Enamel changes of bleached teeth following application of an experimental combination of chitosan-bioactive glass.

BACKGROUND: Considering the extensive use of bleaching agents and the occurrence of side effects such as enamel demineralization, this study aimed to assess the enamel changes of bleached teeth following the experimental application of chitosan-bioactive glass (CH-BG). METHODS: In this in vitro study, CH-BG (containing 66% BG) was synthesized and characterized by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Thirty sound human premolars were bleached with 40% hydrogen peroxide, and the weight% of calcium and phosphorus elements of the buccal enamel surface was quantified before and after bleaching by scanning electron microscopy/ energy-dispersive X-ray spectroscopy (SEM, EDX). Depending on the surface treatment of the enamel surface, the specimens were divided into three groups (n = 10): control (no treatment), MI Paste (MI), and CH-BG. Then the specimens were stored in artificial saliva for 14 days. The SEM/EDX analyses were performed again on the enamel surface. Data were analyzed by one-way ANOVA and Tukey's test and a p-value of < 0.05 was considered statistically significant. RESULTS: In all groups, the weight% of calcium and phosphorus elements of enamel decreased after bleaching; this reduction was significant for phosphorus (p < 0.05) and insignificant for calcium (p > 0.05). After 14 days of remineralization, the weight% of both calcium and phosphorus elements was significantly higher compared to their bleached counterparts in both MI and CH-BG groups (p < 0.05). Following the remineralization process, the difference between MI and CH-BG groups was not significant (p > 0.05) but both had a significant difference with the control group in this regard (p < 0.05). CONCLUSIONS: The synthesized CH-BG compound showed an efficacy comparable to that of MI Paste for enamel remineralization of bleached teeth.

Effectiveness and Safety of Over-the-Counter Tooth-Whitening Agents Compared to Hydrogen Peroxide In Vitro.

(1) This study investigated the whitening effect, cytotoxicity and enamel surface alterations induced by different over-the-counter (OTC) bleaching agents in comparison to hydrogen peroxide. (2) Human teeth (n = 60) were randomly assigned into 6 groups (n = 10), stained with coffee solution for 7 d, followed by a whitening period of 7 d with either placebo, bromelain, sodium bicarbonate, sodium chlorite, PAP or hydrogen peroxide. Color measurements were performed with a spectrophotometer. Scanning electron micrographs (SEM) were taken to assess the enamel structure. Cytotoxicity of the tested substances was assessed based on the cell viability of primary human fibroblasts. (3) The application of all whitening gels resulted in a greater color difference of the enamel (ΔE) in comparison to the negative control. Hydrogen peroxide caused the greatest color difference. Bromelain and PAP treatment showed no enamel surface changes, in contrast to hydrogen peroxide treatment, which showed very mild interprismatic dissolution. Bromelain was the only non-cytotoxic agent. (4) The maximum effect achieved by all OTC bleaching agents was the removal of stains, whereas hydrogen peroxide was capable of further whitening the teeth. Bromelain treatment was neither cytotoxic, nor resulted in enamel surface alterations, and its whitening effect was less, yet still effective, compared to hydrogen peroxide.

Use of infrared photobiomodulation with low-level laser therapy for reduction of bleaching-induced tooth sensitivity after in-office bleaching: a double-blind, randomized controlled trial.

The purpose of this study is to evaluate the use of infrared photobiomodulation with low-level laser therapy (PBM) to reduce bleaching-induced tooth sensitivity (TS) after in-office bleaching. Eighty-three participants were randomized in blocks into two groups. In the experimental group, the patients received an application after each session of in-office bleaching (35% hydrogen peroxide, 1 × 50 min; 2 sessions with 1-week interval), while the laser application was simulated in the control group. The PBM system was operated in continuous mode, using 3 J of energy. A dose of 100 J/cm2 was applied for 30 s with 808 nm (100 mW of power) in the middle third of the crown. The risk and intensity of TS were recorded immediately after bleaching, 1 h, 24 h, and 48 h after each bleaching session, with a visual scale analog (0-10) and a five-point numerical scale (0-4). The color was recorded at the beginning, weekly, and 1 month after the end of the bleaching (VITA Classical, VITA Bleachedguide, and digital spectrophotometer). The risk of TS was 98% (95% CI 88 to 99%) for the laser group and 95% (95% CI 83 to 99%) for the control (RR = 1.03; 95% CI 0.94 to 1.12; p = 1.0). Similarly, no difference in the intensity of TS was detected for both pain scales (p > 0.65). Improvement in color change, regardless of the group, was observed (p > 0.15). The application of an PBM did not reduce the risk and intensity of TS when applied after the procedure using the parameters recommended by the manufacturer.Trial registration number and date of registration: RBR-4HCVSG-04/06/2019.

The application of casein phosphopeptide and amorphous calcium phosphate with fluoride (CPP-ACPF) for restoring mineral loss after dental bleaching with hydrogen or carbamide peroxide: An in vitro study.

OBJECTIVE: To conduct an in vitro evaluation of the effect of casein-phosphopeptide and amorphous calcium phosphate with fluoride [CPP-ACPF] upon the calcium [Ca] and phosphorus [P] composition and morphology of dental enamel and dentin after the application of two bleaching agents: 37.5% hydrogen peroxide [HP]) and 35% carbamide peroxide [CP]. MATERIALS AND METHODS: The crowns of 40 extracted human teeth were divided into four groups (n=10 each). The crowns were sectioned along the cervical-incisal axis, and each half was embedded in acrylic resin, leaving a window 3mm in diameter to explore the enamel or dentin (according to the study group involved). Groups 1a and 1b corresponded to the two halves belonging to the same tooth and were treated with HP applied to enamel three times for 10min. Afterwards, CPP-ACPF was applied in group 1b for five minutes. The same procedure was carried out in groups 2a and 2b, but application was done on dentin. Groups 3a and 3b were treated with CP applied to enamel once for 30min. Posteriorly, CPP-ACPF was applied in group 3b for five minutes. Groups 4a and 4b were treated in the same way as groups 3a and 3b, but application was done on dentin. The morphological changes were evaluated using confocal laser scanning microscopy (CLSM), and the changes in Ca and P composition were assessed by environmental scanning electron microscopy coupled to a microanalytical system (ESEM+EDX). Comparisons between groups were made using the Kruskal-Wallis test, and Duncan test was applied for two-by-two comparisons, with a significance level of p<0.05. RESULTS: Both HP and CP produced similar changes in enamel morphology and produced no changes in dentin. Groups treated with CPP-ACPF after bleaching improved the percentage of Ca and P. Statistical significance was reached only in the case of the percentage of Ca in enamel (group 1b versus group 1a, p=0.01) (group 3b versus group 3a, p=0.03). CONCLUSIONS: The application of CCP-ACPF for five minutes on the enamel surface after tooth bleaching is effective in restoring the Ca lost as a result of the bleaching process, while their effect in dentin could not be demonstrated.

Does bond integrity of bleached enamel increases with phototherapy? A systematic review.

BACKGROUND: The aim of the current systematic review was to evaluate the efficacy of phototherapy (PT) on bond strength of bleached enamel. METHODS: Electronic databases including MEDLINE (PubMed), ISI Web of Science, Scopus, ScIELO, LILACS and EMBASE until January 2019. The addressed focused question was: "Does PT increase the bond integrity of bleached enamel?" Only in-vitro studies evaluating the effect of PT compared with bleaching agent or no phototherapy were included. The outcome measures of interest was shear bond strength. RESULTS: A total of 5 in-vitro studies were included. Different concentrations of hydrogen peroxide were used in the included studies. The frequency of laser used in the included studies ranged from 20 Hz to 60 Hz. Pulse duration was reported in only 3 studies that ranged from 100 µs to 320 µs. The overall main outcomes of the included studies showed that in 4 studies, application of phototherapy resulted in significantly higher bond integrity of bleached enamel as compared to enamel which underwent acid etching with bleaching alone, while 1 study showed comparable shear bond strength of bleached enamel achieved by PT as compared to bleaching alone. CONCLUSION: The evidence from the current systematic review suggests that phototherapy increases the bond strength of bleached enamel. Further in-vitro studies should be performed in order to obtain stronger conclusions.

Effect of photobiomodulation with low-level laser therapy combined with potassium nitrate on controlling post-bleaching tooth sensitivity: clinical, randomized, controlled, double-blind, and split-mouth study.

OBJECTIVES: To evaluate the effect of photobiomodulation with low-level laser therapy (PBM-LLLT) combined with 5% potassium nitrate (KNO3) on controlling tooth sensitivity (TS) after in-office tooth bleaching. MATERIALS AND METHODS: Fifty volunteers were selected based on the inclusion and exclusion criteria and were randomly allocated into four groups: G1 (control): placebo gel application, 35% hydrogen peroxide bleaching (HP35) and mock PBM-LLLT without light emission; G2: placebo gel application, bleaching with HP35 and PBM-LLLT; G3: application of KNO3, bleaching with HP35 and mock PBM-LLLT; and G4: application of KNO3, bleaching with HP35 and PBM-LLLT. A pain assessment questionnaire was used to evaluate TS during the 21 days of treatment. The Friedman test was used for intragroup analysis, and the Wilcoxon and Mann-Whitney tests were used for intergroup comparisons. RESULTS: The intragroup evaluation showed significant differences among the evaluation times in all groups (p ≤ 0.05). The highest pain sensitivity levels were recorded on the 1st, 8th, and 15th days. In G1, TS manifested for up to 3 days after each bleaching session, while G2, G3, and G4 presented TS only on the days of the bleaching sessions. Intergroup analysis showed that TS manifestation differed significantly between G1 and the other groups (p ≤ 0.05) but did not differ significantly among G2, G3, and G4 (p ≥ 0.05). CONCLUSION: PBM-LLLT and KNO3 are effective at reducing pain sensitivity after tooth bleaching, but no synergistic effect between these treatments was observed for the different evaluation periods. CLINICAL RELEVANCE: The effect of PBM-LLLT combined with KNO3 on post-bleaching tooth sensitivity is similar to their individual use alone.

Effect of carbamide peroxide bleaching on enamel characteristics and susceptibility to further discoloration.

STATEMENT OF PROBLEM: Whether tooth whitening alters the surface topography of enamel causing an increase in surface roughness that could increase susceptibility to restaining is unclear. PURPOSE: The purpose of this in vitro study was to evaluate whether immersing enamel in common solutions produces a color change of ΔE greater than 2; whether the highest concentration carbamide peroxide bleaching agent produces the greatest ΔE; whether bleaching increases the susceptibility to further staining by common solutions; and whether morphologic changes to the enamel surface are observed after staining and bleaching as evidenced by scanning electron microscopy (SEM) analysis and energy-dispersive X-ray spectroscopy (EDS). MATERIAL AND METHODS: Forty-five extracted human teeth were immersed in 5 solutions (wine, coffee, tea, soda, and water) for 15 days at 80°C, and the change in ΔE was assessed with a colorimeter. The teeth were bleached using different concentrations of carbamide peroxide (20%, 35%, and 44%) and ΔE was measured at different time intervals. The teeth were then restained with the same solutions. The ΔE after initial staining was compared with the ΔE after bleaching and restaining of the same teeth. SEM was performed at baseline, after staining, bleaching, and restaining to evaluate the changes in the enamel surface topography. EDS was used to determine the elemental composition of tooth surfaces after restaining. RESULTS: All liquids caused a ΔE greater than 2 after 15 days. The concentration of bleaching agent was not significantly associated with ΔE for any stain types. No significant difference was found in the rate of staining between initial staining and restaining after bleaching. However, a significant effect of time was found for the staining, where the overall ΔE increased by 0.34 for each day in the solution (P<.001). SEM images showed no major changes to enamel topography after bleaching. However, a coating was noted on teeth stained with wine and tea, which had different elemental compositions when compared with the tooth surface. CONCLUSIONS: Based on SEM observation, bleaching teeth with carbamide peroxide does not increase the susceptibility of enamel to staining and does not alter the topography of the enamel. Using higher bleaching concentrations did not increase tooth whitening as a function of time.

A comparison of the effect of application of sodium ascorbate and amla (Indian gooseberry) extract on the bond strength of brackets bonded to bleached human enamel: An In vitro study.

INTRODUCTION: Whitening of teeth is a popular choice among dental clinicians and patients. However, the changes in enamel structure and composition induced by the bleaching agents cause a decrease in the shear bond strength of brackets leading to premature bracket debonding. Among several methods to overcome this, the most common is delaying bonding by 2-4 weeks. This waiting period can be eliminated by applying an antioxidant (sodium ascorbate) which causes a reversal in the reduction of bond strength. AIM: This study aims to compare the efficacy of a naturally occurring antioxidant (gooseberry) and sodium ascorbate in normalizing the bond strength of enamel to prebleached levels. MATERIALS AND METHODS: Seventy-two extracted premolars were divided into 4 equal groups; 1st group - control group - unbleached teeth, bonded directly, 2nd group - bleached with 16% carbamide peroxide (8 h for 1 week), then bonded. 3rd and 4th group - similarly bleached, followed by application of 10% sodium ascorbate and gooseberry extract (3 h respectively), then bonded. Bond strength was checked using Instron Universal Testing Machine. RESULTS: The bond strength of the control group was the highest and that of the carbamide group was drastically reduced. Considerable increase in the bond strength was seen after treatment with sodium ascorbate with negligible difference between sodium ascorbate and control group (P > 0.05). CONCLUSION: Treatment with gooseberry extract did improve the bond strength but was not as effective as sodium ascorbate postbleaching.

Effect of mangosteen peel extract as an antioxidant agent on the shear bond strength of orthodontic brackets bonded to bleached teeth.

INTRODUCTION: The number of patients who seek orthodontic treatment that may have a history of tooth bleaching is increasing over the time. Bleaching may influence the decrease of the bond strength of orthodontic brackets. OBJECTIVE: To determine and prove the effect of mangosteen peel (MP) extract to reverse the reduced shear bond strength (SBS) of orthodontic brackets after bleaching. METHODS: A total of 150 maxillary first premolar teeth were randomly divided into 6 experimental groups as follow (n=25): negative-control (N: no bleaching), positive-control (P: bleaching + no treatment), and the treatment groups (bleaching + 10% sodium ascorbate (SA), 10% (MP-10), 20% (MP-20) and 40% (MP-40) MP extract gel). After treatment, the brackets were bonded with the resin-modified glass ionomer cement, SBS testing was performed using universal testing machine, and the adhesive remnant index (ARI) was examined using stereoscopic microscope after debonding. The SBS data were analyzed by analysis of variance (Anova) and the Tukey test. For the ARI, the Kruskal-Wallis test was performed. RESULT: There was significant SBS difference (p< 0.001) between various groups. The group without bleaching showed significantly higher SBS (8.19 ± 2.26 MPa) compared to others, while SBS in the group treated with 40% MP gel was significantly higher (7.93 ± 1.92 MPa) than other groups treated with antioxidants. The failure of orthodontic brackets bonded after bleaching and treatment using MP extract occurred at the enamel-adhesive interface. CONCLUSION: The application of MP extract as an antioxidant after bleaching was effective in reversing the reduced shear bond strength of orthodontic brackets after bleaching.

Effect of mangosteen peel extract as an antioxidant agent on the shear bond strength of orthodontic brackets bonded to bleached teeth

Abstract Introduction: The number of patients who seek orthodontic treatment that may have a history of tooth bleaching is increasing over the time. Bleaching may influence the decrease of the bond strength of orthodontic brackets. Objective: To determine and prove the effect of mangosteen peel (MP) extract to reverse the reduced shear bond strength (SBS) of orthodontic brackets after bleaching. Methods: A total of 150 maxillary first premolar teeth were randomly divided into 6 experimental groups as follow (n=25): negative-control (N: no bleaching), positive-control (P: bleaching + no treatment), and the treatment groups (bleaching + 10% sodium ascorbate (SA), 10% (MP-10), 20% (MP-20) and 40% (MP-40) MP extract gel). After treatment, the brackets were bonded with the resin-modified glass ionomer cement, SBS testing was performed using universal testing machine, and the adhesive remnant index (ARI) was examined using stereoscopic microscope after debonding. The SBS data were analyzed by analysis of variance (Anova) and the Tukey test. For the ARI, the Kruskal-Wallis test was performed. Result: There was significant SBS difference (p< 0.001) between various groups. The group without bleaching showed significantly higher SBS (8.19 ± 2.26 MPa) compared to others, while SBS in the group treated with 40% MP gel was significantly higher (7.93 ± 1.92 MPa) than other groups treated with antioxidants. The failure of orthodontic brackets bonded after bleaching and treatment using MP extract occurred at the enamel-adhesive interface. Conclusion: The application of MP extract as an antioxidant after bleaching was effective in reversing the reduced shear bond strength of orthodontic brackets after bleaching.

Resumo Introdução: o número de pacientes que procuram o tratamento ortodôntico e têm histórico de clareamento dentário tem aumentado. O clareamento pode levar à diminuição da resistência adesiva dos braquetes ortodônticos. Objetivos: comprovar a efetividade do extrato de casca de mangostão (CM) em reverter a diminuição da resistência ao cisalhamento de braquetes ortodônticos colados após o clareamento. Métodos: 150 primeiros pré-molares superiores foram aleatoriamente divididos em seis grupos experimentais (n= 25): controle negativo (grupo N, sem clareamento), controle positivo (grupo P, clareamento + sem tratamento) e os grupos com tratamento (clareamento + ascorbato de sódio a 10% [grupo AS], gel de extrato de CM a 10% [grupo CM-10], a 20% [grupo CM-20] e a 40% [grupo CM-40]). Após o tratamento, os braquetes foram colados com cimento de ionômero de vidro modificado por resina e, depois, fez-se o teste de resistência ao cisalhamento (SBS) em uma máquina universal de ensaios. Após a descolagem dos braquetes, verificou-se o índice de adesivo remanescente (ARI), com o uso de um microscópio estereoscópico. Os dados da SBS foram submetidos a uma análise de variância (ANOVA) e ao teste de Tukey. Para o ARI, foi utilizado o teste de Kruskal-Wallis. Resultados: houve diferença significativa na SBS (p< 0,001) entre os diferentes grupos. O grupo sem clareamento mostrou resistência ao cisalhamento significativamente maior (8,19 ± 2,26 MPa) do que os outros grupos, enquanto a resistência ao cisalhamento do grupo tratado com o gel de extrato de CM a 40% foi significativamente maior (7,93 ± 1,92 MPa) do que nos outros grupos tratados com antioxidantes. A falha na colagem dos braquetes ortodônticos após o clareamento e tratamento com o extrato de CM ocorreu na interface adesivo/esmalte. Conclusão: a aplicação do extrato de CM como agente antioxidante foi efetiva em reverter a diminuição, que ocorre após o clareamento dentário, na resistência ao cisalhamento da colagem de braquetes ortodônticos.

Evaluation of in-office tooth whitening treatment with violet LED: protocol for a randomised controlled clinical trial.

INTRODUCTION: In-office tooth whitening treatment using violet light emited diode (LED) (405 nm) is a novel bleaching method that causes less sensitivity while offering the same effectiveness as the gold standard (35% hydrogen peroxide, H2O2). This study describes a protocol for the first randomised controlled clinical trial to compare the effects of the two methods. METHODS AND ANALYSIS: Eighty patients will be divided into four groups: G1 violet LED; G2 violet LED +35% carbamide peroxide; G3 35% H2O2 and G4 violet LED +gingivoplasty. Colour will be measured at baseline, immediately after the first session and at the 15 and 180 days follow-up using the Vita Classical and the digital Easyshade V spectrophotometer (Vita, Zahnfabrik, Germany). Sensitivity after whitening will be measured using the Visual Analogue Scale at baseline and at each session in all groups and in all follow-ups. The tissue removed during gingivoplasty (G4) will be submitted to immunohistochemical analysis for the determination of inflammatory changes caused by violet LED. The Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) will be evaluated before, as well as at established time point controls. The results will be expressed as mean and SD values. After determining the normality of the data, a one-way repeated-measures analysis of variance will be used for the comparison of data with normal distribution and the Kruskal-Wallis test will be used for data with non-normal distribution. A p<0.05 will be considered indicative of statistical significance. After determining the normality of the data, the Kruskal-Wallis test will be used for non-parametric data. Multivariate analysis of variance (MANOVA) and the Wilcoxon test will be used for comparing data from the PIDAQ. ETHICS AND DISSEMINATION: This protocol has been approved by the Human Research Ethics Committee of UniversidadeNove de Julho (certificate: 2.034.518). The findings will be published in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: NCT03192852; Pre-results.

Effect of low-level laser therapy combined with 5000 parts per million fluoride dentifrice on postbleaching sensitivity: A clinical, randomized, and double-blind study.

OBJECTIVE: The aim of this double-blind, randomized, controlled clinical study was to assess the efficacy of low-level laser therapy (LLLT) combined with 5000 ppm fluoride dentifrice on postbleaching sensitivity in teeth exposed to 35% hydrogen peroxide for four weeks. MATERIALS AND METHODS: Twenty-five volunteers were evaluated using the split-mouth model in which the right and left maxillary/mandibular quadrants were randomized and allocated to one of two groups: GPLACEBO, in which the laser tip was positioned without the emission of light (placebo effect) + 5000 ppm sodium fluoride, or GLASER, which comprised LLLT + 5000 ppm sodium fluoride. For both groups, LLLT and placebo were used before bleaching, whereas fluoride was applied after bleaching. LLLT was applied at two points: on the central cervical and medial regions of the incisors, canines, and premolars in the corresponding hemi-arch. At each point, 60 J/cm2 was applied for 16 seconds with an irradiance of 3.75 W/cm2 using the therapeutic infrared device. To assess tooth sensitivity, a modified visual analogue scale was used after an evaporative stimulus, and a daily pain questionnaire was also applied. RESULTS: The Wilcoxon and Friedman tests demonstrated a significant difference in the incidence of sensitivity pain between GPLACEBO and GLASER (P ≤ .05), with different evaluation times. CONCLUSION: Teeth treated with laser therapy in combination with the topical use of sodium fluoride at each bleaching session demonstrated less sensitivity compared with the application of sodium fluoride only. CLINICAL SIGNIFICANCE: The use of a low-level laser therapy in combination with topical use of sodium fluoride improves symptoms of dentin sensitivity at each bleaching session.

Photobiomodulation in the Prevention of Tooth Sensitivity Caused by In-Office Dental Bleaching. A Randomized Placebo Preliminary Study.

OBJECTIVE: Analyze the effect of photobiomodulation in the prevention of tooth sensitivity after in-office dental bleaching. BACKGROUND DATA: Tooth sensitivity is a common clinical consequence of dental bleaching. Therapies for prevention of sensitivity have been investigated in literature. MATERIALS AND METHODS: This study was developed as a randomized, placebo blind clinical trial. Fifty patients were selected (n = 10) and randomly divided into five groups: (1) control, (2) placebo, (3) laser before bleaching, (4) laser after bleaching, and (5) laser before and after bleaching. Irradiation was performed perpendicularly, in contact, on each tooth during 10 sec per point in two points. The first point was positioned in the middle of the tooth crown and the second in the periapical region. Photobiomodulation was applied using the following parameters: 780 nm, 40 mW, 10 J/cm2, 0.4 J per point. Pain was analyzed before, immediately after, and seven subsequent days after bleaching. Patients were instructed to report pain using the scale: 0 = no tooth sensitivity, 1 = gentle sensitivity, 2 = moderate sensitivity, 3 = severe sensitivity. RESULTS: There were no statistical differences between groups at any time (p > 0.05). More studies, with others parameters and different methods of tooth sensitivity analysis, should be performed to complement the results found. CONCLUSIONS: Within the limitation of the present study, the laser parameters of photobiomodulation tested in the present study were not efficient in preventing tooth sensitivity after in-office bleaching.

The potential of low-power laser for reducing dental sensitivity after in-office bleaching: a case report.

Postoperative sensitivity is one of the most common side effects of in-office bleaching with hydrogen peroxide. Laser phototherapy (LPT) has been suggested as an adjunctive treatment to prevent or minimize tooth sensitivity. This case report aimed to verify the efficacy of LPT in the reduction of sensitivity after in-office bleaching. Tooth bleaching was performed with 35% hydrogen peroxide activated with a hybrid LED-laser device. Immediately after the bleaching treatment, the patient reported dental sensitivity, as measured with a visual analog scale (VAS). To reduce sensitivity, LPT was applied with a 780-nm laser using the following parameters: 70 mW, exposure time of 10 seconds per point of irradiation (middle region of the buccal surfaces of each compromised tooth) in contact mode, energy of 1 J per point. Immediately after LPT, the patient reported a substantially lower level of pain on the VAS. Twenty-four hours after bleaching, the score on the VAS indicated that sensitivity levels had rebounded, and the patient received additional LPT. After 48 hours, the patient reported no dental sensitivity. The results in this patient indicated that irradiation with an infrared low-power laser substantially reduced dental pain generated by bleaching, suggesting that LPT should be considered as an auxiliary method to reduce postbleaching tooth sensitivity.

Effects of green tea on the shear bond strength of orthodontic brackets after in-office vital bleaching.

The application of bleaching agents before placement of resin-bonded fixed appliances significantly, but temporarily, reduces bond strength to tooth structure. Antioxidants have been studied as a means to remove residual oxygen that compromises bonding to bleached enamel. This in vitro study evaluated whether green tea (GT) could restore the shear bond strength between bonded orthodontic brackets and bleached enamel. Six experimental groups were compared: group 1, no bleaching plus bracket bonding (positive control); group 2, bleaching with 35% hydrogen peroxide (HP) plus bracket bonding (negative control); group 3, 35% HP plus 10% sodium ascorbate (SA) plus bracket bonding; group 4, 35% HP plus 10% GT plus bracket bonding; group 5, no bleaching plus 10% SA plus bracket bonding; group 6, no bleaching plus 10% GT plus bracket bonding. Results suggested that GT, like SA, may be beneficial for bracket bonding immediately after bleaching.

Enamel alteration following tooth bleaching and remineralization.

The purpose of this study was to compare the effects of professional tooth whitening agents containing highly concentrated hydrogen peroxide (with and without laser activation), on the enamel surface; and the potential of four different toothpastes to remineralize any alterations. The study was performed on 50 human molars, divided in two groups: treated with Opalescence(®) Boost and Mirawhite(®) Laser Bleaching. Furthermore, each group was divided into five subgroups, a control one and 4 subgroups remineralized with: Mirasensitive(®) hap+, Mirawhite(®) Gelleѐ, GC Tooth Mousse™ and Mirafluor(®) C. The samples were analysed by SEM/3D-SEM-micrographs, SEM/EDX-qualitative analysis and SEM/EDX-semiquantitative analysis. The microphotographs show that both types of bleaching cause alterations: emphasized perikymata, erosions, loss of interprizmatic substance; the laser treatment is more aggressive and loss of integrity of the enamel is determined by shearing off the enamel rods. In all samples undergoing remineralization deposits were observed, those of toothpastes based on calcium phosphate technologies seem to merge with each other and cover almost the entire surface of the enamel. Loss of integrity and minerals were detected only in the line-scans of the sample remineralized with GC Tooth Mousse™. The semiquantitative EDX analysis of individual elements in the surface layer of the enamel indicates that during tooth-bleaching with HP statistically significant loss of Na and Mg occurs, whereas the bleaching in combination with a laser leads to statistically significant loss of Ca and P. The results undoubtedly confirm that teeth whitening procedures lead to enamel alterations. In this context, it must be noted that laser bleaching is more aggressive for dental substances. However, these changes are reversible and can be repaired by application of remineralization toothpastes.

Effect of low-level laser therapy on tooth sensitivity induced by in-office bleaching.

This study aimed to investigate the effect of low-level laser therapy (LLLT) on tooth sensitivity induced by in-office bleaching. Sixty-six patients enrolled in this randomized clinical trial. Following the in-office procedure with 40% hydrogen peroxide, the participants were randomly divided into three groups. The patients in group 1 received irradiation from a low-level red laser (LLRL; 660 nm, 200 mW, 15 s, 12 J/cm(2)), whereas participants in group 2 were subjected to a low-level infrared laser (LLIL; 810 nm) under similar conditions as in group 1. In group 3 (placebo), the laser treatment was the same as that in groups 1 and 2, but without energy output. The degree of tooth sensitivity was recorded at 1, 24, and 48 h after bleaching using a visual analog scale (VAS). The change in tooth shade was measured 30 days after tooth whitening. The intensity of tooth sensitivity was not significantly different between groups at 1 h after bleaching (p > 0.05). At 24 h after therapy, pain level was significantly lower in the LLIL group compared to the LLRL and placebo groups (p < 0.05). At 48 h after bleaching, VAS scores in the LLIL and LLRL groups were comparable to each other (p > 0.05) and both were significantly lower than that of the placebo group (p < 0.05). There was no significant difference in the efficacy of tooth whitening among groups (p > 0.05). LLLT with an infrared diode laser could be recommended as a suitable strategy to reduce the intensity of tooth sensitivity after in-office bleaching.

Can green tea be used to reverse compromised bond strength after bleaching?

The objective of this study was to evaluate the antioxidant effect of green tea on microtensile bond strength (µTBS) to bleached enamel. Forty-two human third molars were randomly divided into six experimental groups (n = 7 each group): group 1, no treatment; group 2, bleaching (10% carbamide peroxide); group 3, bleaching + 10% sodium ascorbate gel (SA); group 4, bleaching + 10% green tea gel (GT); group 5, SA; and group 6, GT. In groups 2, 3, and 4, bleach was applied onto the enamel surface for 6 h, every day for 14 d. In groups 3 and 5, SA was applied for 1 h; and in groups 4 and 6, GT was applied for 1 h. Immediately after treatment, the specimens were bonded with Adper Single Bond 2 and Filtek Z350 XT. The µTBS of the specimens was tested using a universal testing machine. Fracture mode analysis of the bonded enamel surface was performed using scanning electron microscopy. The mean µTBS values for each group were: group 1, 33.2 ± 5.8 MPa; group 2, 22.6 ± 5.5 MPa; group 3, 30.0 ± 5.2 MPa; group 4, 31.6 ± 3.8 MPa; group 5, 29.1 ± 4.2 MPa; and group 6, 32.2 ± 4.5 MPa. All groups had a higher percentage of mixed failures. In conclusion, green tea can be used as an alternative antioxidant on bleached enamel before bonding procedures.

Evaluation of bleaching efficacy and erosion potential of four different over-the-counter bleaching products.

PURPOSE: To evaluate the bleaching efficacy and erosion potential of various over-the-counter bleaching products following a test method specified in ISO 28399. METHODS: Specimens were prepared from bovine molars, stained in tea solution, embedded and randomly assigned to six groups of 10 enamel and dentin specimens each. Color was assessed at baseline, 1 day and 1 month post-bleaching with the Vita Bleachedguide 3D Master shade guide. Surface roughness changes (deltaRa), determined by baseline and post-treatment values were measured with a profilometer. The negative (NC) and positive control (PC) was treated with grade 3 water and 1.0% citric acid, respectively. Over-the-counter products were used according to manufacturer's instructions. Brite Teeth Pro (BT), Natural White 5-Minute Whitening (NW), Luster Premium White (LP), and Crest 3D Whitestrips (WS) represented a brush-on-paint system, tray system, light-activated system and adhesive-strip system, respectively. Kruskal-Wallis procedure was used to compare surface roughness changes among groups. Color change was assessed with Friedman-test and stratified by hard tissue type with alpha= 0.05. RESULTS: WS was the only group demonstrating color changes in enamel and dentin (P< 0.05). There were no differences in deltaRa for enamel and dentin among NC, BT, LP, and WS. NW showed increase in deltaRa in dentin (P< 0.05), while PC demonstrated an increase in deltaRa regardless of hard tissue type (P< 0.05).

Effect of grape seed extract on the bond strength of bleached enamel.

OBJECTIVE: This in vitro study assessed the neutralizing effect of grape seed extract (oligomeric proanthocyanidin complexes [OPCs]) on the bond strength of bleached enamel. MATERIALS AND METHODS: Labial enamel surfaces of 70 extracted human maxillary central incisors were randomly divided into four groups based on the antioxidant used as follows: Group I (n=20): bleaching with 38% hydrogen peroxide gel for 10 minutes, without the use of an antioxidant; Group II (n=20): bleaching followed by the use of 10% sodium ascorbate solution; Group III (n=20): bleaching followed by the use of 5% proanthocyanidin solution; and Group IV (n=10): control group in which no bleaching was done. Groups I, II, and III were further subdivided into two subgroups of 10 teeth each, based on whether composite build-up was done immediately (subgroup A) or after a delay of 2 weeks (subgroup B) post bleaching. Shear bond strength of the specimens was tested under a universal testing machine. The data were tabulated and statistically analyzed. RESULTS: Significantly higher shear bond strength values were observed in teeth treated with 10% sodium ascorbate (Group II) and 5% proanthocyanidin (Group III) as compared with the control group (Group IV). Among the antioxidants used, teeth treated with proanthocyanidin showed significantly higher shear bond strength values than those treated with sodium ascorbate. CONCLUSION: It can be concluded that the use of grape seed extract prior to bonding procedures on bleached enamel completely neutralizes the deleterious effects of bleaching and increases the bond strength significantly.