Effects of bleaching agents on human enamel light reflectance.

OBJECTIVES: Tooth whitening has been associated with splitting-up chromogenic molecules by hydrogen peroxides. Though micromorphological alterations are well documented, little is known about optical changes as a function of shifting in wavelengths. Therefore, the aim of the current study was to measure reflectance changes after bleaching in vitro by using a spectrometer. METHODS: Forty-eight enamel slabs (diameter = 5 mm) were prepared from the sound enamel of extracted human teeth that were: 1) fully impacted, 2) from juveniles ages 10 to 16 years, 3) from adults 35 to 45 years of age and 4) from seniors older than age 65. In all specimens, the baseline total reflectance measurement was performed with a computer-assisted spectrometer (Ocean Optics, Dunedin, FL, USA) within wavelengths (wl) from 430 nm to 800 nm. Four enamel samples of each age group were exposed to either 10% or 15% carbamide peroxide (Illuminé Home, Dentsply, Konstanz, Germany) or 35% hydrogen peroxide (Pola Office, SDI Limited, Victoria, Australia). After surface treatment, all slabs underwent total reflectance measurement again. Statistical analysis was calculated at wl 450, 500 and 750 nm using the Student's paired t-test and one-way variance analysis. RESULTS: Total reflectance significantly increased after bleaching at all enamel maturation stages, irrespective of the bleaching agent concentration, for wl 450 nm (blue) and 500 nm (green) with p<0.0001. At 750 nm (red), significant changes only occurred in enamel from adults and seniors (p<0.04). However, the efficacy of bleaching was significantly increased in the blue and green light spectra as compared to the red spectra (p<0.0001). CONCLUSIONS: The results of the current study showed that the exclusive assumption of the "chromophore effect" in dental bleaching could not be sustained, because whitening of the dental enamel works at different maturation stages, even in impacted teeth. This effect is irrespective of the bleaching protocol used and the bleaching agent concentration.

[Bleaching of non-vital discolored tooth: clinical analysis of 30 cases].

PURPOSE: The purpose of this study was to evaluate the bleaching efficacy of non-vital discolored tooth. METHODS: Thirty-three non-vital discolored anterior teeth with intact crowns from 30 patients were included in this clinical study. Bleaching treatment was performed using a combination of intracoronal and extracoronal applications of 15% carbamide peroxide. Intracoronal bleaching with 30% hydrogen peroxide was used as control group. The effective cases of the experimental group were reexamined one year later. Statistical analysis of all data was performed with SPSS 17.0 software package. RESULTS: Combined therapy with intracoronal and extracoronal applications of 15% carbamide peroxide presented higher bleaching efficacy than intracoronal applications of 30% hydrogen peroxide alone, the difference was significant. But the color shade change one year later was not significant. CONCLUSION: A combination of intracoronal and extracoronal applications of 15% carbamide peroxide was an effective bleaching technique for non-vital discolored teeth.Supported by Key Research Project of Science and Technology Bureau of Hefei City (Grant No.2007-1016).

Prediction of color change after tooth bleaching using fuzzy logic for Vita Classical shades identification.

Tooth bleaching is becoming increasingly popular among patients and dentists since it is a relatively noninvasive approach for whitening and lightening teeth. Instruments and visual assessment with respect to commercial shade guides are currently used to evaluate tooth color. However, the association between these procedures is imprecise and the degree of color change after tooth bleaching is known to vary substantially between studies; there are currently no objective guidelines to predict the effectiveness of a tooth-bleaching treatment. We propose a new methodology based on fuzzy logic as a natural means of representing the imprecision present when modeling the color change produced by a tooth-bleaching treatment on the basis of a tooth's initial chromatic values. This system has the advantage of producing a set of interpretable fuzzy rules that can subsequently be used by scientists and dental practitioners. The fuzzy system obtained has the special characteristic whereby the rule antecedents correspond to prebleaching shades of the well-known Vita commercial shade guide. Additionally, the rule consequents directly correspond with the expected CIELAB postbleaching values for each Vita shade, thanks to a modification of the system's inference structure. Finally, the values of these postbleaching CIELAB coordinates have been associated with Vita shades by evaluating their respective membership functions, thereby approximating which posttreatment Vita shades are to be expected for each prebleaching shade.

Aesthetic demand of French seniors: a large-scale study.

OBJECTIVES: The needs of seniors for oral health and aesthetics are growing, as are their demands for aesthetics. This large-scale study aims to identify the demand for aesthetics for a population aged over 55, and the influence of age and gender. METHODS: A 15-item questionnaire was placed on the web in partnership with a major magazine dedicated to seniors. It reflected practitioners' questions with regard to senior patient expectations: aesthetic demand assessment, most commonly expressed complaints, the importance given to tooth colour, knowledge of available therapeutic treatments and motivation levels for treatment. RESULTS: The survey generated 3868 responses, 61% from women; 77% of respondents declared being satisfied to very satisfied with their smile. Their highest priority to improve their smile was tooth alignment, followed by their shape, length and shade. Although 60% of respondents were satisfied with their current shading, 53% would prefer to have them whitened. Aesthetic treatments were well-known to seniors. Over four-fifths of them had heard of dental implants and ceramic crowns. Two-thirds of those who wished to improve their smile were considering dental treatment. CONCLUSION: The high number of collected questionnaires confirms the strong interest shown by seniors for dental aesthetics, particularly from women. Baby-boomers seem more attentive to the appearance of their smile than their elders. However, the importance of appearance decreases with age, as it becomes less of a priority, with attention more focused on general health.

Prevention of lingual calculus formation with daily use of 6% H2O2/2% pyrophosphate whitening strips.

OBJECTIVE: This randomized controlled clinical trial was conducted to evaluate whether daily use of a hydrogen peroxide/ pyrophosphate-containing antitartar whitening strip might safely yield clinical reductions in post-prophylaxis calculus accumulation. METHODS: A three-month, randomized controlled trial was conducted to compare calculus accumulation with a daily 6% hydrogen peroxide/pyrophosphate strip versus regular brushing. After an eight-week run-in phase to identify calculus formers, a prophylaxis was administered, and 77 subjects were randomly assigned to daily strip or brushing only groups. All subjects received an anticavity dentifrice (Crest Cavity Protection) and manual brush for use throughout the three-month study; for subjects assigned to the experimental group, strip application was once daily for five minutes on the facial and lingual surfaces of the mandibular teeth. Efficacy was measured as mm calculus (VMI) before prophylaxis and after six and 12 weeks of treatment, while safety was assessed from examination and interview. RESULTS: Subjects ranged in age from 21-87 years, with groups balanced (p > 0.26) on pertinent demographic and behavioral parameters, and pre-prophylaxis calculus baseline mean scores (16.0 mm). At Week 6, calculus accumulation was lower in the strip group, with adjusted mean (SE) lingual VMI of 12.0 (0.87) for the strip group and 17.0 (0.88) for the brushing control. At Week 12, calculus accumulation was lower in the strip group, with adjusted mean (SE) lingual VMI of 14.3 (0.85) for the strip group and 17.2 (0.86) for the brushing control. Treatments differed significantly (p < 0.02) on calculus accumulation at both time points. A total of three subjects (8%) in the strip group and two subjects (5%) in the brushing control had mild oral irritation or tooth sensitivity during treatment; no one discontinued early due to an adverse event. CONCLUSION: Daily use of hydrogen peroxide whitening strips with pyrophosphate reduced calculus formation by up to 29% versus regular brushing, without meaningful adverse events.

Clinical validation and calibration of in vitro peroxide tooth whitening.

OBJECTIVE: The purpose of this study was to validate and calibrate an in vitro test method for screening the performance of peroxide-containing toothpastes against actual clinical whitening performance. An additional objective was to estimate the whitening performance of a new peroxide-additive gel using the in vitro methodology. METHODS: A one-month longitudinal clinical study was performed to provide a benchmark for the in vivo intrinsic whitening performance of a peroxide-containing fluoride toothpaste. An in vitro study was then conducted, using freshly prepared slurries of the same peroxide-containing toothpaste in artificial saliva, to repeatedly treat extracted human teeth with natural intrinsic stain. The effect of cumulative treatment time on whiteness was determined using objective chromometer whiteness measurements (L*, a*, and b*), and more subjective Vita Shade guide (Vitapan) comparisons, and the results were correlated. A non-peroxide fluoride toothpaste was used as a negative control. The peroxide gel additive, combined in a 1:1 ratio with each of two non-peroxide toothpastes and diluted in artificial saliva, was evaluated using the same instrumental and subjective measures for in vitro whitening efficacy. The previously evaluated peroxide toothpaste and one of the non-peroxide toothpastes were used as positive and negative controls, respectively. RESULTS: In the clinical study, the peroxide-containing toothpaste produced a linear increase in tooth whiteness with time, achieving an approximately two Vita Shade guide improvement in whiteness at the end of four weeks. The same peroxide toothpaste in vitro produced a curvilinear increase in tooth whiteness versus cumulative treatment time, with a two-shade increase being achieved in 116 minutes. The non-peroxide control toothpaste produced less than half a shade guide increase in whiteness within the first 30 minutes, and none thereafter. Both the clinical and in vitro studies indicated that further whitening can be obtained with longer use of the peroxide-containing toothpaste or peroxide-additive gel. CONCLUSION: Treatment of naturally stained teeth in vitro with the peroxide toothpaste for 116 cumulative minutes produced the same two-shade increase in whiteness as obtained with twice-daily brushing for four weeks in vivo. The peroxide-additive gel, combined with a non-peroxide toothpaste, is projected to provide a similar two-shade increase in whiteness when used twice daily for four weeks. There are indications that greater intrinsic whiteness increase would be achieved with the peroxide toothpaste or with the peroxide-additive gel plus non-peroxide toothpaste with more extended regular twice-daily use in vivo.

Placebo-controlled clinical trial of use of 10% hydrogen peroxide whitening strips for medication-induced xerostomia.

OBJECTIVE: A randomized, double-blind, placebo-controlled clinical trial was conducted to evaluate the effectiveness and safety of peroxide-containing strip-based tooth whitening among subjects with medication-induced hyposalivation. METHODS: Eligibility for this tooth whitening study was limited to dentate adults taking xerogenic medications with an unstimulated salivary flow < or = 0.2 ml/min. After giving informed consent, 42 subjects were randomized using a 2:1 ratio to 10% hydrogen peroxide whitening strips (Crest Whitestrips Premium) or placebo strips without peroxide. Strips were used for 30 min twice daily for a 14-day period. Usage was unsupervised, and only the maxillary arch was treated. On days 8 and 15, efficacy was assessed from standard digital images of the anterior dentition and quantified using the Cielab color system, while safety was assessed from interviews and clinical examinations. RESULTS: At day 8, the peroxide group experienced significant (p < 0.001) color improvement relative to baseline and placebo. Adjusted means +/- standard errors for yellowness reduction were -1.65 +/- 0.115 units for the peroxide group and -0.32 +/- 0.170 units for the placebo group. For the increase in lightness, adjusted means +/- standard errors on day 8 were 1.53 +/- 0.130 units for the peroxide group and 0.37 +/- 0.191 units for the controls. Continued strip use through day 15 yielded incremental color improvement for the peroxide group. Mild and transient tooth sensitivity represented the most common adverse events. No subject discontinued treatment due to a product-related adverse event. CONCLUSION: Twice daily use of 10% hydrogen peroxide whitening strips by adults with medication-induced xerostomia was well tolerated, with significant tooth color improvement evident within 7 days.

Dental esthetic satisfaction, received and desired dental treatments for improvement of esthetics.

AIM: The purposes of this research were to investigate factors influencing patients' satisfaction with their present dental esthetic, received previous dental treatments on anterior teeth and basic treatments that they wanted to undergo to improve their dental appearance. MATERIALS AND METHODS: A total of 1014 patients who attended a dental school in a major city in Turkey participated in the study. The participants were surveyed with a questionnaire containing questions about gender, age, education level, self-reported tooth appearance, received previous dental treatments on anterior teeth and desired basic esthetic dental treatments. Statistical analysis of the verifying data was made with descriptive statistics, chi2 test and multiple logistic regression analyses. RESULTS: According to the analyses of the verifying data, 55.1% of the patients were dissatisfied with the color of their teeth, 42.7% with dental appearance, 29.9% with crowding of anterior teeth, 23.3% were hiding teeth while smiling, 16.1% had non-esthetic restorations and 11.9% thought that their anterior teeth were protruding. Esthetic restoration was found to be the most-performed treatment recently (29.0%) and whitening of teeth was the most-desired dental treatment (49.0%). Gender, age and education level had an effect on satisfaction and received previous and desired dental treatments for improvement of esthetics. CONCLUSION: Many of the Turkish patients surveyed in the study were dissatisfied and desired the improvement of dental esthetics. Therefore, dentists should consider this as an important dimension in their practice.

A clinical evaluation of two in-office bleaching regimens with and without tray bleaching.

This study evaluated the degree of color change of teeth, the rebound effect and the sensitivities of teeth and gingiva associated with the use of an in-office bleaching agent followed by an at-home bleaching agent to lighten stained teeth in an in vivo study. Thirty-seven subjects who met the Inclusion/Exclusion criteria were divided into two cells. Twenty-five subjects received three 15-minute in-office bleaching treatments in succession with 36% hydrogen peroxide (HP) on the maxillary anterior teeth, followed by at-home overnight bleaching with 15% carbamide peroxide (CP) for seven days on one side of the dental arch. Twelve other subjects received a 40-minute in-office bleaching treatment on their maxillary anterior teeth, followed by at-home overnight bleaching for seven days on one side of the dental arch with the same product. The cells of teeth on the other side of the dental arch received the same in-office treatment but were not bleached overnight for seven days. Color was subjectively evaluated using the Vitapan Classical Shade Guide and was objectively evaluated using the Chroma Meter at the baseline appointment, immediately after in-office bleaching and at 4, 7 and 14 days and 3 months after the in-office treatment. For two weeks, the subjects completed sensitivity evaluations of gingival tissues and hard tooth tissues. The cells that did not receive the at-home bleaching had significantly less color change than the cells that received at-home bleaching. The cell that was bleached for 40 minutes and received the at-home treatment had significantly less overall change (deltaE) at 14 days and 3 months than the cell that received three 15-minute treatments with the at-home treatment. Throughout the study, the subjects in the three 15-minute treatment cells had less gingival and tooth sensitivity than the other cells.

Single site meta-analysis of 6% hydrogen peroxide whitening strip effectiveness and safety over 2 weeks.

OBJECTIVES: This research evaluated efficacy and safety of 6% hydrogen peroxide whitening strips from a clinical trials database accumulated over a multi-year period at a single site. METHODS: The inclusive meta-analysis involved seven different randomized clinical trials at one dental school. Each study used 6% hydrogen peroxide whitening strips twice daily for 30min over a 2-week period. Common efficacy (digital images) and safety (examination and interview) methods were used across studies. Pooled subject-level data were analyzed using a general linear mixed model to determine overall response and effects of treatment duration on whitening. RESULTS: The 148 treated subjects were 18-71 years old, with b* (yellowness) ranging from 12 to 22, and L* (lightness) ranging from 69 to 80. After 1-week strip use, the adjusted mean (S.E.) for Deltab* was -1.6 (0.08), differing significantly from baseline (p<0.0001). After 2 weeks, the adjusted mean (S.E.) for Deltab* was -2.3 (0.07), differing significantly from Week 1 (p<0.0001). The estimated correlation between Weeks 1 and 2 for Deltab* was 0.74. Study-to-study variation contributed less than 2% of Deltab* variability. Results were similar for DeltaL*, with Weeks 1 and 2 estimated means (S.E.) of 1.5 (0.13) and 2.0 (0.12). Occurrence of oral irritation (22%) and tooth sensitivity (20%) did not adversely affect whitening. Other side effects were unremarkable, and only 1 subject (0.7%) discontinued treatment early due to an adverse event. CONCLUSIONS: The meta-analysis of multiple studies conducted at a single clinical site over several years establishes consistent, effective and safe vital bleaching with 6% hydrogen peroxide whitening strips.

Patients' ranking of interdental "black triangles" against other common aesthetic problems.

The purpose of this study is to assess patients' aesthetic perceptions of interdental "black triangles", both in terms of the number of triangles visible and their severity; and to ascertain how patients rank the presence of "black triangles" against other aesthetic problems. It is based on a questionnaire of 80 randomly selected individuals who were asked to rate the aesthetics of digitally-manipulated images. Patients'perceptions of interdental "black triangles" were compared with their perceptions of other 'non-aesthetic' features. Interdental "black triangles" were rated as the third most disliked aesthetic problem below caries and crown margins. This study demonstrates the importance of interdental "black triangles" to patients, and therefore, as they can occur during prosthetic treatment, must be discussed with patients prior to commencing therapy.

Instant tooth whitening from a silica toothpaste containing blue covarine.

OBJECTIVE: To measure the instant whitening effect delivered immediately after brushing with a novel silica whitening toothpaste containing blue covarine. METHODS: A controlled, single blind, cross-over study was performed to compare the tooth colour measured in a group of subjects at baseline and immediately after brushing with a silica whitening toothpaste containing blue covarine versus a clear gel negative control toothpaste. Measurements of tooth colour were made using a mobile non-contact camera-based digital imaging system and expressed as CIELAB and WIO whiteness index. RESULTS: Analysis of covariance (ANCOVA) showed that the silica whitening toothpaste containing blue covarine was significantly more effective than the negative control toothpaste (p < 0.05), and made teeth measurably less yellow, less red and overall whiter immediately after brushing. CONCLUSION: A statistically significant reduction in tooth yellowness and improvement in tooth whiteness was measured immediately after brushing with a novel whitening toothpaste containing blue covarine.

Preoccupation with one's appearance: a motivating factor for cosmetic dental treatment?

BACKGROUND: It has been estimated that among patients presenting for cosmetic treatments up to 15% suffer from Body Dysmorphic Disorder (BDD), a psychiatric condition characterised by a preoccupation with an imagined defect in appearance. OBJECTIVES: The main purpose of the current study was to establish the relationship between presence of BDD characteristics and interest in aesthetically motivated dental treatments. METHODS: Data were obtained by means of a survey within a sample of 879 Dutch citizens of 16 years and older. Characteristics of BDD were assessed based on DSM-IV criteria. RESULTS: Only one of the BDD features (ie a preoccupation with a defect of appearance) emerged as a significant predictor of undergoing cosmetic dental treatments. Patients with such preoccupation were nine times more likely to consider tooth whitening, and six times more likely to consider orthodontic treatment. They were also five times more likely to be dissatisfied about their most recent treatment. CONCLUSIONS: The results suggest that preoccupation with one's physical appearance is a motivating factor for undergoing certain types of cosmetic dental procedures.

A clinical study to evaluate the efficacy of a novel tray based tooth whitening system.

OBJECTIVES: The study was designed to test the whitening efficacy of a new prefabricated tray based whitening system. METHODS: A parallel, examiner blind, stratified two group clinical study was carried out in the Department of Fixed and Removable Prosthodontics, Leeds Dental Institute, United Kingdom. Forty-nine male and female subjects aged 18-70 years participated in the study and they underwent both clinical and digital evaluation at baseline, 3, 7 and 14 days, respectively. The non-intervention control group was given no treatment and the test group received a tray based whitening system (Colgate Visible White PF Mint, Colgate Palmolive Company, NY, USA) that uses a 6% hydrogen peroxide gel applied in the tray twice daily for 30 min. Digital images of teeth were captured using a Jai 3CCD digital camera under an annular LED illumination array (SCHOTT North America, Inc., USA) and the data obtained was used to calculate colour parameters (L(*), a(*) and b(*)) and whiteness index WIO. RESULTS: Clinical data and digital data showed significant difference for the Visible White group from the control group for the mean difference in its values from the baseline to each visit (p<0.001). Digital data showed significant correlation to clinical data. CONCLUSION: In the present study statistically significant tooth whitening was evident after 3 days treatment with the tray based whitening system and colour improved with continued usage over 14 days. It also supports our previous study results that the WIO index is appropriate for assessing changes in tooth whiteness.

Clinical studies to assess the extrinsic stain prevention and stain removal efficacy of a variant of a commercially available dentifrice containing a new dual silica system.

OBJECTIVE: The objective of these two six-week, double-blind clinical studies was to compare the extrinsic stain prevention (Study #1) and stain removal (Study #2) efficacy of a new dentifrice (Colgate Total Advanced Toothpaste) containing 0.3% triclosan/ 2.0% polyvinylmethyl ether/maleic acid (PVM/MA) copolymer/0.243% sodium fluoride in a 17% dual silica base, to a commercially available fluoride dentifrice without tooth whitening ingredients (Crest Cavity Protection Toothpaste) containing 0.243% sodium fluoride in a silica base. METHODS: Following baseline examinations for extrinsic tooth stain and an oral tissue examination, qualifying adult male and female subjects from the northern and central New Jersey, USA areas were randomized for each study into two treatment groups which were balanced for gender and level of extrinsic tooth stain. Subjects received a full oral prophylaxis at the start of Study #1 only. All subjects were provided with their assigned product and a soft-bristled adult toothbrush for home use. Subjects were instructed to brush their teeth for one minute twice daily (morning and evening) using only the dentifrice and toothbrush provided, and to refrain from using any other oral hygiene products for the entire six weeks of the study. There were no restrictions regarding diet or smoking habits during the course of the study. Examinations for extrinsic tooth stain and oral tissue assessments were repeated after three weeks and six weeks of product use. RESULTS: One-hundred fourteen (114) subjects participating in Study #1 and 119 subjects participating in Study #2 complied with the protocol and completed the entire study. In both studies, at the three-week and the six-week examinations, subjects who used the new dentifrice exhibited statistically significantly lower levels of extrinsic tooth stain area and extrinsic tooth stain intensity than did those subjects who used the commercially available fluoride control dentifrice. CONCLUSION: A new dentifrice containing 0.3% triclosan/2.0% PVM/MA copolymer/0.243% sodium fluoride in a 17% dual silica base is more efficacious in the prevention and removal of extrinsic tooth stain than a commercially marketed fluoride dentifrice.

Blanqueamiento dentario: aplicaciones clínicas / Tooth bleaching: clinical applications

El presente artículo describe al blanqueamiento dental como una técnica de mínima intervención dentro de laodontología estética actual, la enumeración de los agentes blanqueadores y su mecanismo de acción, sus indicaciones y limitaciones así como los protocolos clínicos con el fin de lograr la armonía óptica de las piezas dentarias.

Tooth whitening through the removal of extrinsic stain with two sodium hexametaphosphate-containing whitening dentifrices.

PURPOSE: To evaluate the tooth whitening benefit through stain removal delivered by a marketed whitening dentifrice (Crest Vivid White) used twice a day or a combination regimen of two marketed dentifrices (Crest Vivid White Night used at night and Crest Cavity Protection used in the morning) relative to a positive control over a 2-week period. METHODS: Both studies were randomized, two treatment, parallel group, examiner-blind, 2-week clinical trials involving 22 and 30 healthy adults with longstanding visible extrinsic stain on the facial surfaces of at least six anterior teeth. In each study, subjects were randomized to one of two treatments: a sodium fluoride/sodium hexametaphosphate whitening dentifrice used alone (Study 1) or in combination with a cavity protection dentifrice (Study 2) with an ADA reference manual toothbrush versus a control power toothbrush with a cavity protection dentifrice (both studies). RESULTS: In both studies, all treatment groups statistically significantly (P < 0.001) reduced baseline stain scores following 1 and 2 weeks of brushing. After 2 weeks, the whitening dentifrice used twice daily had a median percent stain removal of 90% and the night-time whitening dentifrice (used once a day) in combination with the cavity protection dentifrice had a median percent stain removal of 85% while powered toothbrush groups showed median percent stain removal of 88-89% in both studies. Stain removal scores after 1 and 2 weeks of brushing did not differ significantly between the two treatment groups in either study.

Clinical evaluation of the stain removal efficacy of a novel stannous fluoride and sodium hexametaphosphate dentifrice.

PURPOSE: Recently, sodium hexametaphosphate has been introduced in dentifrice formulations to aid in the control of extrinsic stain. Two independent studies were conducted to evaluate the stain removal efficacy of a novel 0.454% stannous fluoride and sodium hexametaphosphate dentifrice (Crest Pro-Health) relative to a positive control whitening dentifrice (Colgate Total + Whitening) over a 2-week period in a subject population with pre-existing natural extrinsic stain. METHODS: These studies were randomized, positive-controlled, parallel groups, double-blind, 2-week trials. Each study involved approximately 30 healthy adults with visible stain of the facial surfaces of the 12 anterior teeth. After baseline examination, subjects were randomly assigned to a treatment and instructed to brush unsupervised with the assigned dentifrice at least twice daily as they normally do. Efficacy was evaluated by modified Lobene examination on anterior teeth at baseline and end-of treatment (Week 2). RESULTS: 59 subjects, 29 in Study 1 and 30 in Study 2, were evaluable and included in the Week 2 analyses. Subjects ranged from 21-68 years of age. In each study, the positive control dentifrice statistically significantly (P < 0.0001) reduced stain scores following 2 weeks of brushing with median reductions of 61.9% and 94.4%. Similarly, the experimental 0.454% stannous fluoride and sodium hexametaphosphate dentifrice statistically significantly (P < 0.0001) reduced stain scores by 61.8% and 96.6% following 2 weeks of brushing. The adjusted mean changes between treatment groups did not differ significantly between the two dentifrice groups (P > 0.70 in each study). Both dentifrices were well tolerated. No subject discontinued treatment due to an adverse event.

Efficacy of intracoronal bleaching techniques with different light activation sources.

AIM: To evaluate ex vivo the efficacy of 35% hydrogen peroxide for intracoronal bleaching when activated by LEDs, halogen lamp or by the walking bleach technique. METHODOLOGY: Forty extracted human maxillary central incisors had their crowns resected 1 mm below the amelo-cemental junction and were submitted to artificial staining in centrifuged rat haemolysed blood. A 2-mm thick glass ionomer cervical plug was placed inside the canal, at the level of the amelo-cemental junction. Samples were divided randomly into five groups: group I received 35% hydrogen peroxide gel activated by LEDs. Group II received 35% hydrogen peroxide gel activated by a halogen lamp-based light curing unit. Group III received 35% hydrogen peroxide gel followed by the walking bleach technique. Group IV was neither artificially stained nor bleached (positive control) and group V was stained, but not bleached (negative control). The shade of the teeth was assessed visually by three independent and calibrated evaluators, before and after bleaching. The results were analysed using Kruskal-Wallis one-way analysis of variance and Dunn's post-test. RESULTS: No statistical differences regarding sample shades were found amongst groups for the tested internal bleaching techniques (P > 0.05). CONCLUSIONS: Hydrogen peroxide for intracoronal bleaching when activated either by LEDs, halogen lamp or by the walking bleach technique presented similar efficacy.

Comparison of the ability of different colour indices to assess changes in tooth whiteness.

OBJECTIVES: The study investigates the suitability of different whiteness indices and colour parameters in assessing changes in tooth whiteness using a digital-colour imaging system. METHODS: Forty-six male and female subjects aged 18-70 years participated in the study and were divided into two groups. The control group was given a standard "non-whitening" dentifrice (Colgate Great Regular Flavour) and the test group received whitening strips (crest white strips). The latter contained 6% hydrogen peroxide and were worn for 30 min twice daily on the six maxillary anterior teeth. Digital images of teeth were captured using a Jai 3CCD digital camera with annular LED illumination array and the data obtained was used to calculate colour parameters (L*, a* and b*) and whiteness indices (WIC, WIO, W). Colour differences (delta L, delta a, delta b and delta E) and differences in whiteness indices were obtained and were compared between the test and control groups. Reliability and repeatability of the instrument were checked by comparing the digital data to the clinical data and also by comparing data obtained from different camera views for the same tooth. RESULTS: The test group showed significant changes in the colour parameters and whiteness indices over the 2-week period. It also showed significant correlation between the digital data obtained from lateral and central camera views for the same teeth. Digital data showed a similar trend to that of clinical data. The WIO index demonstrated the strongest discrimination between the test and control groups. CONCLUSION: The WIO index is appropriate for assessing changes in tooth whiteness. The digital imaging system is reproducible and reliable in evaluating changes in whiteness of teeth.