Impact of transparent tray-based application of bioactive glasses desensitizer on the permeability of enamel and dentin to hydrogen peroxide: an in vitro study.

BACKGROUND: To investigate the effect of transparent tray-based application of bioactive glasses (BGs) desensitizer on the permeability of enamel and dentin to hydrogen peroxide (H2O2). METHODS: Freshly extracted human first premolars were divided into 6 groups (n = 8). Group A and B: without pretreatments; Group C and E: treated with BGs desensitizer only; Group D and F: treated with BGs desensitizer dispensed with a transparent tray. After roots and pulp tissues of the treated tooth specimens were thoroughly removed, acetate buffer was added into pulp chambers and the treated specimens were immersed in distilled water (Groups A, E, and F) or 30% H2O2 (Groups B, C, and D) for 30 min at 37 °C. The amount of H2O2 in the pulp chamber of each group was measured using ultraviolet-visible spectrophotometry. RESULTS: In control groups (Group A, E, and F), H2O2 was not detected. The amount of pulpal H2O2 in Group B, C, and D were 21.149 ± 0.489 µg, 9.813 ± 0.426 µg, and 4.065 ± 0.268 µg respectively. One-way ANOVA analysis indicated that significant differences existed in these groups (F = 459.748, p < 0.05). CONCLUSIONS: The effect of BGs desensitizer in reducing the permeability of enamel and dentin to H2O2 could be enhanced when dispensed with a transparent tray.

In vivo and in vitro assessment of the bleaching effectiveness of a brush-off patch containing 3.0% hydrogen peroxide.

OBJECTIVES: To evaluate the efficacy of a brush-off patch containing 3.0% hydrogen peroxide, which is a new over-the-counter (OTC) product for tooth whitening, and determine the optimal protocol for use. MATERIALS AND METHODS: We performed an in vitro study using hydroxyapatite specimens and a clinical trial involving 140 volunteers. The brush-off patch was applied to the specimens (in vitro) or the maxillary anterior teeth (in vivo; 14 days) for 10 min twice daily (case 10 group) or 30 min once daily (case 30 group). We also included control groups in both experiments. Lightness (L*), redness (a*), and yellowness (b*) values were measured using a colorimeter. In the in vivo study, color changes were measured at baseline and 7 and 14 days after the start of patch application. The overall color change (ΔE) was statistically analyzed. RESULTS: In the in vitro study, the color change (ΔE*) after the experiment was significantly different between the two case groups and the control group (p < 0.001). In the in vivo study, the case groups showed color changes at both 7 and 14 days after patch application. In particular, the change in the case 30 group was significantly more prominent on day 14 than on day 7 (p < 0.05). CONCLUSION: Our findings suggest that brush-off patches containing 3.0% hydrogen peroxide are effective OTC products for tooth whitening. CLINICAL RELEVANCE: For best results, brush-off patches containing 3.0% hydrogen peroxide can be applied once daily for 30 min.

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 gel replacement during in-office dental bleaching: a case report.

In-office dental bleaching allows the dentist to have greater control of the procedure and prevents patients from ingesting chemicals. To obtain optimum results, in-office bleaching usually requires a longer period of application as well as changes of the bleaching agent applied to the tooth surfaces at each appointment. The objective of this case report was to assess, by means of a split-mouth design in a single patient, the final tooth color and tooth sensitivity resulting from 2 different bleaching protocols: 1 application of 35% hydrogen peroxide for 45 minutes and 3 applications of 35% hydrogen peroxide for 15 minutes each. Neither the patient nor 5 individuals who were blinded to the techniques noted a difference in the final esthetic results of the 2 protocols immediately after the procedure. In addition, the patient reported that no tooth sensitivity was associated with either protocol. The results of dental bleaching on both sides were maintained after 15 days. The results shown in the present case report suggest that there may be no need to renew the gel during in-office dental bleaching.

Quality of life and stability of tooth color change at three months after dental bleaching.

PURPOSE: Intracoronary bleaching is a minimally invasive, alternative treatment that addresses aesthetic concerns related to non-vital teeth discoloration. However, to the best of our knowledge, no studies have assessed the psychosocial impacts of such procedures on patients' aesthetic perceptions. The aim of this study was to evaluate aesthetic perceptions and the psychosocial impact of patients up to 3 months after their teeth had been bleached with hydrogen peroxide (35%) and carbamide peroxide (37%) using the walking bleach technique. METHODS: The patients were randomly divided into two groups according to the bleaching agent used: G1 = hydrogen peroxide 35% (n = 25) and G2 = carbamide peroxide 37% (n = 25). Non-vital bleaching was performed in four sessions. Color was objectively (ΔE) and subjectively (ΔSGU) evaluated. Aesthetic perception and psychosocial factors were evaluated before, 1 week and 1 month after the bleaching using the Oral Health Impact Profile (OHIP) and Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) questionnaires. RESULTS: The color change (ΔE) values at 1 month were G1 = 16.80 ± 6.07 and G2 = 14.09 ± 4.83. These values remained stable until the third month after treatment (p > 0.05). There was a decrease in the values of OHIP-aesthetics and PIDAQ after treatment versus baseline (p < 0.05). This status was maintained through the third month after treatment. CONCLUSIONS: Both agents were highly effective and had a positive impact on the aesthetic perception and psychosocial impact of patients, values that also remained stable over time. Non-vital bleaching yields positive and stable impacts on aesthetic perception and psychosocial factors. ClinicalTrials.gov identifier NCT02718183.

Effectiveness and effect of non-vital bleaching on the quality of life of patients up to 6 months post-treatment: a randomized clinical trial.

OBJECTIVES: The aim of this study was to evaluate the esthetic perception of patients at 6 months after bleaching of non-vital teeth with 35% of hydrogen peroxide and 37% of carbamide peroxide using a walking bleach technique. We also assessed psychosocial impacts as well as the clinical effectiveness and stability of the color change. MATERIALS AND METHODS: The teeth bleaching treatment was randomly assigned to two groups according to the bleaching agent used: G1 HP = 35% of hydrogen peroxide (n = 25) and G2 CP = 37% of carbamide peroxide (n = 25). The non-vital bleaching was performed in four sessions using the walking bleach technique. The color was objectively (ΔE) and subjectively (ΔSGU) evaluated. The esthetic perception and psychosocial factors were evaluated before treatment as well as one and 6 months post-treatment using Oral Health Impact Profile (OHIP) esthetics and Psychosocial Impact of Dental Esthetics Questionnaire (PIDAQ). RESULTS: The color change (ΔE) at 6 months (G1 = 14.53 ± 5.07 and G2 = 14.09 ± 6.61) for both color groups remained stable until the 6-month post-treatment (p > 0.05). There was a decrease in the values of OHIP esthetics and PIDAQ after treatment compared to the baseline (p < 0.05), and this effect was maintained 6 months post-treatment. CONCLUSIONS: Both agents were highly effective and maintained the color stability at 6 months; this positively affected the esthetic perception and psychosocial impact of patients who also remained stable over time. CLINICAL RELEVANCE: Non-vital bleaching produces a positive and stable impact on the esthetic perception and psychosocial factors at medium-term follow-ups.

Randomized clinical trial of 2 nonvital tooth bleaching techniques: A 1-year follow-up.

STATEMENT OF PROBLEM: Controlled clinical trials comparing the effectiveness of the walking bleaching (WB) technique and the inside-outside (I-O) technique used in a short daily regimen are lacking. PURPOSE: The purpose of this randomized clinical trial was to investigate the effectiveness of WB with that of the I-O technique conducted over 4 weeks and to compare color changes after 1 year. MATERIAL AND METHODS: Discolored and endodontically treated anterior teeth received a cervical seal and were randomly divided into groups according to the technique. In the WB group (n=9), a mixture of sodium perborate and 20% hydrogen peroxide was applied in the pulp chambers and replaced weekly up to 4 weeks. For the I-O group (n=8), participants applied 10% carbamide peroxide in the pulp chambers and wore custom-fitted trays for 1 hour per day over 4 weeks. CIELab parameters were obtained using a spectrophotometer at baseline, during bleaching (1, 2, 3, and 4 weeks) and after 1 year. Changes in color (ΔE), lightness (ΔL*), green-red axis (Δa*), blue-yellow axis (Δb*), and absolute color parameters (L*, b*, and a*) for each evaluation time were calculated and analyzed by repeated measures analysis of variance (ANOVA) and post hoc Bonferroni test (α=.05). RESULTS: No significant differences between WB and I-O techniques were observed for ΔE, ΔL*, Δa*, Δb*, L*, a*, or b* values (P>.05); however, significant differences were observed among the evaluation times (P<.05). Color changes observed after 2 weeks were stable after 1 year; ΔL* and Δa* values after 1 year were not significantly different from the 1-week evaluation, and significant changes in Δb* after 3 weeks were maintained at the 1-year follow-up. The same trend was observed for the absolute CIELab color parameters. CONCLUSIONS: Both WB and I-O regimens were similarly effective as shown by significant ΔE after 2 weeks and no color regression after 1 year.

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

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

Effects of the Ratio between Pigment and Bleaching Gel on the Fracture Resistance and Dentin Microhardness of endodontically treated Teeth.

INTRODUCTION: The aim of this study was to evaluate the effects of bleaching gel using 35% hydrogen peroxide (HP), associated with red carmine pigment (RC), in the 3:1 or 1:1 ratio, on fracture resistance and dentin microhardness of endodontically treated teeth. MATERIALS AND METHODS: A total of 40 lower incisors were endodontically treated and divided into four groups (n = 10), according to the bleaching protocol: G1 (HP3), 35% HP + RC (3:1); G2 (HP1), 35% HP + RC (1:1); G3 (positive), 38% HP; and G4 (negative), unbleached. Four dental bleaching sessions were performed. The dental crowns were restored after the last session and submitted to the fracture resistance test. Totally, 60 specimens from the endodontically treated lower incisor crowns were prepared to evaluate the effects on dentin microhardness. The analysis was measured (in Knoop) prior to and after the last dental bleaching session using similar bleaching protocols. RESULTS: G2 presented the lowest fracture resistance (p < 0.05). The other groups were similar to each other (p > 0.05). No difference was observed in the reduction of dentin microhardness among the groups (p > 0.05). CONCLUSION: A 1:1 ratio (bleaching gel:pigment) caused a significant fracture resistance reduction in relation to the other protocols. No effect on the dentin microhardness reduction was observed. CLINICAL SIGNIFICANCE: The pigment addition to the bleaching agent accelerates the bleaching chemical reaction. However, no studies have evaluated the ideal proportion to optimize tooth bleaching.

Efficacy and safety of over-the-counter whitening strips as compared to home-whitening with 10 % carbamide peroxide gel--systematic review of RCTs and metanalysis.

OBJECTIVES: The study aims to compare the efficacy and safety of over-the-counter whitestrips with the American Dental Association (ADA)-recommended home-whitening using the 10 % carbamide peroxide gel. MATERIALS AND METHODS: Randomized controlled trials (RCTs) comparing the clinical efficacy and safety of the whitestrips with the 10 % carbamide peroxide (10 % CP) gel applied on tray for tooth whitening in adults were searched at PubMed and Cochrane Central Register of Controlled Trials databases and selected up to October 2014. Efficacy of the whitening techniques was assessed through ∆E, ∆L, and ∆b parameters, while side effects were analyzed as dichotomous variables. Data was extracted independently by two reviewers. Metanalysis was performed using random- and fixed-effect models (RevMan 5.3). RESULTS: Eight studies were included in the metanalysis. The metanalysis revealed no significant difference between the intervention groups for tooth-whitening efficacy measured as ΔE (mean difference [MD]-0.53; 95 % CI [-1.72;0.66]; Z = 0.88; p = 0.38) and ΔL (MD-0.22; 95 % CI [-0.81;0.36]; z = 0.75; p = 0.45); reduction of yellowing was higher with the whitestrips (MD-0.47; 95 % CI [-0.89; -0.06]; Z = 2.25; p = 0.02). Tooth sensitivity (risk ratio [RR] 1.17; 95 % CI [0.81-1.69]; Z = 0.81; p = 0.42) and gingival sensitivity (RR 0.76; 95 % CI [0.53-1.10]; Z = 1.44; p = 0.15) were similar, regardless of the whitening method used. The observed gingival irritation was higher when the 10 % CP gel was applied on tray (RR 0.43; 95 % CI [0.20-0.93]; Z = 2.14; p = 0.03). The quality of evidence generated was rated very low for all outcomes. CONCLUSIONS: There is no sound evidence to support the use of the whitening strips in detriment of the ADA-recommended technique based on the 10 % carbamide peroxide gel applied on tray. CLINICAL RELEVANCE: To the moment, there is no sound evidence in dental literature to suggest that the ADA-recommended whitening technique based on 10 % carbamide peroxide gel could be substituted by the whitening strips. The existing studies, with their limitations, revealed similar tooth whitening and tooth and gingival sensitivity for both whitening techniques.

Insight in the chemistry of laser-activated dental bleaching.

The use of optical radiation for the activation of bleaching products has not yet been completely elucidated. Laser light is suggested to enhance the oxidizing effect of hydrogen peroxide. Different methods of enhancing hydrogen peroxide based bleaching are possible. They can be classified into six groups: alkaline pH environment, thermal enhancement and photothermal effect, photooxidation effect and direct photobleaching, photolysis effect and photodissociation, Fenton reaction and photocatalysis, and photodynamic effect.

Antimicrobial effects of carbamide peroxide against a polymicrobial biofilm model.

PURPOSE: To investigate the in vitro antimicrobial effects of carbamide peroxide (CP) and CP-based home bleaching agents against polymicrobial (PM) biofilms. METHODS: Using a high-throughput active attachment model, PM biofilms were cultured on glass coverslips by diluting the stimulated saliva of one healthy adult. All experiments were performed anaerobically in McBain medium, which was refreshed twice daily. After biofilm formation for 24 or 72 hours, the biofilms were treated with 0.5%, 2.5%, 5%, or 10% CP, 20-fold dilutions of HiLite Shade Up (HS) or Opalescence Regular (OR), 0.2% chlorhexidine digluconate (CHX), 0.2% NaF, or deionized water (n = 10 each). Biofilms were dispersed and the number of colony forming units (CFU) was measured on tryptic soy agar blood plates. Coverslips containing 72-hour biofilms treated with 0.5% and 10% CP and deionized water were stained and scanned by confocal laser scanning microscopy (CLSM). RESULTS: Treatment of 24- and 72-hour biofilms with HS, OR and CH yielded significantly fewer colonies than treatment with water or 0.2% NaF. No growing colonies were observed after treatment with 10% CP. CLSM showed that the percentage of dead bacteria increased as the concentration of CP increased.

Comparison of treatment time versus patient satisfaction in at-home and in-office tooth bleaching therapy.

STATEMENT OF THE PROBLEM: There are different approaches and treatment times to achieve tooth whitening. PURPOSE: The purpose of this study was to evaluate the efficacy of different agents and the treatment time required to achieve participant satisfaction with at-home and in-office tooth whitening. MATERIAL AND METHODS: Thirty participants were selected based on the shade of the anterior teeth (between A2 and A3.5; Vita Classic Shade Guide). Each participant received both in-office and at-home bleaching agents in a split-mouth design at both arches. In-office bleaching was performed in the maxillary quadrants, applying 35% hydrogen peroxide (HP35%) (right) and 35% HP with calcium (HP35%Ca) (left) for 40 minutes/week. Home bleaching was performed in mandibular quadrants using carbamide peroxide 10% (CP10%) (right) and CP22% (left) for 2 hours/day. Bleaching treatments were performed until participant satisfaction was achieved (maximum 6 sessions [S] in the dental office or 6 weeks [W] in the home). The shade was measured with a spectrophotometer before treatment, then at 2 and 4 weeks, and at the last week for at-home bleaching; and 1 week after the second, fourth, and last sessions for in-office bleaching. Student t and Tukey-Kramer tests were used (α=.05). RESULTS: All bleaching agents were effective for vital tooth whitening. No significant differences were observed for color changes between CP10% and CP22% or between HP35% and HP35%Ca for all periods. Treatment times required to achieve patient satisfaction for the in-office bleaching technique were 4S (12 participants), 5S (10 participants), and 6S (8 participants); and 4W (6 participants), 5W (8 participants), and 6W (16 participants) for the at-home bleaching technique. CONCLUSIONS: Treatment time to participant satisfaction ranged from 4 to 6 weeks regardless of the bleaching agent used in at-home and in-office therapy.

In vitro evaluation of calcium and phosphorus concentrations in enamel submitted to an in-office bleaching gel treatment containing calcium.

The aim of this in vitro study was to evaluate the calcium and phosphorus concentrations in enamel surfaces before, during, and after treatment with in-office 35% hydrogen peroxide bleaching agents with 2% calcium gluconate (WCa) or without calcium gluconate (W). Twenty sound human third molars were divided into 2 groups of 10. The bleaching agents were applied to the tooth surfaces in accordance with the manufacturer's instructions: WCa, 40 minutes per day at 3 sessions with 7-day intervals; W, 3 × 15 minutes per day at 3 sessions with 7-day intervals. Enamel microbiopsies were performed prior to the bleaching treatment, immediately after each bleaching session (first, second, and third applications), and 7 and 14 days following the last bleaching treatment. The concentration levels of calcium and phosphorus in the microbiopsy specimens were recorded spectrophotometrically. There was a statistically significant decrease in the calcium concentration 7 days after the last bleaching treatment, but there was a recovery to baseline values at 14 days, regardless of the bleaching agent used (WCa and W). When W was used, there was no difference in the phosphorus concentration over time. The phosphorus concentration in the WCa group decreased after the third application, showing a significant difference from the W group at this time. However, an increase in the phosphorus concentration was observed in the posttreatment period, and no significant differences were observed between values at baseline and those at 14 days posttreatment. The in-office bleaching gel containing 2% calcium gluconate did not affect the calcium and phosphorus concentrations in enamel as compared to a calcium-free bleaching agent.

Employment of Reservoirs in At-Home Whitening Trays: Efficacy and Efficiency in Tooth Whitening.

AIM: This study aimed to determine the efficacy of trays made with and without reservoirs, in conjunction with time and cost evaluations, by measuring color change with home whitening procedures. MATERIALS AND METHODS: Extracted human maxillary teeth (central incisors n = 20; canines n = 20; molars n = 20) and 60 artificial teeth (lateral n = 20; premolar n = 40) were mounted into ten typodonts. Tray fabrication was completed such that a block-out resin reservoir was placed on half of the buccal surface of the tray, while the other half remained without a reservoir. Whitening with custom fabricated trays was performed based on two different whitening regimens, where each regimen was assigned to five typodonts: Night-time: Opalescence PF 10% carbamide peroxide for 8 hours daily and Day-time: Philips DayWhite 9.5% hydrogen peroxide for 30 minutes, twice daily. Both systems were applied for 1 week. To evaluate tooth shade, the VITA Easyshade® Advance 4.0 spectrophotometer was used. Color measurements were obtained at baseline (T1), 1-day post-whitening (T2), and 1 month post-whitening (T3). One-way ANOVA, followed by post-hoc Tukey's HSD test, was used to detect significant difference in the overall color change (ΔE*) among the four groups at T2 and T3. Additionally, paired-sample t-test was used to assess difference in ΔE* between T2 and T3 treatment within each of four techniques of tray fabrication. RESULTS: No significant difference in ΔE* was found among the four groups at T2 and T3 (p > 0.05 in each instance). There were significant differences in mean ΔE* between T2 and T3 treatment for the day white treatment groups without reservoir (6.96 vs 10.19 respectively; p = 0.0026) and with reservoirs (6.23 vs 9.79 respectively; p = 0.0031). CONCLUSION: The use of reservoirs does not have a significant effect on whitening efficacy, regardless of type of whitening material and regimen. CLINICAL SIGNIFICANCE: The use of custom fabricated trays with or without reservoirs were equally effective in whitening teeth.

An overview on the Effects of 10% and 15% Carbamide Peroxide and its Relationship to Dentine Sensitivity.

The purpose of this overview was to review the available literature to determine if there was any evidence that the application of 10% and 15% carbamide peroxide in tooth whitening procedures resulted in tooth (dentine) sensitivity. The conclusions from the review would indicate that tooth whitening with either 10% or 15% carbamide peroxide is an effective and safe treatment when under a dental professionals' supervision. Reported side-effects were considered mild to moderate in nature and were transient in duration. Reported incidences of dentine sensitivity range from 15-65% of patients using 10% carbamide peroxide.

Effect of incorporation of remineralizing agents into bleaching gels on the microhardness of bovine enamel in situ.

AIM: This study evaluated the effect of adding calcium or fluoride to 35% hydrogen peroxide (HP) bleaching gel and the effect of human saliva on the microhardness of sound and demineralized enamel, using an in situ model. MATERIALS AND METHODS: Cylindrical bovine enamel specimens (3 × 2 mm) were divided into two groups (n = 30): sound enamel (SE) and demineralized enamel (DE). Each group was divided into three subgroups, according to the bleaching gel: 35% HP; 35% HP + calcium; 35% HP + fluoride. After bleaching therapy, the specimens were fixed to intraoral devices worn by 10 volunteers for 7 days. Surface enamel microhardness (SMH) was measured before and after bleaching procedures, and after 1 and 7 days of saliva exposure. Data were analyzed by Repeated Measures ANOVA (5%). RESULTS: The variable time resulted in significant differences for SE and DE groups (p = 0.001). For SE, significantly lower SMH was detected for control at post-bleaching period in comparison to the baseline and after 7 days. For DE, the lowest mean values were obtained before bleaching, and the addition of calcium to the peroxide significantly increased enamel SMH. The exposure to human saliva resulted in increased SMH. CONCLUSION: The addition of potential remineralizing agents into bleaching gels might play an important role in maintaining the microhardness of sound enamel and in inducing remineralization of artificially demineralized enamel right after bleaching, and the remineralizing action of human saliva might minimize the deleterious effects of bleaching gels on enamel. Clinical significance: The incorporation of calcium into HP bleaching gel might be beneficial for the initial phases of the bleaching procedure.

The effect of three whitening oral rinses on enamel micro-hardness.

The purpose of this study was to determine the effect on human enamel micro-hardness of three over-the-counter whitening oral rinses available in South Africa. Enamel fragments were gathered into three groups of 15 each. One group was exposed to Colgate Plax Whitening Blancheur, the second group to White Glo 2 in 1 and the third to Plus White, in each case for periods recommended by the respective manufacturers. Surface micro-hardness of all groups was measured before and after a 14 day treatment period. pH levels of the oral rinses were also determined with a combination pH electrode. Pre- and post- treatment data were analysed by the Wilcoxon Signed Rank Sum Test. According to the micro-hardness values no significant (p > 0.05) enamel damage was found as a result of treatment. However, it was observed that Colgate Pax and White Glo decreased the enamel hardness, an early sign of enamel damage, while Plus White showed a small increase in hardness. The three whitening oral rinses on the South African market do not damage the tooth enamel significantly when used as recommended by the manufacturers. However, extending the contact period and increasing the frequency of application might lead to damage of enamel.

Clinical trial of tooth desensitization prior to in-office bleaching.

The aim of this clinical trial was to compare tooth sensitivity during and after bleaching with hydrogen peroxide gel following application of GLUMA Desensitizer PowerGel or placebo. Forty-six subjects with sound maxillary incisors and canines were enrolled. Tooth shades were determined by comparison with a Vitapan Classic Shade guide. GLUMA Desensitizer PowerGel and placebo were randomly applied to the labial surfaces of the left or right anterior teeth for 1 min, which were then rinsed and dried. Then, Opalescence Boost PF 40% gel was applied onto labial enamel for 15 min. Sensitivity scores [recorded on a 10-point visual-analog scale (VAS)] were determined before, at 5, 10, and 15 min during, and 1, 24, 48 h and 1 wk after, the bleaching treatment. Shades were determined postbleaching and after 1 wk. Prebleaching application of GLUMA Desensitizer PowerGel significantly reduced tooth sensitivity during and after bleaching when compared with treatment with placebo. The whitening effects immediately and 1 wk after bleaching were significant when compared with the prebleaching shades. In conclusion, tooth pretreatment with GLUMA Desensitizer PowerGel for 1 min prior to 15 min of in-office bleaching with 40% hydrogen peroxide gel was highly effective in reducing tooth sensitivity during and after bleaching.

Influence of two different methods of delivering fluoride on bond strength and degree of conversion of an adhesive after bleaching.

PURPOSE: To evaluate the influence of fluoride delivery and restoration time point on the microshear bond strength (mSBS) and degree of conversion (DC) values of an adhesive applied on bleached enamel. MATERIALS AND METHODS: Fifty-four enamel specimens were submitted to bleaching and divided into 3 groups of n = 18: group HP: 35% hydrogen peroxide (HP); group HPF: HP + 1.23% sodium fluoride application (F); group PF: 38% HP with F. A control group of n = 6 was neither bleached nor fluoridated. Subsequently, each group except the control was subdivided into 3 subgroups (n = 6) to be restored immediately, or at 7 or 14 days. Tygon tubes were filled with composite resin and placed on enamel surfaces, then the mSBS test was performed. The DC of the interface was observed with Raman spectroscopy. The data were submitted to two-way ANOVA and Tukey's and Dunnet's post-hoc test (α = 0.05). RESULTS: The mSBS results showed higher values for groups HP and HPF at 14 days compared with immediate and 7 days (p < 0.05). Lower DC values were obtained in the immediately restored groups HP and HPF, which were significantly different from 7 and 14 days (p < 0.05). mSBS and DC for group PF was similar at all restoration time points and to the control group (p > 0.05). CONCLUSION: Only the use of a fluoridated in-office bleaching agent (Opalescence Boost PF) proved to be effective for immediately reversing the side effects of low mSBS and DC values when in-office bleaching is used.