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The emergence of toothpastes containing different abrasive and whitening substances has been a constant concern among dental professionals. The aim of the present study was to perform an in vitro assessment of the surface topography of nanoparticle composite resins subjected to simulated brushing with dentifrices. Test samples were prepared with Filtek Universal (3M ESPE), Filtek Bulkfill (3M ESPE) and Z350 (3M ESPE), with 24 samples per resin. A testing machine was used to simulate brushing with the dentifrices Colgate Total 12, Oral B 100% and Oral B Gengiva Detox Gentle Whitening (8 samples per group). The constant speed of the machine was 250 cycles per minute, and 20.000 cycles were carried out, which corresponds to 24 months (1 hour and 20 minutes). Roughness features and qualitative surface topography were investigated. Statistical analysis involved the Kruskal-Wallis, Wilcoxon and Mann-Whitney tests. A significant increase in surface roughness was found for all the resins (p < 0.05). However, no significant difference was found among the resins in terms of final roughness values (p = 0.690). In contrast, a significant difference among dentifrices was found with respect to roughness measurements (p < 0.001). The qualitative analysis revealed an increase in surface roughness in all the samples and differences in the abrasive potential of the dentifrices. In conclusion, brushing with dentifrices increases the surface roughness parameters of composite resin restorations. Moreover, the differences in the abrasive effects of the dentifrices indicate a need for further studies to establish efficacy and safety criteria.

Objectives: This study aimed to determine whether incorporating nanostructured additives into bleaching agents enhances efficacy and reduces side effects while identifying gaps for further investigation., Methods: A comprehensive search was conducted in electronic databases, including PubMed/Medline, Embase, Scopus, and ISI Web of Science. Two reviewers independently screened articles based on predefined criteria, resolving discrepancies through discussion or consultation with a third reviewer. Data extraction focused on key details, including study design, interventions, and outcomes., Results: Twenty-one articles were reviewed, consisting of nine clinical studies, one in vivo/in situ study, and 11 in vitro studies on tooth bleaching protocols. Hydrogen peroxide was the most commonly used bleaching agent. The primary nanostructured additives studied were titanium dioxide nanoparticles, polymeric carbamide peroxide nanoparticles, chitosan nanoparticles, nano-hydroxyapatite, SiO2/MgO/Fe2O3 nanocomposite spheres, and nano-bioactive glass. Most studies demonstrated an enhanced bleaching effect, reduced bleaching sensitivity, decreased cytotoxicity, reduced hydrogen peroxide penetration into the pulp chamber, and protection of the tooth surface against mineral and structural loss when nanostructured additives were incorporated into the bleaching agent., Conclusions: Incorporating nanostructured additives into tooth-bleaching agents improved efficacy and reduced side effects, especially with titanium oxide nanoparticles. Further clinical studies and systematic reviews are needed to establish strong evidence for safe clinical practice., Clinical Relevance: Including nanostructured additives in bleaching agents, such as titanium oxide nanoparticles, might be a valuable approach to enhancing the bleaching potential while reducing bleaching sensitivity and cytotoxicity, offering safer alternatives for clinical protocols., Competing Interests: Declarations. Ethical approval: Not applicable. Informed consent: Not applicable. Competing interests: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Home bleaching is a promising option for addressing discolored teeth conservatively. However, its impact on the physical and mechanical properties of indirect restorations remains unknown. This study provides comparative insights into the material responses to aesthetic treatments by assessing the effects of home bleaching agents on two hybrid ceramics: VITA ENAMIC ® and Grandio Blocs. The focus is on evaluating color stability and biaxial flexural strength., Methods: 60 discs (12 × 1 mm) were prepared from hybrid ceramics. Specimens were divided into two groups according to type of hybrid ceramic (30 specimens in each group); group A: VITA ENAMIC ® , group B: Grandio Blocs. Each group was further subdivided into 3 subgroups according to the concentration of home bleaching agents used (10 specimens in each subgroup); subgroup C: unbleached control group, subgroup C10%: carbamide peroxide 10% bleaching agent, and subgroup C35%: carbamide peroxide 35% bleaching agent. Samples of subgroup C10% were bleached with Home Bleaching Opalescence PF (10%) for 8 h per day for 14 days, as directed by the manufacturer. Samples of subgroup C35% were bleached using WHITEsmile Carbamide Peroxide (35%), following the manufacturer's directions for 30 min every day for 14 days. Color change (ΔE) was assessed using of the CIE L*a*b* system. Then, the biaxial flexural strength test was done. The data were analyzed using two-way ANOVA tests and Weibull analysis., Results: VITA ENAMIC samples exhibited significantly higher color change than Grandio Blocs (p < 0.001), while Grandio Blocs showed significantly higher biaxial flexural strength (p < 0.001). The concentration of the bleaching agent had no significant effect on color change (p = 0.086). However, regardless of its concentration, bleaching significantly reduced biaxial flexural strength in both materials (p < 0.001). Weibull analysis showed that Grandio Blocs had higher characteristic strength, while VITA ENAMIC demonstrated more reliable failure behavior., Conclusions: Compared to Grandio Blocs, VITA ENAMIC ® exhibited a greater color change with both 10% and 35% carbamide peroxide home bleaching agents. Additionally, both concentrations of carbamide peroxide reduced the biaxial flexural strength of hybrid ceramics. These findings can guide clinicians in selecting hybrid ceramics based on clinical demands for aesthetics and durability. VITA ENAMIC ® offers greater structural reliability and predictability for aesthetic restorations, while Grandio Blocs provide superior durability and stress resistance for high-stress clinical applications., Competing Interests: Declarations. Ethics approval and consent to participate: Ethics committee approval: FDAsu-RecEMo22311 (Research ethics committee of Faculty of Dentistry Ain Shams University) was obtained. Consent of publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Objective: To assess the color stability and surface roughness of bioactive resin-based composite following exposure to coffee staining and brushing with whitening toothpastes., Methods: Disk-shaped specimens of Filtek Z250 (FZ), Beautifil Flow Plus (BFP), Activa Presto (AP), and Fuji II LC (FII) were stained with coffee and then brushed with one of three toothpastes, conventional (C-TP), non-peroxide whitening (W-TP) or hydrogen peroxide-containing whitening toothpaste (HPW-TP) for 10 000 cycles. Changes in color (ΔE 00 ) and surface roughness were measured., Results: Two-way ANOVA revealed a significant interaction between restorative material and toothpaste type in roughness (p = 0.049) and ΔE 00 (p = 0.007). FII consistently had the highest surface roughness change across all toothpastes, and AP showed significantly higher value than BFP and FZ with C-TP and W-TP (p < 0.001). For color change, FII displayed significantly higher ΔE 00 between baseline and staining, as well as between staining and post-brushing with every toothpaste (p < 0.001). All materials had clinically unacceptable ΔE 00 ranging from 4.82 ± 1.72 to 11.15 ± 1.44 post-brushing compared to baseline with every toothpaste, with the lowest value observed in Fll with W-TP (p < 0.001). For individual color parameters (ΔL, Δa, Δb), AP exhibited significantly greater ΔL changes between baseline and post-brushing compared to FZ, BFP, and FII (p < 0.001). No significant differences were observed for Δa or Δb across materials at any measurement stage (p > 0.05). Additionally, the effect of toothpaste type on individual parameters, as well as the interaction between material and toothpaste type, was nonsignificant (p > 0.05)., Conclusion: All materials tested showed increased roughness and unacceptable staining with none returning to baseline color or achieving acceptable color change post toothbrushing, irrespective of toothpaste type., Clinical Significance: Understanding the effects of staining and whitening toothpastes on bioactive resin-based composites is important for optimizing material selection and maintenance protocols to ensure long-lasting esthetic outcomes in patients prone to staining., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background: The aim of this study was to investigate the effects of different types of bleaching methods and repolishing on the whiteness index and staining susceptibility of additive and subtractive production resin-based materials and direct composite resins., Methods: In this study, a total of 96 samples (8*8*2m) were prepared using a nanohybrid composite resin (Neo Spectra TM -ST (NS)), a subtractive-manufactured nanoceramic resin (Cerasmart TM 270 (CS)), and an additive-manufactured permanent resin (Saremco print Crowntec (CT)). The samples were randomly divided into four treatment groups: control (distilled water, 14 days), in-office bleaching (Opalescence Boost-40% HP, 3*20min), at-home bleaching (Opalescence PF-16% CP, 6 h, 14 days), and toothpaste group (Opalescence Whitening, 2*5min, 14 days) (n:8). After each the bleaching procedure was completed, the samples were kept in coffee solution for 7 days. Following, all samples were repolished. The color of the samples was measured with a spectrophotometer at baseline (T 0 ), after bleaching (T 1 ), after staining in coffee (T 2 ) and after repolishing (T 3 ). The whiteness index change (∆W ID , T 1 -T 0 ), staining susceptibility (∆E 1 , T 2 -T 1 ) and color change after repolishing (∆E 2 , T 3 -T 1 ) of the samples were calculated in the CIE (Commission International De I'Eclairage) system. The data were analyzed by SPSS software One-Way ANOVA, post-hoc Tukey, post-hoc Tamhane's-T2 and Paired-samples T test (α = 0.05)., Results: The ∆W ID of all tested materials was significantly different in the in-office bleaching group compared to the control group (p < 0.05). Among the bleaching groups, the highest ∆W ID was obtained in-office bleaching group of CT (2.91 ± 4.12). Staining susceptibility after bleaching (∆E 1 ) was higher in the in-office and at-home bleaching groups compared to the control group in all tested materials. However, the difference between the treatment groups was statistically significant in NS and CS (p < 0.05). The highest ∆E 1 was obtained in the in-office group of CT (7.36 ± 4.82). Color changes after repolishing (∆E 2 ) of the tested materials were less in all groups compared to ∆E 1 ., Conclusion: In-office and at-home bleaching can increase the whiteness index change and stain susceptibility of materials. Among the tested materials, the color stability of additive-manufactured CT was comparatively poorer. The repolishing was found to be beneficial in reducing staining., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Objective: To evaluate a prior application of an experimental desensitizer containing a hydroxyapatite-capsaicin composite (HAp-CAP) in different concentrations on hydrogen peroxide (HP) diffusion into the pulp chamber, bleaching efficacy (BE) and on physical and chemical alterations of the enamel surface after in-office bleaching., Materials and Methods: Forty sound premolars were randomized in five groups according to each experimental condition (n = 8): no bleaching (negative control), only bleaching (positive control), 0.1%, 1% and 5% of HAp-CAP. Four groups were submitted to in-office bleaching (HP 35%) post-desensitizer application. The HP concentration (µg/mL) on the pulp chamber was measured by UV-Vis spectrophotometer. The BE was measured by digital spectrophotometer (ΔE ab , ΔE 00 and ΔWI D ) before and after 7 days bleaching. Enamel tooth fragments obtained from twenty molars were submitted to the same experimental conditions and analyzed using FE-SEM and EDS, Vickers microhardness (VHN), Raman spectroscopy, and nanoroughness (Ra) by AFM to evaluate morphologic and chemical changes on enamel surface. All data were submitted to statistical analysis (α = 0.05)., Results: The groups treated with HAp-CAP exhibited a lower concentration of HP in the pulp chamber compared to only bleaching group (p < 0.05). There were no significant differences observed in BE between HAp-CAP groups and only bleaching group (p > 0.05). Only HAp-CAP 5% showed no significant differences in VHN values when compared to no bleaching group (p > 0.05). There were no significant differences among any group in Ra values (p > 0.05). The groups submitted to HAp-CAP showed a higher mineral concentration when compared to only bleaching group (p < 0.05)., Conclusion: Desensitizers containing HAp-CAP up to 5% effectively reduce HP diffusion into the pulp chamber after in-office bleaching, without interfering to BE and Ra, as well as prevent enamel demineralization., Clinical Relevance: The use of desensitizers containing HAp-CAP during in-office bleaching treatments offers a promising approach to reduce the risk of pulp irritation caused by hydrogen peroxide diffusion, without compromising the bleaching effectiveness or causing surface roughness., Competing Interests: Declarations. Ethical approval: This study was approved by the State University of Ponta Grossa (PR/ Brazil) ethics committee (protocol number 6.051.483). Informed consent: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: To evaluate in vitro the effects of nano-sized sodium trimetaphosphate (TMPnano) and sodium fluoride (F) added to a 17.5 % hydrogen peroxide (H 2 O 2 ) bleaching gel on the color change, enamel mechanical and morphological properties, and H 2 O 2 transamelodentinal diffusion., Materials and Methods: Bovine enamel/dentin discs (n = 180) were divided according to the bleaching gel: 17.5 % H 2 O 2 (17.5 % HP); 17.5 % H 2 O 2 + 0.1 % F (HP/F); 17.5 % H 2 O 2 + 1 % TMPnano (HP/TMPnano); 17.5 % H 2 O 2 + 0.1 % F + 1 % TMPnano (HP/F/TMPnano) and 35 % H 2 O 2 (35 % HP). The gels were applied for 40 min on three sessions, each session spaced 7 days apart. The total color change (ΔE* ab ) according to the Commission Internationale de l'Eclairage (CIE) L*a*b* color change measured by CIEDE2000 (ΔE 00 ), whitening index (ΔWI D ), surface hardness (SH), surface roughness (Ra), cross-sectional hardness (ΔKHN), and transamelodentinal diffusion were assessed. Enamel surfaces were examined using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDS) analysis. The data were analyzed using ANOVA, followed by the Student-Newman-Keuls test (p < 0.05)., Results: ΔE* ab , ΔE 00 , and ΔWI D values were comparable among the gels that produced a bleaching effect post-treatment (p < 0.001). The HP/F/TMPnano group exhibited lower mineral loss (SH and ΔKHN), Ra, and H 2 O 2 diffusion compared to the 17.5 % HP and 35 % HP groups, which had the highest values (p < 0.001). SEM/EDS analysis revealed surface changes in all bleached groups, though these changes were less pronounced with F/TMPnano., Conclusions: The 17.5 % HP gel containing F/TMPnano maintains the bleaching effect while reducing enamel demineralization, roughness, H 2 O 2 diffusion, and enamel morphological changes., Clinical Relevance: Low-Concentration H 2 O 2 bleaching gel containing F/TMPnano can be used as a novel approach to enhance safety and maintain the performance of aesthetic effects., 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; except for the last author, who holds a patent for a product used in the study, issued on November 5, 2019, under BR 102013006761-0., (Copyright © 2024. Published by Elsevier Ltd.)

Objectives: This study aimed to evaluate the effect of whitening toothpastes on the surface roughness and colour change of CAD-CAM materials., Materials and Methods: A total of 96 samples (2 × 10 × 12 mm 3 ) were prepared from Cerasmart (CS) and Celtra Duo blocks. Celtra Duo samples were divided into two groups. One group was fired with glaze paste (CDG) and the other was not treated (CD). All groups were then divided into 4 subgroups (n = 8). The groups were brushed with conventional (Colgate™ Max Fresh), silica (Opalescence™), charcoal (Curaprox™ Black in White) and blue covarine (Signal™ White Now) toothpastes for 30,000 brushing cycles. The initial and final surface roughness values were measured with contact profilometer and a dental spectrophotometer used for obtaining colour values. One sample from each brushed group was analyzed using a scanning electron microscope. Data was analyzed with Kruskal-Wallis and Mann-Whitney tests (p = 0.05)., Results: The surface roughness of CS samples brushed with Opalescence™ and Curaprox™ was significantly higher than CD and CDG. Surface roughness change values of CS samples brushed with Curaprox™ were significantly higher than the CD and CDG. Curaprox™ brushed samples showed significant difference in colour change values for all materials., Conclusions: Brushing increases the surface roughness of CAD-CAM ceramic materials. The roughness of resin-based materials is higher than zirconia-reinforced lithium silicates. Silica-contained toothpastes may cause discoloration of nanoceramic and zirconia-reinforced glass ceramic restorations., Clinical Relevance: It should be clinically considered that whitening toothpastes may cause roughness in ceramic materials and change the desired color., (© 2024. The Author(s).)

Introduction: There is a critical need to address concerns surrounding the potential impact of bleaching gels specifically on the tooth substrate. Therefore, this laboratory investigation aimed to assess the impact of a hydrogen peroxide (HP)-free bleaching (HiSmile TM ) in comparison to an HP-based bleaching (Opalescence Regular TM ) on the surface and mechanical characteristics of tooth substrate., Methods: Sixty sound human premolar teeth were sectioned to produce dentin fragments and divided into two primary groups based on the bleaching agent used. Each group was subdivided into three subgroups (n = 10) per distinct bleaching regimens: (T 1 ) fragments underwent a 7-day immersion in distilled water at 37°C without any bleaching treatment, (T 2 ) fragments underwent a 7-day immersion in distilled water at 37°C, with the application of bleaching gel occurring on the seventh day for 10 minutes, and (T 3 ) fragments underwent a bleaching regimen for seven consecutive days, each session lasting for 10 minutes. The initial and final evaluations of surface roughness, nano-hardness, and elastic modulus were performed. Following the bleaching regimens of T 3 , a composite stub was fabricated on the dentin fragments for the shear bond strength (SBS) test. Statistical testing was accomplished using the analysis of variance (P < 0.05)., Results: HP-based bleaching gel showed significant differences between measurement intervals in surface roughness, elastic modulus, and SBS parameters (P < 0.05). In contrast, HP-free bleaching gel showed insignificant differences within the group (P > 0.05). The SBS between dentin-composite was significantly affected with the use of HP-based bleaching gel, while HP-free bleaching gel showed insignificant difference between measurement intervals. The qualitative validation of the treatment's impact was further demonstrated using the scanning electron microscopy., Conclusion: The findings suggest that the bonding stability of composite restorations to dentin may be compromised after bleaching with an HP-based gel, whereas immediate bonding procedures can be safely conducted following the application of an HP-free bleaching gel., Competing Interests: All authors declare no conflicts of interest in this work., (© 2024 Khan et al.)

The study aimed to investigate the influence of H 2 O 2 -based and H 2 O 2 -free in-office bleaching on the surface and mechanical attributes of CAD/CAM composite blocks. CAD/CAM composite blocks from five different composite materials (CC1, CC2, CC3, CC4, and CC5) were randomly divided into two groups according to bleaching application (H 2 O 2 -based and H 2 O 2 -free). The surface topography, morphology, nanohardness, elastic modulus, flexural strength, and fracture toughness were measured. A paired and unpaired sample t-tests gauged the effect of pre- and post-bleaching on the substrates. The estimated mean differences (before-after bleaching) suggested an increase in surface roughness for two materials CC2 and CC4, and a significant decrease in nanohardness for material CC4 and in elastic modulus for materials CC2 and CC4 with H 2 O 2 -based bleaching, whereas H 2 O 2 -free bleaching resulted in changes compatible with no change in these properties. Flexural strength and fracture toughness showed no evidence of changes, irrespective of the bleaching gel used. Scanning electron microscopic analysis revealed erosive effects and micropore formation due to H 2 O 2 -based bleaching. H 2 O 2 -based bleaching deteriorates the surface of CAD/CAM composite materials while H 2 O 2 -free bleaching gel had an insignificant effect on both surface and bulk properties. The clinician should carefully evaluate the potential effects of H 2 O 2 -based bleaching on the surface properties of CAD/CAM composites., (© 2024 Scandinavian Division of the International Association for Dental Research. Published by John Wiley & Sons Ltd.)

Objective: This study aims to synthesize, characterize, and assess the penetration of hydrogen peroxide (HP), color change (CC), and surface morphology changes after the application of two distinct nano-hydroxyapatite (nano-HAp)., Methods: Two nano-HAp were previously synthesized by co-precipitation: one with rod-shaped particles (RS) and the other with spherical-shaped particles (SS). The surface charge of the nano-HAp particles was determined at varying pH levels and characterized by X-ray diffraction patterns and Fourier transform infrared spectroscopy. The morphology of the samples was assessed using scanning electron microscopy (SEM). The nano-HAp particles were applied before the dental bleaching procedure. Forty teeth were divided into four groups (n = 10) according to the bleaching treatment: no treatment, bleaching with 35 % HP only, RS application and bleaching with 35 % HP, and SS application and bleaching with 35 % HP. HP concentration (µg mL -1 ) was measured using UV-Vis, while CC was evaluated with a digital spectrophotometer (ΔE ab , ΔE 00 and WI D ). Additionally, four teeth from each group were selected for SEM analysis. Statistical analysis encompassed one-way ANOVA, Tukey's, and Dunnet's tests., Results: RS and SS were successfully synthesized by coprecipitation, primarily differing in pH during synthesis. Both variations of nano-HAp morphology significantly reduced HP diffusion into the pulp chamber (p < 0.001). Regarding enamel morphology, groups analyzed post dental bleaching exhibited greater HAp deposition on the enamel surface. Notably, this deposition did not impede CC., Significance: The utilization of different nano-HAp morphologies prior to dental bleaching appears to be a promising strategy for mitigating adverse effects associated with dental bleaching procedures., 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.)

This study evaluated the changes in surface properties of three resin-based restorative materials after two laser-assisted, in-office tooth bleaching protocols using erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) or diode (980 nm) lasers. A nanohybrid composite (Enamel Plus HRi), a Bis-GMA-free composite (Enamel Plus HRi Bio Function), and a resin-matrix CAD-CAM ceramic (Shofu Block HC) were tested. Forty specimens for each material were prepared and divided into four groups (n = 10/group). The control specimens did not undergo any bleaching treatment, whereas group 2 received bleaching with 40% hydrogen peroxide (H 2 O 2 ), while groups 3 and 4 underwent the same bleaching procedure with the use of diode (980 nm) or Er,Cr:YSGG lasers, respectively. Surface microhardness and roughness measurements were conducted using a Vickers tester and an optical profilometer. Microhardness was lower in bleached specimens, with the nanohybrid composite exhibiting the largest difference from the no bleaching group. For the Bis-GMA-free composite the microhardness difference between no bleaching and laser-assisted bleaching were smaller than seen for the conventional bleaching technique. Surface roughness was higher in bleached specimens, with nanohybrid composite showing the largest differences from the control specimens. The examined laser-assisted tooth bleaching protocols were found not to impact surface microhardness and roughness of the tested resin-based specimens and they are deemed suitable for clinical use., (© 2024 The Author(s). European Journal of Oral Sciences published by John Wiley & Sons Ltd on behalf of Scandinavian Division of the International Association for Dental Research.)

Objective: There are many suitable strategies for addressing caries, which is an ongoing worldwide problem. Although white spot lesions (WSLs) can be either remineralized naturally or treated with non- or micro-invasive strategies, their whitish and opaque appearance may persist. To evaluate the effects of tooth bleaching as a complement to fluoride-enhanced remineralization or resin infiltration in masking WSLs, as well as in enamel surface roughness relative to that of the adjacent enamel., Methodology: Flattened rectangular bovine enamel fragments (6×3×~2.9 mm length, width and thickness) were divided into six groups (L/N, F/N, F.BL/BL, I/N, I.BL/BL, N/N; n=15). Treatments applied to the 3×3 mm left half included: L (Lesion) - WSL simulation with 50 mM acetate buffer, 96 hours, 37ºC; F (Fluoride) - WSL treatment with 2% NaF neutral gel, 1x/week, 8 weeks; I (Infiltration) - WSL treatment with H3PO4 37%/10 s; Icon®-Dry/30 s; Icon®-Infiltrant/3 min+1 min; N (Nothing) - sound enamel/control. Treatments applied to both halves after F and I included: BL (Bleaching) - Opalescence Boost 40%, 3×/20 min each; N (Nothing) - control. The differences in color (ΔE00, ΔL, Δa, Δb) and surface roughness (ΔRa) between the left and right halves were measured. Kruskal-Wallis/post-hoc tests were applied to ΔE00, ΔL, Δa and ΔRa, and 1-way ANOVA/Tukey tests to Δb (α=0.05)., Results: The factor under study significantly influenced ΔE00 (p=0.0001), ΔL (p=0.0024), Δb (p=0.0015), and ΔRa (p<0.001), but not Δa (p=0.1592). Both fluoride-enhanced remineralization and resin infiltration were able to mask WSL, regardless of subsequent bleaching. However, when bleaching was performed, ΔE00 median values did not exceed the acceptability threshold for color difference. Only resin infiltration reduced ΔRa between WSL and the adjacent enamel., Conclusions: Both remineralization and infiltration, particularly if complemented by bleaching, fostered satisfactory esthetic results. Only infiltration without bleaching led to really good results in surface roughness.

Background: To predict the long-term performance of restorative materials in the oral environment, it is important to evaluate their resistance to chemical and mechanical degradation and to know the toxic potential of the type and amount of ions eluted from the filling material. In this study, home bleaching was applied to dental materials with different contents and it was aimed to determine the type and amount of ions released from these materials., Methods: In this study, amalgam, posterior composite resin, anterior composite resin, bulk fill composite resin, indirect composite resin, hybrid ceramic and all-ceramic were used as restorative materials. 10 specimens of each material were prepared according to the manufacturer's instructions. Each material group was divided into two subgroups as the bleached group and the control group. After bleaching, all specimens were stored in 1 ml of 75% ethanol/water solution. Solutions were renewed after 1, 14 and 28 days. The type and amount of ions released from the materials were determined using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Data were analyzed using the Friedman, Wilcoxon Signed Ranks, and Mann-Whitney U tests (α = 0.05)., Results: It was determined that the amount of ions release from the restorative materials decreased over time (p < 0.05). According to the results of the Mann-Whitney U test, there was no difference between the bleaching and control groups in most of the restorative materials (p > 0.05)., Conclusion: Within the limits of this study, home bleaching system does not have a significant effect on ion release from restorative materials., (© 2024. The Author(s).)

Objective: Evaluate the penetration of hydrogen peroxide (HP) into the pulp chamber, bleaching efficacy (BE) and amount of gel expended during in-office bleaching using an applicator brush tip and conventional tip from different commercial brands., Materials and Methods: 104 human premolars were randomly distributed into thirteen groups (n = 8) according to the commercial brand: DSP White Clinic 35 % Calcium (DW), Nano White 35 % (NW), Total Blanc One-Step 35 % (TS), Whiteness HP Blue 35 % (WB), Potenza Bianco Pro SS 38 % (PB), Opalescence XTra Boost 40 % (OB), no bleaching (negative control), and application method: applicator brush tip and conventional tip for all groups. Initial HP concentration (%) was determined via titration and pH was measured with digital pH meter. Concentration (µg/mL) of HP into the pulp chamber was measured using UV-Vis spectrophotometry, the BE (ΔE* ab , ΔE 00 and ΔWI D ) was evaluated with a digital spectrophotometer, and the amount of gel expended was evaluated using a precision analytical digital balance. Statistical analysis included two-way ANOVA, Tukey's, and Dunnett's test. Comparison between HP into the pulp chamber vs BE was performed with Person's correlation (α = 0.05)., Results: Brush tip demonstrated a low amount of HP in the pulp chamber compared to the conventional method for all bleaching gels (p < 0.0003), as well as lower amount of gel expended (p < 0.002). The brush tip did not result in a significant difference in BE compared to the conventional (p > 0.05). No correlations were found between both factors (p > 0.05)., Conclusion: Brush tip showed lower penetration of HP in the pulp chamber and a reduced volume of spent gel when compared to the conventional tip, for all commercial brands., Clinical Relevance: Brush tip is recommended for bleaching gels in an attachable syringe due to its ability to reduce the penetration of HP into the pulp chamber and minimize the amount of bleaching gel used., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that might have seemed to influence the findings presented in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Background: This study aimed to investigate the effect of whitening toothpastes on the color stability and surface roughness of resin composites stained with coffee and cigarette smoke., Methods: Seventy-two disk-shaped specimens (6 × 2 mm) of suprananohybrid resin composite were randomly divided into two groups and exposed to coffee and cigarette smoke (n = 36). After staining, the samples randomly divided into four groups according to whitening toothpastes and were brushed for 4 min: Opalescence Whitening (OW); Colgate Optic White (COW); Curaprox Black is White (CPX) and, distilled water (control) (n = 9). Color was measured with spectrophotometer at the initial, after staining, and after brushing, and surface roughness was measured with profilometer at the initial and after brushing. A surface morphology analysis was examined using scanning electron microscopy and atomic force microscopy. The obtained data were statistically analyzed. (p < 0.05)., Results: Cigarette smoke caused a significantly higher color change than coffee in the resin composite (p < 0.05). Brushing with hydrogen peroxide and silica-containing whitening toothpaste showed significant differences in color change (p < 0.05). The lowest whitening effect was found in activated charcoal-containing toothpaste. While all toothpastes increased the degree of surface roughness of resin composites, the highest roughness was caused by whitening toothpastes containing activated charcoal. (p < 0.05)., Conclusions: The color stability and surface properties of resin composites can be affected by brushing them with whitening toothpaste. The utilization of whitening toothpaste containing hydrogen peroxide can be considered a safe method for increasing the whiteness of discolored resin composites., (© 2024. The Author(s).)

Background: To evaluate the decomposition rate of active hydrogen peroxide (HP) and bleaching efficacy during in-office bleaching using high-concentration HP gels with different pHs., Method: A randomized, parallel, double-blind controlled trial was conducted with 40 volunteers randomized into four groups (pH 5.4; pH 7.0; pH 7.7, and pH 8.0). During the first session in-office bleaching, approximately 0.01 g of the gel was collected and titrated with potassium permanganate to obtain the concentration of active HP and pH values were measured using an electrode. Bleaching efficacy was assessed using a spectrophotometer [∆E ab , ∆E 00 , and WI D ], Vita Classical and Vita Bleachedguide scales [∆SGU]. The decomposition rate of HP concentration and pH values change were calculated using ANOVA one-way. The bleaching efficacy was assessed using two-way repeated measures ANOVA. Tukey's test was applied as a post-hoc test (p < 0.05)., Results: All gels experienced decreasing HP concentration over time. pH 5.4 gel showed greatest reduction after 50 min (p < 0.001). pH 8.0 and 7.7 gels remained stable; pH 5.4 remained acidic, while pH 7.0 turned acidic (p < 0.001). No significant difference in bleaching degree was observed among gels. They all showed a similar and clinically important color change after two clinical sessions, remained stable 1-month post-treatment (p > 0.05)., Conclusions: All bleaching gels kept at least 70% of their HP content after 50 min, suggesting that there is a surplus of HP. They provided similar whitening efficacy 1-month after bleaching., Practical Implications: It is possible that lower HP concentrations may be equally effective in achieving desired results while reducing the potential for side effects., Clinical Trial Registry Name: RBR-35q7s3v., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: To evaluate the effect of whitening toothpastes with different hydrogen peroxide (HP) concentrations on HP permeability, color change, and physicochemical properties, compared to at-home bleaching treatment., Materials and Methods: Forty-nine premolars were randomized into seven groups (n = 7): untreated (control); at-home bleaching with 10% carbamide peroxide gel (AH; 10% CP) with 14 and 28 applications of 180 min each (AH [14 × 180 min] and AH [28 × 180 min]); three whitening toothpastes (3% HP; 4% HP and 5% HP) and 10% CP brushed 28 times for 90 s each (TB [28 × 90 s]). HP permeability was measured using a UV-VIS spectrophotometer and color change by a digital spectrophotometer (ΔE ab , ΔE 00 , and ΔWI D ). Initial concentration, pH, and viscosity were measured through titration, digital pH meter, and rheometer, respectively. Statistical analysis included one-way ANOVA, Tukey's test, and Dunnett's test (α = 0.05)., Results: 4% HP group showed acidic pH, the lowest viscosity and the highest HP concentration into the pulp chamber (p < 0.05). The 10% CP groups had lower HP in the pulp chamber and greater color change than other groups (p < 0.05), except the 5% HP group in ΔE ab and ΔE 00 . For ΔWI D , the 10% CP AH groups showed greater whitening than other groups (p < 0.05)., Conclusions: Whitening toothpaste with up to 5% HP resulted in higher HP permeability and less color change compared to 10% CP. Higher HP commercial concentrations in toothpaste increased whitening effect; however, acidic pH toothpastes exhibited greater HP permeability., Clinical Relevance: Whitening toothpastes with high hydrogen peroxide concentrations were less effective than at-home bleaching, resulting in less color change and greater permeability of hydrogen peroxide, potentially increasing the risk of tooth sensitivity., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Aim: To evaluate the bleaching efficacy and effects on enamel properties of experimental gels with carbamide peroxide (CP; 10%) or hydrogen peroxide (HP; 6%) containing calcium polyphosphate sub-microparticles (CaPPs)., Methods: A total of 216 bovine tooth specimens were divided for microhardness and color analyses (n = 108) and block randomized into nine groups (n = 12): (G1) commercial CP (Whiteness Perfect, FGM; Brazil); (G2) experimental CP; (G3) CP-0.5%CaPPs; (G4) CP-1.5%CaPPs; (G5) commercial HP (Potenza Bianco, PHS; Brazil); (G6) experimental HP; (G7) HP-0.5%CaPPs; (G8) HP-1.5%CaPPs; (G9) artificial saliva. The gels' pH values were determined with a bench pH meter. Color (ΔE, ΔE 00 , ΔWI D ) and microhardness variation were evaluated before and after the therapy. Part of the specimens used for microhardness was submitted to the scanning electron microscopy (SEM) (n = 3) and energy-dispersive X-ray spectroscopy EDX (n = 3) analyses. Statistical analyses were performed in the R statistical software (α = 0.05). Linear mixed models for repeated measures in time were used to analyze microhardness and L* values. Generalized linear models were used to analyze the a*, b*, ΔE, ΔE 00 , and ΔWI D, considering a group effect. The EDX data were analyzed using a one-way ANOVA with Tukey's test., Results: The gels' pH remained over 6,0. All gels effectively bleached the specimens and did not differ significantly. When compared to the control group, the hardness was significantly lower in the G1, G2, G6, and G7 groups. The G3, G4, G5, and G8 groups did not differ significantly (p > 0.05)., Conclusion: The incorporation of CaPPs in low-concentration whitening gels reduces its negative effects on microhardness without interfering with their bleaching efficacy., (© 2023. The Author(s), under exclusive licence to The Society of The Nippon Dental University.)

Objectives: This study evaluated the efficacy of simulated brushing with toothpastes containing different concentrations of hydrogen peroxide (HP) in pulp chamber penetration and color change. Also, physical-chemical properties (concentration, pH and viscosity) were evaluated., Methods: Forty-nine premolars were divided into seven groups (n = 7): untreated (control); whitening gel (White Class 6 %, 6 %BG) with one 90  min application (6 %BG 90  min) and 14 applications of 90  min (6 %BG 14×90 min); toothpastes (Colgate Luminous White Glow 3 %, 3 %TP; Crest 3D White Brilliance 4 %, 4 %TP; Colgate Optic White Pro-Series 5 %, 5 %TP) and 6 %BG toothbrushing for 14 applications of 90 s. HP penetration into the pulp chamber was measured through UV-Vis spectrophotometry and color change with a spectrophotometer (ΔE ab , ΔE 00 , and ΔWI D ). Initial concentration, pH, and viscosity were measured through Titration, Digital pH-meter, and Rheometer, respectively. Statistical analysis used one-way ANOVA and Tukey's test (α = 0.05)., Results: 6 %BG (14×90 min) and 4 %TP groups showed acidic pH and higher concentrations of HP in the pulp chamber compared to the other groups (p < 0.05). On the other side, 3 %TP and 5 %TP groups showed alkaline pH, higher viscosity between the toothpastes and lower HP penetration (p < 0.05). The 6 %BG AH (14×90 min) group exhibited the most significant color change (ΔE ab , ΔE 00 , and ΔWI D ) (p < 0.05)., Conclusions: Brushing with whitening toothpaste with an acidic pH leads to greater HP penetration into pulp chamber; but, even when a high concentrated HP whitening toothpaste was used, a lower whitening effect was observed when compared to a two-week at-home bleaching., Clinical Significance: Whitening toothpastes containing up to 5 % HP produced lower whitening effect than two-week at-home bleaching. Additionally, HP was detected within the pulp chamber which can potentially impact in tooth sensitivity., 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.)

Objective: To evaluate if distinct 20%-22% carbamide peroxide bleaching gels present similar decomposition pattern and pH during the clinical use in both arches, as well as gels viscosity., Methods: Participants randomly received treatments with carbamide peroxide gels (n = 10): OPF (OpalescencePF-20%); PNT (Polanight-22%); and WPC (Whiteness Perfect-22%) in three different days, with 2-day washout. Decomposition pattern was assessed by peroxide concentration. Both PC and pH of bleaching gels were measured in different time points in upper and lower trays during a total of 120 min of clinical use. Viscosity of bleaching gels was measured in triplicate. ANOVA and Tukey's test were applied (α = 0.05)., Results: Regarding decomposition pattern, no significant differences were observed for the interaction between gel, time, and tray position factors. The peroxide concentration progressively reduced until 120 min of trays use (p < 0.001), being overall more notable in lower trays (p < 0.001). Regarding pH, the lowest values were verified in WPC within time. At 120 min, an increase of pH was observed for both WPC and OPF (p < 0.001) compared to baseline means. PNT exhibited constant pH values over time. The values of viscosity were: OPF (1.682.000 ± 19 cP)a, WPC (1.388.667 ± 172.63 cP)ab, PNT (579.567 ± 0.98 cP)b., Conclusions: The bleaching gels presented overall decomposition pattern clinically equivalent, being more notable in lower trays over time. Nevertheless, distinct pH and viscosities were observed among the products., Clinical Significance: Although the manufacturers recommend different times of use for bleaching gels with similar peroxide concentrations, the commercial products tested did not exhibit clinically relevant difference in the decomposition pattern during the 120 min of clinical procedure., (© 2022 Wiley Periodicals LLC.)

This study aimed to evaluate the effect of human saliva in vitro and salivary flow in situ on the roughness and mineral content of bleached enamel. Dental specimens were divided into five groups (n=15): not bleached (NB); bleached (35% hydrogen peroxide) and exposed to distilled water (DW); human saliva in vitro (IV); normal salivary flow in situ (NSF); and low salivary flow (LSF) in situ. Enamel roughness (Ra, Rz) and calcium/phosphorus contents were evaluated with laser profilometry and energy-dispersive spectroscopy, respectively, at baseline (T1), after bleaching (T2), and after seven days (T3). Salivary pH and buffer capacity were evaluated with colorimetric strips and salivary calcium and phosphorus with absorbance spectrophotometry. Data were analyzed with non-parametric tests and linear regression (α=0.05). After contact with saliva, Ra and Rz of LSF=DW>IV=NSF=NB was found. For DW and LSF, the roughness of T1

Objectives: This study aimed to evaluate the effects of 30% hydrogen peroxide (HP) solution containing various contents of 45S5 bioactive glass (BAG) on whitening efficacy and enamel surface properties after simulating the clinical bleaching procedure., Materials and Methods: A total of 60 bovine enamel specimens discolored with black tea were divided into five groups treated with distilled water (DW), HP, 0.01 wt.% BAG + HP, 1.0 wt.% BAG + HP, and 20.0 wt.% BAG + HP (n = 12). The pH change was observed for 20 min immediately after mixing the experimental solutions, which were applied for 20 min/week, at 37 °C over 21 days. Color, gloss, roughness, microhardness, and micromorphology measurements were conducted before and after bleaching treatment., Results: All groups containing BAG experienced an increase in pH from 3.5 to 5.5 in less than 1 min, and the final pH increased as the BAG content increased. The ΔE of all experimental groups was significantly higher than that of the DW group (p < 0.05), but there were no significant differences between different BAG contents (p > 0.05). Gloss significantly decreased in all experimental groups compared to the DW group, and the increased BAG content had significantly affected the decrease in gloss (p < 0.05). There was no statistical difference in surface roughness (p > 0.05), but hardness increased significantly with BAG content after bleaching treatment (p < 0.05)., Conclusions: HP containing 45S5 BAG showed efficacy in tooth whitening. Also, the pH value of the HP remained acidic near 3.5 for 20 min, while the HP containing the 45S5 BAG showed an increase in pH, which inhibited the demineralization of the enamel surface, and maintained the surface morphology., Clinical Relevance: These novel materials are promising candidates to minimize enamel surface damage caused by HP during bleaching procedure in dental clinic., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: The aim of this study was to evaluate the mineral content, expressed by calcium (Ca) and phosphate (P), in dental enamel exposed to bleaching agents using micro-computed tomography (micro-CT), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM)., Methods: Sixty bovine dental enamel specimens were randomly divided into three groups (n=20): HP35ca (bleached using 35% hydrogen peroxide with Ca); HP35wca (bleached using 35% hydrogen peroxide without Ca); and control (without bleaching). Five specimens from each group were used for SEM and EDS analyses, 10 specimens were used for AFM analysis, and the remaining five specimens were used for micro-CT analysis. The pH of the gels was measured using a pH meter. The EDS and micro-CT data were analyzed using one-way ANOVA and Pearson's correlation test. The AFM data were analyzed using one-way ANOVA (α=0.05)., Results: The weight percentages of Ca and P obtained using EDS were similar between the bleached and control groups. Small, superficial changes were observed by SEM in the HP35wca group. The HP35ca group showed similar patterns to the control group. AFM results showed no significant changes in the enamel roughness in any of the tested groups. No significant difference in the volume or depth of structural enamel loss was found between gels with and without Ca. No mineral loss was observed in the dentin substrate. The EDS and micro-CT analysis data exhibited a high correlation (p<0.001)., Conclusion: The addition of Ca to the bleaching gel had no beneficial effect on the bleached tooth enamel in terms of composition, mineral loss, and surface roughness. Micro-CT results exhibited a high correlation with the EDS results., (©Operative Dentistry, 2022.)

Objective: To evaluate the physical-chemical (weight, pH, quantification of hydrogen peroxide) and mechanical (texture profile and rheology tests) properties of the experimental bleaching gel based on the bioadhesive polymer Aristoflex® AVC, after accelerated stability testing., Materials and Methods: A total of 300 syringes of bleaching gels were divided into 5 groups (n = 60): Whiteness Perfect® 10%-FGM (WP); carbamide peroxide 10% with aristoflex (CPa); carbamide peroxide 10% with Carbopol (CPc); aristoflex thickener (A); and Carbopol thickener (C). According to the following requirements and time, the accelerated stability test was performed: in an incubator at 40 °C and 75% humidity per 1, 3, and 6 months, and baseline (refrigerator at 5 °C and 25% humidity). The variables were analyzed following the statistical tests: Two-way ANOVA and Tukey's test were applied to pH; weight data were analyzed using a mixed model for repeated measurements over time and the Tukey-Kramer test; one-way ANOVA and Tukey's test analyzed the rheology test; generalized linear models were used to quantify the peroxide amount and texture profile data. A significance level of 5% was considered., Results: The experimental bleaches CPa and CPc had the highest pH values when compared to the others in 6 months. Thickeners A and C did not change the pH, weight, and active content over the accelerated stability times (p > 0.05). Furthermore, there was weight loss after 3 months of storage for CPa and CPc (p < 0.05). In the quantification of hydrogen peroxide, the WP group showed the highest values over time (p < 0.0001), only showing a significant loss after the 3rd month. Meanwhile, CPa and CPc showed a reduction in quantification from the 1st month., Conclusions: Temperature and humidity directly influenced the active content and properties of bleaching gels. In addition, the presence of components regardless of thickeners, such as stabilizers, in the commercial gel allowed for greater stability over time., Clinical Relevance: The development of experimental bleaching gels for clinical use requires careful testing. Therefore, accelerated stability testing represents a valuable tool in the development and evaluation of cosmetic formulations., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The growing demand for charming smiles has led to the popularization of tooth bleaching procedures. Current tooth bleaching products with high-concentration hydrogen peroxide (HP, 30-40%) are effective but detrimental due to the increased risk of enamel destruction, tooth sensitivity, and gingival irritation. Herein, we reported a less-destructive and efficient tooth whitening strategy with a low-concentration HP, which was realized by the remarkably enhanced Fenton-like catalytic activity of oxygen-deficient TiO 2 (TiO 2- x ). TiO 2- x nanoparticles were synthesized with a modified solid-state chemical reduction approach with NaBH 4 . The Fenton-like activity of TiO 2- x was optimized by manipulating oxygen vacancy (OV) concentration and further promoted by the near-infrared (NIR)-induced photothermal effect of TiO 2- x . The TiO 2- x sample named BT45 was chosen due to the highest methylene blue (MB) adsorption ability and Fenton-like activity among acquired samples. The photothermal property of BT45 under 808 nm NIR irradiation was verified and its enhancement on Fenton-like activity was also studied. The BT45/HP + NIR group performed significantly better in tooth whitening than the HP + NIR group on various discolored teeth (stained by Orange II, tea, or rhodamine B). Excitingly, the same tooth whitening performance as the Opalescence Boost, a tooth bleaching product containing 40% HP, was obtained by a self-produced bleaching gel based on this novel system containing 12% HP. Besides, negligible enamel destruction, safe temperature range, and good cytocompatibility of TiO 2- x nanoparticles also demonstrated the safety of this tooth bleaching strategy. This work indicated that the photothermal-enhanced Fenton-like performance of the TiO 2- x -based system is highly promising in tooth bleaching application and can also be extended to other biomedical applications.

The aim of this in vitro study was to evaluate the effect of bleaching protocols on the surface roughness (Ra), color change and surface micromorphology of a low-viscosity bulk-fill composite (Filtek Bulk Fill Flow, 3M ESPE), a highviscosity bulk-fill composite (Filtek Bulk Fill, 3M ESPE) and a conventional nanoparticulate composite resin (control) (Filtek Z350 XT, 3M ESPE). Forty samples of each composite (disks 5 mm in diameter and 2 mm thick) were randomly divided into four groups (n=10), according to bleaching protocol: a) 10% carbamide peroxide gel (Opalescence, Ultradent Products) (2 h/ day, for 14 days); b) 40% hydrogen peroxide gel (Opalescence Boost, Ultradent Products) (three bleaching sessions, once a week, 45 min/session); c) whitening rinse (Listerine Whitening Extreme, Johnson & Johnson) (2 min/day, for 14 days); and d) distilled water (control). The samples were submitted to triplicate readings (Ra and color [CIELAB parameters]) before and after contact with bleaching protocols. Micromorphology was analyzed in a scanning electron microscope (SEM). Ra and color parameters (ΔL, Δa, Δb and ΔE) were analyzed by generalized linear models (α=0.05). The Ra of the high-viscosity bulk-fill was significantly higher than that of the other composites (p<0.05). Ra increased significantly (p<0.05) and surface became more irregular (SEM analysis) in all the composite resins, regardless of the bleaching protocol (p<0.05). The high-viscosity bulk-fill composite resin group had significantly lower ΔE (p<0.05) than the nanoparticulate composite resin group immersed in distilled water. It was concluded that the characteristics of each resin significantly influenced the Ra more than the bleaching protocol. The high-viscosity bulk-fill resin presented minor color change., Competing Interests: none, (Sociedad Argentina de Investigación Odontológica.)

Objectives: This study evaluated if the use of a bioactive glass-ceramic-based gel, named Biosilicate (BS), before, after or mixed with bleaching gel, could influence the inflammation of the dental pulp tissue of rats' molars undergoing dental bleaching with hydrogen peroxide (H2O2)., Methodology: The upper molars of Wistar rats (Rattus norvegicus, albinus) were divided into Ble: bleached (35% H2O2, 30-min); Ble-BS: bleached and followed by BS-based gel application (20 min); BS-Ble: BS-based gel application and then bleaching; BS/7d-Ble: BS-based gel applications for 7 days and then bleaching; Ble+BS: blend of H2O2 with BS-based gel (1:1, 30-min); and control: placebo gel. After 2 and 30 days (n=10), the rats were euthanized for histological evaluation. The Kruskal-Wallis and Dunn statistical tests were performed (P<0.05)., Results: At 2 days, the Ble and Ble-BS groups had significant alterations in the pulp tissue, with an area of necrosis. The groups with the application of BS-based gel before H2O2 had moderate inflammation and partial disorganization in the occlusal third of the coronary pulp and were significantly different from the Ble in the middle and cervical thirds (P<0.05). The most favorable results were observed in the Ble+BS, which was similar to the control in all thirds of the coronary pulp (P>0.05). At 30 days, the pulp tissue was organized and the bleached groups presented tertiary dentin deposition. The Ble group had the highest deposition of tertiary dentin, followed by the Ble-BS, and both were different from control (P<0.05)., Conclusion: A single BS-based gel application beforehand or BS-based gel blended with a bleaching gel minimize the pulp damage induced by dental bleaching.

Objective: This in vitro study evaluated the effect of commercial whitening dentifrices on erosive tooth wear (ETW) of bovine enamel samples, in comparison with commercial regular dentifrices., Methodology: Sixty bovine crowns were embedded in acrylic resin, polished and then had their baseline profile determined. They were randomly assigned to 5 groups (n=12/group), according to the type of commercial dentifrice to be tested: GI - Crest Anti-cavity Regular; GII - Crest 3D White; GIII - Colgate Total 12 Clean Mint; GIV - Colgate Optic White; GV - Placebo (negative control, fluoride-free dentifrice). The samples were submitted to daily erosive and abrasive challenges for 3 days. The erosive challenges were performed 3 times a day by immersing the specimens in 0.1% citric acid solution (pH 2.5) for 90 s. Each day after the first and last erosive challenges, the specimens were subjected to the abrasive challenge for 15 s, using a toothbrushing machine (Biopdi, São Carlos, SP, Brazil), soft toothbrushes and slurry (1:3 g/ml) of the tested toothpastes (1.5 N). The specimens were kept in artificial saliva between the challenges. The final profile was obtained and the ETW (µm) was calculated. Data were analyzed by Kruskal-Wallis and Dunn's tests (p<0.05)., Results: All dentifrices tested significantly reduced the enamel wear in comparison with the Placebo, except GIII. The median (95% CI) ETW was 1.35 (1.25-1.46)bc for GI, 1.17 (1.01-1.34)cd for GII, 1.36 (1.28-1.45)ab for GIII, 1.08 (1.04-1.14)d for GIV and 2.28 (2.18-2.39)a for GV., Conclusion: When dentifrices from the same manufacturer were compared, the whitening dentifrices led to similar or less wear than the regular ones.

Objective: This study was designed for the chemical activation of a 35% hydrogen peroxide (H2O2) bleaching gel to increase its whitening effectiveness and reduce its toxicity., Methodology: First, the bleaching gel - associated or not with ferrous sulfate (FS), manganese chloride (MC), peroxidase (PR), or catalase (CT) - was applied (3x 15 min) to enamel/dentin discs adapted to artificial pulp chambers. Then, odontoblast-like MDPC-23 cells were exposed for 1 h to the extracts (culture medium + components released from the product), for the assessment of viability (MTT assay) and oxidative stress (H2DCFDA). Residual H2O2 and bleaching effectiveness (DE) were also evaluated. Data were analyzed with one-way ANOVA complemented with Tukey's test (n=8. p<0.05)., Results: All chemically activated groups minimized MDPC-23 oxidative stress generation; however, significantly higher cell viability was detected for MC, PR, and CT than for plain 35% H2O2 gel. Nevertheless, FS, MC, PR, and CT reduced the amount of residual H2O2 and increased bleaching effectiveness., Conclusion: Chemical activation of 35% H2O2 gel with MC, PR, and CT minimized residual H2O2 and pulp cell toxicity; but PR duplicated the whitening potential of the bleaching gel after a single 45-minute session.

Introduction: Sodium hypochlorite is used as a bleaching and disinfecting agent and is commonly found in household bleach., Objective: The objective is to review critically the epidemiology, mechanisms of toxicity, clinical features, diagnosis, and management of hypochlorite poisoning., Methods: PubMed was searched from January 1950 to June 2018 using the terms "Hypochlorite", "Sodium Hypochlorite", "Sodium Oxychloride", "Hypochlorous Acid", "Bleach", "Chlorine Bleach", in combination with the keywords "poisoning", "poison", "toxicity", "ingestion", "adverse effects", "overdose", and "intoxication". In addition, bibliographies of identified articles were screened for additional relevant studies including non-indexed reports. Non-peer-reviewed sources were also included. These searches produced 110 citations which were considered relevant., Epidemiology: There is limited information regarding statistical trends on world-wide poisoning from sodium hypochlorite. In the United States of America, poison control center data have shown that enquiries regarding hypochlorite bleaches have ranged from 43,000 to 46,000 per year over the period 2012-2016. Mechanisms of toxicity: Hypochlorite's potential to cause toxicity is related to its oxidizing capacity and the pH of the solution. Toxicity arises from its corrosive activity upon contact with mucous membranes and skin. Features following ingestion: While small accidental ingestions are very unlikely to cause clinically significant toxicity, large ingestions may cause corrosive gastrointestinal injury and systemic effects, including metabolic acidosis, hypernatremia, and hyperchloremia. Features following dental exposure: Hypochlorite is used extensively by dentists for cleaning root canals and is safe if the solution remains within the root canal. Extrusions into the periapical area can result in severe pain with localized large and diffuse swelling and hemorrhage. Features following skin exposure: Prolonged or extensive exposure may cause skin irritation and damage to the skin or dermal hypersensitivity. Such exposures can result in either immediate or delayed-type skin reactions. High concentration solutions have caused severe chemical skin burns. Features following inhalation: Although there are only limited data, inhalation of hypochlorite alone is likely to lead to no more than mild irritation of the upper airways. Features following ocular exposure: Corneal injuries from ocular exposure are generally mild with burning discomfort and superficial disturbance of the corneal epithelium with recovery within 1 or 2 days. With higher concentration solutions, severe eye irritation can occur., Diagnosis: The diagnosis can typically be made on the basis of a careful history, including details of the specific product used, its hypochlorite concentration, and the amount involved. As hypochlorite bleach produces a characteristic smell of chlorine, this may provide a diagnostic clue. In severe cases, corrosive injury is suggested on presentation because of hypersalivation, difficulty swallowing, retrosternal pain or hematemesis., Management: Symptom-directed supportive care is the mainstay of management. Gastrointestinal decontamination is not beneficial. Local corrosive injury is the major focus of treatment in severe cases. Fiberoptic endoscopy and CT thorax/abdomen are complimentary and have been shown to be useful in corrosive injuries in assessing the severity of injury, risk of mortality and risk of subsequent stricture formation and should be performed as soon as possible after ingestion. Dental periapical extrusion injuries should be left open for some minutes to allow bleeding through the tooth and to limit hematoma development in tissue spaces. Once the bleeding has ceased, the canal can be dressed with non-setting calcium hydroxide and sealed coronally., Conclusions: Accidental ingestion of household bleach is not normally of clinical significance. However, those who ingest a large amount of a dilute formulation or a high concentration preparation can develop severe, and rarely fatal, corrosive injury so prompt supportive care is essential as there is no specific antidote. Treatment primarily consists of symptom-directed supportive care.

Objectives: To evaluate the effects of 10% carbamide peroxide (CP) with two different thickeners, carbopol (CPc) and natrosol (CPn), on color variation (CV), tooth sensitivity (TS), and cytotoxicity (CC)., Methods: Seventy subjects were distributed into the CPc or CPn groups (n = 35), in a parallel group, randomized, controlled, single-blind clinical trial. Bleaching gels were used by volunteers for 4 h daily for 2 weeks. Color evaluation was performed using a reflectance spectrophotometer, before bleaching treatment (BT), immediately after the first and second weeks of BT, and 1 week and 1 month after BT ended. TS was evaluated using two pain scales, before, during, and after BT. CC was evaluated using MTT after exposure of MDPC-23 cells to the bleaching gels for 4 h. Epoxy replicas of the subjects teeth were made before and after BT and analyzed using a scanning electronic microscope. The data was analyzed using statistical methods., Results: CV and TS showed similar variation between both bleaching gels (p ≤ 0.05). None of the protocols affected cellular metabolism or the surface morphology of enamel., Conclusions: Bleaching gels with carbopol and natrosol as thickening agents produced similarly effective tooth bleaching and TS, but did not cause cytotoxicity., Clinical Relevance: Natrosol could be an alternative as a thickener used in bleaching gels due to its similar bleaching effect and TS when compared with Carbopol.

Objective: This single-blind, parallel, randomized clinical trial evaluated the genotoxic potential and effectiveness of 10% hydrogen peroxide (HP) in patients submitted to at-home bleaching., Materials and Methods: Sixty young volunteers with maxillary incisors equal to or darker than M1.5 were included in the study. Patients were submitted to bleaching for 14 days (30 min/day) with one of the three 10% HP treatments: the bleaching agent was delivered in a bleaching tray (White Class, FGM), whitening strips (White Strips, Oral-b), or in prefilled disposable trays (Opalescence Go, Ultradent). The color change was evaluated with the Vita Bleachedguide, and the micronucleus test of exfoliative oral mucosa was carried out, starting from a count of 1000 cells, at the baseline, immediately after and 30 days after the end of the treatment. The micronucleus data were evaluated with the Kruskal-Wallis and Wilcoxon tests and color change with the two-way ANOVA test and the Tukey test (α = 0.05)., Results: Significant whitening was observed for all groups after 14 days (p = 0.001) and was maintained after 30 days, with no difference between groups (p = 0.42). The micronucleus count did not indicate genotoxic potential in any of the groups studied (p = 0.32), irrespective of the time intervals (p = 0.62)., Conclusion: No genotoxic effects of 10% HP were observed in patients submitted to at-home bleaching systems (30 min/day for 14 days), even 30 days after the end of treatment., Clinical Significance: It is safe to use different systems to deliver 10% HP during at-home bleaching according to the manufacturers' recommendations, with no risk of genotoxic effects applied.

Introduction: The aim of this study was to determine the effect of bleaching and desensitizing on shear bond strength (SBS) of metal brackets to enamel., Methods: One hundred extracted human premolar were randomly assigned to 5 groups of 20. In the first group (control), no bleaching or desensitizing agent was used. Groups 2 to 5 were bleached with 37.5% hydrogen peroxide and desensitized with 6.0% potassium nitrate. Surface treatment comprised of etching for 15seconds in groups 1, 2 and 3, Er:yag laser irradiation and etching in group 4 and sandblasting and etching in group 5. Premolar brackets were bonded with Transbond XT and cured for 20seconds and the SBS was tested using a universal testing machine. Adhesive remnant index (ARI) score was used to record the mode of bond failure., Results: No significant difference was found between the mean SBS (MPa) in groups 1(15.22), 4(14.02), and 5(12.62). SBS in group 4 was significantly higher than group 2 (8.15) (P<0.001). Also, SBS in groups 2 (P<0.001) and 3(11.74) (P=0.012) were significantly lower than group 1. An increased frequency of ARI score of 2 and 3 was observed in groups 1, 4 and 5., Conclusions: Bleaching plus desensitizing significantly decreased the SBS of orthodontic brackets. Delaying the bonding procedure for at least 2 weeks or alternative surface treatment methods such as combined laser and acid etching or combined sand blasting and acid etching can improve the SBS., (Copyright © 2019 CEO. Published by Elsevier Masson SAS. All rights reserved.)

The efficacy of whitening toothpastes is questionable and controversial. Clinicians, patients and researchers have expressed concern with whitening toothpastes due to the risk of wearing the dental structure and the potential for disappointment if the advertised cosmetic results are not achieved., Objective: This study compared the whitening performance of toothpastes with different whitening technologies after initial and continued use., Material and Methods: Ninety bovine incisors were stained using a concentrated solution of black tea. They were randomly distributed into 6 groups, according to the toothpaste whitening technology: activated charcoal (B&W), blue covarine (WAD), hydrogen peroxide (LWA), microbeads (Oral B 3D White Perfection - 3DW) and optimized abrasives (XW4D). They were compared to a traditional toothpaste without a whitening agent (TA - control). Specimens underwent a brushing machine with controlled pressure, time and temperature. A calibrated examiner measured the color using a VITA-Classical scale before the first brushing cycle (T0), after the first brushing cycle (TI), and after a brushing cycle that simulates continuous use (TCU). Whitening performance was evaluated by the difference of shades (ΔSGU) between T0-TI and T0-TCU timepoints, using the Kruskal-Wallis and Dunn's non-parametric test. The Wilcoxon test was used to evaluate the cumulative effect (α=0.05)., Results: Statistically significant differences were observed between toothpastes in both TI and TCU (p<0.05). The time of use also had a significant effect (p<0.05)., Conclusion: Only WAD and 3DW showed whitening performance after the first use (TI). The greatest whitening performance after continuous use was obtained by WAD, followed by LWA and 3DW. The use of conventional toothpaste (TA) promotes no tooth whitening., Clinical Relevance: Microbead abrasives (3DW) and blue covarine (WAD) were the active technology tested that presented the best global tooth whitening performance.

In this laboratory study, a composite resin was stained to a visibly discernible level using both coffee and red wine over 14 days (change was considered clinically noticeable and significant when ΔE ab *≥2.7). Color change was measured at one, three, seven, and 14 days of staining. Although the nature of color change was different for the two staining solutions, the overall degree of staining (ΔE ab *) rendered by either coffee or wine at each time interval was not significantly different ( p≥0.05). Four whitening protocols were applied to stained composites. Treatment included applications of distilled water (control), Crest Pro-Health [HD] toothpaste, Crest Whitestrips, Opalescence PF bleach (15%), and application of a fine pumice polishing (Preppies). HD toothpaste and Whitestrips were applied daily for 21 days, Opalescence was applied daily for 10 days, and polishing was applied once. Each of the whitening products, applied in a manner simulating at-home or in-office treatment, was effective in producing color improvements (lightening) over controls ( p<0.05), but none of the four treatments produced lightening that was significantly different from the other treatments ( p≥0.05). A comparison of final composite color with that measured at baseline showed that Opalescence returned composite color to an acceptable level following exposure to both staining solutions (ΔE ab *<2.7), Whitestrips returned color close to baseline for wine-stained composites, and HD paste and polishing permitted residual stain to remain (ΔE ab *≥2.7).

This study aimed to evaluate the effect of repolishing after bleaching on color stability and smoothness of two resin composites aged in a high-staining beverage. Fifty-six disc-shaped specimens (8×2 mm) of each resin composite were fabricated (Filtek Z250, 3M ESPE, microhybrid, and Filtek Z350 XT, 3M ESPE, nanofilled) and then divided according to treatment: bleached or nonbleached. After treatment application, groups were subdivided according to the surface treatment: repolished or unrepolished. A new subdivision was performed according to aging conditions: immersion in red wine for 15 min/d or in artificial saliva for 24 h/d during 30 days. Color (CIE L*a*b* system) and roughness (Ra) were assessed at baseline (P0), after bleaching procedures (P1), after surface treatment (P2), and after aging (P3). Color change (ΔE 00 ) was calculated through the CIEDE2000 formula. Statistical analysis was performed using repeated measures analysis of variance and the Tukey post hoc test. Bleached repolished groups presented lower color alteration than the bleached unrepolished groups from both resin composites when aged in red wine. Repolishing (P1 vs P2) promoted a slight decrease in roughness values of almost all groups. Nanofilled composite presented greater ΔE 00 values than microhybrid composite when aged in red wine.

Objective: To analyze color change, microhardness and chemical composition of enamel bleached with in-office bleaching agent with different desensitizing application protocols., Materials and Methods: One hundred and seventeen polished anterior human enamel surfaces were obtained and randomly divided into nine groups (n = 13). After recording initial color, microhardness and chemical composition, the bleaching treatments were performed as G1: Signal Professional White Now POWDER&LIQUID FAST 38% Hydrogen peroxide(S); G2: S+Flor Opal/0.5% fluoride ion(F); G3: S+GC Tooth Mousse/Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP) paste(TM); G4: S+UltraEZ/3% potassium nitrate&0.11% fluoride(U); G5: S+Signal Professional SENSITIVE PHASE 1/30% Nano-Hydroxyapatite (n-HAP) suspension(SP); G6: S-F mixture; G7: S-TM mixture; G8: S-U mixture; G9: S-SP mixture. Color, microhardness and chemical composition measurements were repeated after 1 and 14 days. The percentage of microhardness loss (PML) was calculated 1 and 14 days after bleaching. Data were analyzed with ANOVA, Welch ANOVA, Tukey and Dunnett T3 tests (p<0.05)., Results: Color change was observed in all groups. The highest ΔE was observed at G7 after 1 day, and ΔE at G8 was the highest after 14 days (p<0.05). A decrease in microhardness was observed in all groups except G6 and G7 after 1 day. The microhardness of all groups increased after 14 days in comparison with 1 day after bleaching (p>0.05). PML was observed in all groups except G6 and G7 after bleaching and none of the groups showed PML after 14 days. No significant changes were observed after bleaching at Ca and P levels and Ca/P ratios at 1 or 14 days after bleaching (p>0.05). F mass increased only in G2 and G6, 1 day after bleaching (p<0.05)., Conclusions: The use of desensitizing agents containing fluoride, CPP-ACP, potassium nitrate or n-HAP after in-office bleaching or mixed in bleaching agent did not inhibit the bleaching effect. However, they all recovered microhardness of enamel 14 days after in-office bleaching.

Recent studies suggested that bleaching agents may whiten teeth by oxidizing the fluorescent materials, which are the proteins located in the organic-inorganic interface. Therefore, we postulated that fluorescence of dentin came from dentin phosphoprotein (DPP) and that bleaching agents might bleach dentin by oxidizing DPP. Fifty-six specimens were randomly divided into 4 groups and exposed to distilled water, hydrogen peroxide (HP), ethylenediamine tetraacetic acid disodium salt (EDTA), and acetic acid for 24 h. After measuring the organic and inorganic components, fluorescence, and color characteristics of dentin before and after exposure, we found that when DPP was removed from dentin by EDTA, fluorescent intensity declined proportionally with the reduction in Raman relative intensity, and dentin was whitened considerably, with an Δ E value 6 times higher than that of the distilled water group. On the contrary, due to the incapability of acetic acid to dissolve DPP during decalcification, fluorescent intensity values and tooth color remained nearly unchanged after exposure to acetic acid. Dentin exposed to neutral HP showed no obvious morphologic and organic/inorganic component changes except for the destruction of DPP. Similarly, dramatically decreased fluorescent intensity and lightened color were found in the HP group. Moreover, DPP solution of the HP group exhibited decreased ultraviolet absorbance, especially between 250 and 300 nm, which arose from aromatic amino acids. The results indicated that DPP was responsible for the fluorescent properties of dentin and that HP might bleach dentin by the oxidization of aromatic amino acids in DPP. These findings are of great significance in promoting our further understanding of the mechanism of tooth bleaching and the fluorescent property of normal dentin.

This study aimed to evaluate the morphological and elemental changes that occur on the surface of calcium silicate-based cement (CSC) and to analyze the bond strength of composite resin to CSC after application of various bleaching agents. One hundred twenty-five CSC blocks (Biodentine) were prepared and randomly divided into five groups according to the bleaching agent applied over the material surface (n=25): SP-DW (sodium perborate-distilled water mixture), SP-HP (sodium perborate-3% hydrogen peroxide [H 2 O 2 ] mixture), CP (37% carbamide peroxide gel), HP (35% H 2 O 2 gel), and a control group (no bleaching agent). After 1 week, scanning electron microscopy provided an analysis of the surface morphology and elemental composition for 10 specimens from each group. Composite resin was placed at the center of each cement surface in the remaining specimens (n=15). A universal testing machine determined shear bond strength (SBS) and fracture patterns were identified with a dental operating microscope. Data were analyzed using one-way analysis of variance and Tukey HSD tests. The cement surface in the CP and HP groups presented changes in structure and elemental distribution compared with the remaining groups. The former groups exhibited a decrease in the calcium level and an increase in the silicon level and presented significantly fewer SBS values than the remaining groups ( p<0.05). Most failures were adhesive in the CP and HP groups, while they were predominantly cohesive in the remaining groups. The bleaching agents with higher concentration induced deterioration of the cement surface and negatively affected the bond strength of the composite resin to CSC. The use of CSC is recommended as a cervical barrier when intracoronal bleaching is performed with a mixture of sodium perborate with water or 3% H 2 O 2 .

Objective: High concentrations of hydrogen peroxide can cause adverse effects on composition and structure of teeth. However, the addition of calcium and fluoride in bleaching agents may reduce enamel demineralization. To evaluate chemical changes of sound and demineralized enamels submitted to high concentrations of hydrogen peroxide containing fluoride (F) or calcium (Ca)., Material and Methods: Enamel blocks of bovine incisors with standard dimensions were obtained and half of them were submitted to pH-cycling to promote initial enamel caries lesions. Sound and demineralized enamel samples were divided into (n=10): (C) Control (no whitening treatment); (HP) 35% hydrogen peroxide; and two experimental groups: (HPF) 35% HP+0.2% F and (HPC) 35% HP+0.2% Ca. Experimental groups were submitted to two in-office bleaching sessions and agents were applied 3 times for 15 min to each session. The control group was kept in remineralizing solution at 37°C during the bleaching treatment. The surface mineral content of sound and demineralized enamels was determined through Fourier Transform Raman spectroscopy (FT-Raman), Energy dispersive Micro X-ray fluorescence spectroscopy (μ-EDXRF); and the subsurface, through cross-sectional microhardness (CSMH). In addition, polarized light microscopy (PLM) images of enamel subsurface were observed., Results: According to three-way (FT-Raman and μ-EDXRF analyses) or two-way analysis of variance (ANOVA) (CSMH) and Tukey test (α=5%), the calcium or fluoride added to high-concentrated bleaching agents increased phosphate and carbonate concentrations on sound and demineralized enamels (p<0.05). However, HPC and HPF were unable to completely reverse the subsurface mineral loss promoted by bleaching on sound and demineralized enamels. The calcium/ phosphate (Ca/P) ratio of sound enamel decreased after HP treatment (p<0.001)., Conclusion: Even though experimental bleaching agents with Ca or F reduced mineral loss for both sound and demineralized enamel surfaces, these agents were unable to reverse the enamel subsurface demineralization.

Objectives: Whitening efficacy has been related to hydrogen peroxide (HP) diffusion into tooth structure. However, little information is available relating rheological properties to whitening efficacy. The purpose was to evaluate the whitening efficacy and HP penetration level of a 10% HP gel at three different viscosities and to compare them to a strip delivery system., Methods and Materials: Extracted molars (n=120) were randomly assigned into five groups (n=24/ group): NC&#95;MED (negative control; median): medium viscosity gel without HP; LOW: 10% HP gel (low viscosity experimental gel, Ultradent Products Inc); MED: 10% HP gel (medium viscosity experimental gel, Ultradent); HIGH: 10% HP gel (high viscosity gel, Ultradent); and CWS: Crest 3D Whitestrips 1-Hour Express (Procter & Gamble). All teeth were subjected to five 60-minute whitening sessions. Instrumental color measurements were performed at baseline (T 0 ), and 1-day after each application (T 1 -T 5 ), and 1-month after whitening (T 6 ). HP penetration was estimated with leucocrystal violet and horseradish peroxidase. A Kruskal-Wallis test and post hoc Bonferroni test were performed to assess the difference in tooth color change and HP penetration among the groups (α=0.05)., Results: Hydrogen peroxide penetration levels and overall color changes at T 6 were 0.24 μg/mL / 2.80; 0.48 μg/mL / 8.48; 0.44 μg/mL / 7.72; 0.35 μg/mL / 8.49; 0.36 μg/mL / 7.30 for groups NC, LOW, MED, HIGH, and CWS, respectively. There was a significant difference for HP penetration, while there was no significant difference among the four experimental groups for tooth color change., Conclusion: Rheological properties should be considered when developing new whitening formulations.

Bleaching of vital teeth has become common practice in cosmetic dentistry today. Tooth sensitivity and demineralization of the enamel are, however, common side effects associated with hydrogen and carbamide peroxide bleaching. This study investigated if calcium phosphate microspheres, which have remineralizing properties, could be used as an additive without hindering the diffusion of the bleaching agent and if the spheres could be used as a carrier for carbamide peroxide. A remineralizing agent could increase the safety of bleaching and decrease the severity of its side effects. Comparisons between current hydrogen peroxide diffusion studies and previously published work are difficult since many studies include challenging-to-replicate conditions or lack reporting of important parameters. Hence, a diffusion model was designed by Wu Lab (School of Dentistry, University of California, Los Angeles) to measure the diffusion flux and determine the diffusivity of hydrogen peroxide. Physical parameters (e.g., diffusivity) could then be used for direct comparison to the results obtained by future studies. Three whitening gels with increasing amounts of spheres were formulated and tested with 2 commercially available whitening gels. The flux of hydrogen peroxide through 1-mm discs of bovine enamel was measured at steady-state conditions, and the diffusivity was calculated. The results showed that the spheres could be used as a carrier for carbamide peroxide and that the amount of spheres did not affect the diffusivity of peroxide through the enamel discs. Hence, the microspheres are considered promising as an additive to minimize side effects in bleaching gel formulation.

Tooth bleaching is considered a non-invasive treatment, although the use of highly-concentrated products may provoke increased surface roughness and enamel demineralization, as well as postoperative sensitivity. Thus, the aim of this study was to investigate whether hydrogen peroxide (H 2 O 2 ) concentration would affect tooth bleaching effectiveness and the enamel surface properties. Enamel/dentin bovine specimens (6 × 4 mm) were immersed in coffee solution for 7 days and evaluated with a spectrophotometer (Easyshade; baseline), using the CIEL * a * b * color parameters. Hardness was measured using a hardness tester. The specimens were randomly assigned into four groups: one negative control, in which the specimens were not bleached, but they were irradiated with a laser-light source (Whitening Lase II, DMC Equipments); and three groups using distinct H 2 O 2 concentration, namely LP15% (15% Lase Peroxide Lite), LP25% (25% Lase Peroxide Sensy), and LP35% (35% Lase Peroxide Sensy), all products from DMC. The bleached specimens were also irradiated with the laser-light source. After bleaching, all specimens were evaluated using scanning electron microscopy (SEM). pH kinetics and rate was monitored during bleaching. The data were analyzed using ANOVA and Tukey's test (p < 0.05). All bleaching gels produced similar color change (p > 0.05). Concerning hardness, only the LP25% and LP35% significantly reduced hardness after bleaching; also, there was a progressive tendency for a greater percentage reduction in hardness with increased H 2 O 2 concentration of the gel (R 2  = 0.9973, p < 0.001). SEM showed that LP25% and LP35% produced an etching pattern on enamel with prism rods exposure. In conclusion, H 2 O 2 concentration above the 15% level does not increase bleaching effectiveness, and may increase the possibility for alteration of enamel hardness, surface morphology, and acidity of the medium. When using H 2 O 2 -based bleaching agents, dental practitioners should choose for less concentrated gels, e.g., around the 15% level., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Corrosion resistance is an important requirement for orthodontic appliances. Nickel and chromium may be released from orthodontic wires and can cause allergic reactions and cytotoxicity when patients use various mouthwashes to whiten their teeth. Our study aimed to assess the release of nickel and chromium ions from nickel titanium (NiTi) and stainless steel (SS) orthodontic wires following the use of four common mouthwashes available on the market., Methods: This in vitro, experimental study was conducted on 120 orthodontic appliances for one maxillary quadrant including five brackets, one band and half of the required length of SS, and NiTi wires. The samples were immersed in Oral B, Oral B 3D White Luxe, Listerine, and Listerine Advance White for 1, 6, 24, and 168 h. The samples immersed in distilled water served as the control group. Atomic absorption spectroscopy served to quantify the amount of released ions., Results: Nickel ions were released from both wires at all time-points; the highest amount was in Listerine and the lowest in Oral B mouthwashes. The remaining two solutions were in-between this range. The process of release of chromium from the SS wire was the same as that of nickel. However, the release trend in NiTi wires was not uniform., Conclusions: Listerine caused the highest release of ions. Listerine Advance White, Oral B 3D White Luxe, and distilled water were the same in terms of ion release. Oral B showed the lowest amount of ion release.

Besides the effects on the health of individuals, cigarette smoking can also interfere with the appearance of their teeth. To evaluate the effect of cigarette smoking-toothbrushing-cycling (CSTC) with whitening toothpastes on the roughness and optical behavior of bovine enamel for eight weeks. Thirty bovine dentin/enamel discs, 8.0 mm in diameter and 2.0 mm thick, were randomly divided into three groups according to the toothpastes: whitening (Colgate Luminous White - CW and Oral B 3D White - OW), and a non-whitening (Colgate - C). The roughness, color (CIE L*a*b* system), translucency and gloss were measured before and after the specimens were submitted to CSTC. The topography of the specimens was analyzed by scanning electron microscopy. During the first week, the specimens were daily subjected to the consumption of 20 cigarettes and brushed (40 strokes/100 g) with the toothpastes' slurries. Thereafter, the CSTC was weekly applied in an accumulated model (140 cigarettes/280 strokes) for seven weeks. The data were submitted to two-way ANOVA, Tukey's HSD test, and paired-t test (α=0.05). The three toothpastes produced significant changes in roughness, color, translucency and gloss (p<0.05). After eight weeks, the roughness and the gloss produced by the three toothpastes were similar (p>0.05), while OW produced the lowest color change and the translucency of C was lower than that of CW (p<0.05). The three toothpastes produced a significant decrease in L* values and a significant increase in a* values after eight weeks (p<0.05). No significant difference in the b* coordinate was found for OW (p=0.13) There were topographic changes in the enamel surfaces. The whitening toothpastes increased the roughness, changed the topography and were not able to maintain the optical stability of enamel exposed over eight weeks.

Introduction: Force decay elastomeric chains are significant, and it is a clinical problem., Aim: The aim of this study was to evaluate the effects of bleaching agent in the mouthwash on the force decay of orthodontic chains., Materials and Methods: In this experimental study, 160 gray closed elastomeric chains were randomly divided into three groups (one control and two test groups). Four loops of chains were stretched for 25 mm on custom-made jig. Control group specimens were immersed in artificial saliva during the test period. Test group specimens were immersed twice a day for 30 seconds in the whitening (LISTERINE® HEALTHY WHITE™) and daily sodium fluoride (LISTERINE® TOTAL CARE ZERO) mouthwashes. All specimens were immersed in artificial saliva at 37°C. Force was measured at different time points (initial, 1, 7, 14, 21, 28 days). Statistical analysis was performed by two-way analysis of variance (ANOVA) and Bonferroni methods (a = 0.05)., Results: Force of elastomeric chains was decreased dramatically in all groups during the experiment. After 24 hours, force was decreased by 42.18, 48.34, and 53.38% in control group, daily, and bleaching mouthwash groups respectively. The corresponding numbers after 4 weeks were 66.30, 76.73, and 86.48. The difference between three groups at days 1 and 28 was statistically significant (p < 0.05)., Conclusion: Within the limitations of the current in vitro study, bleaching and sodium fluoride mouthwashes could cause force decay of orthodontic elastomeric chains. Whitening mouthwash is more weakening for elastomeric chains., Clinical Significance: Use of whitening mouthwash by orthodontic patients could decrease the force of elastomeric chains, so it could be recommended to use them for a short time.

In the present study, the modified white rice of Jasmine (JM) and Saohai (SH) were used to prepare the rice gels. Carbamide peroxide (CP) containing rice gels (CP rice gels) of JM (CP-JM) and SH (CP-SH) were prepared. The rice gels and CP rice gels show homogenous texture. Rice variety influences the characteristics and properties of the rice gels. Amylose content of JM was lower than SH. Rheological behavior of JM and CP-JM was pseudoplastic without thixotropy whereas that of SH and CP-SH was pseudoplastic with thixotropy. CP-SH showed higher adhesive property and viscosity than CP-JM whereas CP-JM showed faster in vitro drug release than CP-SH. For ex vivo efficacy evaluation, 55 normal human teeth were subjected to the CP rice gels. Samples were applied on tooth surface according to the dental bleaching techniques. For at-home bleaching technique, the CP rice gels with 10% and 20% CP were used with bleaching time of 8h and 4h, respectively. For in-office bleaching technique, the CP rice gels with 35% CP was used with bleaching time of 1 h. The developed CP rice gels showed significantly higher efficacy than the positive and negative controls. For at-home bleaching technique, CP-SH was the most effective gels whereas for in-office bleaching technique, CP-JM was the most effective gels.

The aim of this in vitro study was to evaluate the long-term effect of bleaching on human enamel. Four groups of enamel specimens were prepared (n = 20): group 1: bleaching with Opalescence Boost [40% hydrogen peroxide (H 2 O 2 ), 3 × 20 min/week]; group 2: control group (the specimens were stored in human saliva); group 3: beaching with Vivastyle Paint on Plus (6% H 2 O 2 , 2 × 10 min/day), and group 4: bleaching with Opalescence PF 16% [16% carbamide peroxide (CP), 6 h/day]. After each bleaching session the specimens were stored in human saliva. Knoop microhardness and surface roughness were measured: before bleaching, after 2-week and after 8-week bleaching. After 2-week treatment, surface roughness was significantly increased in all experimental groups (p < 0.05), while among them no significant difference was found (p > 0.05). The roughness changes exerted after 8-week bleaching were not significantly higher than the ones after 2 weeks (p > 0.05). After 8-week treatment, the increase in roughness caused by 16% CP was significantly higher (p < 0.05) than the one caused by 40% H 2 O 2 . Microhardness increased in all groups including control; however, only 40% H 2 O 2 increased the microhardness significantly (p < 0.05). The effect of bleaching on enamel was not shown to be dependent on the method or the H 2 O 2 concentration. Bleaching with CP 16% resulted in higher roughness than bleaching with H 2 O 2 , while 40% H 2 O 2 caused the higher microhardness increase. The present study showed that in-office bleaching with 40% H 2 O 2 seems to be at least as safe as home bleaching as far as their effects on human enamel are concerned.

Objectives: The study aimed to compare the tooth sensitivity (TS) and bleaching efficacy of two hydrogen peroxide gels with different pHs (acid pH [Pola Office, SDI] and the neutral pH [Pola Office+, SDI]) used for in-office bleaching., Materials and Methods: Fifty-four patients from Brazil and Chile, with right superior incisor darker than A2, were selected for this double-blind, split-mouth randomized trial. Teeth were bleached in two sessions, with 1-week interval. Each session had three applications of 8 min each, according to the manufacturer's instructions. The color changes were evaluated by subjective (Vita Classical and Vita Bleachedguide) and objective (Easy shade spectrophotometer) methods. Participants recorded TS with 0-10 visual analog scale. Color change in shade guide units (SGU) and ΔE was analyzed by Student's t test (α = 0.05). The absolute risk and intensity of TS were evaluated by McNemar's test and Wilcoxon-paired test, respectively (α = 0.05)., Results: All groups achieved the same level of whitening after 30 days of clinical evaluation. The use of a neutral in-office bleaching gel significantly decreases the absolute risk of TS (28%, 95% CI 18-41) and intensity of TS when compared to the acid bleaching gel (absolute risk of 50%, 95% CI 37-63)., Conclusion: The use of a neutral in-office bleaching agent gel produced the same whitening degree than an acid bleaching gel but with reduced risk and intensity of tooth sensitivity., Clinical Significance: Clinicians should opt to use in-office bleaching with a neutral gel than an acid product because the former causes a significant lower risk and intensity of tooth sensitivity.