Two-year clinical evaluation of tooth whitening using an at-home bleaching system

Evaluating the efficiency of two different over-the-counter tooth whitening systems: a randomised controlled clinical trial

OBJECTIVES

To compare whitening efficiency and tooth sensitivity (TS) of two different over the counter (OTC) whitening systems in comparison to conventional at-home bleaching using 20% carbamide peroxide.

MATERIALS AND METHODS

A randomised controlled clinical trial was conducted with three parallel groups (n = 13): (A) at-home whitening using 20% carbamide peroxide (20% CP), (B) OTC ready-to-use gel trays and (C) OTC-paint on gel. Clinical colour change values (ΔE) were measured using spectrophotometry at T0: baseline, T1: 7-day and T2: 14-day from whitening start, T3: 2 weeks and T4: 6 months after whitening end. TS was recorded using a visual analogue scale (VAS). ΔE and TS values were statistically analysed. The level of significance for all tests was 5%.

RESULTS

Significant differences in ∆E values were recorded between the experimental groups. ∆E values were significantly higher in the 20% CP conventional at-home whitening group. TS measurements were significantly higher in the 20% CP whitening group (p < 0.05).

CONCLUSION

Conventional at-home whitening revealed significantly improved colour change when compared to the OTC-paint on gel and OTC ready-to-use gel tray whitening systems. There was a significant colour relapse in OTC systems.

CLINICAL RELEVANCE

The use of tested OTC systems is not recommended as they are not effective in a clear and prolonged improved shade change. Conventional at-home whitening using 20% CP showed higher whitening efficiency and colour stability. This trial was registered with a International Standard Randomised Controlled Trial Number (ISRCTN23096480), Registration date: 12/04/2023.

Randomized clinical trials of dental bleaching - Compliance with the CONSORT Statement: a systematic review

We reviewed the literature to evaluate: a) The compliance of randomized clinical trials (RCTs) on bleaching with the CONSORT; and b) the risk of bias of these studies using the Cochrane Collaboration risk of bias tool (CCRT). We searched the Cochrane Library, PubMed and other electronic databases, to find RCTs focused on bleaching (or whitening). The articles were evaluated in compliance with CONSORT in a scale: 0 = no description, 1 = poor description and 2 = adequate description. Descriptive analyses of the number of studies by journal, follow-up period, country and quality assessments were performed with CCRT for assessing risk of bias in RCTs. 185 RCTs were included for assessment. More than 30% of the studies received score 0 or 1. Protocol, flow chart, allocation concealment and sample size were more critical items, as 80% of the studies scored 0. The overall CONSORT score for the included studies was 16.7 ± 5.4 points, which represents 52.2% of the maximum CONSORT score. A significant difference among journal, country and period of time was observed (p < 0.02). Only 7.6% of the studies were judged at "low" risk; 62.1% were classified as "unclear"; and 30.3% as "high" risk of bias. The adherence of RCTs evaluating bleaching materials and techniques to the CONSORT is still low with unclear/high risk of bias.

Longevity, Esthetic Perception, and Psychosocial Impact of Teeth Bleaching by Low (6%) Hydrogen Peroxide Concentration for In-office Treatment: A Randomized Clinical Trial

OBJECTIVE

The aim was to evaluate the color longevity after nine months of in-office bleaching with gel (6% hydrogen peroxide), to compare this to a control concentration of 35% in a split-mouth study model, and to assess the dental confidence and psychosocial impact on patients.

METHODS AND MATERIALS

Twenty-seven patients were assessed at the nine-month recall. The bleaching procedure with 6% or 35% hydrogen peroxide gel was performed randomly in the upper hemi-arch of each patient. The color was measured at baseline and at one week, one month, and nine months after the procedure, using the Vita Easyshade spectrophotometer, the Vita classical shade guide organized by value, and Vita Bleach Guide 3DMaster. Moreover, two surveys, OHIP-Esthetics and PIDAQ, were used to assess the esthetic self-perception and psychosocial impact of the bleaching procedure. During the nine-month recall, the color was assessed before and after dental prophylaxis.

RESULTS

Twenty-seven patients participated in the nine-month recall. There was a significant difference in ΔE between the two groups at all times assessed (p<0.011). The ΔL, Δa, and Δb showed a difference between the two groups at all times assessed (p<0.038), except for ΔL from the baseline vs nine-month after prophylaxis value (p>0.20). There was no significant difference in ΔSGU at all times (p>0.05). There was a significant difference in OHIP-Esthetics and PIDAQ sums compared with baseline scores (p<0.03).

CONCLUSION

The two compounds remained effective at nine months, with a slight rebound of color, and maintained their objective color difference but not the subjective color difference. Patients were satisfied with the bleaching procedure, and this had a positive impact on esthetic perception and a positive psychosocial impact at the nine-month recall.

The degree of color change, rebound effect and sensitivity of bleached teeth associated with at-home and power bleaching techniques: A randomized clinical trial

Aim:

The purpose of the present randomized clinical trial was to evaluate the color change, rebound effect and sensitivity of at-home bleaching with 15% carbamide peroxide and power bleaching using 38% hydrogen peroxide.

Materials and Methods:

For bleaching techniques, 20 subjects were randomized in a split mouth design (at-home and power bleaching): In maxillary and mandibular anterior teeth (n = 20). Color was recorded before bleaching, immediately after bleaching, at 2 weeks, 1, 3 and 6 month intervals. Tooth sensitivity was recorded using the visual analog scale. The Mann-Whitney test was used to compare both groups regarding bleaching effectiveness (ΔE₁), rebound effect (ΔE₂) and color difference between the rebounded tooth color and unbleached teeth (ΔE₃) while the Wilcoxon compared ΔE within each group. Distribution of sensitivity was evaluated using the Chi-square test (α =0.05).

Results:

There was no significant difference between groups regarding ΔE₁ and ΔE₃ (P > 0.05). Even though, ΔE₂ showed no significant difference between groups after bleaching as well as at 2 week, 1 month and 3 month follow-up periods (P > 0.05). Although, significant difference was found in ΔE₂ (P < 0.05 Mann-Whitney) between two methods after 6 months and a high degree of rebound effect was obtained with power bleaching. Within each group, there was no significant difference between ΔE₁ and ΔE₃ (P < 0.05 Wilcoxon). The distribution of sensitivity was identical with both techniques (P > 0.05).

Conclusion:

Bleaching techniques resulted in identical tooth whitening and post-operative sensitivity using both techniques, but faster color regression was found with power bleaching even though color regression to the baseline of the teeth in both groups was the same after 6 months.

Comparative clinical study of the effectiveness of different dental bleaching methods - two year follow-up

This study evaluated color change, stability, and tooth sensitivity in patients submitted to different bleaching techniques.

MATERIAL AND METHODS

In this study, 48 patients were divided into five groups. A half-mouth design was conducted to compare two in-office bleaching techniques (with and without light activation): G1: 35% hydrogen peroxide (HP) (Lase Peroxide - DMC Equipments, São Carlos, SP, Brazil) + hybrid light (HL) (LED/Diode Laser, Whitening Lase II DMC Equipments, São Carlos, SP, Brazil); G2: 35% HP; G3: 38% HP (X-traBoost - Ultradent, South Jordan UT, USA) + HL; G4: 38% HP; and G5: 15% carbamide peroxide (CP) (Opalescence PF - Ultradent, South Jordan UT, USA). For G1 and G3, HP was applied on the enamel surface for 3 consecutive applications activated by HL. Each application included 3x3' HL activations with 1' between each interval; for G2 and G4, HP was applied 3x15' with 15' between intervals; and for G5, 15% CP was applied for 120'/10 days at home. A spectrophotometer was used to measure color change before the treatment and after 24 h, 1 week, 1, 6, 12, 18 and 24 months. A VAS questionnaire was used to evaluate tooth sensitivity before the treatment, immediately following treatment, 24 h after and finally 1 week after.

RESULTS

Statistical analysis did not reveal any significant differences between in-office bleaching with or without HL activation related to effectiveness; nevertheless the time required was less with HL. Statistical differences were observed between the results after 24 h, 1 week and 1, 6, 12, 18 and 24 months (intergroup). Immediately, in-office bleaching increased tooth sensitivity. The groups activated with HL required less application time with gel.

CONCLUSION

All techniques and bleaching agents used were effective and demonstrated similar behaviors.

Susceptibility of enamel treated with bleaching agents to mineral loss after cariogenic challenge

Objectives. Controversial reports exist whether bleaching agents cause a susceptibility to demineralization. The aim of this study was to compare the calcium loss of enamel treated with different bleaching agents and activation methods. Method and Materials. The specimens obtained from human premolars were treated in accordance with manufacturer protocols; 10% carbamide peroxide, 38% hydrogen peroxide light-activated, 38% hydrogen peroxide laser-activated, and no treatment (control). After cariogenic challenge calcium concentrations were determined by Inductively Coupled Plasma Mass Spectrometry. Results. No differences were found between the calcium loss of the laser-activated group and 10% carbamide peroxide group (p > 0.05). However, the differences between laser-activated and control groups were statistically significant (p < 0.05). The differences between 10% carbamide peroxide and the control group were not significant (p > 0.05). On the other hand, the light-activated group showed a significantly higher calcium loss compared with the other groups (p < 0.05). Conclusions. The results show that bleaching agents may cause calcium loss but it seems to be a negligible quantity for clinical aspects.

A clinical study of the effectiveness of two different 10% carbamide peroxide bleaching products: a 6-month followup

The purpose of this study was to evaluate the efficacy of two different 10% carbamide peroxide bleaching products just after treatment and after a 6-month follow-up period. Methods. Two 10% carbamide peroxide products (Opalescence PF and Nite White ACP) were applied nightly for 14 days, according to the manufacturers' instructions. The color of teeth 11 and 21 of thirty-four subjects having A2 or darker teeth were measured with a spectrophotometer (L^∗; a^∗; b^∗) before treatment, just after treatment (14 days) and after 6 months. Results and Conclusions. Both products produced significant whitening of teeth with total color change (ΔE_ab^∗) of approximately 5.20 units. There was a significant improvement in all 3 color coordinates (L*, a*, and b^∗) for up to 6 months postbleaching (P < .05). Nite White showed a higher degree of relapse (27%) than Opalescence (18%) over the 6-month period. It is suggested that rebleaching after 6 months is not necessary.

A double-blind randomized clinical trial of two carbamide peroxide tooth bleaching agents: 2-year follow-up

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).

One-year clinical evaluation of the efficacy of a new daytime at-home bleaching technique

The aim of this study was to compare the clinical efficacy and side effects of a new daytime at-home bleaching technique (28% carbamide peroxide [CP] gel) with the overnight application of 10% CP and to determine the change of tooth color 1-year post-treatment. Twenty healthy volunteers were assigned to one of two sample groups of 10. All participants employed one of the two at-home bleaching systems: (1) the new daytime at-home bleaching system including 28% CP gel with a non-custom-fit tray (Meta Tray, Remedent, Deurle, Belgium) for 20 minutes, and (b) the conventional overnight at-home bleaching system with a 10% CP gel and a custom-fit tray (Opalescence PF, Ultradent, South Jordan, UT, USA) for 6 to 8 hours. Digital images and CIE (International Commission on Illumination) L*, a*, and b* spectrophotometric measurements were taken at baseline, after the bleaching treatment and 1-year post-treatment. Tooth and gingival sensitivity was measured with a specially designed 4-point scale. Significant differences were found in L*, a*, and b* values, between initial and post-treatment, for both bleaching systems (p < 0.05). However, no significant difference was detected between post-treatment and 1-year follow-up. The bleaching effectiveness of Opalescence PF was found to be superior to that of Meta Tray, considering the color parameter of DeltaE (p < 0.05). Meta Tray provoked less tooth sensitivity (p < 0.05), however gingival sensitivity appeared more in this group (p < 0.05). Within the limitations of this study, it can be concluded that the new daytime at-home bleaching system tested (Meta Tray) produced significant bleaching effects. However, the clinical efficacy of the overnight bleaching system was found to be superior to the daytime at-home bleaching system evaluated in this study. The whitening effect remained similar 1-year after the bleaching treatment for both at-home bleaching systems. CLINICAL SIGNIFICANCE Although the new daytime at-home bleaching system tested exhibited significant bleaching effects, overnight bleaching with a 10% CP gel resulted in a higher bleaching effectiveness than this new system. Although the participants using the new bleaching system exhibited less tooth sensitivity probably because of the reduced contact time of bleaching gel with tooth surfaces, the application of the bleaching agent with a non-customized tray provoked more gingival sensitivity in this group.

Clinical performance of vital bleaching techniques

This study compared the clinical outcome of bleaching techniques in vital teeth. After IRB approval and informed consent, 90 subjects were selected based on the shade of their anterior teeth (A2 or darker, Vita Classic shade guide). Subjects were assigned to three treatment groups in a split-mouth study design: Group I: HB (at-home bleaching with 10% carbamide peroxide for two weeks) vs OBL (in-office bleaching with 35% hydrogen peroxide, two sessions, two-week intervals, with light irradiation); Group II: OB (in-office bleaching without light irradiation) vs OBL; Group III: HB vs combination (one session plus HB). Color change and color rebound (deltaE) were measured for a 16-week period. Color measurements were carried out with both a spectrophotometer and a shade guide at baseline, 1, 2, 4, 8 and 16 weeks. Tooth sensitivity was evaluated using a VAS scale for 15 days. Both the Student's t-test and Tukey-Kramer test were used to analyze the results (p < 0.05). After one week, one session of OBL followed by HB resulted in lower color values, compared with the other bleaching methods. Group III resulted in the least shade values at one-week evaluation, when compared with the other bleaching methods. After two weeks, HE alone resulted in similar color changes as OB, OBL and OBL+HB. The use of light irradiation did not improve bleaching efficacy (OB = OBL). OBL and OB resulted in higher sensitivity rates than HB.

Efficacy and Safety of 10% and 16% Carbamide Peroxide Tooth-whitening Gels: A Randomized Clinical Trial

This clinical trial suggests that two carbamide peroxide concentrations, when used once a day for three weeks, were well tolerated by patients and were effective in tooth whitening. Although some tooth sensitivity occurred during treatment, this side effect was mostly mild and transient.

Spectrophotometric and visual evaluation of vital tooth bleaching employing different carbamide peroxide concentrations

OBJECTIVE

The aim of the present study was to assess the hypothesis that the efficiency of vital tooth bleaching depends on the concentration of carbamide peroxide agents.

METHODS

The front teeth of 30 subjects were bleached at home with 10%, 17% or 0% (control) carbamide peroxide for 1 week in a double-blind study design. Tooth shades were determined in the LCH color space employing a visual shade matching system and a spectrophotometer. Differences in lightness (Deltal), chroma (Deltac) and hue (Deltah) were measured to assess the treatment process. After 2 weeks of no treatment, tooth shades were evaluated again to assess stability of the resultant shade.

RESULTS

First-time changes of shade values could be observed after 3 days in the 17% group and after 7 days in the 10% group. After 1 week, in both the 17% group (Deltal: 2.80, Deltac: -3.33, Deltah: 0.60) and the 10% group (Deltal: 2.61, Deltac: -2.54, Deltah: 0.09), values for lightness and chroma were significantly different from the control (Deltal: 0.13, Deltac: 0.14, Deltah: 0.21, p<0.05) with no difference between the test groups (p>0.05). Two weeks after treatment, a rebound of shade values could be observed in the test groups (p<0.05).

SIGNIFICANCE

The study indicates that higher concentration bleaching agents might whiten teeth faster with major changes in lightness and chroma. However, by bleaching daily for 1 week, similar effects can be achieved with both a high and a low concentration agent. After treatment, a regression of the resultant shade has to be expected.

Home-based chemically-induced whitening of teeth in adults

BACKGROUND

During the last decade tooth whitening products have become widely available in the USA for sale over-the-counter or dispensed by dentists for use at home. With the current rapid growth in demand for tooth whitening it is imperative that the dental community base its recommendations to patients on sound scientific evaluations conducted in well-designed and independent studies.

OBJECTIVES

To evaluate the effectiveness (versus a placebo or another active product) and side effects of over-the-counter or dentist-dispensed chemically-based tooth whitening products designed for home use.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2005, Issue 3); MEDLINE (January 1966 to September week 2 2005); and EMBASE (1988 to week 39 2005). The tables of content of selected dental journals published since 1995 were searched for additional references. Written requests for additional studies and information were mailed to experts in this area of research. After a final set of studies was identified, the list of references reported in the included reports was reviewed to identify additional studies. Studies published in English and non-English were considered in this review.

SELECTION CRITERIA

Randomised controlled trials and quasi-randomised controlled trials of dentist-dispensed or over-the-counter tooth whitening products with a chemical action (rather than abrasive action), for home use.

DATA COLLECTION AND ANALYSIS

Screening of titles and abstracts, data extraction and quality assessment were undertaken independently and in duplicate.

MAIN RESULTS

A total of 416 articles were identified, 25 of which met the inclusion criteria and presented data that could be used in the analysis. All included trials measured effectiveness immediately after 2 weeks of product application. Only 13 studies reported outcome data 1 week after the 2-week application period, and of those only six reported outcome data after 1 month or longer. Four of the included trials were assessed as at moderate risk of bias and the remainder at high risk of bias. All trials were sponsored by the manufacturers of tooth whitening products. Six trials compared different whitening products (gel in trays, paint-on films and whitening strips) with placebo/no treatment and all analyses showed the products to be effective, although most comparisons were based on single trials. Nineteen trials compared different whitening products with each other. There was only one meta-analysis which included more than one trial which showed statistically significant differences between the different whitening products. Strips (5.5% to 6.5% hydrogen peroxide(HP)) are more effective than gel in tray at 10% carbamide peroxide (CP) mean difference 1.82 (95% confidence interval (CI) 0.26 to 3.38). All of these trials were assessed as of high risk of bias. 'Mild' to 'moderate' tooth sensitivity and gingival irritation were the most common side effects. The whitening strips and products with high concentrations of HP caused more users to complain from tooth sensitivity. The protocols for preparation of participants prior to bleaching were inconsistent among the studies. Data on baseline scores of whiteness were not reported by the majority of the studies. The current evidence base on tooth whitening products suffers from methodological and publication biases.

AUTHORS' CONCLUSIONS

There is evidence that whitening products work when compared with placebo/no treatment. There are differences in efficacy between the products, mainly due to the levels of active ingredients, hydrogen peroxide and carbamide peroxide. All trials were however short term and the majority of the studies were judged to be at high risk of bias and were either sponsored or conducted by the manufacturers. There is a need for pragmatic long-term and independent clinical studies that include participants representing diverse populations. There is also a need to evaluate long-term harms. Several studies reported (where measured) the common side effects of tooth sensitivity and gingival irritation, and people should be informed of this.

Hydrogen peroxide tooth-whitening (bleaching) products: review of adverse effects and safety issues

Hydrogen peroxide in the form of carbamide peroxide is widely used for tooth whitening (bleaching), both in professionally- and in self-administered products. Adverse effects have become evident. Cervical root resorption is a possible consequence of internal bleaching and is more frequently observed in teeth treated with the thermo-catalytic procedure. Tooth sensitivity is experienced in 15-78% of patients undergoing external tooth bleaching. However, clinical studies addressing other adverse effects are lacking. Direct contact with hydrogen peroxide induces genotoxic effects in bacteria and cultured epithelial cells, but the effect is reduced or totally abolished in the presence of metabolising enzymes. Several carcinogenesis studies, including the hamster cheek pouch model, indicate that hydrogen peroxide (H(2)O(2)) might possibly act as a promoter. Until further clinical research is concluded to address the question of possible carcinogenicity, it is recommended that: tooth-bleaching products using concentrated H(2)O(2) should not be used without gingival protection; that H(2)O(2) containing products should be avoided in patients with damaged or diseased soft tissues. For nightguard vital bleaching, minimal amounts of low dose H(2)O(2) (including in the form of carbamide peroxide) are preferred, thereby avoiding prolonged and concentrated exposures.

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

PURPOSE

The purpose of this study was to compare the color changes achieved with two commonly used bleaching systems on the basis of a spectrophotometric analysis.

MATERIALS AND METHODS

Two commercially available 10% carbamide peroxide bleaching systems were used by a total of 48 individuals. Subjects who had intact natural maxillary anterior teeth void of any restorations or decay that had not been subjected to any prior bleaching were included. Opalescence 10% PF (Ultradent Products Inc., South Jordan, UT, USA) was used by 23 patients for 14 days, whereas Nite White Excel (Discus Dental, Culver City, CA, USA) was applied by 25 patients for the same duration. Tooth colors for the middle one-third region of maxillary central incisors and canines were measured with a spectrophotometer prior to bleaching and after 14 days of bleaching. Color difference deltaE and color coordinates L* (lightness), a* (redness), and b* (yellowness) of CIELAB color system (developed by the Commission Internationale de l'Eclairage) were calculated.

RESULTS

Mean deltaE values for Opalescence ranged from 5.03 to 8.92 and from 5.84 to 9.61 for Nite White. The most significant factor of the color change was b* followed by L* and a*. L* values were higher after bleaching, whereas values for both a* and b* decreased. There were no significant differences between the two systems examined (p < .05).

Effect of light energy on peroxide tooth bleaching

BACKGROUND

Light-activated bleaching is a method of tooth whitening. The authors conducted a study to compare the whitening effects and tooth temperature changes induced by various combinations of peroxide bleaches and light sources.

METHODS

The authors randomly assigned 250 extracted human teeth halves into experimental groups (n = 10). A placebo gel (control), a 35 percent hydrogen peroxide or a 10 percent carbamide peroxide bleach was placed on the tooth surface and was irradiated with no light (control); a halogen curing light; an infrared, or IR, light; an argon laser; or a carbon dioxide, or CO2, laser. Color changes were evaluated immediately, one day and one week after treatment using a value-oriented shade guide and an electronic dental color analyzer. The outer enamel and inner dentin surface temperatures were monitored before and immediately after each 30-second application of light using a thermocouple thermometer.

RESULTS

Color and temperature changes were significantly affected by an interaction of the bleach and light variables. The application of lights significantly improved the whitening efficacy of some bleach materials, but it caused significant temperature increases in the outer and inner tooth surfaces. The IR and CO2 laser lights caused the highest tooth temperature increases.

CONCLUSIONS

Dentists performing an in-office bleaching technique with the use of an additional light source to accelerate tooth whitening should consider the specific bleaching agent being used, as well as the potential risks of heating teeth.

CLINICAL IMPLICATIONS

A specific combination of bleach and light that demonstrates good color change and little temperature rise should be selected for in-office tooth bleaching.

Tooth bleaching--a critical review of the biological aspects

Present tooth-bleaching techniques are based upon hydrogen peroxide as the active agent. It is applied directly, or produced in a chemical reaction from sodium perborate or carbamide peroxide. More than 90% immediate success has been reported for intracoronal bleaching of non-vital teeth, and in the period of 1-8 years' observation time, from 10 to 40% of the initially successfully treated teeth needed re-treatment. Cervical root resorption is a possible consequence of internal bleaching and is more frequently observed in teeth treated with the thermo-catalytic procedure. When the external tooth-bleaching technique is used, the first subjective change in tooth color may be observed after 2-4 nights of tooth bleaching, and more than 90% satisfactory results have been reported. Tooth sensitivity is a common side-effect of external tooth bleaching observed in 15%-78% of the patients, but clinical studies addressing the risk of other adverse effects are lacking. Direct contact with hydrogen peroxide induced genotoxic effects in bacteria and cultured cells, whereas the effect was reduced or abolished in the presence of metabolizing enzymes. Several tumor-promoting studies, including the hamster cheek pouch model, indicated that hydrogen peroxide might act as a promoter. Multiple exposures of hydrogen peroxide have resulted in localized effects on the gastric mucosa, decreased food consumption, reduced weight gain, and blood chemistry changes in mice and rats. Our risk assessment revealed that a sufficient safety level was not reached in certain clinical situations of external tooth bleaching, such as bleaching one tooth arch with 35% carbamide peroxide, using several applications per day of 22% carbamide peroxide, and bleaching both arches simultaneously with 22% carbamide peroxide. The recommendation is to avoid using concentrations higher than 10% carbamide peroxide when one performs external bleaching. We advocate a selective use of external tooth bleaching based on high ethical standards and professional judgment.

Safety issues when using a 16% carbamide peroxide whitening solution

BACKGROUND

The scientific literature is lacking on the occurrence of side effects and other safety issues when using carbamide peroxide whitening solutions of concentrations greater than 10%. This double-blind nightguard vital bleaching study compares safety issues when using 16% carbamide peroxide against a placebo or 10% carbamide peroxide (Nite White Classic by Discus Dental Inc.). Evaluated were changes in gingival index, plaque index, nonmarginal gingival index, nongingival oral mucosal index, tooth vitality, and the patients' perceptions of tooth sensitivity and gingival irritation.

MATERIALS AND METHODS

Twenty female dental hygiene students participated in the study. Each participant wore a maxillary treatment tray for 1 week without any solution and then for 8 to 10 hours per night for 14 nights, filling each quadrant with placebo, 10% carbamide peroxide, or 16% carbamide peroxide, using a split tray design.

RESULTS

With respect to gingival index, plaque index, nonmarginal gingival index, nongingival oral mucosa index, tooth vitality, and tooth sensitivity, there were no statistically significant differences between the 16% carbamide peroxide solution and the other two solutions (p > .05). Quadrants receiving the 16% carbamide peroxide solution experienced more gingival irritation than quadrants receiving placebo or 10% carbamide peroxide solution (p > .05).

CONCLUSIONS

When evaluating the above-mentioned safety issues, except for gingival irritation, there were no statistically significant differences between a 16% carbamide peroxide solution and 10% carbamide peroxide solution or a placebo when used as described here.

CLINICAL SIGNIFICANCE

Among the 20 participants whose data were analyzed, it was found that a 16% carbamide peroxide whitening solution (Nite White Classic), when used as described in this study, can be effective in nightguard vital bleaching with no statistical differences in gingival index, plaque index, nonmarginal gingival index, nongingival oral mucosa changes, tooth vitality, or tooth sensitivity, compared with a 10% whitening solution (Nite White Classic). More gingival irritation was experienced with 16% carbamide peroxide. Additionally, 20% of the participants in this study self-reported sensitivity when wearing their treatment tray without any solution, and 36% of the participants reported sensitivity to the placebo solution.

Effect of bleaching agents on the hardness and morphology of enamel

PURPOSE

The goal of the present laboratory study was to analyze the effect of two home bleaching agents (Opalescence 10%, Ultradent, and Hi-Lite II, Shofu) as well as the separate solutions of 10% carbamide peroxide primary components (3% hydrogen peroxide and 7% urea) on enamel microhardness and surface morphology.

MATERIALS AND METHODS

Thirty human molars stored in water for no longer than 3 months were selected. Their facial and lingual surfaces were embedded in acrylic resin, and the specimens were polished with up to 600-grit sandpaper. The 30 molar sections were divided into five groups as per treatment modality (n = 6); group 1, 10% carbamide peroxide bleach with carbopol (Opalescence, Ultradent); group 2, oxygen-free gel bleach (Hydroxylite, Hi-Lite II, Shofu); group 3, 3% hydrogen peroxide with carbopol (Dermus Pharmacy, Florianópolis, SC, Brazil); group 4, 7% urea treatment (Dermus Pharmacy); and control, group 5, artificial saliva (Dermus Pharmacy). Prior to treatment, six indentations (Vickers) were made on each of the six surfaces in each group under a load of 100 g for 30 seconds. Bleaching procedure was conducted for 3 hours per day for 2 weeks, the control group excepted. Following each bleaching session, the specimens were washed with deionized water and kept in artificial saliva at 37 degrees C, this solution being changed daily. Pre- and post-treatment microhardness data were analyzed using a two-way analysis of variance. In a similar way, 30 other specimens underwent the same procedures. After the bleaching period, the samples were observed under the scanning electron microscope.

RESULTS

Specimens submitted to bleaching treatment with 3% hydrogen peroxide gel as described in this study showed a significant reduction of surface microhardness (p < .0001). The other treatment modalities had no effect on surface microhardness. No morphologic alterations were observed on enamel submitted to bleaching gel of 10% carbamide peroxide (Opalescence), oxygen-free gel (Hi-Lite II, Shofu), or 7% urea solution compared with the control (artificial saliva). However, the specimens bleached for 3 hours per day for 2 weeks with 3% hydrogen peroxide gel presented areas of mild erosion. The effect, nevertheless, was not uniform, occurring with varying intensity on all samples of enamel bleached with 3% hydrogen peroxide.

CLINICAL SIGNIFICANCE

Bleaching treatment conducted with two home bleaching agents (Opalescence 10%, Ultradent, and Hi-Lite II, Shofu) had no adverse effects on enamel microhardness or on surface morphology. Bleaching with 3% hydrogen peroxide can have a negative effect on enamel hardness and surface morphology when performed as described in this study.

Nightguard vital bleaching: a long-term study on efficacy, shade retention. side effects, and patients' perceptions

BACKGROUND

The scientific literature is lacking in long-term clinical data on the duration of efficacy and post-treatment side effects of nightguard vital bleaching.

PURPOSE

This longitudinal clinical study was undertaken (1) to determine the clinical efficacy and duration of efficacy at 3, 6, and 47 months post treatment of a peroxide-containing whitening solution; (2) to evaluate safety issues with respect to using a peroxide whitening solution; and (3) to determine patients' perceptions of the whitening technique.

MATERIALS AND METHODS

This project was part of a nightguard vital bleaching study involving human participants. The study teeth for efficacy and duration of efficacy when using a 10% carbamide peroxide solution were the four maxillary central and lateral incisors, with the tooth shade being taken from the middle third of the tooth. Safety issues evaluated were the changes in gingival index (GI), plaque index (PI), nonmarginal gingival index (NMGI), nongingival oral mucosal index (NGOMI), and tooth vitality (TV). Radiographic changes of the study teeth and the patients' perceptions of tooth sensitivity (TS) or gingival irritation (Girr) during treatment and post treatment were also evaluated.

RESULTS

The active 10% carbamide peroxide whitening solution used in this study was effective in lightening teeth (98%), and this effect was sustained at a mean of 47 months post treatment in 82% of the participants. When evaluating safety issues, 66% of the participants using the active solution reported TS or Girr. No one reported TS or Girr or any other adverse effects at the end of the study.

CONCLUSIONS

The results of this study concur with those of previously reported studies that nightguard vital bleaching using a 10% carbamide peroxide whitening solution according to the manufacturer's instructions is efficacious and safe, with minimal side effects. In addition, long-term shade retention was reported by 82% of the participants at the end of the study, with no adverse side effects.

CLINICAL SIGNIFICANCE

Results of this study should reassure dentists that nightguard vital bleaching is a safe, effective, and predictable method to lighten teeth. The whitening effect lasted up to 47 months in 82% of the patients, with no adverse side effects reported at the end of the study.

Dental discoloration: an overview

Often the first evidence of variation from normal in human dentition is an observable difference in the color of the teeth. During the past decade, the demand for conservative esthetic dentistry has grown dramatically. Tooth discoloration is a frequent dental finding, associated with clinical and esthetic problems. It differs in etiology, appearance, composition, location, severity, and firmness in adherence to the tooth surface. Basically, there are two types of tooth discolorations: those caused by extrinsic factors and those caused by intrinsic congenital or systemic influence. The intensity of stains may be worsened if there are enamel defects. Tooth discoloration presents two major challenges to the dental team. The first challenge is to ascertain the cause of the stain; the second is its management.

CLINICAL SIGNIFICANCE

This article reviews the etiology and clinical presentation of dental stains and outlines treatment options.