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Objectives: This study aimed to synthesize and evaluate the in vitro effects of varying concentrations (0.25%, 0.5%, and 1%) of calcium-substituted sodium trimetaphosphate (CaNaTMP) incorporated into 17.5% and 35% hydrogen peroxide (HP) whitening formulations on enamel color change, microhardness, morphology, surface roughness, mineral content, and transamelodentinal diffusion of HP., Materials and Methods: Enamel/dentin discs (N = 288) were allocated into eight groups according to the bleaching gel: (1) 35% HP; (2) 35% HP + 0.25% CaNaTMP; (3) 35% HP + 0.5% CaNaTMP; (4) 35% HP + 1% CaNaTMP; (5) 17.5% HP; (6) 17.5% HP + 0.25% CaNaTMP; (7) 17.5% HP + 0.5% CaNaTMP; and (8) 17.5% HP + 1% CaNaTMP. Gels were applied for 40 min across three weekly sessions. Evaluated parameters included total color change according to CIELab (ΔE), CIEDE2000 equation (ΔE 00 ), whiteness index (ΔWI D ), surface hardness (SH), surface roughness (Ra), enamel mineral content (g HAp × cm⁻³ × µm), and transamelodentinal of HP. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analyses were used to assess enamel surface characteristics. Data were analyzed using ANOVA and the Student-Newman-Keuls test (p < 0.05)., Results: All bleaching gels caused significant color changes after treatment (p < 0.001), with similar ΔE, ΔE 00 , and ΔWI D values among them. Mineral loss (SH, g HAp × cm⁻³ × µm), Ra, and HP diffusion were highest with the 35% HP gel (p < 0.001) and lowest in groups containing CaNaTMP, particularly at 1% (p < 0.001). SEM/EDX analysis revealed no visible surface alterations in the 17.5% HP group, with prominent amorphous apatite precipitation in the 1% CaTMP-containing group. Incorporating CaNaTMP, particularly at 0.5% and 1%, into the 35% HP gel reduced surface changes., Conclusions: This study demonstrated that the addition of CaNaTMP to bleaching gels with 17.5% and 35% HP reduces mineral loss, changes in roughness, and surface morphology of enamel, as well as decreasing trans-amelodentinal diffusion of H₂O₂, without compromising the bleaching efficacy. The incorporation of 1% CaNaTMP was particularly more effective in protecting the dental enamel., Clinical Relevance: The incorporation of CaNaTMP to 17.5% and 35% HP bleaching gels enhances safety and biocompatibility by reducing enamel damage. The lower HP concentration (17.5%) combined with 1% CaNaTMP provides a safer whitening option, maintaining effectiveness while minimizing adverse enamel changes, aimed at improving patient comfort during treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025. Published by Elsevier Ltd.)

Objective: This randomized controlled clinical trial evaluated the whitening efficacy, tooth sensitivity (TS), and volunteers' satisfaction following the use of activated charcoal powder and toothpaste., Methods: Fifty-six volunteers were randomly allocated into 4 groups (n = 14) according to a 14-day toothbrushing or whitening treatment with activated charcoal powder (ACPW), activated charcoal toothpaste (ACT), regular fluoridated toothpaste (RT), and 10 % carbamide peroxide (CP). Objective (ΔE 00 ) and subjective (ΔSGU) color and whiteness index (ΔWI D ) changes were calculated. Patients self-reported the risk and intensity of TS using a visual analogue scale and the volunteer's satisfaction was determined by a questionnaire. Color assessments were analyzed by Kruskal-Wallis followed by Dwas-Steel-Crithlow-Fligner, and absolute TS risk and volunteer's satisfaction by Fisher exact test (p < 0.05)., Results: ACPW and ACT promoted similar effects in ΔE 00 , ΔSGU, and ΔWI D to that observed for RT. No significant difference was found in terms of TS risk intensity. TS risk became high after 7 and 14 days, with higher TS prevalence in CP. Volunteers reported that ACPW exhibited the lowest ease-of-use, comfort, and whitening satisfaction among groups (p < 0.05)., Conclusion: Activated charcoal-based products presented a minor and unsatisfactory whitening effect while CP resulted in optimal tooth whitening and the highest level of satisfaction among volunteers. Risk was higher from 7 days onwards and was more pronounced in the CP., Clinical Relevance: Based on the whitening effect and patient satisfaction, this controlled-randomized clinical evidence supports that the use of activated charcoal-based products should be discouraged., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Objectives: To assess the efficacy of a bleaching enzyme-based toothpaste.Material and Methods: A randomized clinical trial was carried out, comprising 48 participants with teeth exhibiting color A3 or higher according to the Vita Classical guide. One-half of the sample received the bleaching enzyme-based toothpaste (White Kin(®)), while the other received placebo toothpaste. Both products were supplied in identical containers and had the same composition except for the active components. The teeth color was measured with a spectrophotometer. The patients were instructed to brush their teeth three times a day during 3 min with the assigned product, during 12 weeks. The color measurements were repeated after 3, 6, 9 and 12 weeks of treatment. Color variation was based on the CIE L*a*b* coordinates, ΔE and the EW index. The relationship of these variables at different observation times were performed using a generalized estimating equations model, which evaluated the effect of treatment, time and interaction.Results: The patients using the bleaching enzyme-based toothpaste showed an increase in lightness (80.14 -treatment- versus 79.25 -control group-) and a reduction in component b*. ΔE was found higher in the treatment group (p=0.064), close to statistical significance.Conclusions: The bleaching enzyme-based toothpaste could be potentially efficient in the modification in tooth color progressing from the third to ninth week of treatment, tending to stabilize after the ninth week.Clinical Relevance: A very low carbamide peroxide concentration, with the incorporation of lactoperoxidase, tooth paste, tends to offer clinically satisfactory results, in terms of modifications in tooth color, nevertheless no significant differences were founded when compared to the control group, with an oral hygiene controlled along the study. [ABSTRACT FROM AUTHOR]

Objective: This clinical study evaluated the color longevity after one-year of at-home bleaching with 10% carbamide peroxide (CP) in smokers and nonsmokers.Methods: Sixty patients, 30 smokers and 30 non-smokers were subjected to bleaching with 10% CP during three hours daily for three weeks. The color was measured at baseline and one week, one month and one year after the completion of dental bleaching using the spectrophotometer Vita Easyshade (ΔE*), shade guide Vita classical organized by value and Vita Bleachedguide 3D-MASTER (ΔSGU). In the one-year recall, the color was assessed before and after dental prophylaxis with Robinson brush and prophylaxis paste. Data from color evaluation were analyzed by two-way repeated measures ANOVA and Tukey's test for the contrast of means (α=0.05).Results: Twenty-seven smokers and 28 non-smokers attended the one-year recall. For both study groups, only the main factor assessment time was statistically significant for ΔSGU (Vita classical) and ΔE* (p<0.001). Effective whitening was observed for both groups at baseline, which was stable at one-month and one year after dental prophylaxis. A slight darkening was observed after one year when the color was measured without prophylaxis. For the Vita Bleachedguide 3D-MASTER, color rebound was observed irrespectively of dental prophylaxis.Conclusion: The bleaching with 10% CP remained stable in both groups as long as extrinsic stains from diet and cigarette smoke were removed by professional dental prophylaxis.Clinical Trials Registry: NCT02017873.Clinical Relevance: The results of this study indicate that the bleaching is effective in smokers even after one-year, but dental prophylaxis may be necessary to remove extrinsic stains caused by diet and smoking. [ABSTRACT FROM AUTHOR]

Objectives: This meta-analysis was performed to evaluate the efficacy of potassium nitrate and sodium fluoride as desensitizing agents during tooth bleaching treatment. Data, sources and Study selection: An electronic systematic literature search was conducted in Cochrane Center Register of Controlled Trials, MEDLINE (PubMed) and EmBase in April, 2014 in English and without time restrictions. Study information extraction and methodological quality assessments were accomplished by two reviewers independently. Methodological quality was assessed by using the "Criteria for judging risk of bias in the 'Risk of bias' assessment tool". Dichotomous data was summarized by odds ratio (OR) with 95% confidence interval (CI) and continuous data was summarized by mean difference (MD) or standardised mean difference (SMD) with 95% confidence interval (CI). Statistical analyses were carried out by using Review Manager 5.2. For evaluation of percent of patients experiencing tooth sensitivity (POTS), the pooled OR of desensitizers vs. placebo was 0.45 (95% CI: 0.28-0.73, P = 0.29). The pooled SMD of desensitizers vs. placebo was −0.47 (95% CI: −0.77 to −0.18, P = 0.13) in evaluation of level of tooth sensitivity (LOTS). The results of shade evaluation remained inconsistent by evaluating subjective shade guide unit difference (ΔSGU or SGU) and objective colour difference (ΔE). Conclusions: This meta-analysis was performed to evaluate the efficacy of desensitizing agents, potassium nitrate and sodium fluoride, for tooth bleaching treatments. Potassium nitrate and sodium fluoride reduce tooth sensitivity while no consistent conclusion of tooth colour change was found. Clinical significance: Tooth sensitivity is a typical side effect associated with tooth bleaching procedures. Potassium nitrate and sodium fluoride are used widely to treat tooth sensitivity. This meta-analysis was performed to evaluate the efficacy of potassium nitrate and sodium fluoride as desensitizing agents during tooth bleaching treatment. [ABSTRACT FROM AUTHOR]

Objective: The aim of this clinical randomized double-blind split-mouth study was to assess the effectiveness of a 6% hydrogen peroxide with nitrogen-doped titanium dioxide light activated bleaching agent. Method: 31 patients were treated with: one upper hemiarcade with a 35% hydrogen peroxide bleaching agent and the other hemiarcade with a 6% hydrogen peroxide. Two applications were completed each treatment session and three sessions were appointed, with one week interval between them. Tooth colour was registered each session and 1 week and 1 months after completing the treatment by spectrophotometer, registering parameters L*, a* and b*, and subjectively using VITA Classic guide. Tooth sensitivity was registered by VAS and patient satisfaction and self-perception result was determined using OHIP-14. Tooth colour variation and sensitivity were compared between both bleaching agents. Results: Both treatment showed a change between baseline colour and all check-points with a ΔE = 5.57 for 6% and of ΔE = 7.98 for the 35% one month after completing the (p < 0.05). No statistical differences were seen when subjective evaluations were compared. Also, no differences were seen in tooth sensitivity between bleaching agents. OHIP-14 questionnaire demonstrated a significant change for all patients after bleaching. Conclusions: A 6% hydrogen peroxide with nitrogen-doped titanium dioxide light activated agent is effective for tooth bleaching, reaching a ΔE of 5.57 one month after completing the treatment, with no clinical differences to a 35% agent neither in colour change or in tooth sensitivity. Clinical significance: A low concentration hydrogen peroxide bleaching agent may reach good clinical results with less adverse effects. [ABSTRACT FROM AUTHOR]

Objectives: In-office bleaching is usually performed in 2-3 sessions with one-week interval. The impact of shorter interval times on tooth sensitivity has not been evaluated. This study aimed to compare the absolute risk of tooth sensitivity (TS) and colour change after in-office bleaching with a two- and seven-day intervals between sessions. Methods: We selected for this randomized, single-blind study, 40 patients with colour C2 or darker. We performed two bleaching sessions with a 35% hydrogen peroxide gel with either a 1-week or 2-day interval. We recorded the TS up to 48 h with a VAS scale and the colour at baseline and 30 days after bleaching with a value-oriented shade guide and a spectrophotometer. The risk and intensity of TS were compared with the Fisher's exact test and twoway repeated measures ANOVA. Colour change (ΔSGU and ΔE) were evaluated by Student's t-test (alpha = 5%). Results: Approximately 60% of the participants reported TS (65% and 55% for the 7 and 2-day groups). A significant whitening of approximately 6 shade guide units was detected for both groups. No difference was detected between groups. Conclusions: The reduction of the interval between bleaching sessions from seven to two days reduced the treatment time without increasing the bleaching-induced TS (clinicaltrials. gov identifier: NCT1959789). Clinical significance: In-office bleaching with a 2-day interval did not increase the risk and intensity of bleaching-induced tooth sensitivity. [ABSTRACT FROM AUTHOR]

Objectives: We provide a quantitative predictive model for the extent to which coloured dentine, visible through the enamel, contributes to tooth colour. Our model uses (L*, a*, b*) measurements rather than spectral measurements. Methods: We have used a model system, composed of a slice of bovine enamel placed on top of coloured paper. We have measured the colour of the enamel-paper combination, as an analogue for a tooth, and have related this to the colour of the paper, as an analogue for dentine. By changing the paper colour, we have been able to explore how the colour of dentine determines tooth colour, according to our model system. We have also compared hydrated and desiccated samples. Results: In qualitative terms, superimposing the enamel on top of the paper increases the "lightness" for all colours tested except white while simultaneously reducing the chromaticity, a measure of the extent to which the colour differs from grey. Desiccated enamel is much more effective at increasing the lightness and reducing the chromaticity than hydrated enamel. Quantitatively, our measurements are reproduced by the mathematical model we have developed to within 2% in "lightness" and about 8% in chromaticity. Conclusions: We are able to predict the colour of an analogue for a tooth, composed of bovine enamel and coloured paper, from the colour of an analogue for the dentine, the coloured paper alone, with good accuracy. This understanding provides insights into the role of dentine colour in determining tooth colour. Clinical Significance: Our work helps quantify the importance of dentine colour, compared to other, extrinsic causes of colour, such as staining, in determining the visible colour of teeth. Our predicted colours represent a baseline to which extrinsic sources will add. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the effects of experimental protocols on bleaching effectiveness and hydrogen peroxide (HP) diffusion through enamel and dentine. Methods: Enamel/dentine discs were subjected to six bleaching sessions, consisting of 1 or 3 applications of 17.5% or 35%-HP gel for 5/15 min, or 37% carbamide peroxide (CP) gel for 10/ 20 min. Discs undergoing the regular protocol (35%-HP; 3 s 15 min) constituted the positive control group. Colour change (DE) was assessed (CIE L*a*b* system) after each session. HP diffusion was quantified (sessions 1, 3, and 6) in enamel/dentine discs adapted to artificial pulp chambers. Data were analysed by Pillai's Trace and Bonferroni test, or by one-way ANOVA and SNK/Tamhane's test (a = 5%). Results: All tooth-bleaching protocols significantly increased the DE values. A reduction in HP diffusion and no significant difference in DE compared with the positive control were observed for the following bleaching protocols: 17.5%-HP 3:15 min, at the 4th session; and 35%-HP 1 s 15 and 3 s 5 min, at the 5th session. HP diffusion in the 37%-CP 3 s 20 min bleaching protocol was statistically similar to that in the positive control. The other experimental bleaching protocols significantly decreased HP diffusion through enamel/ dentine discs, but the DE values were statistically lower than those observed in the positive control, in all sessions. Conclusion: Shortening the contact time of a 35%-HP gel or reducing its concentration pro- duces gradual tooth colour change and reduced HP diffusion through enamel and dentine. Clinical significance: A reduction in HP concentration, from 35% to 17.5%, in a bleaching gel or shortening its application time on enamel provides a significant tooth-bleaching improvement associated with decreased HP diffusion across hard dental tissues. Therefore, these protocols may be an interesting alternative to be tested in the clinical situation. [ABSTRACT FROM AUTHOR]

Objectives: To assess the whitening effectiveness and the trans-enamel/trans-dentinal toxicity of experimental tooth-bleaching protocols on pulp cells. Methods: Enamel/dentine discs individually adapted to trans-well devices were placed on cultured odontoblast-like cells (MDPC-23) or human dental pulp cells (HDPCs). The following groups were formed: G1 - no treatment (control); G2 to G4 - 35% H2O2, 3 × 15, 1 × 15, and 1 × 5 min, respectively; and G5 to G7 - 17.5% H2O2, 3 × 15, 1 × 15, and 1 × 5 min, respectively. Cell viability and morphology were evaluated immediately after bleaching (T1) and 72 h thereafter (T2). Oxidative stress and cell membrane damage were also assessed (T1). The amount of H2O² in culture medium was quantified (Mann-Whitney; α = 5%) and colour change (DE) of enamel was analysed after 3 sessions (Tukey's test; α = 5%). Results: Cell viability reduction, H2O2 diffusion, cell morphology alteration, oxidative stress, and cell membrane damage occurred in a concentration-/time-dependent fashion. The cell viability reduction was significant in all groups for HDPCs and only for G2, G3, and G5 in MDPC-23 cells compared with G1. Significant cell viability and morphology recovery were observed in all groups at T2, except for G2 in HDPCs. The highest DE value was found in G2. However, all groups presented significant ΔE increases compared with G1. Conclusion: Shortening the contact time of a 35%-H2O2 gel for 5 min, or reducing its concentration to 17.5% and applying it for 45, 15, or 5 min produce gradual tooth colour change associated with reduced trans-enamel and trans-dentinal cytotoxicity to pulp cells. Clinical significance: The experimental protocols tested in the present study provided significant tooth-bleaching improvement associated with decreased toxicity to pulp cells, which may be an interesting alternative to be tested in clinical situations intended to reduce tooth sensitivity and pulp damage. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the potential of bio-active glass (BAG) powder and BAG containing polyacrylic acid (PAA-BAG) to remineralise enamel white spot lesions (WSL). Methods: 32 human enamel samples with artificial WSLs were assigned to 4 experimental groups (n = 8); (a) BAG slurry, (b) PAA-BAG slurry, (c) ''standardised'' remineralisation solution (positive control) and (d) de-ionised water (negative control). Mechanical properties of enamel were assessed using surface and cross-section Knoop microhardness. Micro- Raman spectroscopy in StreamLineTM scan mode was used to scan lesion cross-sections. The intensity of the Raman phosphate peak at 959 cm-1 was fitted and measured producing depth profiles analysed using a double-step fitting function. A further 20 samples (n = 5) were used to obtain 3D images of surfaces using non-contact white light profilometry permitting measurement of lesion step height in relation to the sound enamel reference level, and to scan the lesion surface using scanning electron microscopy (SEM). Data were analysed statistically using one-way ANOVA with Tukey's HSD post-hoc tests. Results: BAG, PAA-BAG and the remineralisation solution exhibited statistically significantly higher surface and cross-section Knoop microhardness compared to the negative control. Micro-Raman spectroscopy detected significantly higher phosphate content within the treated groups compared to the negative control group. Lesions' depth was not significantly reduced. SEM images revealed mineral depositions, with different sizes and shapes, within BAG, PAA-BAG and the positive control groups. Conclusion: BAG and PAA-BAG surface treatments enhance enamel WSL remineralisation, assessed by the resultant improved mechanical properties, higher phosphate content and morphological changes within the artificial lesions. [ABSTRACT FROM AUTHOR]

Objectives: To assess the accuracy of a novel, non-invasive method for determining the axis of rotation of articulated dental study casts. Method: A 3D structured light scanner was constructed using a projector and two CMOS cameras. Dental stone casts were arbitrarily mounted on an average value articulator. With the teeth together, sets of 10 scans were taken from three different viewpoints. Each scan captured approximately six upper teeth and six lower teeth. The teeth were then propped open, creating 10 mm of incisal separation, and the three sets of 10 scans were repeated. From each pair of scans an axis of rotation was calculated using custom software. A total of 900 axes were created this way. The locations of these axes were plotted in sagittal planes located 57.5 mm left and right of the midline to represent the position of the temporo- mandibular joints (TMJs). The accuracy of axis location was then assessed. Results: The average radius of error of the individual axes, compared to the real axis, was 2.65±1.01mm. 61.3% of the axes lay within 3 mm of the true axis, and 99.2% of the axes lay within 5 mm of the true axis. Conclusions: The accuracy of this method is clinically acceptable. Further studies are required to confirm the accuracy of the virtual inter-occlusal records at the level of the dentition. Clinical studies are then indicated to determine whether the transverse horizontal axis on a patient can similarly be determined. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to assess changes in oral health-related quality of life (OHRQoL) in individuals enroled in a double-blind randomized clinical trial conducted to evaluate the efficacy and safety of two carbamide peroxide concentrations used in at-home vital bleaching in the city of Pelotas, Southern Brazil. Methods: Ninety-two volunteers with a shade mean of C1 or darker for the six maxillary anterior teeth wererandomizedintotwo balancedgroups(n = 46) accordingtobleaching agent concentration:10% or 16% carbamide peroxide. The patients were instructed to use the whitening agent in a tray for 2 h once a day for three weeks. To assess changes in OHRQoL, participants completed the oral impact on daily performance (OIDP) at the start and one week after the completion of treatment. Because there was no difference with regard to whitening effect or tooth sensitivity during or after treatment the two groups were merged for the analyses of the current article. Before-and-after changes in OIDP scores were assessed by chi-square and McNemar tests ( p < 0.05). Results: Mean pre- and post-treatment OIDP scores varied from 0.42 to 0.60. When the frequency of impacts for different activities were compared, there was an increase in difficulty in cleaning teeth ( p = 0.02) and a significant reduction in smiling and showing teeth with embarrassment ( p = 0.03). Regarding the symptoms and main oral conditions thatgenerated impact, there was higher number of participants reporting pain ( p = 0.05) after treatment. In opposite, significant decrease was observed in individuals reporting being unhappy with their appearance ( p = 0.03). On the contrary, it was showed a decrease in impacts resulting from dental colour was observed after bleaching ( p = 0.03). Conclusion: Quality of life is complex and encompasses different domains. Although positive impact of the dental bleaching was detected, with patients showing more their teeth without embarrassment, difficult in dental hygiene and pain resulting from the treatment were also reported, and this can negatively impact daily performances. Dentists must consider these aspects when performing aesthetics procedures. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to investigate the whitening properties and rate of bleaching action of chlorine dioxide and compare them with those of hydrogen peroxide of similar concentration. Methods: Sixty bovine central incisor crowns were ground and polished until flat surfaces were obtained. The crowns were subjected to extensive staining cycles of artificial saliva, chlorehexidine and tea before being randomly assigned to three groups: chlorine dioxide (ClO2), hydrogen peroxide (H2O2) and deionised water (H2O). The crowns in each group were subjected to seven 2 min exposure cycles in addition to an extra 30 min cycle. CIE LAB spectrophotometric measurements were taken at baseline, after each 2 min, and each extended 30 min bleaching cycle. Results: L* for ClO2 specimens was significantly higher only after the first 2 min cycle ( p < 0.001) while for H2O2 specimens, L* significantly increased after the first two cycles ( p < 0.001) and continued to increase, at a slower rate, until the end of the treatment cycles. ΔE was significantly greater within H2O2 than within ClO2 specimens ( p < 0.001). Conclusion: Chlorine dioxide whitens teeth at a faster rate than hydrogen peroxide. Specimens treated with chlorine dioxide were significantly lighter than those treated with hydrogen peroxide at the end of the first 2 min application cycle, however, extended exposures did not enhance color. [ABSTRACT FROM AUTHOR]

Objectives: This randomised controlled clinical trial assessed the efficacy of color change and sensitivity after in surgery whitening with and without light activation. Methods: Twenty two patients were randomly assigned to one of two different groups: Group A - in-surgery bleaching with light activated 25% hydrogen peroxide gel followed by 2 weeks at home, night time bleaching with 10% carbamide peroxide gel in a customised bleaching tray. Group B - in-surgery bleaching with 25% hydrogen peroxide without light activation followed by 2 weeks at home, night time bleaching with 10% carbamide peroxide gel in a customised bleaching tray. The efficacy of tooth whitening was assessed by determining the color change associated with the six maxillary anterior teeth. Sensitivity was self-assessed with the use of a visual analogue scale (VAS). Results: Overall, there was no significant difference in shade change between the two groups immediately after the in surgery whitening phase, and at one or two weeks post in surgery treatment. With regard to sensitivity immediately following the in surgery whitening participants in Group B reported a significantly higher level of sensitivity in comparison to Group A ( p = 0.03). Conclusions: There was no significant difference between the shade improvements achieved by the two whitening protocols tested throughout the 2-week period of the study ( p > 0.05). There was no statistical significant difference in sensitivity at the one and two week review periods, however, immediately after treatment participants in Group B reported a significantly higher level of sensitivity than participants in Group A ( p = 0.03). [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effect of desensitising agents on human dentine morphology and composition. Methods: Randomly assigned human coronal-dentine specimens were subjected to: (a) no treatment (smear-layer control, n=4); (b) acid etching with 6% citric acid (demineralised control, n=4); (c) treatment with desensitising agents (12 cycles of 60 s treatment with 60 s between-treatment rinsing, n=6 per agent ); and (d) exposure to acidic challenge (pH 5.0 for 90 s, n=6 per agent). The tested products were: Listerine® Advanced Defence Sensitive (LADS; 1.4% potassium oxalate) mouthrinse, Colgate® Sensitive Pro-Relief™ mouthrinse, and toothpaste slurries (paste/water 1:2 wt/wt ratio) of Colgate® Sensitive Pro-Relief™ paste, Crest® Sensitive paste and Sensodyne® Repair and Protect paste. All dentine surfaces were studied by attenuated total refl ectance Fourier transform infrared (ATR-FTIR) spectroscopy, Raman microscopy and high vacuum scanning electron microscopy with energy-dispersive X-ray microanalysis (HV-SEM/EDX). Results: Desensitising slurry treatments occluded tubule orifices of acid-etched dentine, creating a randomly distributed surface pattern of particle aggregates. The greatest intratubular penetration of occluding particles was found in dentine treated with LADS. The atomic ratios of Ca/N and Ca/P, and the mineral/matrix ratios increased after toothpasteslurry treatments compared with the acid-etched dentine. However, the acidic challenge removed most surface precipitates and further demineralised these substrates. Before the acidic challenge, the surface features were least affected in specimens treated with Sensodyne® Repair and Protect. After the acidic challenge, the sub-surface occlusion features were least affected in specimens treated with LADS. Clinical significance: Although most tested products achieved occlusion of dentinal tubules and provided evidence of mineral deposits, the deposit formed by LADS demonstrated the greatest resistance to acidic challenge, which simulates intra-oral demineralisation phases. [ABSTRACT FROM AUTHOR]

Objectives: This study aims to update the computer color matching method by generating a new ceramic shade system that covers the entire spectrum of natural tooth color and has an efficient design. Methods: First, the color map of 176 maxillary natural incisors and two commercially available and commonly used shade guide systems (Vitapan classic and 3D master) were drawn. Then, 15 shades of layered disks (NW-0: neutral white-0, A1, A2, A3, A4, B1, B4, C4, and D4, and six modifiers; white, pink, grey, blue, cervical-1 and cervical-2, Cerabien ZR) were plotted on the tooth color distribution map. Ultimately, 12 target shades were selected around the perimeter of the natural tooth color space, and nine different shades were selected within the cluster. By trial and error informed by known formulations published previously, the formulations of Cerabien ZR porcelain powders necessary to achieve these 21 target shades in thickness of 1.0 mm layered on zirconia substrate were then determined and ceramic disks were fabricated. Results: Color distribution L*-C* and a*-b* maps showed that new 21 shade system covers a slightly broader range than the natural tooth distribution, and its distribution is larger than the 3D Master shade's range. Conclusions: In the present study, a 21 custom dental porcelain shade system was developed with a 1.0 mm porcelain thickness overlying a zirconia substrate, which can be incorporated into the computer color matching system. This new shade system has homogeneity with 3D Master, and has a slightly wider color distribution than that of natural teeth. [ABSTRACT FROM AUTHOR]

Objectives: To determine the effect of light activation on tooth whitening efficacy and hydrogen peroxide penetration into the pulp cavity and correlate tooth color change with penetration levels. Methods: Extracted human canines (40) were randomized into four groups, Group A: placebo gel, Group B, placebo gel with light activation, Group C: 40% hydrogen peroxide gel, and Group D: 40% hydrogen peroxide gel with light activation. Treatment was performed three times, at 1-week intervals. Hydrogen peroxide penetration (HPP) was estimated spectro-photometrically and specimen color measured using the Vita Easy Shade Compact at baseline, after whitening, 1-h, 1-day, 1-, 4-, 8-, 12-, 16-, 20-, and 24-week post-whitening. Color change was measured per Commission Internationale de l'Eclairage methodology. ANCOVA was performed to compare color change and HPP level among the four groups. Partial nonparametric correlations between color change and HPP levels were performed with rank transformations. Tests of hypotheses were two-sided with alpha level of 0.05. Results: Greater HPP was observed in Groups C and D compared to Groups A and B (p < 0.001). Highest overall color change (ΔE*ab) values after treatment were observed in Group D and remained higher than Groups A-C (p < 0.01). Changes in lightness and in the yellow-blue dimension (ΔL* and Δb*) were higher in Groups C and D compared to Groups A and B from post-whitening until 24 weeks (p < 0.05). HPP levels were not correlated to color change (p > 0.05). Conclusions: Light activation enhanced whitening efficacy without affecting hydrogen peroxide penetration levels. [ABSTRACT FROM AUTHOR]

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 2 h, 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* (yellowness) 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. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this clinical trial was to evaluate efficacy (BE) and tooth sensitivity (TS) of in-office bleaching with a 35% hydrogen peroxide (HP) in patients with aesthetic restorations. Methods: Hydrogen peroxide 35% was applied in two sessions, of three 15 min applications, in 15 patients with upper anterior sound teeth (S) and 15 with aesthetic restorations (R). The colour was recorded at baseline, one week and 6 months after treatment completion. Patients recorded TS on a 0-4 scale. The BE was evaluated by two-way ANOVA and Tukey's tests (α = 0.05). The percentage of patients with TS was evaluated by Fisher's exact test and TS intensity of treatments was compared with Mann-Whitney U-test (α = 0.05). Results: All participants experienced TS at least once during treatment. Higher TS intensity was observed in R (1.5 [1/1.75]) compared to S (0.5 [0/1.25]) during the bleaching (p < 0.05). S and R demonstrated similar tooth colour enhancement compared to baseline (p < 0.05) and both presented colour stability after 6 months of evaluation (p > 0.05). Conclusions: The in-office bleaching with 35% HP was effective in patients with aesthetic restorations, however, a higher intensity of TS was observed during the bleaching protocol. Clinical relevance: In-office dental bleaching can be performed in patients with adhesive restorations promoting satisfactory results; however, it can promote higher intensity of sensitivity compared to patients with sound teeth. [ABSTRACT FROM AUTHOR]

Abstract: Objective: This study is to evaluate the effect of laser activation on the whitening and crystalline structure of enamel surface during whitening treatment with hydrogen peroxide. Methods: Bovine teeth were treated with whitening gel containing 35% hydrogen peroxide. A whitening gel was applied on the enamel surface for a period of 5min, and then irradiated using a diode laser (740nm) during whitening treatment for 0, 30, 60, 120 and 180s for the GL0-W, GL30-W, GL60-W, GL120-W and GL180-W groups, respectively. The total whitening application time was 30min for all groups. Results: Laser-irradiated enamel groups showed a similar lightness compared to the GL0-W group. The thickness of porous layer observed on the enamel surface of GL0-W group was decreased by increasing the laser irradiation time. While the Ca and P contents of the GL0-W group were lower than those of the non-whitening treated group (GL0-C), the Ca and P contents of the GL180-W group were similar to those of the GL180-C group. The enamel crystallinity was dramatically decreased by whitening treatment without laser irradiation. However, the decrease of crystallinity was protected by laser irradiation during whitening treatment. Raman measurement verified that laser irradiation could prevent the loss of mineral compositions on enamel and maintain its crystalline structure. Significance: The professional whitening treatment with hydrogen peroxide and diode laser activation improves not only the whitening effect but also protects the change of enamel structure compared to the treatment with only gel. [Copyright &y& Elsevier]

Summary: Objectives: The aim of this study was to evaluate the separate contribution of enamel (E) and dentine (D) to the colour change of tooth which subjected to 10% carbamide peroxide (CP) gels using a novel recombined enamel–dentine (Recombined-ED) study model. Methods: 120 enamel–dentine (ED) samples (four homogeneous premolar ED from each patient; total=30×4 ED) were involved in the present study. Two homogeneous ED samples were bleached with 10% CP and the other two ones were stored in artificial saliva for one, two or four weeks. After treatment, four kinds of layers were prepared from each four homogeneous ED samples by removing enamel or dentine part: bleached-enamel (BE), bleached-dentine (BD), control-enamel (CE) and control-dentine (CD). Initial and final colour records of samples were taken with a spectrophotometer in CIELab system. The contribution of enamel/dentine to the colour change of tooth (CTCC) was calculated by measuring the colour difference ΔE between two different enamel–dentine combinations (ΔE between BE/BD and CE/BD for enamel; ΔE between BE/BD and BE/CD for dentine). Translucency parameter (TP) was obtained by calculating the colour difference between enamel on black and white backings. Results: ED and recombined-ED were significantly correlated in L * a * b * values both for unbleached samples and bleached samples. Bleaching resulted in a significant colour change (ΔE) of E, D and ED samples. The TP of BE was significantly lower than that of CE. The CTCC of enamel was significantly higher than that of dentine all through the time points. Conclusions: Enamel played a more important role than dentine in tooth bleaching due to the changes in translucency and colour. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: To investigate the effects of acidic and neutral 30% hydrogen peroxide (HP) on human tooth enamel in terms of chemical structure, mechanical property, surface morphology and tooth colour. Methods: Twenty-seven human dental blocks were obtained from premolars and randomly divided into three groups (n =9): Group acidic HP (30% HP, pH≈3.6), Group neutral HP (30% HP, pH≈7.0) and Group DW (distilled water, pH≈6.8). Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, atomic force microscopy (AFM) investigation, microhardness test and colour measurements were carried out before and after treatments. ATR-FTIR and Raman spectroscopy were analysed and then the carbonate:mineral ratio (C:M), Raman absolute intensity (RAI), Raman relative intensity (RRI), and laser-induced fluorescence intensity (FI) were obtained for evaluation. Results: The C:M, percentage microhardness and percentage RRI of group acidic HP decreased more significantly than those of group neutral HP (P =0.02, P =0.001, P <0.001, respectively) and group DW (P =0.01, P =0.008, P <0.001, respectively). Whilst group neutral HP and group DW had no statistical difference in above terms (P =0.818, P =0.528, P =0.158, respectively). Significant morphological alterations were observed in group acidic HP. Group acidic HP and neutral HP had no significant difference in percentage FI (P =0.652) and ΔE (P =0.906). Conclusions: This study suggested that neutral 30% HP had the same efficiency in tooth bleaching and it caused less deleterious effects on enamel than acidic 30% HP. [Copyright &y& Elsevier]

Abstract: Objectives: This study examined the effect of nano-carbonate apatite (n-CAP) to prevent re-staining and the change of enamel surface after dental bleaching in vitro. Methods: Twenty-four bovine specimens were bleached for 2 weeks with 10% carbamide peroxide (CP). After bleaching, the specimens were divided into the following four groups: distilled and deionized water (DDW, negative control), 10% n-CAP, NaF (positive control) and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP, positive control). Each group was subjected to pH cycling for 7 days. The specimens were treated for 4 min 3 times per day and re-staining was induced naturally by artificial saliva in the remineralization process. After pH cycling, the changes in colour were evaluated with spectrophotometry and scanning electron microscopy (SEM). The difference in colour between before and after pH cycling was evaluated using an ANOVA and Tukey test. Results: After pH cycling, the colour difference of n-CAP group was significantly lower than that of the DDW and CPP-ACP groups (p <0.05). SEM showed that n-CAP particles were deposited regularly on the damaged surface compared to the other groups. Conclusion: 10% n-CAP could significantly maintain the initial colour and protect the damaged enamel structure after bleaching. [Copyright &y& Elsevier]

Abstract: Objectives: A carious lesion is initiated through the subsurface demineralization of enamel, and presents clinically as a white spot, interfering with the aesthetics. This lesion should not receive restorative treatment because it is capable of remineralization. The aim of this study was to evaluate the performance of different treatments on masking white spot lesions by assessing the colour change. Methods: Artificial white spot lesions were produced in bovine enamel of 60 cylindrical-shaped samples. The samples were randomly divided into four groups: CON (control) – immersion in artificial saliva; DF – daily application of 0.05% fluoride solution; WF – weekly application of 2% fluoride gel; and IC – resin infiltration (Icon® – DMG). The assessment of colour was performed by a spectrophotometer in four distinct stages: baseline, after the production of artificial caries; after 4 weeks; after 8 weeks; and after a new acid challenge. The ΔL values were calculated at each stage in relation to the baseline colour. Results: The application of RM ANOVA revealed significant differences between the factors’ treatment and time (p =0.001). For the interaction between factors there were no significant differences (p =0.27). The Tukey''s test (p <0.05) was then applied and showed that the specimens treated with Icon® exhibited the lowest means, followed by Group DF, Group CON, and Group WF, in that order. Conclusion: Resin infiltration was proven to be an effective treatment for masking white spot lesions. Also, after a new acid challenge, the group infiltrated with low viscosity resin presented the lowest means of colour change. [Copyright &y& Elsevier]

Summary: Objectives: This double-blind randomized clinical trial aimed to evaluate the whitening effect of two at-home tooth bleaching agents and the effect of dietary habits after 2 years. The patients’ view about bleaching longevity was also investigated. Methods: Ninety-two subjects with mean shade of C1 or darker for the six maxillary anterior teeth were randomized into two groups (n =46) according to the carbamide peroxide (CP) concentration: 10% (CP10) or 16% (CP16). The treatment was performed using the whitening agent in a tray for 2h/day during 3 weeks. Shade evaluations were done with a shade guide and a spectrophotometer at baseline, 1-month, 6-month, 1-year and 2-year post-bleaching. Results: Eighty-one (88%) of the original 92 subjects enrolled in the study were recalled at 2-year follow-up and, the tooth shade remained significantly lighter than at baseline, in both treatment groups, considering the tooth shade median values (p <0.001) or the color parameters: L*a* (p <0.001) for CP10 and, L*b* for CP16 group (p <0.001). Subjects from CP10 and CP16 reported a consumption of beverage and food stains as high as at 6-month and 1-year recalls and, more than 66% of the participants from each group reported a tooth shade relapse from mild to moderate (p =0.6). Significance: At 2-year post-bleaching, tooth shade remained lighter than at baseline for both CP concentrations tested. Tooth shade relapse associated to increasing of a* and b* color parameters were observed for both groups when compared to the end of the treatment (CEP # 37/05). [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The aim of this study was to evaluate the effects of chemical activation of hydrogen peroxide (HP) gel on colour changes and penetration through the tooth structure. Methods: One hundred and four bovine incisors were used. One dentine (CD) disc and one enamel–dentine (ED) disc were prepared from each tooth. They were positioned over artificial pulpal chambers and the bleaching was performed with an experimental 35% HP gel. Two control and six experimental groups were prepared. In the positive control group (PC) no chemical activator was used. In the negative control group (NC) the specimens did not receive any bleaching. Each experimental group received a different chemical activator (manganese gluconate—MG; manganese chlorite—MC; ferrous sulphate—FS; ferrous chlorite—FC; and mulberries root extract—MRE). After the bleaching procedure a sample of solution was collected from the artificial pulpal chamber and the HP concentration was measured. The data were analysed using ANOVA, Tukey''s, and Dunnett''s tests. Results: The groups MG and FS showed a significantly lower penetration of HP than the PC group. For the parameter Delta E, all the groups, with the exception of the group MRE, showed a significantly higher means in relation to the PC group in ED colour. For dentine colour, just the groups MG and FS had significant differences in relation to PC. Conclusions: The addition of MG and FS decreases the penetration of HP. The chemical activation using metal salts tested was effective in increasing the bleaching effect. [Copyright &y& Elsevier]

Abstract: Objectives: Effective delivery of active agents to dental hard tissues is critical to product performance and pertinent to biofilm control, caries, erosion, hypersensitivity and tooth bleaching. The aim of this study was to investigate in vitro the bioadhesion and retention behaviour of non-aqueous delivery systems (NADS) based on glycerol, PEG 400, Carbopol 974P and triclosan. Methods: Tensile testing was employed to calculate the work of adhesion (WOA) and maximum force of detachment (F max) for formulations applied to hydroxyapatite (HA) and pellicle-coated HA surfaces (HAP). Formulation substantivity under conditions of dynamic flow was studied by monitoring the release of incorporated triclosan. The release data were fitted to a first-order model to generate a removal half-life (t 1/2). Results: Tensile testing showed a clear positive relationship between Carbopol concentration and bioadhesion. Increasing the PEG 400 concentration in formulations containing glycerol, 2% (w/w) Carbopol and 0.30% triclosan produced a local minimum for both WOA and F max at 10% (w/w). Values for WOA and F max decreased threefold in the presence of a salivary pellicle. Good correlations were obtained between (i) WOA and F max and (ii) WOA and t 1/2 and (iii) the elastic modulus of the formulations and t 1/2. Conclusion: The presence of a salivary pellicle markedly reduced the bioadhesive interaction between the NADS and the substrate. Increased Carbopol content appeared to be the dominant factor in promoting the WOA, elasticity and retention of NADS to HA surfaces. Such formulations might provide a suitable platform for developing systems suitable for promoting retention to hard surfaces within the oral cavity. [Copyright &y& Elsevier]

Abstract: Objectives: This literature review assessed how changing the metal substructure or ceramic substructure affected the colour of samples or restorations after they have been overlaid by veneering ceramic. Sources and study selection: Studies indexed in journals in MEDLINE were retrieved by searching with the terms “metal, ceramic, substructure, coping, colour and shade.” The articles were screened for further relevant investigations. The colour co-ordinates (L*a*b*) and information relating to the substructure and veneering ceramic were recorded or calculated from the relevant articles. Data: No clinical studies were identified. It was found that gold-backed samples were lighter and had different a* and b* values from those backed with base metal and silver–palladium. Colour differences were also found between different all-ceramic copings after the application of the veneering ceramic. However, no studies used the same protocol for all-ceramic and metal–ceramic specimens making comparisons impossible. Some of the colour differences observed would have been perceptible in a clinical setting. Conclusions: Altering the substructure of an extra-coronal restoration changed its colour. This potentially may lead to additional laboratory and clinical time to produce an aesthetic restoration. [Copyright &y& Elsevier]

Abstract: Objective: To evaluate the colour regression of bleached teeth in four experimental environments, and to explore the relationship between colour change and bulk miners loss. Materials and methods: Forty freshly extracted sound human incisors were in vitro treated using an in-office bleaching gel containing 38% hydroxide carbamide. The bleached teeth were subsequently divided into four groups and stored in four different environments: purified water, artificial saliva, a commercial remineralisation gel, and a desiccator. A spectrophotometer and a μ-CT were used to investigate the colour parameters (L*, a*, and b*) and the mineral content of the teeth pre- and post-bleaching. ANOVA and Tukey''s post hoc analysis were performed to investigate the effect of time on the colour coordinates. Paired t-tests were used to compare the mineral content changes. Linear regression test was performed to explore the relationship of the colour coordinates and mineral content change in the colour regression process. Results: Colour regression occurred in the mineral containing environment accompanying with the mineral content remarkable increase in the outer layers of teeth tissue (P <0.05). No colour regression and mineral content change were found in the anhydrous environment (P >0.05). The regression of lightness is significantly correlated with the density change of teeth hard-tissue (P <0.001, r =0.611). Conclusion: In this in-office bleaching system, the colour regression is mainly resulted by the reversal of lightness, and is correlated with the presence of the remineralisation processes within the teeth tissue. [Copyright &y& Elsevier]

Abstract: Objectives: The aim of this clinical study was to evaluate tooth color change after exposure to 25% hydrogen peroxide in-office tooth whitening system, with and without supplementary light exposure. Methods: Twenty subjects were treated with two separate 45-min exposures of bleach, with and without light using an opposing-arch design. Visual and instrumental color measurements were obtained from eighty teeth before bleaching and seven days after treatment using two different shade guides, Vitapan Classical (VC), Vita Bleachedguide 3D-Master (BG) and an intraoral spectrophotometer. Data were analyzed using ANOVA, paired t-test, and Wilcoxon signed rank tests at the 0.05 level of significance. Results: Instrumental method revealed significant difference in color between treatment with light and without light after seven days (p <0.05). No differences were visually detected between treatment with light and without light using the VC (p =0.56). However, a significant difference was recorded using the BG (p <0.01). Instrumental measurements of color change were in better accordance with visual findings using the BG guide (R 2 =0.60) rather than the VC (R 2 =0.20). Conclusions: Within the limitations of this study, the treatment with supplementary light showed significantly greater bleaching-dependent changes in color compared to treatment without light when assessed using instrumental methods. The same was determined for the visual method with Vita Bleachedguide 3D-Master. No significant difference in color change with respect to light exposure was detected for the Vitapan Classical. [Copyright &y& Elsevier]

Abstract: Objective: To study the effects of 6% H2O2 activated with LED light on surface enamel as compared to orange juice challenges in vitro. Methods: A total of 40 human enamel discs were incubated in saliva overnight to allow pellicle formation and then divided into three groups: 15 for whitening treatments, 15 for orange juice immersions and 10 for normal saline controls. Baseline microhardness was measured with a microhardness Knoop indenter (50g, 10s) and surface topography was evaluated with a focus-variation 3D scanning microscopy. Enamel discs were treated with H2O2 or orange juice for 20min each cycle for five cycles to simulate daily treatment with the products for 5 days. The discs were stored in saliva between treatment cycles. Microhardness and surface topography were evaluated again after treatments. Changes in microhardness and in surface area roughness (Sa), mean maximum peak-to-valley distance (Sz) and the developed surface area ratio (Sdr) were compared before and after treatments (t-test) and among groups (ANOVA). Results: Enamel surface hardness decreased by 84% after orange juice immersion but no statistically significant changes were observed in the whitening and control groups. Surface topography changed significantly only in the orange juice group as shown by increased Sa (1.2μm vs. 2.0μm), Sz (7.7μm vs. 10.2μm) and Sdr (2.8% vs. 6.0%). No such changes were observed in the whitening and control groups. Conclusion: In comparison to orange juice challenges, the effects of 6% H2O2 on surface enamel are insignificant. Orange juice erosion markedly decreased hardness and increased roughness of enamel. [Copyright &y& Elsevier]

Abstract: 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 Δb* was −1.6 (0.08), differing significantly from baseline (p <0.0001). After 2 weeks, the adjusted mean (S.E.) for Δb* was −2.3 (0.07), differing significantly from Week 1 (p <0.0001). The estimated correlation between Weeks 1 and 2 for Δb* was 0.74. Study-to-study variation contributed less than 2% of Δb* variability. Results were similar for ΔL*, 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. [Copyright &y& Elsevier]

Abstract: Objectives: The aim of this in vivo study was to evaluate the effects of a home-bleaching agent on the color and surface properties of four tooth-colored restorative materials. Methods: Two composite resins (a nano-hybrid and a packable), a polyacid-modified composite and a conventional glass-ionomer were tested. Specimens were inserted into custom-fabricated trays, and underwent a routine home-bleaching treatment. CIE Lab* color coordinates of the specimens were obtained using a spectrophotometer. Ultra-structural effects were investigated by SEM and ATR–FTIR. The color data were analyzed with ANOVA and Tukey''s post hoc analysis. Results: Significant color changes were found among all the materials after bleaching. However, the color differences decreased and fell into the clinically acceptable range (except for the compomer) after withdrawal of the bleaching treatment. Surface dissolution was detected in the polyacid-modified composite and glass-ionomer cement. ATR–FTIR analyses found chemical composition alterations in the polyacid-modified composite. Significance: A 15% carbamide peroxide home-bleaching gel did not cause color changes in the composites and glass-ionomer cement. However, significant color and chemical composition alterations were found in the polyacid-modified composite. [Copyright &y& Elsevier]

Abstract: Objectives: The purpose of this study was to evaluate the nanohardness and elastic modulus of human enamel after treatment with tray and strip bleaching systems. Methods: Fifty-five human enamel samples were exposed to five different bleaching agents. Nanoindentations were made before and after bleaching treatments following the manufacturer''s directions using a Nanoindenter XP (MTS Systems Corporation, Oak Ridge, TN, USA). Nanohardness and elastic modulus measurements were obtained and the results were statistically analyzed using a repeated measures analysis of variance with a post-hoc Tukey–Kramer multiple comparison test. Results: Nanohardness and elastic modulus measurements showed decrease of mean values for each group except the control which remained the same. There were significant differences due to time (before and after treatment) and material effects in nanohardness (P <0.0001) and elastic modulus (P =0.0241). Measurements after treatment showed significant decrease in nanohardness between all groups and the control group. There was a significant difference in hardness between CP and TO after treatment. Additionally, there were significant differences in elastic modulus between the control group when compared to OB and TO after treatment. While there were significant changes in the elastic modulus due to treatment for both CP and TO, there were no significant differences between any of the groups after treatment. Conclusions: Nanohardness and elastic modulus of human enamel were significantly decreased after the application of home-bleaching systems. [Copyright &y& Elsevier]

Abstract: Objectives: This study evaluated possible differences regarding the remineralization of predemineralized enamel after exposure to fluoridated or non-fluoridated bleaching gels. Methods: 120 enamel specimens were prepared from sixty bovine incisors; before and after demineralization (37°C; pH 4.95; 10d), one-quarter of each specimen''s surface was covered with nail varnish (control sound/demineralized). Subsequently, the specimens were stored for 16h daily in a remineralizing solution (pH 7.0; 14d), while for the remaining time (8h) various bleaching gels were applied: (1) no treatment (control), (2) Opalescence regular (O, Ultradent), (3) Opalescence PF (O-PF), (4) Nite White ACP (NW-ACP, Discus Dental) and (5) Nite White ACPF (NW-ACPF). Following, half of the bleached parts were nail-varnished and stored for another 3-weeks period in a remineralizing solution. Differences in mineral losses (ΔΔZ) and lesion depths (ΔLD) before and after treatment/remineralization period were evaluated from microradiographs. ΔΔZ surface values (mineral loss of the outer 18μm of the lesion) were calculated. Results: After 2 and 5 weeks ΔΔZ/ΔLD values of the bleaching groups did not differ significantly from the controls. Treatment with NW-ACPF for 2 weeks resulted in significantly lower ΔΔZ values compared to NW-ACP (p =0.032) and NW-ACPF in higher values than Opalescence regular (p =0.006). Two weeks treatment with O and O-PF resulted in decreased ΔΔZ surface values compared to control (p <0.0005), whereas with NW-ACPF no significant differences could be observed (p =0.062). Application of NW-ACP induced significantly increased ΔΔZ surface values compared to control (p =0.001). Conclusions: No supporting influence of fluoride-containing bleaching gels on remineralization could be observed. [Copyright &y& Elsevier]

Abstract: Objectives: To evaluate the effect of combination of hydroxyapatite (HA) and hydrogen peroxide (HP) on color, microhardness and morphology of human tooth enamel. Methods: Forty-eight human dental blocks were obtained from 12 pairs of premolars and were randomly divided into four groups. Group DW was treated with distilled water, group HP with 30% HP, group HA+DW with HA mixed with distilled water and group HA+HP with HA mixed with 30% HP. Baseline and final color measurements and microhardness test were carried out before and after bleaching experiments. Two specimens from each group were selected for morphological investigation after final tests. Results: The ΔE of group HP and HA+HP were significantly higher than those of group DW (p =0.000 and p =0.000) and group HA+DW (p =0.000 and p =0.000). The percentage microhardness loss of group HA+HP was significantly lower than that of group HP (p =0.047), but significantly higher than those of group DW (p =0.000) and group HA+DW (p =0.000). The obvious variation of morphology was only observed on enamel surfaces in group HP. Conclusions: This study suggested that combination of HA and HP was effective in tooth whitening. HA could significantly reduce the microhardness loss of enamel caused by 30% HP and keep enamel surface morphology almost unchanged. [Copyright &y& Elsevier]

Abstract: Objectives: This double blind randomized clinical trial evaluated the longevity of the whitening effect (6-month follow-up) of two carbamide peroxide concentrations used in at-home vital bleaching. Methods: Ninety-two volunteers with shade mean C1 or darker for the six maxillary anterior teeth were randomized into two balanced groups (n =46) according to bleaching agent concentration: 10% (CP10) or 16% (CP16) carbamide peroxide. Patients were instructed to use the whitening agent in a tray for 2h/day during 3 weeks. Shade evaluations were done with a value-oriented shade guide, and a spectrophotometer at baseline, and at 1-week and 6-month post-bleaching. Volunteers for both treatment groups had to answer questions related to dietary and oral hygiene behavior. Results: At 6-month recall, tooth shade remained significantly lighter than at baseline, in both treatment groups, considering the color parameters: ΔL*, Δa*, Δb*, ΔE* (p <0.0001) or the tooth shade median values (p <0.001). Additionally, shade median relapse at 6-month follow-up was not statistically different between CP10 and CP16 groups using the spectrophotometer (p =0.1) or the visual matching (p =0.7) analyses. Overall, subjects from CP10 and CP16 reported high consumption of beverage and food stains, which was not different between groups (p =0.5). Conclusions: The whitening effect remained similar 6-month after the bleaching treatment for both carbamide peroxide concentrations tested. Additionally, the high consumption of staining beverages and foods reported by patients had no influence in the whitening effect longevity at 6-month. [Copyright &y& Elsevier]

Abstract: Objectives: The aim of this study was to assess the fracture resistance of endodontically treated teeth submitted to bleaching with 38% hydrogen peroxide activated by light-emitting diode (LED)-laser system. Methods: Fifty maxillary incisors were endodontically treated, received a zinc phosphate barrier and were embedded in acrylic resin until cemento-enamel junction. The specimens were distributed into five groups (n =10) according to the number of bleaching sessions: GI, no treatment (control); GII, one session; GIII, two sessions; GIV, three sessions and GV, four sessions. The whitening gel was applied to the buccal surface of the tooth and inside the pulp chamber for three times in each session, followed by LED-laser activation. Specimens were submitted to the fracture resistance test (kN) and data were submitted to the Tukey–Kramer multiple comparisons test. Results: No significant difference (p >0.05) was found between GI (0.71±0.30) and GII (0.65±0.13), which presented the highest strength values to fracture. Groups III (0.35±0.17), IV (0.23±0.13) and V (0.38±0.15) showed lower resistance to fracture (p <0.01) when compared to GI and GII. Conclusions: The fracture resistance of endodontically treated teeth decreased after two sessions of bleaching with 38% hydrogen peroxide activated by LED-laser system. [Copyright &y& Elsevier]

Abstract: Purpose: The aim of this study was to comparatively investigate the effect of antioxidant treatment and delayed bonding after bleaching with carbamide peroxide on the shear bond strength (SBS) of a luting resin to enamel. Materials and methods: Forty flat enamel surfaces were prepared from freshly extracted human molars using a low speed diamond saw, then divided into three bleaching groups (n =10/group) and a control group (n =10). Group 1 consisted of specimens bonded immediately after bleaching. Group 2 specimens were treated with an antioxidant agent, 10% sodium ascorbate, while Group 3 specimens were immersed in artificial saliva for 1 week after bleaching. Specimens in Group 4 were not bleached, but immersed in artificial saliva for 1 week before bonding. Forty ceramic blocks (Empress 2, Ivoclar) were prepared and luted to teeth using a dual-curing resin cement (Variolink II, Ivoclar). The specimens were thermocycled and the SBS tests were performed using a universal testing machine (crosshead speed: 0.5mm/min). Fracture analysis of the bonded surfaces was done using a scanning electron microscope. Statistical analysis was carried out by Kruskall–Wallis and Mann–Whitney U-tests. Results: While the samples that were immediately bonded after bleaching (Group I) demonstrated significantly lower shear bond strengths and 10% sodium ascorbate group (Group II) demonstrated significantly higher bond strengths than control group samples (p <0.05), no significant differences were found among delayed bonded group and control group (p >0.05). Conclusion: Using sodium ascorbate with a concentration of 10% may be reliable for reversing the compromised bond strength. [Copyright &y& Elsevier]

Abstract: Objective: Carbamide peroxide and hydrogen peroxide have been used as tooth whitening agents. The aim of this paper was to determine the efficiency of several enzyme-containing whitening systems. A method to determine the rate of ‘in vitro’ tetracycline whitening was also developed. Methods: We determined the tetracycline whitening ability of carbamide peroxide and hydrogen peroxide, and the influence of peroxidase and lactoperoxidase on this tetracycline whitening rate. Results: High peroxidase and lactoperoxidase concentrations increased the rate of tetracycline decoloration obtained with carbamide peroxide or hydrogen peroxide. The decoloration rate observed was lower when the glucose/glucose oxidase system was used to generate hydrogen peroxide ‘in situ’. The presence of peroxidase increased the decoloration rate of extracted teeth obtained with carbamide. Conclusions: Enzymes such as peroxidase could be used as whitening catalysts to increase the rate of tetracycline decoloration. [Copyright &y& Elsevier]

Abstract: Objective: To assess the safety and tolerability of 6% hydrogen peroxide whitening strips over 12 months. Methods: 80 adults were randomly assigned equally to one of two treatments: 6% hydrogen peroxide strips or placebo strips. Strips were worn 5min daily for 12 months. Safety and tolerability were assessed via oral status interviews and oral examinations at baseline and after 1, 2, 3, 6, 9, and 12 months of use. Results: Tooth sensitivity and oral irritation were the two most common adverse events. After 12 months use, tooth sensitivity was reported by 10% of subjects in the 6% strip group with a 95% confidence interval (CI) of (2.8%, 23.7%) and 5% of subjects in the placebo group with a 95% CI of (0.6%, 16.9%). The occurrence of reported oral irritation was 0% in the 6% strip group with a 95% CI of (0%, 8.8%) and 2.5% in the placebo strip group with a 95% CI of (0.1%, 13.2%). The occurrence of observed oral irritation was also similar between groups. The groups did not differ significantly (p >0.67) for the percent of subjects with each type of adverse event. In the 6% strip group, two subjects discontinued product use due to an adverse event (tooth sensitivity) compared to no subjects in the placebo group. Groups did not differ significantly (p >0.49) with respect to this outcome. Conclusion: Use of 6% hydrogen peroxide whitening strips over 12 months resulted in a safety profile similar to that seen with placebo strips. [Copyright &y& Elsevier]

Abstract: Objectives: To evaluate the effects of fluoridated bleaching agents and post-bleaching fluoridation treatment on the whitening efficiency and microhardness of bovine enamel. Methods: Twenty five freshly extracted bovine incisors were cut into halves, embedded and then divided into the following five groups: Group 1, untreated controls; Group 2, treatment with 10% carbamide peroxide (CP) bleaching agent; Group 3, treatment with 10% CP followed by a 0.9% sodium fluoride gel application, Group 4, treatment with 10% CP containing 0.11% fluoride; Group 5, treatment with an experimental bleaching agent consisting of 10% CP and 0.37% fluoride. Groups 2–5 were treated 8h per day for 14 days then immersed in saliva for 2 weeks. Enamel morphology changes were evaluated under SEM on Day 14. Changes in enamel color and microhardness were evaluated on Days 7 and 14, and compared with the baseline data. Additionally, microhardness was determined on post-bleaching Days 21 and 28. Results: After 2 weeks, an erosion pattern was noted on the specimens in Groups 2 and 3. Groups 4 and 5 showed a milder demineralized pattern. All the bleached enamel specimens revealed increased whiteness and overall color value. Groups 2 and 3 showed significantly decreased enamel microhardness compared to their baseline data. The specimens treated with fluoridated bleaching agents showed relatively less reduction in enamel microhardness than those treated with nonfluoridated agents during the bleaching treatment. Conclusions: The fluoridated bleaching agents produced less demineralization of surface morphology and microhardness. The addition of fluoride did not impede the whitening effect. [Copyright &y& Elsevier]

Abstract: Objective: To investigate whether bleaching prior to placement of a composite veneer had an effect on the final shade of the restoration and whether this was affected by the thickness or shade of the veneer. Methods: Twenty bovine teeth were collected, sectioned and divided into two groups. One group was the non-bleached control, while the other was the bleached group. A colour reading was recorded using a spectrophotometer. The bleached group then underwent external bleaching with 38% hydrogen peroxide and a colour reading was recorded. Each of these two groups were further sub-divided into four subgroups, on which composite veneers were placed. These subgroups were: 0.5mm thick A1, 1mm thick A1, 0.5mm thick A4 and 1mm thick A4 composite veneers. Colour readings were recorded after veneer placement. Statistical significance was assessed using analysis of variance. Results: There was a difference between the colour produced for the same veneer properties, between the bleached and non-bleached groups. For a thin (0.5mm) A4 veneer bleaching produced a statistically significant difference in the amount of colour change (ΔE) compared to veneering alone. For A1, non-bleached group there is a significant difference in the ΔE produced by altering the thickness of the veneer. Conclusion: Within the limitations of this study, we can conclude that bleaching prior to placement of a thin A4 dark veneer produces a significant difference in colour change. If no bleaching is performed, altering the thickness of an A1 veneer produces a significant colour difference ΔE. However, if bleaching is carried out there is no significant difference. [Copyright &y& Elsevier]

Abstract: Objectives: The purpose of this study was to evaluate the effects of a home bleaching gel containing 15% carbamide peroxide on the surface microhardness of four tooth-colored restorative materials in situ. Methods: Four types of tooth-colored restorative materials, including a nanocomposite resin (Filtek Z350), a packable composite resin (Filtek P60), a polyacid-modified composite (Dyract AP), and a glass-ionomer cement (Ketac Molar Easymix), were used in this study. Each material was divided into two groups equally (n =18): bleaching group and control group. Thirty-six Chinese volunteers were recruited and stone casts were constructed for their upper jaws. Two of the four types of restorative materials were randomly selected and mounted on the first or second molar of the cast for each subject. With respect to each material selected, two specimens from each group were put at a random side. Then custom-fabricated trays containing specimens were fabricated. The participants wore the tray in the daytime, and applied the bleaching gel for the side containing specimens of bleaching group during the night. Surface microhardness measurements were obtained on the top surface of each sample on the different time periods. Results: There was a statistically significant increase in the surface microhardness of Ketac Molar Easymix due to the exposure to 15% carbamide peroxide, while it produced a significant decrease for Dyract AP. Following immersing in saliva without bleaching agent, Ketac Molar Easymix showed a significant increase in surface microhardness. Conclusions: The effects of 15% carbamide peroxide on surface microhardness were material dependent. Immersing in saliva produced a surface hardening effect of glass-ionomer cement. [Copyright &y& Elsevier]

Abstract: Objectives: To investigate the stain removal ability, abrasivity towards enamel and dentine, and fluoride efficacy of a new silica based blue covarine whitening toothpaste in vitro. Methods: Stain removal was assessed by brushing artificially stained bovine specimens with slurries of either the new toothpaste or one of two whitening products or a non-whitening silica product. Toothpaste abrasivity was assessed by brushing enamel/dentine specimens with slurries of either the new toothpaste, a whitening toothpaste or a non-whitening toothpaste and measuring the wear via a combination of changes in geometry of Knoop indents and surface profilometry. Fluoride efficacy was assessed using remineralisation, demineralisation and fluoride-uptake methods. Results: The in vitro cleaning study showed that the silica based blue covarine whitening toothpaste removed significantly (p <0.05) more stain than the non-whitening toothpaste and was as effective as the two marketed silica based whitening toothpastes. This enhanced tooth whitening benefit did not give rise to a concomitant statistically significant increase in the level of wear to enamel and dentine compared to the non-whitening silica based toothpaste. The fluoride efficacy was superior to a non-fluoridated control and was as effective as a clinically tested formulation containing the same fluoride source. Conclusions: The studies show that the new whitening toothpaste is effective in extrinsic stain removal, does not have an undue degree of abrasivity to enamel or dentine compared to other relevant commercially available products, and is an efficacious source of fluoride. [Copyright &y& Elsevier]

Abstract: Objective: To investigate a new optical approach to tooth whitening by enhancing the measurement and perception of tooth whiteness using blue coloured materials deposited onto the tooth surface. Methods: Salivary pellicle coated human extracted teeth or polished enamel specimens were used as substrates and their colour was measured using a colorimeter in the CIELAB mode. Whole teeth were treated with a range of blue dyes and pigments and the colour measured following rinsing with water. Whole teeth were treated with Blue Covarine for 30s, rinsed with water and colour changes assessed via colorimetric and visual assessment with a Vita Shade guide under controlled lighting (D65). Deposition of Blue Covarine onto cut enamel specimens was investigated using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Tooth colour changes were also investigated following brushing for 1min with toothpaste formulations containing Blue Covarine. Results: Blue Covarine gave a significantly greater Δb* shift (p <0.0001) compared to water. Blue Covarine gave a mean Vita Shade change of 1.18 compared to the water control (−0.03) (p <0.0001) and an increase in objectively measured whiteness index (WIO) (p <0.0001). Blue Covarine was chemically detected on enamel surfaces using TOF-SIMS. Toothpaste formulations containing Blue Covarine gave improvements in tooth whiteness. Conclusions: Blue Covarine has been identified as a new approach to tooth whitening. Its mode of action involves deposition and retention on tooth surfaces where it alters the optical properties of the tooth. This gives rise to an increase in the overall measurement and perception of tooth whiteness. [Copyright &y& Elsevier]