Six-month clinical evaluation of a tooth whitening system using an innovative experimental design

Tooth Sensitivity After Dental Bleaching With a Desensitizer-containing and a Desensitizer-free Bleaching Gel: A Systematic Review and Meta-analysis

Objectives:

A systematic review and meta-analysis were performed to evaluate the risk and intensity of tooth sensitivity (TS) after dental bleaching with a desensitizer-containing and a desensitizer-free bleaching gel in adult patients. Color change and risk of gingival sensitivity was also evaluated.

Methods:

A comprehensive search was performed MEDLINE via PubMed, Scopus, Web of Science, Latin American and Caribbean Health Sciences Literature database (LILACS), Brazilian Library in Dentistry (BBO), EMBASE and Cochrane Library, and System for Information on Grey Literature in Europe (SIGLE) without restrictions to identify randomized clinical trials. Abstracts from the annual conference of the International Association for Dental Research (1990–2016), unpublished and ongoing trials registries, dissertations, and theses were also searched. The quality of the evidence was rated using the Grading of Recommendations: Assessment, Development and Evaluation (GRADE) approach.

Data:

After duplicates were removed, 1352 articles were identified. After title and abstract screening, only 47 studies remained for qualitative evaluation. Most of the studies had unclear risk of bias. No difference between groups were observed for the risk ratio of TS (risk ratio = 0.99; 95% confidence interval [CI] = 0.74–1.33); intensity of TS (standardized difference in means [SMD] = 0.04; 95% CI = 0.79–0.70); color change in shade guide units (SMD – 0.04; 95% CI = 0.50–0.42); color change in ΔE* (SMD = 0.41 (95% CI = 0.07–0.89); and risk ratio of gingival irritation (SMD = 1.05; 95% CI = 0.81–1.36). Except for the risk of TS, graded as moderate quality of evidence, all other outcomes were rated as low and very low quality.

Conclusions:

Incorporating desensitizers in the bleaching gel did not reduce the risk of TS, and the quality of this evidence was considered moderate. On the other hand, the intensity of TS, color change, and risk of gingival irritation was similar between groups, but the quality of the evidence for these outcomes was graded as low or very low, thus reducing the level of confidence in these outcomes.

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.

Comparison of efficacy of tray-delivered carbamide and hydrogen peroxide for at-home bleaching: a systematic review and meta-analysis

OBJECTIVES

The aim of the study was to compare the color change produced by tray-delivered carbamide peroxide [CP] versus hydrogen peroxide products [HP] for at-home bleaching through a systematic review and meta-analysis.

MATERIALS AND METHODS

MEDLINE via PubMeb, Scopus, Web of Science, Latin American and Caribbean Health Sciences Literature database (LILACS), Brazilian Library in Dentistry (BBO), and Cochrane Library and Grey literature were searched without restrictions. The abstracts of the International Association for Dental Research (IADR) and unpublished and ongoing trial registries were also searched. Dissertations and theses were explored using the ProQuest Dissertations and Periodicos Capes Theses databases. We included randomized clinical trials that compared tray-delivered CP versus HP for at-home dental bleaching. The color change in shade guide units (SGU) and ΔE were the primary outcomes, and tooth sensitivity and gingival irritation were the secondary outcomes. The risk of bias tool of the Cochrane Collaboration was used for quality assessment.

DATA

After duplicate removal, 1379 articles were identified. However, only eight studies were considered to be at "low" risk of bias in the key domains of the risk bias tool and they were included in the analysis. For ΔE, the standardized mean difference was -0.45 (95 % CI -0.69 to -0.21), which favored tray-delivered CP products (p < 0.001). The color change in ΔSGU (p = 0.70), tooth sensitivity (p = 0.83), and gingival irritation (p = 0.62) were not significantly different between groups.

CONCLUSIONS

Tray-delivered CP gels showed a slightly better whitening efficacy than HP-based products in terms of ΔE, but they were similar in terms of ΔSGU. Both whitening systems demonstrated equal level of gingival irritation and tooth sensitivity.

CLINICAL SIGNIFICANCE

Tray-delivered CP gels have a slightly better whitening efficacy than HP-based products in terms of ΔE. This should be interpreted with caution as the data of ΔSGU did not show statistical difference between the products.

Safety and efficacy of a high-adhesion whitening strip under extended wear regimen

OBJECTIVES

This randomized, parallel group, single centre clinical trial was conducted to evaluate the safety and compare the whitening efficacy for an extended wear of an experimental 9.5% H₂O₂ high-adhesion whitening strip, relative to a marketed 10% H₂O₂ control strip.

METHODS

Twenty-nine eligible adult volunteers were randomly assigned to either a treatment series with an experimental 9.5% H₂O₂ high-adhesion whitening strip at home for 2h, once a day, for 8 days; or a marketed 10% H₂O₂ whitening strip for 30 min, on a similar daily regimen. Tooth color/whitening progression was recorded under standardized lighting conditions at baseline, day 3, day 5, and day 9, via digital imaging. Outcomes were reported using the CIELAB system. Usage safety was also assessed at each follow-up visit. Whitening efficacy for each group was investigated using a paired-difference t-test. The treatment groups were compared among each other using the analysis of covariance, with the baseline value and age as the covariates.

RESULTS

Both treatment groups demonstrated statistically significant mean color improvement from baseline for b* (yellow ness) and L* (lightness) at each post-baseline visit. In addition, the 2-h high-adhesion strips demonstrated significantly greater improvement in b* and L* relative to the 30-min strip group at each follow-up visit.

CONCLUSIONS

The 2-h regimen for the 9.5% H₂O₂ high-adhesion whitening strip was more efficient for tooth whitening than the 30-min regimen of 10% H₂O₂ whitening strip. Both treatments were well tolerated and the use of the test products during the study time frame was considered safe.

CLINICAL RELEVANCE

Extending the daily wear time of whitening strips can improve the efficacy of the treatment and ultimately shorten the length of the treatment without any significant adverse effects.

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.

Effect on enamel microhardness of two consumer-available bleaching solutions when compared with a dentist-prescribed, home-applied bleaching solution and a control

BACKGROUND

There exists limited data in the literature regarding the efficacy and safety of consumer-available, paint-on bleaching solutions.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of two consumer-available, paint-on bleaching products on enamel microhardness against a control and a dentist-prescribed, home-applied (DPHA) bleaching product.

MATERIALS AND METHODS

Eighty enamel slabs were obtained from extracted human teeth and randomly divided into four treatment groups: (1) control; (2) Opalescence (Ultradent Products, Inc., South Jordan, UT, USA); (3) Crest Night Effects (Procter & Gamble, Cincinnati, OH, USA); and (4) Colgate Simply White Night (Colgate-Palmolive Co., Piscataway, NJ, USA). Opalescence is a carbamide peroxide DPHA product, whereas Crest Night Effects and Colgate Simply White Night are consumer-available products. The specimens in groups 2 to 4 underwent 2 weeks of treatment for 8 h/d. Specimens were maintained in artificial saliva at 37 degrees C between treatments. Subsequently, one-half of the specimens in groups 2 to 4 (n=10) underwent an additional seven treatments for 8 h/d, while the other half were stored in artificial saliva, receiving no further treatment. Microhardness was measured as Knoop hardness numbers (KHNs) at baseline and after 1, 7, 14, and 21 treatment days. The results were analyzed for statistical significance both intra- and intergroups using analysis of variance (p=.05).

RESULTS

A statistically significant reduction in mean KHN was observed compared with baseline at 1, 7, 14, and 21 treatment days for group 4 and at 7 treatment days for group 3. When compared with the control or DPHA product, group 4 was the only treatment that resulted in significantly lower mean KHNs at 7, 14, and 21 treatment days.

CONCLUSION

When evaluating enamel microhardness, consumer available, paint-on bleaching solutions may adversely affect enamel microhardness compared to a control and 10% carbamide peroxide DPHA bleaching solution.

CLINICAL SIGNIFICANCE

With numerous consumer-available bleaching products on the market, it is crucial to be judicious in their selection and use. The results of this in vitro study showed that the consumer-available, paint-on bleaching solutions adversely affected enamel microhardness at some time during the study. Consumers should be made aware of this effect on enamel.

Nightguard vital bleaching of tetracycline-stained teeth: 90 months post treatment

PURPOSE

The purpose of this longitudinal whitening study was to determine the stability, post-treatment side effects, and patient satisfaction at 90 months post treatment after 6 months of active treatment of tetracycline-stained teeth with 10% carbamide peroxide.

MATERIALS AND METHODS

Fifteen of 21 participants enrolled in the study (71%) were contacted and asked to participate in a survey concerning their whitening experience. Participants were asked whether there had been any change in the shade of their teeth after treatment and if they had experienced any side effects that they believed were treatment related. Eight of the 15 participated in a clinical examination.

RESULTS

Nine participants (60%) reported no obvious shade change or only a slight darkening not noticed by others. None reported darkening back to the original shade; however, four had re-treated their teeth. Examiners were in agreement with the participants' perception of shade change upon comparing pretreatment and post-treatment photographs and Vita shade (Vita Zahnfabrik D-79713, Bad Sackingen, Germany) values. The degree of improvement over the pretreatment shade was significant for the 90-month post-treatment shade (p < .01). All respondents (n = 15) denied having to have a crown or root canal or tooth sensitivity that they believed was treatment related.

CLINICAL SIGNIFICANCE

The results of this study of nightguard vital bleaching indicate that tetracycline-stained teeth can be whitened successfully using extended treatment time and that shade stability may last at least 90 months post treatment (range 84-100 mo). Patients participating in this study were over-whelmingly positive about the procedure in terms of shade retention and lack of post-treatment side effects.

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.

Sensitivity and tooth whitening agents

PURPOSE

Three commercially available dentist-prescribed home-applied bleaching systems were evaluated to identify the incidence of sensitivity and to compare the efficacy of whitening the maxillary anterior teeth of 18 patients.

METHODS

NiteWhite Excel 2Z (Discus Dental), fx (Challenge Products), and Rembrandt Xtra-Comfort (DenMat Corp.) were randomly assigned to six patients each. The fx product was used as a control since it was not advertised as a zero sensitivity product. The manufacturers' instructions for tray fabrication and use were followed while the patients bleached for 2 weeks. The patients kept a diary and were recalled at 1 week, 2 weeks, and 4 weeks. The shade change and the presence or absence of any sensitivity were evaluated at each recall.

RESULTS

NiteWhite Excel 2Z was used for 83 days of treatment with the following percentage of positive sensitivity reported: 0% hot and cold, 2.4% throat sensitivity, 2.4% tongue sensitivity, and 25.3% gingival sensitivity. Rembrandt Xtra-Comfort was used for 84 days with 0% hot and cold, 0% throat, 11.9% tongue, and 27.4% gingival sensitivity reported. The fx product was used for 83 days and resulted in 14.5% hot and cold, 3.6% throat, 1.2% tongue, and 16.9% gingival sensitivity. All products lightened the teeth an average of eight shade tabs on the Vita guide. There was a statistically significant difference between the groups when comparing the presence of sensitivity (chi-squared test, p < .001) but not when comparing the shade tab change.

CLINICAL SIGNIFICANCE

Of the products tested, all produced similar change in shade tab value, none were sensitivity free, but NiteWhite Excel 2Z and Rembrandt Xtra-Comfort did not produce thermal sensitivity.

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.

Nightguard vital bleaching and its effect on enamel surface morphology

BACKGROUND

The effect that nightguard vital bleaching (NGVB) has on enamel surface morphology is a subject of debate. Previous studies that have evaluated the effect of NGVB on the enamel surface report minimal changes to changes that appear to worsen post-treatment. The purpose of this in vivo NGVB study was to evaluate by scanning electron microscopy (SEM) the effects that 10% carbamide peroxide has on enamel morphology after 2 weeks of treatment and at 6 months post-treatment.

MATERIALS AND METHODS

Ten patients participated in the study. Each participant wore a guard filled with an active whitening solution for 8 to 10 hours per day for 14 treatment days. An impression of the study teeth (maxillary incisors) was taken at baseline, after 14 days of treatment, and at 6 months post-treatment, and an epoxy cast made. The epoxy casts were prepared for viewing under the SEM and photographs were taken at 200 times and 2,000 times magnification. Six examiners evaluated changes in enamel surface morphology by comparing the SEM photographs taken at baseline, on treatment day 14, and at 6 months post-treatment. Still masked, the examiners also compared each patient's baseline:treatment day 14 and baseline:6 months post-treatment photographs with photographs of a known standard.

RESULTS

This in vivo study demonstrated that a 14-day regimen of NGVB using a 10% carbamide peroxide solution had minimal effect on the surface morphology of enamel and that the effects did not worsen over time.

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

PURPOSE

The purpose of this study was to evaluate the 2-year effectiveness of a carbamide peroxide at-home bleaching gel used to provide tooth lightening treatment.

MATERIAL AND METHODS

Twenty-nine patients participated in the original study, during which they treated their maxillary teeth with a 10% carbamide peroxide gel nightly for 2 weeks. Shades were determined before and after treatment by comparison with a Vita shade guide. Twenty-four patients (a recall rate of 83%) were recalled for evaluation 2 years after the initial bleaching treatment. The shade of the maxillary incisors was evaluated and compared with shades before, immediately after, and at 6 months and 2 years after initial treatment. Data were analyzed using a repeated-measures analysis of variance.

RESULTS

At 2 years after bleaching with a 10% carbamide peroxide gel, the median shade was D2, a six-increment difference from the baseline median of D3. Twenty of 24 patients (83.3%) had a shade change of two or more units, which is the threshold value for bleaching efficacy using American Dental Association guidelines. The lightening result remained statistically significant (p < .0001) at 2 years.

CLINICAL SIGNIFICANCE

Although some reversal of the lightening effect occurs over time following the original bleaching treatment, loss of the lighter color appears to be gradual for most patients. Although the longevity of the lightening effect remains to be determined, this clinical trial indicates that the majority of patients have a satisfactory result 2 years after treatment.

A clinical evaluation of 10 percent vs. 15 percent carbamide peroxide tooth-whitening agents

BACKGROUND

Agents with carbamide peroxide, or CP, in various concentrations are widely prescribed for at-home tooth whitening. It is not clear, however, if the more concentrated gels will whitening teeth to a greater extent, as no controlled clinical trials have been reported. The authors conducted a double-blind study of human subjects to evaluate whether a 15 percent CP tooth-whitening system was more effective than a 10 percent CP system, and to determine if tooth sensitivity increased with use of the higher concentration.

METHODS

The authors recruited 57 subjects with maxillary anterior teeth of shade A3 or darker (as gauged against a value-oriented shade guide). The subjects were 18 to 65 years of age and in good general and dental health. After matching the subjects by sex and age, the authors randomly assigned them to either a control group, which used a 10 percent CP whitening agent, or an experimental group, which used a 15 percent CP agent.

RESULTS

The results indicated that there was no significant difference in shade change between the groups after one week of treatment (t = 1.455, P = .05), but there was a significant difference at the end of the treatment period (t = 2.303, P < .05), as well as two weeks after treatment concluded (t = 2.248, P < .05). There was no significant difference in sensitivity (t = 1.399, P > .05).

CONCLUSIONS

There was a significant difference in color change between the 10 percent CP and 15 percent CP groups at the end of the study period. There was no significant difference in level of tooth sensitivity between the two groups, and the incidence was equal; there was, however, a significant difference in variability of tooth sensitivity between the two groups.

CLINICAL IMPLICATIONS

If performed under the careful guidance of a dentist, at-home whitening is an effective treatment, regardless of whether 10 percent CP or 15 percent CP is used. There may be added color change and varying sensitivity with the use of 15 percent CP.

Nightguard vital bleaching of tetracycline-stained teeth: 54 months post treatment

PURPOSE

The purpose of this longitudinal whitening study was to determine the stability, post-treatment side effects, and patient satisfaction after 6 months of active treatment of tetracycline-stained teeth with 10% carbamide peroxide at 0 and 54 months post treatment.

MATERIALS AND METHODS

Twelve patients who completed the study (80%) were contacted and asked to participate in a survey concerning their whitening experience. Subjects were asked whether there had been any change in the shade of their teeth after treatment, and if they had experienced any side effects that they believed were treatment-related. Eight of the twelve patients underwent clinical examination.

RESULTS

Ten patients (83%) reported no obvious shade change or only a slight darkening not noticed by others. Two (17%) reported a slight darkening that is probably noticeable by other people, but no one reported moderate darkening or significant darkening back to original shade. All respondents (n = 12) denied having to have a crown or root canal that they believed was treatment-related. Examiners who compared preoperative and post-treatment photographs and Vita shade values were in agreement with the patient's perceptions of shade change. The degree of improvement was significant for both the immediate (0 mo) and the 54-month post-treatment comparison with the pretreatment shade (p < .005 and p < .01 respectively).

CLINICAL SIGNIFICANCE

Results of this nightguard vital bleaching study indicate that tetracycline-stained teeth can be whitened successfully using extended treatment time, and that shade stability may last at least 54 months after treatment. Patients who participated in this study were overwhelmingly positive about the procedure in terms of shade retention and lack of post-treatment side effects.