Effect of potassium nitrate and fluoride on carbamide peroxide bleaching.

OBJECTIVES: The purpose of this study was to assess the effect on tooth sensitivity when potassium nitrate and fluoride were added to a 10% carbamide peroxide bleaching gel. METHOD AND MATERIALS: Seventeen maxillary and four mandibular arches were bleached using the at-home bleaching technique. The bleaching treatment consisted of the simultaneous use of a 10% carbamide peroxide gel containing 3% potassium nitrate wt/vol and 0.11 fluoride ion wt/vol on one side of the midline and a 10% carbamide peroxide gel only (control) on the other side of the midline for 14 nights. A visual analog scale for each side of the dental arch was used by the patients to assess tooth sensitivity and tooth whitening. Preoperative and postoperative photographs were also taken. RESULTS: The addition of potassium nitrate and fluoride significantly decreased the total tooth sensitivity reported by the patients. The addition did not significantly change the whitening efficacy of the carbamide peroxide bleach. CONCLUSION: A 10% carbamide peroxide bleaching gel containing potassium nitrate and fluoride produced less tooth sensitivity than did the control bleaching gel during a 2-week at-home bleaching treatment.     

Clinical evaluation of in-office and at-home bleaching treatments

This three-month, single-blind clinical study compared two whitening treatments, at-home with 10% carbamide peroxide and in-office with 35% hydrogen peroxide, for the degree of color change of teeth, color relapse and tooth and gum sensitivity. The degree of color change and color relapse was evaluated by using a colorimeter, shade guide and color slide photography. Teeth and gum sensitivity were self-evaluated by the subjects, who recorded daily the tooth and gum sensitivity they experienced during the two weeks of treatment and one week post-treatment. A 14-day at-home treatment was compared with 60 minutes of in-office treatment (two appointments, each with three 10-minute applications). The at-home treatment produced significantly lighter teeth than the in-office treatment during all active-treatment periods and follow-up visits according to all three-color evaluation methods. Color relapse for both treatments stabilized by six weeks. At-home treatment resulted in statistically significant higher gum sensitivity than in-office treatment during the latter part of the first week. For tooth sensitivity there were no significant differences between the treatments. Eighty four percent of the subjects reported at-home treatment to be more effective and 16% found no difference between the treatments. There were no subjects who reported the in-office treatment to be superior in tooth whitening to the at-home treatment.     

Clinical evaluation of the effectiveness of different bleaching therapies in vital teeth

The aims of this in vivo study were to compare the effectiveness and color stability of at-home and in-office bleaching techniques and to evaluate whether the use of light sources can alter bleaching results. According to preestablished criteria, 40 patients were selected and randomly divided into four groups according to bleaching treatment: (1) at-home bleaching with 10% carbamide peroxide, (2) in-office bleaching with 35% hydrogen peroxide (HP) without a light source, (3) in-office bleaching with 35% HP with quartz-tungsten-halogen light, and (4) in-office bleaching with 35% HP with a light-emitting diode/laser. Tooth shade was evaluated using the VITA Classical Shade Guide before bleaching as well as after the first and third weeks of bleaching. Tooth shade was evaluated again using the same guide 1 and 6 months after the completion of treatment. The shade guide was arranged to yield scores that were used for statistical comparison. Statistical analysis using the Kruskal-Wallis test showed no significant differences among the groups for any time point (P > .01). There was no color rebound in any of the groups. The bleaching techniques tested were equally effective. Light sources are unnecessary to bleach teeth.     

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.     

A clinical study comparing the efficacy and sensitivity of home vs combined whitening

This randomized clinical study assessed efficacy in terms of color change and production of sensitivity after home whitening alone and home whitening supplemented with in-office bleaching. Thirty-six subjects (aged 19 to 58 years) were randomly assigned to one of three different treatment groups: (A) home whitening for two weeks, with 16% carbamide peroxide in custom-made trays; (B) home whitening for two weeks, with 16% carbamide peroxide in custom-made trays supplemented with in-office bleaching with 9% hydrogen peroxide (in the same trays); or (C) home whitening for two weeks, with 16% carbamide peroxide in custom-made trays supplemented with in-office bleaching with 27% hydrogen peroxide (in the same trays). The efficacy of tooth whitening was assessed by determining the color change associated with the six upper anterior teeth using a value-ordered shade guide. Sensitivity was self-assessed with the use of a visual analog scale (VAS). Tooth shade and sensitivity were assessed at the following points: pretreatment; immediately after the home whitening phase; immediately after the in-office phase (groups B and C); and one week post active treatment. At the one week follow-up visit, subjects in group A had a mean (SD) color change of 5.9 (1.83) (teeth were lighter) immediately after cessation of treatment (p<0.01). Subjects in groups B and C experienced a greater change in mean (SD) shade immediately following their respective in-office treatments of 5.1 (1.53) and 5.4 (1.55). However, within one week, the shade of these teeth regressed to a similar degree to that achieved by subjects treated in group A. Overall, no significant difference in shade change or sensitivity was produced between the three groups. Investigators concluded that the in-office element of combined whitening produced no significant difference in tooth color or sensitivity when compared with home whitening alone.     

Two-Year Clinical Evaluation of Tooth Whitening Using an At-Home Bleaching System

Abstract: 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.     

A clinical study evaluating a new chairside and take-home whitening system

This study evaluated the efficacy of tooth color modifications with a 15% hydrogen peroxide in-office whitening system when applied for a 30-, 45-, or 60-minute period and combined with a 10% carbamide peroxide take-home system. Twenty-four patients participated in this randomized, parallel clinical evaluation. Six maxillary anterior teeth with a shade of A3 or darker were selected. Patients were randomly divided into 3 groups of 8: Group I patients received a 30-minute application, Group II received a 45-minute application, and Group III received a 60-minute application of the initial in-office treatment. All patients returned at 24 hours for shade evaluation and receipt of a whitening tray with a 10% carbamide peroxide for 7 consecutive days. Patients returned at 24 hours, 72 hours, and on the 8th day of take-home treatment for shade evaluation. Kruskal-Wallis ANOVA showed no statistically significant difference between the groups (P > .10) at completion of treatment. When all three groups were combined, a mean shade change > 8 was seen. No significant difference existed for tooth color modifications when varied application times of 30-, 45- or 60-minute in-office whitening with 15% hydrogen peroxide was used in combination with 10% carbamide peroxide take-home whitening.     

The efficacy of reservoirs in bleaching trays

Thirty patients were selected to bleach their maxillary teeth. Vacuum-formed trays were fabricated for the maxillary arch so that only one quadrant of bleaching tray had reservoirs. Nupro Gold 10% carbamide peroxide gel was given to patients. They were instructed to place a drop of gel in each tooth area and wear the trays twice a day for two-hour periods. After 10 days the patients were evaluated for shade changes in each quadrant. No clinical difference was observed in the after-shade match of the two quadrants. It appears that the addition of blockout spacers to create reservoirs does not increase the success of home bleaching.     

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 carbamide peroxide and hydrogen peroxide whitening agents during daytime use

BACKGROUND: Vital tooth bleaching for esthetic reasons has gained in popularity during the last few years. However, few studies have investigated the efficacy of daytime bleaching products. The purpose of this double-blind in vivo study was to evaluate the efficacy of 20 percent carbamide peroxide, or CP, and 7.5 percent hydrogen peroxide, or HP, during daytime use. The degree of color change, any color relapse, and tooth or gingival sensitivity were evaluated. METHODS: Twenty-four patients participated in this study. The bleaching gels were randomly applied to the right and left maxillary anterior teeth. Patients were shown how to place the two bleaching agents in a custom tray for one hour, twice a day for two weeks. Patients returned in one, two, three, six and 12 weeks for color evaluation with the colorimeter and shade guides as well as to have color slide photographs taken. The authors evaluated sensitivity by asking the patients to record daily for 21 days any tooth or gingival sensitivity they experienced. RESULTS: Use of the 20 percent CP resulted in significantly more lightness than the 7.5 percent HP during the first 14 days of the study, but at the end of the study, there was no significant difference between products with regard to tooth lightness. In addition, the authors found no statistically significant difference between products with regard to gingival or tooth sensitivity. CONCLUSIONS: Both CP and HP are effective at-home bleaching agents when daytime bleaching is preferred. CLINICAL IMPLICATIONS: Dentists who choose to use daytime bleaching can select either CP or HP.     

Randomized clinical trial on the efficacy of a new bleaching lacquer for self-application

BACKGROUND: This study evaluated the clinical efficacy and duration of effectiveness of a new bleaching lacquer for self-application without the use of mouth guards. It compared two different application times. METHODS: Forty-six adult subjects who requested bleaching treatment were selected to participate in this randomized, single-blind (examiner-blinded), single center, two-group trial. The subjects were randomly divided into two groups (n=23 each), each being instructed to bleach (8% carbamide peroxide) their six maxillary anterior teeth for two weeks. Daily contact time in Group 1 was 20 minutes once a day and, in Group 2, the time was 20 minutes twice a day. Efficacy was measured subjectively using the Chromascop Complete shade scores obtained at baseline and after one, two and three weeks, as well as after one, three, six and nine months. RESULTS: After two weeks of treatment, the teeth in the Group 1 subjects exhibited a 2.4 +/- 0.2 mean shade scores improvement compared to baseline (p < 0.001; t-test for paired samples), and the subjects' teeth in Group 2 exhibited a 3.5 +/- 0.1 mean shade scores improvement (p < 0.001). However, the difference between both groups was not statistically significant (p > 0.05). The observed effects were stable for six months. CONCLUSIONS: It can be concluded that the new bleaching lacquer is efficacious; however, a double application does not seem to be obligatory.     

Postoperative dental bleaching: effect of microleakage on Class V tooth colored restorative materials

The effect of 3 percent, 11 percent, and 16 percent carbamide peroxide bleaching solutions and 35 percent hydrogen peroxide bleaching gel on microleakage of Class V composite resins, resin modified glass ionomer cements, and compomer restorative materials together with corresponding (if indicated) fourth/fifth generation bonding agents was evaluated using previously extracted human teeth. Five groups of Class V cavity preparations were placed in enamel of the facial surfaces of 200 teeth. Groups A through D included 40 restorations each (4 different restorative materials and their accompanying bonding agent multiplied by 10 teeth) treated with 3 percent, 11 percent, and 16 percent carbamide peroxide bleach and 35 percent hydrogen peroxide bleach. Group E included 40 restorations without treatment of bleach and stood as the control. The restorative materials included were: Fuji II LC resin modified glass ionomer cement, Helioprogress composite resin/-Heliobond adhesive system, Aelitefil composite resin/Allbond 2 adhesive and Dyract compomer material/Prime & Bond adhesive system. Bleaching agents included were Rembrandt 3 percent peroxide gel, Perfecta 16 percent carbamide peroxide gel, White & Brite 11 percent carbamide peroxide solution and Superoxyl 35 percent hydrogen peroxide gel. All teeth were thermally stressed for 100 cycles and microleakage were assessed by dye penetration. The results were tabulated using Analysis of Variance (ANOVA) testing procedures. The Aelitefil composite resin material behaved the least favorably (relative to microleakage) compared to the other materials when exposed to various concentrations of dental bleaching agents.     

A randomized clinical trial comparing at-home and in-office tooth whitening techniques: A nine-month follow-up

BackgroundThe aim of this split-mouth, randomized controlled trial was to compare the whitening results of at-home and in-office tooth bleaching techniques and the longevity of their effects at nine months after teeth had been bleached.MethodsThe authors conducted a study involving a 14-day bleaching period, during which the first maxillary premolars of 17 participants, who were 20 to 25 years of age, were bleached by means of either an at-home technique involving 10 percent carbamide peroxide or an in-office technique involving 38 percent hydrogen peroxide. The authors recorded color variables as proposed by the Commission Internationale de l'Eclairage—lightness (L*), redness (a*) and yellowness (b*)—by using a spectrophotometer at baseline and at one week, one month and nine months after bleaching. They also calculated a whiteness (W) index that was based on the distance of the color value in the color space from a nominal white point.ResultsAt the nine-month recall visit, comparison between the at-home and the in-office techniques did not show significantly different values for L* (P = .448), a* (P = .350), b* (P = .144) and W (P = .151) color variables. None of the participants experienced any adverse events related to the bleaching during the treatment period.ConclusionsThe study results showed no clinically significant difference in bleaching efficacy. Both techniques produced satisfactory and long-lasting bleaching results.Clinical ImplicationsIn young adults, either the at-home or the in-office technique can be used effectively.     

Scanning electron microscopy study of dental enamel surface exposed to 35% hydrogen peroxide: alone,with saliva,and with 10% carbamide peroxide

Several vital bleaching systems have been introduced in response to the demand in esthetic dentistry. The active agents are commonly hydrogen peroxide or carbamide peroxide used in at-home or in-office techniques. Although generally positive results have been reported concerning the whitening ability of these agents, concerns still remain as to their effects on dental tissues. The purpose of this investigation was to evaluate the effect of these bleaching agents on the enamel surface morphology. Twelve extracted teeth were used according to three experimental protocols. In experimental protocol 1, specimens were treated with 35% hydrogen peroxide. In experimental protocol 2, after treatment with 35% hydrogen peroxide the specimens were immersed in natural saliva for 1 week. In experimental protocol 3, 35% hydrogen peroxide was applied once and 10% carbamide peroxide was applied for 1 week (12 h of 10% carbamide peroxide alternating with 12 h saliva). Scanning electron microscopy evaluation revealed that regional variation in tooth morphology surface sometimes exceeded the effects of the peroxide used according to experimental protocols. Thirty-five percent hydrogen peroxide had a tendency to promote an increase in density of pits. Precipitates were observed on specimen surfaces immersed in natural saliva according to protocol 2. A smooth and shiny surface was observed in specimens treated according to protocol 3. The potential relationship between surface alterations and differences in enamel permeability is currently under investigation. CLINICAL SIGNIFICANCE The differences in various articles written on the subject cannot be reconciled because of the lac of standardization of baseline data regarding factors such as location on the tooth, type of tooth eruption or noneruption, and age in the oral cavity. This article demonstrates that, despite changes observed in the enamel surface after bleaching, normal variation in tooth morphology may exceed the effects of 35% hydrogen peroxide and 10% carbamide peroxide on the teeth. Hence, considering the morphologic features of the tooth surface, bleaching, as described in thi study, can be considered safe for enamel.     

Clinical Comparative Study of the Effectiveness of and Tooth Sensitivity to 10% and 20% Carbamide Peroxide Home-use and 35% and 38% Hydrogen Peroxide In-office Bleaching Materials Containing Desensitizing Agents

SUMMARY The aim of this study was to compare the effectiveness of and tooth sensitivity to 10% and 20% carbamide peroxide (CP) home-use bleaching agents and 35% and 38% hydrogen peroxide (HP) in-office bleaching agents, all of which contain desensitizing agents, in a clinical trial. Four agents were evaluated: 10% CP and 20% CP (Opalescence PF 10% and Opalescence PF 20%, Ultradent, both with 0.5% potassium nitrate and 0.11% fluoride ions), 38% HP (Opalescence Boost PF, Ultradent, with 3% potassium nitrate and 1.1% fluoride ions), and 35% HP (Pola Office, SDI, with potassium nitrate). The initial screening procedure included 100 volunteers, aged 18 to 42, with no previous sensitivity or bleaching treatment and with any tooth shade. Volunteers were randomly assigned among the technique/bleaching agent groups. A run-in period was performed 1 week before the beginning of the bleaching treatment. For the home-use bleaching technique, each volunteer was instructed to dispense gel (10% CP or 20% CP) into the trays and then insert them into his or her mouth for at least two hours per night for three weeks. For the in-office bleaching technique, the bleaching agents (38% HP or 35% HP) were prepared and used following the manufacturer's instructions, with three applications performed in each session. Three sessions were carried out with an interval of seven days between each session. The participants were evaluated before, at one week, two weeks, and three weeks after the beginning of the bleaching treatment, and again one and two weeks after the bleaching treatment ended. A shade guide (Vita Classical, Vita) was used by a blinded examiner to perform shade evaluations before bleaching and two weeks after the end of bleaching. At the time of the shade evaluations, tooth sensitivity was also recorded by asking the volunteers to classify the sensitivity during bleaching treatment as absent, mild, moderate, or severe. The present study found that 13.8% of the volunteers withdrew from the study due to tooth sensitivity, and 43.2% of the participants experienced some type of sensitivity during bleaching treatment. The χ( 2 ) test showed that there was a significant prevalence of tooth sensitivity during bleaching treatment using the home-use 20% CP agent, with 71.4% of volunteers reporting any level of tooth sensitivity (p=0.0032). A low prevalence of tooth sensitivity was observed for volunteers who used the in-office 38% HP agent (15.0%). The Wilcoxon test (p<0.05) showed that all of the bleaching treatments were effective in bleaching teeth and that there were no differences between the final color shade results among the treatments (Kruskal-Wallis, p<0.05). This study showed that 43.2% of all the volunteers experienced mild or moderate tooth sensitivity during the treatment with bleaching agents. A higher prevalence of tooth sensitivity was observed for 71.4% of the volunteers who used the 20% CP home-use bleaching agent, which may be ascribed to the peroxide concentration and/or the time/length the agent was in contact with the dental structures.     

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.     

Randomized clinical trial on the efficacy of 2 over-the-counter whitening systems.

OBJECTIVE: The purpose of this clinical trial was to evaluate the efficacy of 2 over-the-counter whitening systems: a liquid whitening gel (5.9% hydrogen peroxide, twice a day for 15 minutes), and a sodium chlorite-based whitening gel applied in a tray system (10 minutes twice a day). METHOD AND MATERIALS: Sixty volunteers (minimum shade A3 on 1 maxillary tooth) were selected to participate in this single-blind (examiner-blinded), single-center, 2-group trial. The subjects were randomly divided into 2 groups (n = 30 each) and instructed to bleach their teeth for 2 weeks. Efficacy was measured using the Vita Classical shade guide and a spectrophotometer at baseline, as well as after 2 weeks and 6 months. RESULTS: For the subjectively measured tooth shades, improvement for maxillary canines was 2.03 +/- 3.67 tooth shades in group 1 and 1.08 +/- 2.19 tooth shades in group 2 after 2 weeks; the maxillary incisors revealed a tooth shade improvement of 0.83 +/- 1.71 tabs in group 1 and 0.73 +/- 2.22 tabs in group 2 (P < .05, except maxillary incisors in group 2; t test). Objectively measured tooth shade scores revealed a change of 0 +/- 0.25 tooth shade tabs (P > .05). CONCLUSIONS: The bleaching gel containing hydrogen peroxide achieved a slight improvement, and the sodium chlorite-based bleaching gel achieved only a small tooth color improvement. Moreover, subjectively and objectively measured tooth shades revealed considerably different results in the clinical situation.     

Tooth whitening: facts and fallacies

Since the introduction of nightguard vital bleaching (tray bleaching) in 1989, dentistry has witnessed an astronomical rise in the interest in tooth whitening.(1) As a result, the most frequently asked question is, 'what bleaching technique works best?' Virtually all of today's whitening approaches work, because bleach is bleach. Whether a nightguard bleach is used with only 10% carbamide peroxide (which contains only 3% hydrogen peroxide), over-the-counter (OTC) whitening strips are applied containing 6% hydrogen peroxide, or an in-office bleach is employed using 25-35% hydrogen peroxide, the end results can potentially be the same. Similarity of results is possible because the mechanism of action is the same: oxidation of organic pigments or chromogens in the tooth. Granted, some bleaching approaches are more expeditious than others, owing to differences in concentration or exposure time. But as just noted, the most important factors in the efficacy of any bleaching treatment are concentration of the bleaching agent and duration of the exposure time.     

Randomized controlled trial of professional at-home tooth whitening in teenagers

A randomized controlled clinical trial was conducted to compare two professional at-home tooth whitening systems in a teenage population. Informed consent and child assent were obtained from 60 teenagers aged 12-17 (mean age = 14.8). After baseline measurements, subjects were randomized to one of two groups, using either 14% hydrogen peroxide whitening strips or 10% carbamide peroxide in a custom bleaching tray. Strips were used for 30 minutes twice daily, while the tray was worn overnight. Treatment took place for 14 days sequentially, first on the maxillary arch and then on the mandibular arch; all use was unsupervised. Efficacy was measured objectively by L*a*b* color change from digital images obtained at baseline and end of treatment, using combined color measures for both arches. Both professional whitening systems had significant (p < 0.0001) reductions in yellowness (Deltab*) and increased lightness (DeltaL*) after two weeks of treatment on each arch. At the end of treatment, Deltab* or DeltaL* did not differ significantly between the groups (p > 0.28). Tooth sensitivity and mild oral irritation represented the most common adverse events, with only one subject discontinuing treatment as a result. Teenagers who used either bleaching method for two weeks experienced significant tooth whitening without serious adverse events.     

The effect of fluoride gel use on bleaching sensitivity: a double-blind randomized controlled clinical trial

BACKGROUND: Fluoride has been recognized as a desensitizer; however, no study has addressed its effects to decrease tooth sensitivity when compared with a placebo in a double-blind randomized clinical study. METHODS: The authors divided 30 participants into two groups: one that received a placebo and another that was treated with fluoride. All patients used 16 percent carbamide peroxide (CP) in a custom-fitted tray until their teeth achieved shade A1 or lighter. After daily removal of CP, the patients wore a tray containing either sodium fluoride or placebo for four minutes. The authors statistically analyzed the perception of the intensity of tooth sensitivity and the weekly shade changes for both groups, as well as the intensity of tooth sensitivity (alpha = .05). RESULTS AND CONCLUSIONS: The use of fluoride gel did not affect the whitening efficacy of the CP. The authors observed no difference between the groups receiving the placebo and the fluoride treatment in terms of tooth sensitivity experience (P > .05); however, patients who received the placebo had a higher-intensity tooth sensitivity than that of patients who received the fluoride (P < .001). CLINICAL IMPLICATIONS. The use of 1.23 percent sodium fluoride after each bleaching regimen does not affect the bleaching efficacy of CP. Also, the use of sodium fluoride gel reduces the intensity of tooth sensitivity.