 15%, 25% and 35% can increase enamel hardness after the bleaching process. [ABSTRACT FROM AUTHOR]

Bleaching refers to tooth whitening through the application of chemicals to the tooth surface, to oxidize organic pigmentation. This method has become a favored treatment in the community, to support the appearance of teeth. However, the use of chemicals during the bleaching process can result in reductions in tooth enamel hardness due to demineralization. The aim of the present study to determine the effects of hydroxyapatite (HA) paste, synthesized from chicken eggshells, on the microhardness of tooth enamel after the application of external bleaching materials. This study was conducted using 24 permanent maxillary central incisors, which were divided into four groups. Group 1 received sequential at-home bleaching and HA paste; group 2 received sequential at-home bleaching and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste; group 3 received sequential in-office bleaching and HA paste; and group 4 received sequential in-office bleaching and CPP-ACP paste. Enamel hardness tests were performed using a Universal Hardness Tester tool. Statistical analysis was performed using the Wilcoxon signed-rank test. The results show that the applications of HA paste, synthesized from eggshells, after the application of in-office bleaching, resulted in significant (p<0.05) increases in tooth enamel microhardness. In contrast, no significant effect was observed after the application of at-home bleaching. In conclusion, HA paste derived from eggshells can increase the microhardness of tooth enamel after the application of external bleaching materials. [ABSTRACT FROM AUTHOR]

The aim of this in vitro study was to evaluate the bleaching efficacy of high concentration bleaching agents activated by chemical or physical catalysts. This study was divided into two parts. Part 1 evaluated the efficacy of tooth whitening after treatment with 35% hydrogen peroxide (Whiteness HP Maxx) that was activated by different light-curing units: halogen lamp (conventional and bleach mode)(Optilux 501C, Demetron/Kerr), LED first generation (Ultrablue IV, DMC), LED/ diode laser (Ultrablue IV, DMC), LED second generation (Bluephase 16i, Ivoclar Vivadent), and no light source (control group). Part 2 provided an analysis of the effect of chemical and physical catalysts on high concentration bleaching agents: 35% hydrogen peroxide (Whiteness HP Maxx) + 20% sodium hydroxide; 35% hydrogen peroxide + 7% sodium bicarbonate; 38% hydrogen peroxide (Opalescence Xtra Boost); 35% hydrogen peroxide + halogen lamp; 35% hydrogen peroxide + 20% sodium hydroxide + halogen lamp; 35% hydrogen peroxide + 7% sodium bicarbonate + halogen lamp; 38% hydrogen peroxide + halogen lamp; and 35% hydrogen peroxide. Blocks obtained from human molars were randomly divided into groups (n = 5) in accordance with bleaching treatments. The efficacy of bleaching was measured using a spectrophotometer. Three bleaching sessions were performed. The results were submitted to ANOVA followed by the Tukey test (5%).For both parts of the study, activatedvs. non-activated bleaching did not differ significantly for all sessions tested. Activating systems did not improve the whitening effectiveness of high concentration bleaching agents. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the durability of bleaching results achieved with (1) 15% carbamide peroxide home bleaching and (2) 38% hydrogen peroxide in-office bleaching. A total of 231 extracted anterior teeth were randomly divided into three groups (n = 77 in each group) with comparable mean baseline L*-values (68.24 ± 0.8): a non-bleached control group A, a 15% carbamide peroxide group B (5 bleaching intervals of 8 hours), and a 38% hydrogen peroxide group C (3 intervals of 15 minutes). Durability of bleaching was assessed by comparing CIE-L*a*b* data after intervals of 2, 4, 12, and 26 weeks from baseline. Both bleaching regimes initially produced a highly significant increase in lightness parameter L*, with no significant difference between the respective bleaching regimes (B: 68.23 / 72.48; C 68.32 / 73.25). Six months after starting the trial, L*-values for group B yielded no significant differences compared to baseline (69.55), whereas L*-values for group C were still significantly raised (69.91), despite a highly significant decrease when compared to initial bleaching results. In both treatment groups, there was a lasting response to bleaching in terms of CIE-a* and -b* value decreases. Results for both home- and in-practice regimes were found to be similar for about 12 weeks. However, in-office results were longer lasting, despite the shorter treatment intervals. Summarized bleaching effects, in terms of delta E values, revealed no significant differences between treatment groups and the control group after 6 months, indicating an abatement of the bleaching results achieved. [ABSTRACT FROM AUTHOR]

Objectives: This double-blind study examined the bleaching effectiveness of two 30% carbamide peroxide bleaching gels: one with 5% potassium nitrate (treatment A) and one without (treatment B). The treatment time was reduced for this pilot study to 1 hour per day for 10 days to determine whether the higher concentration would whiten teeth and to ascertain the tooth sensitivity and gingival effects of the 30% solution. Method and Materials: Forty subjects were selected with an initial tooth shade corresponding to Bioform shade guide B65 or darker. After obtaining consent, subjects were randomly divided into two groups (n = 20). Custom-fabricated bleaching trays were made for each subject. Trays did not extend onto the gingiva. Each subject was instructed in the placement and wear of the tray and bleach and supplied with one of the two bleaching gels. Subjects had 10 hours of treatment time with the bleaching gel. Photographs and shades (using a standardized Bioform shade guide) were taken at baseline and at final recall to determine bleaching effectiveness. Tooth sensitivity was measured at baseline and final recall by applying a pellet saturated with skin refrigerant to the tooth for 2 seconds. The sensitivity was recorded on a scale ranging from 1 to 10. Gingival index was also measured at baseline and at final recall. Data were analyzed with Wilcoxon rank-sum and Wilcoxon signed rank tests. Results: No significant differences were found for changes in color, tooth sensitivity, and gingival condition between the two bleaching gels ( P = .899, P = .375, and P = .056, respectively). Within each group, bleaching gel A and B significantly whitened teeth ( P < .0001 for both groups). There were no significant changes in tooth sensitivity and gingival condition for gel A ( P = .057 and .063, respectively) or gel B ( P = .911 and .510, respectively). Conclusion: Thirty percent carbamide bleaching gels effectively whiten teeth without causing a significant increase in tooth sensitivity or changes in gingival condition. Potassium nitrate has little effect in sensitivity when treatment time is short. [ABSTRACT FROM AUTHOR]

Objectives: It has been suggested that tooth whitening might cause considerable pain. The aim of this study was to evaluate subjective intensities of pain during bleaching of vital teeth and to assess the patients' contentment with the treatment outcome. Method and Materials: Thirty patients were treated for 1 week in a double-blind study design. Employing gels containing 17%, 10%, or 0% (control group) carbamide peroxide, patients wore bleaching trays for 2 hours per day and described subjective intensities of pain while wearing the trays by means of a visual analog scale. The patients' subjective contentment with the bleaching outcome was measured with an intermodal intensity comparison. Results: For the 17% gel, a median value of 3.5 U (max: 10; min: 1) for pain intensity was observed; this was statistically different from the value seen with the 10% group (2.0 U; max: 7; min: 0) (P < .05). Both test groups differed significantly from the control group, which had a median value of 0.0 U (max: 3; min: 0) (P < .05). Patients' contentment with the treatment outcome did not differ between the test groups (P > .05), although statistical differences were observed between the control and the test groups (P < .05) after bleaching for 1 week. Conclusion: Application of carbamide peroxide-containing bleaching agents to vital teeth causes pain correlated with the agent's concentration. Since both highly and less concentrated gels might result in a similar contentment with the treatment outcome, the use of highly concentrated agents appears not to be justified to improve vital tooth color. [ABSTRACT FROM AUTHOR]

Objective: This in vitro study aimed to evaluate the effect of bleaching agents on dentin microhardness during and after bleaching. Method and materials: Specimens were randomly assigned to seven groups (n = 15): Nite White Excel 2 Z [NW] 10% and 22%; Rembrandt [REM] 10% and 22%; Opalescence [OPA] 10% and 20%; and a placebo agent. The 42-day whitening treatment consisted of daily application of the agents to the dentin surfaces for 8 hours, followed by immersion in artificial saliva for 16 hours. After the bleaching treatment, specimens were kept immersed in artificial saliva for 14 days. Microhardness was measured at baseline, 8 hours, and 7,14. 21,28, 35, and 42 days of bleaching and during the posttreatment period (7 and 14 days). Results: The analysis of variance for split-plot showed a significant effect on the interaction between bleaching agent and time. Tukey's test and regression analyses revealed that during the bleaching period, the agents NW 10%, NW22%, and OPA 20%, which did not differ from each other, did not alter dentin microhardness, showing constant microhardness values. There were no differences among REM 10%, REM 22%, and OPA 10%, which showed significant reductions in microhardness after day 14 compared to other agents. After bleaching procedures, there was an increase in dentin microhardness for all groups. Conclusion: Throughout the bleaching treatment, depending on the agent applied, dentin showed a transitory decrease in microhardness values. In the posttreatment period, artificial saliva presented a remineralizing effect on the bleached surfaces. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this in vitro study was to evaluate the microhardness of human dentin exposed to two 10% carbamide peroxide agents at different bleaching times. Method and materials: Opalescence 10% and Rembrandt 10% were tested. A placebo agent was used as a control group. The bleaching and placebo agents were applied to the surface of human dentin fragments for 8 hours and then stored in individual receptacles with artificial saliva for the remaining 16 hours each day. Microhardness testing was performed at baseline, after 8 hours, 7, 14, 21, 28, 35, and 42 days of treatment, and 7 and 14 days posttreatment. Results: Analysis of Variance and the Tukey test revealed significant differences in micro- hardness values for dentin treated with the agents within each time interval. There was a decrease in the microhardness values of dentin for both bleaching agents after 8 hours of treatment. Fourteen days after the completion of treatment, the microhardness values for dentinal surfaces treated with either Opalescence or Rembrandt reached the baseline values; the dentinal surfaces treated with a placebo exhibited an increase in microhardness values posttreatment. Conclusion: Ten percent carbamide peroxide bleaching agents decreased dentinal microhardness over time, but after 14 days in artificial saliva storage at the completion of treatment, the baseline microhardness values were recovered. [ABSTRACT FROM AUTHOR]

Objective: After bleaching treatment, esthetic restorations often need lo be replaced due to color changes. Some papers have shown alterations in the bond of adhesive restorations to bleached teeth. The purpose of this study was to evaluate tooth and resin composite adhesion when submitted to nonvital dental bleaching. Method and materials: One hundred and twenty bovine teeth were assigned to 3 groups (n = 40): paste of sodium perborate and water; 37% carbamide peroxide gel; and no bleaching (control). After 3 weeks of continuous bleaching treatment, standardized Class V cavities were prepared at the cementoenamel junction and restored with Single Bond adhesive system and Z100 resin composite. The samples were thermocycled 1,500 times (5 ± 1 / 55 ± 1°C) with a 1-minute dwell time. Then, they were immersed in a 2% methylene blue solution (pH 7) for 4 hours, sectioned, and analyzed by stereomicroscopy. Microleakage analyses were done, using scores from 0 to 4, considering leakage on the incisal wall (enamel) and the cervical wall (dentin). Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (α = 0.05). Results: The results showed that sodium perborate and carbamide peroxide gel significantly increase the microleakage in Class V resin composite restorations to dentin but not to enamel margins. Conclusion: The risk of microleakage in dentin margins is increased soon after bleaching treatment. [ABSTRACT FROM AUTHOR]

The article presents the authors' comments on the difference between dentist-prescribed, home-applied bleaching of teeth from over-the-counter therapies. The author says that concerns are growing related to the rapid proliferation of over-the-counter bleaching materials, despite the success of dentist-supervised nightguard vital bleaching. He says proper check up of teeth is needed before application of bleaching products.

Abstract: Aim: To evaluate lymphocyte‐like cell activation (CD5‐positive cells) and the expression of interleukin (IL)‐6 and IL‐17 in the pulp after tooth bleaching with two concentrations of hydrogen peroxide (H2O2). Methodology: The right and left maxillary molars from 40 rats were treated randomly with bleaching gel with 20% H2O2 (BLUE group, 1 application of 50 min), 35% H2O2 (MAXX group, three applications of 15 min), or placebo gel (control). After 2 and 30 days, the rats were killed (n = 10), and the jaws were processed for histological and immunohistochemistry analysis of the pulp tissue. The scores of inflammation and immunolabelling (IL‐6/IL‐17) were submitted to Mann–Whitney and Kruskal–Wallis followed Dunn tests, respectively; anova tests were used for comparisons of number of CD5‐positive cells and pulp chamber area values (P < 0.05). Results: At 2 days, 60% of specimens of the BLUE group were associated with moderate inflammation in pulp horns, and in the MAXX group with necrosis (P < 0.05). At 30 days, the pulp was organized, and tertiary dentine was formed. The MAXX group had superior immunolabelling of IL‐17 at 2 days differing significantly from other groups (P < 0.05). At 2 days, 90% of the specimens of the BLUE group had moderate immunolabelling of IL‐6, and 50% of the MAXX group had severe immunolabelling, both significantly different from the control (P < 0.05). There was no significant difference between the groups at 30 days (P > 0.05). CD5‐positive cells were present at 2 and 30 days, particularly in the bleached groups (P < 0.05), without significant difference between time periods (P > 0.05). Conclusions: IL‐6 and IL‐17 participated in inflammation in the pulp tissue of rats after tooth bleaching, particularly at 2 days. The immunolabelling was greater with increasing H2O2 concentration. This process was accompanied by the prolonged activation of CD5‐positive cells. [ABSTRACT FROM AUTHOR]

The present case study quantifies the clinical wearing time of an acetate tray/bleaching product during home dental bleaching. The patient was instructed to use a 10% carbamide peroxide gel for 6-8 hours each day for 20 days. The wearing time of the tray was measured by a microsensor from TheraMon microelectronic system (Sales Agency Gschladt, Hargelsberg, Austria) completely embedded in the tray so that the clinician would be informed as to the precise time the tray was placed in the mouth. Evaluation of the daily printout during dental bleaching demonstrated that the patient did not correctly follow the clinician's instructions as to the wearing time of the tray. Recording the wearing time of dental bleaching agents can be beneficial for both dental professional and patient to obtain a more effective treatment according to the patient's needs and expectations. [ABSTRACT FROM AUTHOR]

Background: Tooth discolouration could occur due to bacterial contamination in traumatized teeth. Hydrogen peroxide is the commonly used bleaching agent. However, due to concerns over safety, alternative bleaching regimes such as sodium perborate (S) and thiourea-hydrogen peroxide (T) have been investigated.Methods: Apices resected and pulp extirpated 99 premolars were divided into two groups. Group 1 and 2 was injected with blood and blood/bacteria, stored anaerobically for 35 days. The two groups were treated by bleaching with water, S or T. Teeth were rebleached after 7 days. Colourimetric evaluation was assessed using digital imaging, CasMatch standardization and CIE L*a*b colour system preoperatively, 35 days of staining and 7 and 14 of bleaching. A linear mixed model with fixed effects of time, group and bleach was used to examine colour difference.Results: Blood-stained teeth were significantly redder and darker on day 35 compared with blood/bacteria-stained teeth. After bleaching, blood-stained teeth retained significant redness compared with blood/bacteria-stained teeth using either S or T. T produced a significantly whiter shade in both the groups after 14 days.Conclusions: Blood-stained teeth were significantly darker and red compared with blood/bacteria-stained teeth. T bleaching regime was more effective than S. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Bleachorexia, addiction to tooth bleaching, is a behavioral disorder similar to anorexia. The patient feels that their teeth are always not white enough and continues to use whiteners to obtain a “perfect” smile. Such behavior falls under the category of a body dysmorphic disorder and may need medical counseling. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study is to evaluate clinical and patient reported outcomes of different bleaching products.Materials and Methods: Thirty participants were randomly divided into three bleaching groups (n = 10). Bleaching was performed with high concentrations of hydrogen peroxide (HP) - Boost (40%) and Dash (30%), and with prefabricated splints Bite&White (6% HP). Tooth colour was measured before, immediately after, and 1 and 6 months after the bleaching by using classical shade guide and spectrophotometer. Tooth hypersensitivity was self-rated by patients on the Wong-Baker's face scale. Patient satisfaction was evaluated on a 7-point Likert-type scales that measured perceived performance and importance of different characteristics of bleaching treatment.Results: All products were effective in teeth colour change (ΔE > 3.3), which was significantly higher for Boost (p = .016) and Dash (p = .024) than Bite&White treatment. Perception of hypersensitivity was the highest in Boost group, followed by Dash and Bite&White treatment. Most of the patients were satisfied with final tooth colour, length and comfort during treatment, but were dissatisfied with the stability of bleached tooth colour.Conclusion: Materials with the higher concentrations of bleaching agent demonstrated greater bleaching effectiveness than at-home bleaching product, but also a greater hypersensitivity. Lengthening the treatment process, but achieving a more stable tooth colour may improve the perceived value of a bleaching service. [ABSTRACT FROM AUTHOR]

Aims and Objectives: This study aimed to evaluate the effects of at-home and in-office bleaching on the shear bond strength (SBS) of metal, ceramic, and composite orthodontic brackets and to compare their SBSs.Subjects and Methods: A total of 96 human lower premolar teeth were used for this study. Six teeth were used for scanning electron microscopic study while the remaining ninety were divided into three equal groups. Each group was further subdivided into three subgroups with ten samples each. Three protocols were used. In the at-home bleaching group (n = 30), opalescence non-PF (potassium nitrate and fluoride) bleaching agent (10% carbamide peroxide) was applied onto the teeth daily for 14 days and left for 8 h each day. Teeth in the in-office group (n = 30) were treated twice in consecutive days with Opalescence boost PF (40% hydrogen peroxide). After bleaching, the specimens were stored in distilled water for 1 day before bonding. SBS testing was performed on all teeth using Instron universal testing machine.Results: Analysis of variance indicated a significant difference (P < 0.005) among the groups. Maximum SBS was shown by ceramic brackets in control group (Ib) and minimum was shown by composite brackets of in-office bleached group (IIIc).Conclusions: The results showed that at-home bleaching did not affect the SBS significantly whereas in-office bleaching reduced SBS of metal, ceramic, and composite brackets significantly. It is preferable to use metal or ceramic brackets than composite brackets for bonding 24 h after bleaching. [ABSTRACT FROM AUTHOR]

Purpose: To assess the hypothesis that there was no difference in effect of 10% and 15% tooth bleaching agents on color stability of materials used for provisional fixed dental prosthesis.Methodology: Fifteen samples from two materials used for provisional fixed dental prosthesis: methacrylate-based and composite-based materials and 15 preformed polycarbonate crowns soaked in bleaching gel or distilled water. Spectrophotometer recorded color of specimens at baseline, after 3, 7, and 14 days. Data were statistically analyzed using two-factor ANOVA test to compare the color stability of tested materials.Results: Methyl-based provisional material exhibited statistically higher color change when exposed to 10% and 15% bleaching gel (delta EFNx01: 9.0 and 11.1, respectively) as compared to distilled water (delta EFNx01: 2.9). Delta EFNx01 of composite-based material specimens exposed to distilled water was statistically higher (6.3) than specimens exposed to 10% and 15% bleaching gel (1.5 and 1.1, respectively). Polycarbonate crowns showed a statistically lower color change when exposed to 15% (0.9) than to 10% bleaching gel (5.1) or distilled water (5.5).Conclusions: Composite-based provisional material showed highest color stability when exposed to vital tooth bleaching gel, whereas methacrylate-based material was the least color stable. Polycarbonate crowns were more color stable when exposed to 15% bleaching gel as opposed to 10% bleaching gel. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the ability of chromophore to improve laser whitening procedures on bovine teeth. The teeth were previously stained with black tea. We evaluated the color change with the help of the Vita Easy Shade Spectrophotometer. Two batches of four teeth were prepared and immersed for 14 days in a solution of black tea. For the bleaching, an experimental gel was used. Batch I was kept in the gel without chromophore and batch II in the gel with chromophore. The teeth from both batches were kept for 30 sec in the gel and were afterwards irradiated with a diode laser (980nm). The statistical analysis showed significant differences between T1 (the measurement of the color after the staining process) and T2 (the measurement of color after the whitening process) for the first batch and T0 (the initial measurement of the color of the teeth) and T2 (the measurement of color after the whitening process) for the second batch. [ABSTRACT FROM AUTHOR]

Background. Since it is possible for carbamide peroxide (CP) bleaching agent to contact old amalgam restorations, the present in vitro study evaluated the amount of dissolved mercury released from amalgam restorations with various percentages of silver content subsequent to the use of 15% CP. Methods. Thirty ANA 2000 amalgam disks with 43.1% silver content and thirty ANA 70 amalgam disks with 69.3% silver content were prepared. In each group, 15 samples were randomly placed in glass tubes containing 15% CP (as experimental groups) and the remaining 15 samples were placed in buffered phosphate solution (as control groups) with the same 3-mL volume for 48 hours. Subsequently, the amount of mercury dissolved in each test tube was measured using Mercury Analyzing System (Cold Vapor Atomic Absorption, MASLO, Shimadzu, Japan). Data was analyzed with two-way ANOVA and a post hoc Tukey test. (α = 0.05) Results. The amount of mercury released after exposure to CP was significantly higher than that released after exposure to buffered phosphate (P < 0.001). In addition, the amount of mercury released from dental amalgam with a silver content of 43% was significantly higher than that released from dental amalgam with a silver content of 69% (P < 0.001). Conclusion. The amount of mercury release is inversely proportional to the silver content of dental amalgam. [ABSTRACT FROM AUTHOR]

Objective: It was recently demonstrated that using a tray over a bleaching agent reduces its pulpal chamber penetration, which can reduce tooth sensitivity. This study evaluated the effect of the sealed technique on the presence and level of sensitivity reported by patients during and after the bleaching procedure performed in office. Methods: Forty-six patients underwent a bleaching procedure with 35% hydrogen peroxide used in a single application of 45 minutes for two sessions with an interval of seven days. A customized tray was maintained over the bleaching agent during the entire procedure in half of the patients. The sensitivity level was evaluated during and immediately after the bleaching using verbal and visual analogue scales. The shade alteration was evaluated with a bleach guide scale. The peak sensitivity after 24 hours and the presence/level at 24 hours were also evaluated using a verbal rating scale. Relative risks were calculated for all time assessments. Data on the sensitivity level for both scales were subjected to Friedman and Mann-Whitney tests (α=0.05). Data on the shades were analyzed by two-way repeated-measures analysis of variance and Tukey's test (α=0.05). Results: The use of a customized tray increased the relative risks to the tooth measured 24 hours after each bleaching session. The sealed technique also increased the level of tooth sensitivity only at 24 hours after the first session. No difference was observed between the bleaching techniques regarding the shade evaluation. Conclusion: Using a tray over the bleaching agent can increase the level and risk of tooth sensitivity for the first 24 hours after in-office bleaching. [ABSTRACT FROM AUTHOR]

Aim The aim of the present study was to determine the effects of immersion time and 10% carbamide peroxide treatment using a Hertzian indentation test after placing resin-based cements into 37°C distilled water, with and without 10% carbamide peroxide. Methods Disc-shaped specimens (10-mm diameter × 1-mm thick), were prepared from five resin-based cements; se T PP, Maxcem Elite, Rely X Unicem, Panavia F, and G- Cem. The specimens of each material were randomly divided into three groups of six. The study groups were bleached with 10% carbamide peroxide on one surface for 21 days for 2 h per day. Two control groups were kept in distilled water for either 24 h or 21 days. A load was applied to the center of the disc using a hard, steel ball. The load at the first crack was recorded. Results Significant differences were observed between the cements. se T PP showed the highest strength, and G- Cem the lowest. Differences between the treatment and control groups were statistically significant for all cements, except Panavia F. Conclusions The effect of 10% carbamide peroxide treatment reduces cement strength, which could be important for patients undergoing bleaching who have crowns. [ABSTRACT FROM AUTHOR]

Objective: This in vitro study evaluated the effect of different bleaching protocols and the variation of pH levels of bleaching gels regarding roughness and wear of bovine enamel, after in-office bleaching protocols and brushing. Materials and methods: Ninety fragments were randomly divided into nine groups: C, control; WHP15, 35% hydrogen peroxide (HP) (Whiteness HP, FGM) three gel applications of 15 min each, three sessions with 1 week intervals; WHP45, 35% HP (Whiteness HP) one application/45 min, three sessions with 1 week intervals; LPS, 35% HP (Lase Peroxide, DMC) plus hybrid light (HL) [light-emitting diode (LED)/diode laser], four applications/7 min 30 sec (6 min of HL activation), one session; LPSII, 25% HP (Lase Peroxide II, DMC) plus HL, four applications/7 min 30 sec (6 min of HL activation), one session; LPL, 15% HP (Lase Peroxide Light, DMC) four applications/7 min 30 sec (6 min of HL activation), one session; WO, 35% HP (Whitegold Office, Dentsply) three applications/15 min, three sessions with 1 week intervals; WBC40, 35% HP (Whiteness HP Blue Calcium, FGM) one application/40 min, three sessions with 1 week intervals; and WBC50, 20% HP (Whiteness HP Blue Calcium) one application/50 min, three sessions with 1 week intervals. The median pH values were determined utilizing a pH meter during the initial and final gel applications. A rugosimeter was utilized to evaluate the surface roughness (Ra) before and after bleaching and brushing (100,000 strokes), and the surface wear after brushing. Results: For the results of the pH values, there was a decrease in the pH levels from the initial to the final bleaching time, except for the WBC50. The WO and WBC40 groups exhibited higher pH values. For the results of roughness and wear, there was an increase in surface roughness and wear among the groups. Conclusions: The pH values tended to decrease from the initial to the final bleaching. After tooth brushing, bleaching procedures with lower pH products provided a significant increase in enamel wear and surface roughness. [ABSTRACT FROM AUTHOR]

LASER (Light Amplification by Stimulated Emission of Radiation) is a powerful source of light, which has innumerable applications in all the fields of science including medicine and dentistry. It is one such technology that has become a desirable and an inseparable alternative to many traditional surgical procedures being held in the field of dentistry, and orthodontics is no exception. The current article describes the uses of a diode laser as an indispensable tool in an orthodontic office. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to evaluate and correlate the efficacy and cytotoxicity of a 35 % hydrogen peroxide (HP) bleaching gel after different application times on dental enamel. Materials and methods: Enamel/dentin disks in artificial pulp chambers were placed in wells containing culture medium. The following groups were formed: G1, control (no bleaching); G2 and G3, three or one 15-min bleaching applications, respectively; and G4 and G5, three or one 5-min bleaching applications, respectively. Extracts (culture medium with bleaching gel components) were applied for 60 min on cultured odontoblast-like MDPC-23 cells. Cell metabolism (methyl tetrazolium assay) (Kruskal-Wallis/Mann-Whitney; α = 5 %) and cell morphology (scanning electron microscopy) were analyzed immediately after the bleaching procedures and the trans-enamel and trans-dentinal HP diffusion quantified (one-way analysis of variance/Tukey's test; α = 5 %). The alkaline phosphatase (ALP) activity was evaluated 24 h after the contact time of the extracts with the cells (Kruskal-Wallis/Mann-Whitney; α = 5 %). Tooth color was analyzed before and 24 h after bleaching using a spectrophotometer according to the Commission Internationale de l'Eclairage L* a* b* system (Kruskal-Wallis/Mann-Whitney; α = 0.05). Results: Significant difference ( p < 0.05) in cell metabolism occurred only between G1 (control, 100 %) and G2 (60.6 %). A significant decrease ( p < 0.05) in ALP activity was observed between G2, G3, and G4 in comparison with G1. Alterations on cell morphology were observed in all bleached groups. The highest values of HP diffusion and color alterations were observed for G2, with significant difference among all experimental groups ( p < 0.05). G3 and G4 presented intermediate color change and HP diffusion values with no statistically significant differences between them ( p > 0.05). The lowest amount of HP diffusion was observed in G5 ( p < 0.05), which also exhibited no significant color alteration compared to the control group ( p > 0.05). Conclusions: HP diffusion through dental tissues and its cytotoxic effects were proportional to the contact time of the bleaching gel with enamel. However, shorter bleaching times reduced bleaching efficacy. Clinical relevance: Shortening the in-office tooth bleaching time could be an alternative to minimize the cytotoxic effects of this clinical procedure to pulp tissue. However, the reduced time of bleaching agent application on enamel may not provide adequate esthetic outcome. [ABSTRACT FROM AUTHOR]

Background: Non vital bleaching is simple, conservative procedure for esthetic correction of discolored endodontically treated teeth. The aim of this study was to determine and compare the amount of peroxide leakage from four different bleaching agents i.e superoxol, sodium perborate, combination of superoxol & sodium perborate and carbamide peroxide during intracoronal bleaching, as the safe and effective bleaching is the need of the hour. Materials & Methods: 50 extracted maxillary centrals were selected for the study. Following standardized protocol access, cleaning and shaping by step back technique and obturation was done using guttapercha and AH plus sealer. Access was sealed with Cavit G and outer root surface was coated with wax and nail varnish. The teeth were separated into crown and root and the root portion was placed in plastic tube containing distilled water for 7days.After incubation, 3mm of gutta-percha was removed below CEJ and 2mm glass ionomer cement base was placed. Grouped into five categories based on the bleaching agent placed in pulp chamber as -group1 (control)- distilled water, group 2-sodium perborate with distilled water , group 3- 30% hydrogen peroxide ,group 4-mixture of sodium perborate and 30% hydrogen peroxide and group 5-10% carbamide peroxide gel. Peroxide leakage was measured after 24hrs using ferrothiocyanate method and optical density using spectrophotometer. Statistical analysis of the data was conducted using ANOVA and multiple comparisons within the groups was done using BONFERRONI method (Post-Hoc tests). Results: The results showed highest peroxide penetration from 30% hydrogen peroxide followed by mixture of sodium perborate with 30% hydrogen peroxide, mixture of sodium perborate with distilled water and least penetration from 10% carbamide peroxide gel. The results were statistically significant. Conclusion: Radicular peroxide leakage in 10% carbamide peroxide was significantly lower than the other tested bleaching agents making it a very safe alternative for intracoronal bleaching. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine if the actual concentration of bleaching agents available in four different countries were the same as the label indicated and within the recommendations of the International Standard on Tooth Whitening. The method recommended for assaying peroxide by the United States Pharmacopeia was used to determine concentrations. All products in the United States and China were within the standard when products were tested immediately upon delivery at testing sites. One product in Saudi Arabia and three products in Brazil had greater than 30% concentration loss. Three of 24 products in the United States did not meet the International Standard when they were tested at month of expiration. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of different bleaching agents used for teeth whitening on the microhardness of the enamel. 35% HP and 17% CP were applied on several samples of human incisors. Different treatment strategies were followed and the results show that all of bleaching agents caused a reduction in Vickers microhardness of specimens. Remineralization treatment was applied on samples, after this process the microhardness of the teeth being restored close to initial values measured prior to whitening. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to evaluate whether the use of a gel applied for 1 x 45 minutes would have the same bleaching rate and tooth sensitivity levels when compared with 3 x 15-minute applications. Methods: In-office bleaching was performed in 30 participants with 35% hydrogen peroxide gel. In one group (n=15; 3x15 minutes), the bleaching agent was refreshed every 15 minutes, three times at each bleaching appointment. In the other group (n=15; 1x45 minutes) the gel was left undisturbed on the buccal surfaces of all teeth for 45 minutes at each bleaching appointment. This protocol was repeated after one week. The bleaching evaluation was completed by two blinded, calibrated evaluators who compared the baseline color of the maxillary anterior teeth with a value-oriented shade guide after each period. The patients recorded the tooth sensitivity on a 0-4 scale. The color changes were evaluated by appropriate tests (휶=0.05). The percentage of patients with tooth sensitivity and its intensity were also statistically analyzed (휶=0.05), respectively. Results: The use of gel for a single 45-minute period (1x45 minutes) decreased the bleaching efficacy (p<0.05) 86.7%, and 100% of patients from the 3 x 15-minute and 1 x 45-minute groups, respectively, experienced tooth sensitivity (p=0.22). The intensity of sensitivity was lower for the 3 x 15-minute applications (p =0.04). Conclusions: A 35% hydrogen peroxide gel for in-office bleaching preferably should be applied in three 15-minute applications because 1 x 45 minutes reduces the bleaching speed and slightly increases the intensity of tooth sensitivity. [ABSTRACT FROM AUTHOR]

The wide use of dental bleaching treatment has brought concern about the possible effects of hydrogen peroxide on dental tissue and restorative materials. The objective of this study was to evaluate in vitro the effect of nightguard bleaching on the surface roughness of dental ceramics after different periods of bleaching treatment. Fifteen specimens of 5 × 3 × 1 mm were created with three dental ceramics following the manufacturers' instructions: IPS Classic (Ivoclar-Vivadent); IPS d.Sign (Ivoclar-Vivadent); and VMK-95 (Vita). A profilometer was used to evaluate baseline surface roughness (Ra values) of all ceramics by five parallel measurements with five 0.25 mm cut off (λc) at 0.1 mm/s. Afterwards, all specimens were submitted to 6-h daily bleaching treatments with 10% or 16% carbamide peroxide (Whiteness-FGM) for 21 days, while control groups from each ceramic system were stored in artificial saliva. The surface roughness of all groups was evaluated after 18 h, 42 h, 84 h, and 126 h of bleaching treatment. The surface roughness of each specimen (n = 5) was based on the mean value of five parallel measurements in each time and all data were submitted to two-way repeated measures ANOVA and Tukey's post-hoc test (α = 0.05). No significant differences in ceramic surface roughness were observed between untreated and bleached ceramic surfaces, regardless of bleaching intervals or bleaching treatments. This study provided evidence that at-home bleaching systems do not cause detrimental effects on surface roughness of dental ceramics. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to measure the level of postoperative sensitivity after two in-office whitening treatments. Materials and Methods: Twenty-two patients, divided in two groups of 11, took part in this study and they voluntarily agreed to a bleaching treatment. Two different in-of-fice bleaching agents were used: Zoom2, based on 25% hydrogen peroxide and initialized by the light source from the same manufacturer, and Opalescence Boost, based on 38% hydrogen peroxide without the light initiation. The pain was evaluated by the visual analogue scale (VAS) and the data were recorded immediately, and at 6 and 24 hours after bleaching. Results: The data were analyzed by Wilcoxon Signed Rank Test. The difference between postoperative sensitivity after application of Zoom2 and Boost whitening agents, measured immediately after the treatment, 6 and 24 hours after bleaching, was not statistically significant (p>0.05). Both whitening treatments show the same prevalence of postoperative sensitivity, which was the highest immediately after the treatment and 6 hours later (p<0.05). Both agents show obvious appearance of postoperative sensitivity, which decreases to the values measured 24 hours after the treatment. Conclusion: The postoperative pain and sensitivity during and after both in-office whitening treatment agents with different hydrogen peroxide concentrations occur as one of the possible side-effects which were the highest immediately after the treatment and 6 hours later, and then decreasing to the values measured 24 hours after the treatment. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of a high-concentration carbamide peroxide-containing home bleaching system (Opalescence PF) and a hydrogen peroxide-containing over-the-counter bleaching system (Treswhite Supreme) on the microhardness of two nanocomposites (Filtek Supreme XT and Premise) and leucite-reinforced glass ceramic (Empress Esthetic), glass ceramic (Empress 2 layering), and feldspathic porcelain (Matchmaker MC). A total of 100 specimens, 20 of each kind of the restorative materials, 2 mm in thickness and 10 mm in diameter, were fabricated. Then the specimens were polished with SiC paper and 1 µm alumina polishing paste. After polishing, porcelain specimens were glazed in accordance with the manufacturer's instructions. Each type of restorative material was then randomly divided into two groups (n=10), and the specimens were treated with either Opalescence PF or Treswhite Supreme. The microhardness of the specimens before bleaching (baseline) and after bleaching was determined using a digital microhardness tester. Data were analyzed using the Mann-Whitney U-test and the Wilcoxon test. Opalescence PF significantly influenced the hardness of all the restorative materials. Statistically significant decreases with respect to before bleaching were found for Premise (p=0.005), Empress Esthetic (p=0.003), Empress 2 layering (p=0.005), and Matchmaker-MC (p=0.003), whereas a statistically significant increase was observed in Filtek Supreme XT (p=0.028). The difference in the microhardness values between before and after bleaching using Treswhite Supreme was statistically significant only for Premise (p=0.022). High-concentration carbamide peroxide-containing home bleaching may affect the microhardness of restorative materials. [ABSTRACT FROM AUTHOR]

This study investigated the bleaching efficacy of a mixture of sodium hydrogen carbonate (NaHCO3) and 30% hydrogen peroxide (H2O2), the latter being an active ingredient in in-office bleaching products. A commercially available 35% H202-based in-office bleaching product was used as a control and for comparison. Enamel surfaces after bleaching were evaluated for post-bleaching color change, Vickers hardness, surface roughness, erosion depth, and surface morphology (SEM images). The bleaching efficacy of 30%H2O2-NaHCO3 was comparable to that of control, and favorable results over the control were obtained after bleaching with 30%H2O2-NaHCO3, lower increase in surface roughness, smaller erosion depth, and reduced extent of enamel erosion based on SEM images. These results were obtained because an addition of NaH CO3 to H2O2 changed the initially low pH to a higher one. [ABSTRACT FROM AUTHOR]

AbstractObjective:To examine the whitening efficacy of three whitening agents in combination with six different photoactivation systems. Background:Bleaching techniques have achieved significant advances using photoactivation with coherent or incoherent radiation sources. Methods:Quick White, Ena White Power, and Opalescence Endo bleaching agents, all containing 35% hydrogen peroxide, were stimulated with halogen lamp, light-emitting diode (LED), low-power diode laser, and neodymium: yttrium–aluminum–garnet (Nd:YAG), second harmonic of Nd:YAG, and Er:YAG lasers. One hundred twenty-six extracted human incisors were treated, and color change, pulpal temperature, and enamel morphological alterations were evaluated. Results:Only the groups that were photoactivated using a diode laser, halogen lamp, and LED showed statistically significant differences (p< 0.005) in color change when compared with the control group (without photoactivation). All whitening protocols were safe with regard to the increase in pulpal temperature. Scanning electron microscopy showed no evidence of effects on the integrity of enamel. Conclusions:The source of irradiation is more relevant than the bleaching agent for efficient tooth whitening. In addition, photoactivation with LED was found to be the best choice: it yielded significant change in color with only a minor increase in pulpal temperature. [ABSTRACT FROM AUTHOR]

Summary: Objectives: This double-blind randomized clinical trial aimed to evaluate the whitening effect of two at-home tooth bleaching agents and the effect of dietary habits after 2 years. The patients’ view about bleaching longevity was also investigated. Methods: Ninety-two subjects with mean shade of C1 or darker for the six maxillary anterior teeth were randomized into two groups (n =46) according to the carbamide peroxide (CP) concentration: 10% (CP10) or 16% (CP16). The treatment was performed using the whitening agent in a tray for 2h/day during 3 weeks. Shade evaluations were done with a shade guide and a spectrophotometer at baseline, 1-month, 6-month, 1-year and 2-year post-bleaching. Results: Eighty-one (88%) of the original 92 subjects enrolled in the study were recalled at 2-year follow-up and, the tooth shade remained significantly lighter than at baseline, in both treatment groups, considering the tooth shade median values (p <0.001) or the color parameters: L*a* (p <0.001) for CP10 and, L*b* for CP16 group (p <0.001). Subjects from CP10 and CP16 reported a consumption of beverage and food stains as high as at 6-month and 1-year recalls and, more than 66% of the participants from each group reported a tooth shade relapse from mild to moderate (p =0.6). Significance: At 2-year post-bleaching, tooth shade remained lighter than at baseline for both CP concentrations tested. Tooth shade relapse associated to increasing of a* and b* color parameters were observed for both groups when compared to the end of the treatment (CEP # 37/05). [ABSTRACT FROM AUTHOR]

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Background: Tooth whitening is one of the mostly used treatments to improve dental esthetics. Dental bleaching techniques include the use of substances such as carbamide peroxide, sodium perborate, and hydrogen peroxide. Researchers and clinicians are often seeking to know which techniques produce the best results. Purpose: To determine whether the use of halogen light with 25% hydrogen peroxide in in-office tooth bleaching is more effective than the use of hydrogen peroxide alone. Methods: A controlled clinical trial was carried out. Upper maxilla of 10 healthy patients received whitening therapy with 25% hydrogen peroxide. Using the divided maxilla method, one quadrant of each patient was exposed to halogen light for 20 minutes and the other did not. The in-office procedure was carried out in two sessions of 20 minutes each. Color in each quadrant was measured before and after the therapy with the Vita EasyShade color guide. Results: The use of halogen light with tooth bleaching with 25% hydrogen peroxide did not show statistically significant differences with the use of hydrogen peroxide alone regarding color change (p=0,38). [ABSTRACT FROM AUTHOR]

Fernández MR, Carvalho RV, Ogliari FA, Beira FA, Etges A, Bueno M. Cytotoxicity and genotoxicity of sodium percarbonate: a comparison with bleaching agents commonly used in discoloured pulpless teeth. International Endodontic Journal, 43, 102–108, 2010. Aim To evaluate the cytotoxicity and genotoxicity of sodium percarbonate (SPC) in comparison with bleaching agents used on discoloured pulpless teeth. Methodology The cytotoxicity and genotoxicity of bleaching agents were evaluated both in their pure form as well as at concentrations commonly used in clinical practice. Hydrogen peroxide (HP), carbamide peroxide (CP), sodium perborate (SP) and SPC were diluted in Dulbecco’s modified Eagle’s medium (DMEM) in series. To evaluate the cytotoxicity, the survival of 3T3/NIH mouse fibroblasts was measured photometrically using an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay after a 24 h-exposure period. Genotoxicity was indicated by micronuclei (MN) formation, and modification of the normal cell was analysed by light microscopy (400×). Statistical analysis was performed by one-wayanova, followed by a multiple-comparison Tukey post hoc test ( P < 0.05). Results All groups exhibited a dose-dependent cytotoxicity. However, CP showed a similar cytotoxic effect when compared with DMEM-untreated control (UC) group. HP and SPC were significantly more cytotoxic than SP. The genotoxicity test showed that SPC and SP had an intermediate rate of MN frequency when compared with the UC group. The mean rate of MN frequency for HP was higher and statistically more significant than for the other groups tested. No difference was observed when CP and UC groups were compared. Conclusions Sodium percarbonate showed cytotoxicity and genotoxicity similar to those of the other products tested. However, before SPC is used clinically, studies should be conducted to confirm its safety in vivo. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) is a powerful oxidising agent. It gives rise to agents known to be effective bleaching agents. The mechanisms of bleaching involve the degradation of the extracellular matrix and oxidation of chromophores located within enamel and dentin. However, H2O2 produces also local undesirable effects on tooth structures and oral mucosa. In clinical conditions, the daily low-level doses used to produce tooth whitening never generate general acute and sub-acute toxic effects. Genotoxicity and carcinogenicity only occur at concentrations that are never reached during dental treatments. Some transient adverse effects have been reported on the oral mucosa and the digestive tract if the product is swallowed. Local effects may occur on the oral mucosa and dental tissues during whitening, namely, pulp sensitivity, cervical resorption, release of selected components of dental restorative materials, and alteration of the enamel surface. Most of the local effects are dependent of the technique and concentration of the product so far used, but as the results of bleaching obtained are not stable, repeated treatments add to the adverse effects. The informed decision to administer or not and the control of bleaching effects should stand in the hand of dental surgeons and certainly not as it appears at present, as cosmetics sold without any restriction despite the potential health hazards of peroxides. [ABSTRACT FROM AUTHOR]