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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.)

Purpose: To compare the color alteration, surface roughness and microhardness and cross-sectional microhardness of bovine enamel treated with at-home whitening strips and gels., Materials and Methods: Sixty-six pigmented specimens (n = 11) were allocated to six groups: C-cotton wool moistened with distilled water for 1 h; SDS-sodium dithionite strip, for 1 h; HPS-6.5% hydrogen peroxide strip, for 1 h; CPS-20% carbamide peroxide strip, for 1 h; HPG-7.5% hydrogen peroxide gel, for 1 h; CPG-10% carbamide peroxide gel, for 4 h. The treatments lasted 10 days, calculating the ∆E, ∆E 00 , and ∆W ID at baseline, 5 and 10 days, and 14 days after completion. Additional 66 polished discs (n = 11) were used to analyze the surface roughness and microhardness of enamel before and after bleaching, cross-sectional microhardness and integrated mineral loss (ΔZ; %Vol × μm). Data were subjected to statistical analysis by two-way Anova RM and Tukey post-test (α = 0.05)., Results: In ∆E and ∆W ID analysis, greater values were obtained in CPG (p < 0.001), followed by HPG and HPS (p = 0.271). SDS and CPS (p < 0.001) exceeded only C (p < 0.001). In ∆E 00 , at completion of treatments, the results were similar; however, HPG = HPS = CPS (p = 0.237). There was an increase in roughness and decrease in surface microhardness in all bleaching groups (p < 0.005). Concerning the cross-sectional microhardness, the treatments were equal to C at 150 μm, the last depth analyzed. For ΔZ, the values of SDS, CPS, HPG, and CPG groups showed similar mineral loss (p > 0.001), and the lowest value was exhibited in the Control group, followed by HPS group (p < 0.001)., Conclusion: Although the strips were aesthetically effective, the CPG and HPG groups presented highest values in the ∆E 00 and ∆W ID analysis. However, all treatments influenced the enamel surface, increasing roughness and decreasing surface and transverse microhardness., Clinical Relevance: The whitening gels promoted greater chromatic changes, but all treatments affected the enamel surface, increasing roughness and decreasing surface and transverse microhardness., (© 2025 Wiley Periodicals LLC.)

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).)

Background: This single-blind, noninferiority trial evaluated whether 10% carbamide peroxide (CP) applied for 2 or 4 hours daily is noninferior to 8 hours., Methods: A total of 120 healthy adults, with teeth shade A2 or darker, were randomly allocated to 3 groups (n = 40). All participants used 10% CP gel in a bleaching tray for 2, 4, and 8 hours daily for 14 days, with the option to extend treatment if they were dissatisfied. Color change was measured using a spectrophotometer and shade guides at baseline, every 5 days, and 1 month posttreatment. Risk and intensity of tooth sensitivity (TS) were assessed daily using a 0 through 10 visual analog scale. Satisfaction was recorded via a Likert scale wherein 1 corresponded to very dissatisfied and 7 corresponded to very satisfied and the Orofacial Esthetic Scale. Noninferiority was tested for color change using the 1976 formula (ΔEab) at 1 month postbleaching (primary outcome), color change using the 2000 formula (ΔE00), Whiteness Index, and shade guide units, whereas TS and satisfaction were analyzed with χ 2 , analysis of variance, Kruskal-Wallis, and Friedman tests., Results: Color change in ΔEab (2 vs 8 h: mean difference, -0.6; 90% CI, -2.1 to 1.0, 4 vs 8 h: mean difference, 0.0; 90% CI, -1.6 to 1.6) and ΔE00 values for shorter durations were noninferior to 8 hours at 1 month. Whiteness Index results were inconclusive. TS risk and intensity were similar (P > .05), and patient satisfaction improved across all groups similarly (P > .05)., Conclusions: Shorter 2- and 4-hour daily bleaching with 10% CP is noninferior to the 8-hour protocol., Practical Implications: Shorter periods of at-home bleaching (2 and 4 h) can be prescribed depending on the patient's availability or preferences without jeopardizing the bleaching efficacy. This clinical trial was registered at Registro Brasileiro de Ensaios Clínicos (RBR-10vvfpcm)., Competing Interests: Disclosures None of the authors reported any disclosures., (Copyright © 2025 American Dental Association. Published by Elsevier Inc. All rights reserved.)

Objectives: The aim of this study was to analyze the characteristics and trends of publications in clinical trials on tooth bleaching through a bibliometric and altmetric analysis., Methods: A search was conducted in September 2024 on Web of Science Core Collection (WoS-CC) and Scopus. Two researchers selected articles and extracted key study characteristics. VOSviewer was used to generate bibliometric networks. Dimensions was consulted to measure altmetric data., Results: 416 studies were included, published between 1990 and 2024. The most cited study obtained 164 citations on WoS-CC and 201 on Scopus. The studies predominantly investigated bleaching efficacy (n = 232), often employing double-blind designs (n = 146), conducted in adults (n = 403), randomized (n = 307), and mainly using hydrogen peroxide (n = 200) for at-home vital dental bleaching (n = 199). The majority of the articles were published by Brazilian authors (n = 165), with Loguercio AD (n = 70) and Reis A (n = 56) being the most frequent authors. The manufacturer FGM led with the highest number of investigated products (n = 153), particularly highlighting Whiteness HP Maxx 35 % (n = 40). VOSviewer revealed significant collaborations among authors and keywords. According to Dimensions, users of Mendeley and news outlets have shown great interest in whitening clinical trials., Conclusion: This study highlighted a growing trend in clinical trials on tooth bleaching over 30 years, with a strong predominance of studies conducted in Brazil that primarily investigated bleaching efficacy through double-blind designs in adults using hydrogen peroxide., Clinical Significance: Clinical trials on tooth bleaching represent one of the highest levels of scientific evidence guiding clinical practice, thus requiring thorough evaluation., 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.)

Purpose: The aim of this study was to determine whether a sustained-release desensitizing gel containing 3% potassium nitrate and 0.11% fluoride ion reduces the risk of tooth sensitivity without compromising the effectiveness of bleaching treatment., Methods: Thirty-two patients were randomly assigned to 2 experimental groups: desensitizing gel and placebo. The desensitizing gel or placebo was applied for 30 minutes prior to the at-home vital bleaching gel application. A nightguard dental bleaching treatment (NGVB) using a 16% carbamide peroxide gel was performed for 6 hours over a 3-week period. Patients recorded their tooth sensitivity daily using a 5-point Numeric Rating Scale (NRS). Whiteness index measurements were obtained using a dental spectrophotometer on the upper canines (right and left)., Results: The overall risk of sensitivity was 37.5% in the desensitizing gel group compared to 87.5% in the placebo group, yielding a relative risk of 0.42 (95% CI 0.22-0.82), showing a statistically significant difference between the groups (P < .05). During the first week, patients in the placebo group exhibited a higher risk of experiencing mild sensitivity. However, no statistically significant differences in sensitivity intensity were observed overall or during the second and third weeks (P > .05). Regarding color change, the mean difference between groups in the first week was 5.25 (-0.22 to 10.71), in the second week 4.25 (-2.56 to 11.02), and in the third week 2.55(-4.11 to 9.22). No statistically significant differences were found between the groups at any time point (P > .05)., Conclusions: The use of a sustained-release desensitizing gel containing 3% potassium nitrate and 0.11% fluoride ion for 30 minutes prior to the bleaching agent effectively reduced sensitivity during at-home bleaching procedures. Furthermore, the desensitizing gel did not impact the effectiveness of the at-home bleaching treatment., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background/objectives: Tooth whitening is a cosmetic dental treatment that improves the color of natural teeth, making them whiter and brighter; this review aimed to evaluate the greater effectiveness of in-office, at-home, and combined bleaching with hydrogen or carbamide peroxide, also in relation to possible relapses and side effects (tooth sensitivity)., Methods: A literature search has been carried out through electronic databases, PubMed/MEDLINE, and Cochrane Library, focused on the use of the effectiveness of in-office, at-home, and combined dental bleaching. This review has been registered on PROSPERO (ID613248)., Results: 30 articles have been included. Most of the studies did not find any more effective treatment than the proposed treatments; all types of bleaching have been shown to be effective in changing color; in the studies that have compared in-office and at-home bleaching, there was a lower recurrence of treatment with the use of the at-home trays with carbamide peroxide gel. There were no clear positions regarding tooth sensitivity, which would appear to be higher in professional in-office and combined dental bleaching., Conclusions: Bleaching is an effective treatment for the change of color of the tooth regardless of the type used (concentrations, type of gel, and duration of sessions), although, at home, it would seem to be more effective over time. It is, however, a clinical feature that may give a risk of tooth sensitivity after treatment.

The use of bleaching agents to remove stains is one of the main dental procedures to improve the aesthetics of teeth. This review presents the main agents used for tooth whitening, existing clinical protocols, and the structural changes that may occur through their use. The main bleaching agents consist of hydrogen peroxide and carbamide peroxide, which are used in bleaching techniques for vital teeth. These techniques can be performed in the office by a professional or by the individual in a home en-vironment under professional guidance. Bleaching agents come in a variety of concentrations and there are over-the-counter products available on the market with lower concentrations of hydrogen peroxide. Due to the chemical characteristics of the agents, changes in the organic and inorganic content of the tooth structure can be observed. These changes are related to morphological changes characterized by in-creased permeability and surface roughness, such changes compromise the mechanical resistance of the tooth. Furthermore, bleaching agents can promote molecular changes after reaching the dental pulp, resulting in oxidative stress of pulp cells and the release of pro-inflammatory mediators. Despite the bleaching effectiveness, tooth sensitivity is considered the main side effect of use. Therefore, among the heterogeneity of protocols, those that used the bleaching agent for a prolonged time and in lower con-centrations presented more harmful effects on the tooth structure., (©The Author(s) 2024. Open Access. This article is licensed under a Creative Commons CC-BY International License.)

Objective: Compare the tooth sensitivity (TS) and bleaching efficacy (BE) of in-office dental bleaching performed with 35% hydrogen peroxide (HP) or 37% carbamide peroxide (CP)., Materials and Methods: Sixty-six participants were randomly divided into two groups according to the bleaching gel applied to the right hemiarch: 35% HP, or 37% CP. TS was recorded immediately after, up to 1, 24, and 48 h after bleaching, using the VAS and NRS scales. BE was assessed before bleaching and 1 month after using color guide units (ΔSGUs) and a spectrophotometer (ΔE ab , ΔE 00 , and ΔWI D ). TS was assessed using McNemar's and paired t-test (VAS) or Wilcoxon signed rank (NRS). The paired t-test was used to analyze BE (α = 0.05)., Results: TS risk and intensity were lower for the 37% CP (p = 0.003 and p < 0.005). Despite significant differences between the groups after 1 month (ΔSGU and ΔE 00 ; p < 0.05), the color measurements of both groups exceeded the 50%:50% perceptibility/acceptability threshold., Conclusion: In-office dental bleaching using 37% CP resulted in reduced risk and TS intensity, without prejudice to the BE., Clinical Relevance: The use of 37% CP for in-office dental bleaching could decrease TS risk and intensity without affecting BE., Trial Registration: ClinicalTrials.gov identifier: RBR-683qhf., (© 2024 Wiley Periodicals LLC.)

Although at-home bleaching can recover the optical properties of stained CAD-CAM monolithic materials, little is known about its impact on their surface and mechanical properties, especially when successive sessions are performed. This study evaluated the effect of successive at-home bleaching sessions on the microhardness, roughness, topography, biaxial flexural strength (BFS), and reliability of CAD-CAM monolithic materials. Disks from Lava Ultimate (LU), Vita Enamic (VE), and IPS Empress CAD (EMP) were fabricated and submitted to up to three bleaching sessions. At-home bleaching was performed with 10% carbamide peroxide, and each session consisted of one application for 10 hours/day for 14 days. The analyses of the aforementioned parameters were assessed before and after the first, second, and third bleaching sessions, except for BFS, which was evaluated at baseline and after the third session. The Weibull modulus was calculated from the BFS data. The microhardness of the three materials as well as the roughness of LU were not affected by the sessions, whereas the roughness of VE and EMP increased from the second session. All materials displayed topographic changes, which became more pronounced with the increase in the number of sessions. Although bleaching decreased the BFS of the materials, it did not adversely affect their reliability. Successive at-home bleaching sessions with the protocol used in the present study cannot be considered a safe procedure for the materials evaluated., (©Operative Dentistry, 2024.)

Introduction: Traditionally, internal tooth bleaching was performed using sodium perborate slurries. These are banned in some areas for potential carcinogenic effects. More recently, highly concentrated hydrogen peroxide gels have been used, which may cause dentin degradation. Consequently, the search for ideal internal tooth bleaching agents is still on. This study compared pure ROS-releasing granules regarding their liberation of oxidizing species, pH induction, bleaching of blood-stained dentin, and effects on mechanical dentin properties., Materials and Methods: The ROS-releasing granules under investigation were sodium perborate, carbamide peroxide, and sodium percarbonate in aqueous suspension (4:3, wt/wt). The bleaching efficacy of these suspensions was compared in blood-stained human dentin ( n  = 6) ex vivo . In addition, effects on mechanical dentin integrity were tested using bovine dentin beams ( n  = 9) exposed to a 3-point bending test (ISO 4049) after immersion in test suspensions or control solutions (35% H 2 O 2 and physiological saline) for 1 week., Results: Granules release between 21.5% and 35.2% (wt/wt) of H 2 O 2 equivalent. The sodium-containing granules (perborate and percarbonate) caused an alkaline pH of 10.3 and 10.6, respectively. The carbamide peroxide suspension was acidic (pH 3.9), as was the 35% H 2 O 2 solution used as a control (pH 2.2). All the suspensions bleached the blood-stained dentin, albeit with a lesser overall effect by sodium percarbonate (one-way ANOVA and Tukey's HSD, p  < 0.05). The acidic preparations caused a severe (over 50%) reduction in flexural strength of the dentin ( p  < 0.05 compared to physiological saline solution), while the alkaline counterparts did not., Conclusions: Sodium perborate granules in aqueous suspension combined good de-staining properties with limited untoward effects on dentin integrity. Further studies are required to identify alternative compounds with a lesser general health concern., Competing Interests: The authors declare the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2024 Mayer, Gubler, Attin and Zehnder.)

Aim: This study compared the effectiveness of several techniques in restoring compromised bonding to recently bleached enamel., Methods: Seventy-five healthy bovine incisors were divided into five groups (n = 15). Fifteen teeth (Group 1) remained intact, whereas 60 (Groups 2 to 5) underwent at-home bleaching with 16% carbamide peroxide. The bonding procedures were as follows: Group 1: Bonding of resin composite to unbleached enamel; Group 2: Bonding immediately after bleaching; Group 3: Application of a 10% sodium ascorbate solution for 10 min before bonding; Group 4: Enamel removal to the depth of 0.5 mm; and Group 5: Increased curing time of the bonding agent to 80 instead of 20 s. After 24 h, the specimens were subjected to micro-shear testing, and the failure mode was determined., Results: ANOVA revealed a significant difference in bond strength among the groups (P < 0.001). The mean bond strength was significantly lower in group 2 than in other groups (P < 0.05), which showed comparable bond strength to each other (P > 0.05). Adhesive failure was the most predominant failure type in all groups. The mixed failure occurred with a frequency of 26.7% in groups 3 and 5. The Fisher's exact test revealed a significant difference in failure modes among the groups (P = 0.047)., Conclusions: The three experimental procedures used in this study, including the application of 10% sodium ascorbate before bonding, enamel removal to the depth of 0.5 mm, and increasing the curing time of the bonding agent to 80 s, were effective in restoring the compromised bonding to recently bleached enamel., (© 2024. The Author(s).)

Objectives: This study assessed the effects of 15% and 20% carbamide peroxide (CP) on color, surface roughness, and hardness of computer-aided design/computer-aided manufacturing (CAD/CAM) dental ceramics., Materials and Methods: This in vitro study was conducted on 120 Vita Mark II, Celtra Duo, and Suprinity CAD/CAM ceramic specimens. The ceramic specimens in each group (n = 40) were randomly assigned to two subgroups (n = 20) for polishing and glazing, and their baseline color, surface roughness (Ra), and hardness were assessed. In each subgroup, half of the specimens were exposed to 15% CP, while the other half were exposed to 20% CP. Their color change (ΔE), surface roughness, and hardness were then measured again. Surface roughness, hardness, and color were analyzed sequentially by profilometer, Vickers hardness tester, and spectrophotometer, respectively. Data were analyzed by repeated measures ANOVA, one-way ANOVA, and post hoc Bonferroni test (α = 0.05)., Results: The surface roughness of all groups significantly increased after bleaching treatment (p < 0.05). Surface hardness of all groups decreased after bleaching treatment, but this reduction was only significant in Vita Mark II subgroups (glazed, polished, 15%, and 20% CP). The ΔE was not clinically and visually perceivable in any group., Conclusion: The present results revealed that concentration of CP and type of surface treatment affected the surface properties of CAD/CAM ceramics. Type of surface treatment only affected the surface hardness of Vita Mark II ceramics (p < 0.05). Concentration of CP had a significant effect only on polished Vita Mark II., (© 2024 The Author(s). Clinical and Experimental Dental Research published by John Wiley & Sons Ltd.)

Objective: To evaluate the effectiveness of desensitizing toothpastes in reducing post-bleaching tooth sensitivity., Materials and Methods: A systematic review of randomized clinical trials was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. Electronic searches were conducted in the PubMed/MEDLINE, Scopus, Web of Science, The Cochrane Library and Embase databases, using the following terms: (dentifrices OR toothpaste) AND (sensitive OR sensitivity OR dental sensitivity) AND (dental bleaching OR tooth bleaching OR dental whitening OR tooth whitening)., Results: Five studies involving 387 individuals undergoing in-office or at-home teeth bleaching were reviewed. Desensitizing toothpastes reduced sensitivity effectively after home bleaching with 22% carbamide peroxide and single-session in-office bleaching with 35% hydrogen peroxide. However, they were ineffective for home bleaching with 16% carbamide peroxide and in-office bleaching across two sessions with 35% or 38% hydrogen peroxide., Conclusion: Desensitizing toothpastes are effective for home bleaching with high concentration carbamide peroxide and single-session in-office bleaching with highly concentrated hydrogen peroxide, but ineffective for home bleaching with low concentration carbamide peroxide and two-session in-office bleaching with concentrated hydrogen peroxide., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective To evaluate the clinical behavior of different bleaching products - the hydrogen peroxide (H 2 O 2 ), carbamide peroxide (CP), and titanium dioxide bleaching systems. Methods Three bleaching systems with different concentrations (H 2 O 2 15%, 38%, CP 15%, 35%, and titanium dioxide 20% H 2 O 2 ) were used. Sixty participants with discolored teeth were enrolled and equally divided into six groups. Each group was rendered the assigned bleaching protocol against the control group, which received plain dentifrice polishing. Each case was evaluated immediately, two weeks, three months, six months, and one year after the bleaching treatment. The clinical evaluation was made for color change by (shade guide and digital images with L*a*b* parameters), tooth sensitivity, gingival irritation, and participants' satisfaction. Results All bleaching systems showed color improvement after bleaching regimens with significant effect showed by in-office titanium dioxide 20% H 2 O 2 followed by 38% H 2 O 2 with Δ=10.26 and Δ=6.52, respectively, when compared to other bleaching techniques. Higher sensitivity was recorded in group III with 50% of the participants reporting postoperative sensitivity. Higher gingival irritation was recorded in group IV (15% CP) where 60% of the patients reported gingival irritation. Thirty-five of the 60 participants (58.5%) recorded that the treatment whitened their teeth "moderately" and "a lot" while seven participants recorded "a slight" difference. There was a highly significant difference in participants' satisfaction between all bleaching groups (p < 0.05). Conclusion It is evident that there is a development of dental sensitivity and gingival irritation irrespective of the bleaching system used. The color assessment showed that the desired result can be achieved with variable levels of patient satisfaction with excellent overall results with the titanium dioxide system., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Research Unit, Batterjee Medical College issued approval RES-2023-0028. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Elnawawy et al.)

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.)

Purpose: The purpose of this study was to assess, in vitro, the color stability and bleaching response of three bulk-fill composite resins-Activa™, Tetric®-N-Ceram Bulk-Fill, and Filtek™ One Bulk-Fill???and one conventional composite resin, Filtek™ Z250, after immersion in commonly consumed carbonated beverages and subsequent home bleaching with 15 percent carbamide peroxide. Methods: Ninety-six samples (two- and four-mm thick) of the materials were immersed in malt drink, energy drink, cola, or distilled water for one day, one week, and two months. After two months, samples underwent home bleaching with 15 percent carbamide peroxide gel. Spectrophotometric analysis measured color and whiteness changes pre-immersion, post-immersion, and post-bleaching. Statistical significance was determined using factorial mixed analysis of variance (ANOVA), three-way ANOVA, and Bonferroni post hoc tests (P<0.05). Results: All tested composite resins exhibited unacceptable discoloration (color change greater than 3.3) after two months in carbonated beverages. Filtek™ One Bulk-Fill and Filtek™ Z250 displayed the most significant discoloration, particularly when immersed in the malt drink (P<0.05). In contrast, Activa™ samples reached unacceptable discoloration within just one week in malt and cola drinks. Home bleaching yielded limited whiteness recovery, with Activa™ presenting acceptable whiteness post-bleaching after staining with cola and energy drinks. Conclusions: This study highlights the aesthetic risks of prolonged carbonated beverage consumption and the limitations of the assessed home bleaching technique using 15 percent carbamide peroxide. Enhanced dental education on the dietary effects of some beverages on restorative materials is indicated by these findings.

Objective: To investigate the effect of tooth whitening on biomechanical properties of vacuum-formed retainers (VFRs)., Methods: Using a split-mouth, randomised controlled trial design, thirty participants were randomly allocated to receive whitening on either the upper or the lower arch, using 10 % carbamide peroxide for two weeks. Biomechanical properties such as hardness, tensile strength, and surface roughness were assessed two weeks after whitening was completed., Results: Tensile strength of the whitening arch (mean ± SD: 40.93 ± 3.96 MPa) was significantly lower than that of the control (47.40 ± 5.03 MPa) (difference 6.47 MPa, 95 % CI 4.51 - 8.42, p < 0.001). Hardness and internal roughness of the whitening arch (VHN = 14.63 ± 2.29 N/mm 2 and Ra = 1.33 ± 0.35 µm, respectively) were significantly greater than those of the control (12.22 ± 1.86 N/mm 2 and 0.96 ± 0.29 µm, respectively) (differences 2.41 N/mm 2 , 95 % CI 1.56 - 3.25, p < 0.001 and 0.37 µm, 95 % CI 0.23 - 0.51, p < 0.001, respectively). The whitening arch showed greater tooth colour change (ΔE = 6.00 ± 3.32) than the control (ΔE = 2.50 ± 1.70) (difference = 3.50, 95 % CI 2.43 - 4.56, p < 0.001)., Conclusions: Based on this short-term study, marked tooth colour change was achieved by whitening with VFRs as the whitening trays, but this changed the VFRs' biomechanical properties, including a decrease in tensile strength and an increase in hardness and internal roughness., Clinical Significance: The application of carbamide peroxide in VFRs may compromise their mechanical properties., 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 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Wastewater treatment and conversion into renewable energy sources have been of great interest in recent times due to growing environmental pollution concerns and need for sustainable energy sources. Sewage sludge treatment can convert sludge into renewable energy. In this study, the impact of initial pH and urea hydrogen peroxide (UHP) co-pretreatment on sludge hydrolysis and anaerobic digestion was investigated. The pH of sludge was initially adjusted to 7, 9, and 11 before the addition of 8 mmol/g VS UHP. Under 24 h pretreatment, alkaline medium and UHP effectively enhanced sludge solubilization and hydrolysis. The combination of chemical, sonication, and centrifugation improved the extraction of extracellular polymerase substances released in soluble state. Secondly, anaerobic digestion was performed for 11 days to determine the influence of a lower mesophilic temperature (20 °C) and retention time on the pretreated sludge. The highest NH 4 + -N concentration of 5.32 g/L was recorded in pH 7+UHP. The most significant total VFA concentration of 13.1 g COD/L was observed in pH 7+UHP on day 9. Acetic acid, isovaleric acid and propionic acid accounted for 80%-83% of the total VFA composition in all pretreated reactors. Lower mesophilic temperature efficiently optimized UHP and VFA production in the pretreated reactors. Microbial metabolism was stabilized under a longer retention time. Alkaline pH and longer retention time elevated NH 4 + -N and VFA concentration. The results showed that initial pH and UHP co-pretreatment of waste activated sludge offer an alternative pathway for enhancing sludge hydrolysis and VFA production applicable in sludge treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

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

Objectives: To evaluate the bleaching efficacy and permeability of hydrogen peroxide (HP) in the pulp chamber of human teeth bleached with lower concentrations of carbamide peroxide gel (4%, 5% and 7% CP)., Materials and Methods: Bleaching gels with lower concentrations were formulated and a commercial standard gel, 10% CP, was used as a reference. Fifty-six human premolars were randomly divided into four groups. Applications of the bleaching gel were made for 3 h for 21 days. The bleaching efficacy was evaluated by digital spectrophotometry on 1, 7, 14 and 21 days, with analysis in the ∆E ab , ∆E 00 and WI D color spaces. The concentration of HP in the pulp chamber was measured in the same periods by UV-Vis spectrophotometry (µg/mL). Two-way repeated analysis of variance (ANOVA) examined bleaching efficacy and HP permeability, followed by Tukey's post-hoc test (α = 0.05)., Results: All groups showed significant color changes, with no statistical differences after the second and third week of bleaching (p > 0.05). The 'time' factor was statistically different (p < 0.05), increasing the bleaching efficacy throughout the treatment. The 4% CP group had lower HP levels in the pulp chamber (p < 0.05)., Conclusions: The results seem promising, revealing that low concentration gels are as effective as 10% CP with the benefit of reducing the amount of HP in the pulp chamber., Clinical Relevance: Low concentration 4% PC and 5% PC maintains bleaching efficacy, reduces the penetration of HP peroxide into the pulp chamber, and may reduce tooth sensitivity., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study aimed to answer the question through a systematic review: Can carbamide peroxide be as effective as hydrogen peroxide and cause less in-office bleaching sensitivity? A literature survey was performed in PubMed/MEDLINE, Embase, Scopus, ISI Web of Science, and gray literature. Primary clinical trials that compared the efficacy or the in-office bleaching sensitivity between carbamide and hydrogen peroxides were included. The risk of bias was evaluated using the RoB2. The certainty of the evidence was assessed using the GRADE approach. DPI training significantly improved the mean scores of the dental undergraduates from 7.53 in the pre-DPI-training test to 9.01 in the post-DPI-training test ( p < 0.001). After 6 weeks, the mean scores decreased marginally to 8.87 in the retention test ( p = 0.563). DPI training increased their confidence level from 5.68 pre-DPI training to 7.09 post-DPI training. The limited evidence suggests that the 37% carbamide peroxide may be similarly effective to the 35% hydrogen peroxide for bleaching teeth in-office and causes less bleaching sensitivity. However, more well-designed split-mouth clinical trials are necessary to strengthen the evidence., Competing Interests: Conflict of Interest: No potential conflict of interest relevant to this article was reported., (Copyright © 2024. The Korean Academy of Conservative Dentistry.)

Objectives: To assess color change efficacy and the adverse effects of varied over-the-counter (OTC) bleaching protocols., Methodology: The study included randomized clinical trials evaluating color changes from OTC bleaching agents. Nine databases were searched, including the partial capture of the grey literature. The RoB2 tool analyzed the individual risk of bias in the studies. Frequentist network meta-analyses compared treatments through common comparators (∆Eab* and ∆SGU color changes, and tooth sensitivity), integrating direct and indirect estimates and using the mean and risk differences as effect measures with respective 95% confidence intervals. The GRADE approach assessed the certainty of the evidence., Results: Overall, 37 remaining studies constituted the qualitative analysis, and ten composed the meta-analyses. The total sample included 1,932 individuals. ∆Eab* was significantly higher in groups 6% hydrogen peroxide (HP) strips (≥ 14 h). ∆SGU was significantly higher in groups at-home 10% carbamide peroxide (CP) (≥ 14 h), followed by 6% HP strips (≥ 14 h) and 3% HP strips (≥ 14 h). At-home 10% CP (7-13 h) and placebo showed lower risks of tooth sensitivity without significant differences between these treatments., Conclusion: Considering the low level of evidence, OTC products presented satisfactory short-term effects on tooth bleaching compared to the placebo, with little to no impact on dentin hypersensitivity and gingival irritation., Clinical Relevance: OTC products are proving to be practical alternatives for tooth whitening. However, patients should be advised about the possible risks of carrying out such procedures without professional supervision., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: Accumulated and compacted ear wax or cerumen can cause conductive hearing loss, discomfort and vertigo, and infection. This study investigates the effect of Carbamide peroxide (CP) compared with Phenol glycerin (PG) ear drops on cerumen., Materials and Methods: This experimental study investigated the effect of PG and CP ear drops on cerumen in ex vivo and in vivo phases. In the ex vivo phase cerumen degredation was scored following PG and CP treatments. In the in vivo phase, 29 patients with bilateral cerumen impaction were randomly entered the study. PG and CP were applied 3 times a day (each time 5 drops) for 4 days by patients. After treatments, the time of cerumen removal was measured., Results: Instant changes showing degredation of cerumen (grade 1) was evident when it was exposed to CP, on the other hand degredation changes (grade 1) in cerumen treated with PG was only evident after 20 min incubation at 37 o C, while grade 3 degredation was evident in cerumen treated with CP after the same time incubation. Although the time needed for removal of cerumen was lower in CP treatment (54.10±31.77) compared to PG treatment (67.10±35.54), the difference was not statistically significant., Conclusion: Based on the literature and our results, carbamide peroxide is suggested as a proper treatment for patients with EAC obstruction caused by cerumen compaction, because not only it is significantly effective in cerumen degredation, but also no side effects have been reported.

Background and Aim: Teeth bleaching, although considered safe and conservative, cause microscopic changes in the tooth structure. The aim of this study is to evaluate the bleaching efficacy of carbamide peroxide (CP) bleaching gel when modified with the incorporation of bioactive glass (BG) and hydroxyapatite (HA) and its effect on enamel microhardness., Materials and Methods: Forty-five maxillary incisors were decoronated, artificially stained and mounted in acrylic. The samples were divided into three groups of 15 each and subjected to the following bleaching protocol for 8 h/day at 37°C for 2 weeks: Group 1 - 16% CP, Group 2 - CP modified with BG, and Group 3 - CP modified with hydroxyapatite (HA). Spectrophotometric color assessment using CIE L*a*b* system and Vickers microhardness were assessed before and after bleaching. Data were analyzed using Student's paired t -test and one-way ANOVA followed by Tukey's post hoc analysis., Results: There was a significant change in color (L*a*b*) in all the three groups when compared to the baseline values. However, no significant difference in the total color change (ΔE) was observed between the three groups. Enamel microhardness reduced significantly in the CP group, whereas it increased in the BG and HA group after bleaching. Scanning electron microscopy images of BG and HA groups showed crystalline deposits suggesting mineral deposition., Conclusion: Addition of biomaterials can be a beneficial alternative to bleaching with CP alone, considering the increase in microhardness without hindering the bleaching action., Competing Interests: There are no conflicts of interest., (Copyright: © 2024 Journal of Conservative Dentistry and Endodontics.)

This clinical trial investigated the effects of pre-application enamel moistening on the impact of a 37% carbamide peroxide whitener on tooth color changes and the influence of repositioning guide colors. Forty participants were randomly assigned to in-office tooth bleaching with either moistened enamel (experimental) or dry enamel (control). The whitener was applied for 45 min over two sessions. Tooth color was visually measured or assessed using a spectrophotometer with purple or green silicone guides. Tooth bleaching was assessed using CIE76 (ΔE ab ) and CIEDE2000 (ΔE 00 ) formulas and by whitening and bleaching index score changes. Moistening the enamel did not significantly affect tooth color. However, the guide color choice only impacted tooth color when measured instrumentally. At baseline, the green guide resulted in statistically significantly whiter teeth than the purple guide. Less pronounced differences in the b* coordinate between baseline and final measurements were found using the green guide. The green guide also produced lower ΔE ab values and less change in indexes. In conclusion, moistening the enamel did not significantly impact tooth color changes. However, the repositioning guide color influenced the tooth bleaching measured instrumentally, except for ΔE 00 ., (© 2023 Scandinavian Division of the International Association for Dental Research. Published by John Wiley & Sons Ltd.)

Objective: This study assessed whether combining photobiomodulation therapy (PBMT) with casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF) paste can effectively reduce post-home whitening tooth sensitivity (TS) without compromising shade change., Methods: Fifty participants were selected and assigned to one of four groups: (1) PLACEBO group-received a placebo paste and PBMT simulation; (2) PBMT group-received a placebo paste + PBMT; (3) CPP-ACPF group-received CPP-ACPF paste and PBMT simulation; (4) CPP-ACPF + PBMT group-received both CPP-ACPF paste and PBMT. The participants used whitening trays containing 22% carbamide peroxide for 2 h a day for 21 days. TS was measured daily using a visual analog scale, while shade change was assessed using a spectrophotometer: before bleaching treatment (T0), after the first (T1), second (T2), and third (T3) weeks of treatment, and 30 days (T4) after completing the whitening treatment., Results: Intragroup analysis revealed that the PLACEBO group had the highest increase in sensitivity during the whitening treatment. The CPP-ACPF and PBMT groups showed no significant difference tooth whitening (TW) between weeks regarding aesthetic change. The CPP-ACPF and PBMT group exhibited a significant reduction in TS between the first and third and between the second and third weeks TW, but not between the first and second. Conversely, the PLACEBO group showed a higher sensitivity than the other groups (p < .05). The CPP-ACPF and PBMT groups did not differ from each other. Furthermore, the CPP-ACPF and PBMT group showed a greater decrease in sensitivity than the PLACEBO group at T1, T2, and T3 (p < .01), and was significantly differed from CPP-ACPF and PBMT groups only at T2 and T3. All groups confirmed TW effectiveness. Student's and paired t-test did not reveal any significant difference between groups (p > .05)., Conclusion: Therefore, PBMT associated with CPP-ACPF paste can reduce TS without compromising the efficacy of TW., (© 2024 The Authors. Clinical and Experimental Dental Research published by John Wiley & Sons Ltd.)

A greenhouse experiment was conducted to examine the effects of urea hydrogen peroxide (UHP) on reducing the accumulation of As in rice grains. The results show that UHP effectively triggered Fenton-like reaction by reacting with Fe 2+ in the paddy soils. This significantly inhibited the activities of As(V)-reducing microbes, causing impediment of As(V)-As(III) conversion following inundation of dryland crop soils for paddy rice cultivation. As-methylating microbes were also inhibited, adversely affecting As methylation in the soils. These processes led to the reduction in phyto-availability of As in the soil solutions for uptake by rice plant roots, and consequently reduced the accumulation of As in the rice grains. In this study, an UHP application rate of 0.0625% on three occasions (tillering, heading and filling) during the rice growth period was sufficient to lower the rice grain-borne As concentration to below 0.2 mg/kg, meeting the quality standard set by the Chinese government. No additive effect on reducing grain-borne As was observed for the joint application of UHP and biochar or biochar composite. The use of UHP for soil fertilization had no adverse impact on rice yield in comparison with the application of urea at an equal amount of nitrogen., 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 © 2023. Published by Elsevier Ltd.)

Objectives: This study aimed to compare changes in oral health-related quality of life (OHRQoL) resulting from three vital tooth bleaching protocols., Methods: The participants (n = 105) were randomly assigned to one of three vital bleaching treatment groups: home bleaching (HB), in-office bleaching (IOB), or combined bleaching (CB). HB involved the use of custom-made trays and 10% carbamide peroxide for a 14-day treatment period. IOB utilized 37.5% hydrogen peroxide applied in three cycles. CB treatment involved the use of IOB followed by HB. Tooth colour change was evaluated using a shade guide (ΔVS) and a digital spectrophotometry device (ΔES). The Oral Health Impact Profile-14 (OHIP-14) and Oral Impact on Daily Performance-22 (OIDP-22) instruments were used to assess changes in OHRQoL at baseline, 15-days and 6-month recalls. Linear mixed models were used to estimate between- and within-group differences., Results: All bleaching protocols led to significant improvements in overall OHIP-14 scores at the 6-month recall (p ≤ 0.037). CB and IOB treatments were associated with more substantial positive impacts on overall scores, psychological discomfort, physical disability (CB only), and psychological disability (CB only) compared to HB (p ≤ 0.011). Significant enhancements in OIDP-22 scores were observed in the CB and HB groups at the 6-month recall compared to baseline (p ≤ 0.006), with evidence indicating that these improvements were greater in the CB group compared to the IOB group (p = 0.007)., Conclusion: All bleaching treatments demonstrated a positive impact on OHRQoL. However, the positive impact was most consistent across domains and age groups in the CB group. The positive impact was less pronounced in older age groups., Competing Interests: 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., (© 2023 THE AUTHORS.)

Background: This in vitro study evaluated the efficacy and the effect over the dental enamel surface of violet LED dental bleaching associated to different concentrations of carbamide and hydrogen peroxide., Methods: Human dental blocks (n = 100) were randomly distributed into 5 groups: 10% hydrogen peroxide (HP10), 10% carbamide peroxide (CP10), 10% hydrogen peroxide with violet LED (VHP10), 10% carbamide peroxide with violet LED (VCP10) and 35% hydrogen peroxide (HP35). The specimens were analyzed by Vickers microhardness test (n = 50) initially, immediately after and seven days after ending the bleaching protocol. For color analysis (n = 50), the specimens were evaluated for bleaching effectiveness (ΔE2000, ΔE1976) and whiteness index (ΔWID) with EasyShade spectrophotometer, before bleaching protocol and seven days after ending the bleaching protocol. The microhardness and color data were analyzed using one-way ANOVA with post-hoc Tukey test (α = 0.05)., Results: The microhardness values showed difference among the investigated groups only immediately after the end of the dental bleaching (p < 0.05), with reduction for the groups HP35 (p < 0.01) and HP10 (p < 0.05), however the microhardness values were reestablished after seven days. Regarding the color changes, a difference between VHP10 and the others groups evaluated for ΔE2000 and ΔE1976 index was observed (p < 0.05). For ΔWID, there was no difference between the studied groups., Conclusions: Violet LED associated with low concentration bleaching agents did not show a negative effect on dental enamel regarding the surface microhardness. All bleaching protocols were effective, therefore, perceptible to human eyes., Competing Interests: Declaration of Competing Interest The authors declare no known competing financial interests or personal relationships in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Background: The effectiveness of dental color change was assessed by incorporating titanium dioxide (TiO 2 ) into 37% carbamide peroxide bleaching agent associated with hybrid light., Methodology: Fifty bovine incisors were selected to receive the bleaching treatment, and separated into five groups (n = 10): 35% hydrogen peroxide (HP) (Whiteness HP, FGM/HP); 37% carbamide peroxide (CP) (Whiteness SuperEndo, FGM/CP); CP + hybrid light (HL) (CP HL); CP + 1% TiO 2 (CP TiO 2 ); CP TiO 2  + hybrid light (CP TiO 2 HL). The bleaching gels were applied to the dental surface for 30 min. Hybrid light (Whitening Plus, DMC/infrared laser diodes + blue LEDs +violet LEDs) was applied with 1 min of active light, alternating with 1 min of pause. A spectrophotometer (VITA Easyshade® Advance, Vita) was used to determine the color of the dental elements at baseline and time points after the 1st, 2nd and 3rd bleaching sessions. Color change effectiveness was evaluated using Vita Classical, CIEL*a*b*, WI D and ΔE ab , ΔE 00 and ΔWI D parameters., Results: Generalized mixed linear models for repeated measures (α = 5%) showed significant decrease in Vita Classical scores and a* and b* values, as well as an increase in L* and ∆W ID values for all the groups. Higher color change values for ΔE ab were observed for CP HL and CP TiO 2 HL, while those of ΔE 00 and ΔWI D were higher for CP TiO 2 HL at the end of the bleaching treatment., Conclusion: Hybrid light applied with TiO 2 incorporated into CP potentiated the effectiveness of the color change in the tooth structure ., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023. Published by Elsevier B.V.)

Objective: To evaluate the effects of activated charcoal-based products used in two presentation forms (powder or toothpaste), compared to 10 % carbamide peroxide and conventional toothpaste on aesthetic perception and psychosocial impact before and after treatment., Methods: Fifty-six participants were divided into 4 experimental groups (n = 14). Activated charcoal-based powder (PW); Activated charcoal-based dentifrice (AC); Conventional fluoride toothpaste (CD) and 10 % carbamide peroxide (CP). All products were used for 14 days. Psychosocial impact on dental esthetics (PIDAQ), oral health impact profile (OHIP- Esthetics) and orofacial esthetics scale (OES) questionnaires were applied before and after treatment. Descriptive and exploratory data analyses were performed and analyzed using linear mixed models for repeated measures over time considering significance level of α = 0.05., Results: For PIDAQ, the CP group showed significant decrease in psychological impact, aesthetic perception domains and overall score, while in the PW group, there was only a significant decrease in the psychological impact domain. Decrease in OHIP was observed for the functional limitation domain scores for treatments with CP and PW, in the psychological discomfort domain, decrease was observed for all groups, while for the OES questionnaire, significant increase in the color domain was observed for the CP group., Conclusion: Activated charcoal-based products showed lower scores in all questionnaires when compared with carbamide peroxide; thus, charcoal-based products promoted lower impact on quality of life and aesthetic perception., Clinical Relevance: In this randomized clinical trial, charcoal-based OTC products had inferior quality of life and aesthetic perception results compared to conventional carbamide peroxide bleaching., 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 © 2023 Elsevier Ltd. All rights reserved.)

Background: The effectiveness of in-office bleaching protocols performed with violet LED light either combined with a bleaching agent containing 37% carbamide peroxide, or not, was determined by comparing teeth with different degrees of darkening., Methodology: Eighty bovine incisors were separated into groups of "light" teeth (luminosity greater than or equal to B3) and "dark" teeth (less than or equal to A3.5) to receive the protocols: HP - 35% hydrogen peroxide (Whiteness HP), CP - 37% carbamide peroxide (Whiteness SuperEndo), LED - violet LED light (Bright Max Whitening), CPLED - CP associated with the LED. For color analysis the CIEL*a*b* e WI D , ΔE ab , ΔE 00 e ΔWI D parameters were used. Data were analyzed using Mann-Whitney, Kruskal-Wallis, Dunn, Friedman or Nemenyi tests (α = 5%)., Results: HP and CP resulted in similar color change values (ΔE ab , ΔE 00 e ΔWI D ) for light and dark teeth (p > 0.05). Dark teeth showed better bleaching effectiveness (ΔE ab , ΔE 00 e ΔWI D ) than light teeth when CPLED was used (p < 0.05). LED showed color change that were below the limits of acceptability and perceptibility for ΔWI D ., Conclusion: light teeth are effectively bleached with the use of HP or CP, whereas dark teeth respond better to treatment with the CPLED protocol. Violet LED used alone did not show a satisfactory result., Competing Interests: Declaration of Competing Interest The authors declare there is no conflict of interests., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Unsaturated lipids containing different numbers and locations of C═C bonds are significantly associated with a variety of cellular and metabolic functions. Although matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) has been used to visualize the spatial distribution patterns of various lipids in biological tissues, in situ identification, discrimination, and visualization of lipid C═C location isomers remain challenging. Herein, an efficient and fast on-tissue chemical derivatization (OTCD) approach was developed to pinpoint the locations of C═C bonds in complex lipids in situ via methyltrioxorhenium (MTO)-catalyzed epoxidation of C═C with a urea hydrogen peroxide (UHP)/hexafluoroisopropanol (HFIP) system. The efficiency of OTCD could reach 100% via one-step spray deposition of the solution mixture of MTO/UHP/HFIP at room temperature. The developed OTCD method provided rich structural information on lipid C═C location isomers, and their accurate spatial distribution patterns were resolved in mouse brain tissues. Tissue-specific distributions and changes of lipid C═C location isomers in the liver sections of obese ob / ob and diabetic db / db mice were further investigated, and their correlation in two animal models was revealed. The simplicity and high efficiency of the OTCD method developed for MALDI tandem MSI of lipid C═C location isomers possess great potential for functional spatial lipidomics.

Improving the anaerobic treatment performance of waste activated sludge (WAS) to achieve resource recovery is an indispensable requirement to reduce carbon emissions, minimize and stabilize biosolids. In this study, a novel strategy by using urea hydrogen peroxide (UHP) to enhance SCFAs production through accelerating WAS disintegration, degrading recalcitrant substances and alleviating competitive suppression of methanogens. The SCFAs production and acetate proportion rose from 436.9 mg COD/L and 31.3% to 3102.6 mg COD/L and 54.1%, respectively, when UHP grew from 0 to 80 mg/g TSS. Mechanism investigation revealed that OH, O 2 and urea were the major contributors to accelerate WAS disintegration with the sequence of OH> O 2  > urea. Function microbes related to acidification and genes associated with acetate production ([EC:2.3.1.8] and [EC:2.7.2.1]) were upregulated while genes encoding propionic acid production ([EC:6.4.1.3] and [EC:6.2.1.1]) were downregulated. These results raised the application prospects of UHP in WAS resource utilization., 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 © 2023 Elsevier Ltd. All rights reserved.)

This study aimed to clinically evaluate the effectiveness of two different at-home whitening protocols and to determine which is more effective: applying the whitening gel (16% carbamide peroxide) every 24 hours (Group A) or every 48 hours (Group B) for 2 weeks. Group C received a placebo gel (glycerin) without peroxide, which was applied every 24 hours for 2 weeks. The differences in terms of tooth sensitivity were also analyzed. A sample of 60 patients was divided into three groups of 20 patients. To compare the groups, color measurements were made using a spectrophotometer, and Student t test was used for independent samples. The confidence level was set at 95% (P ≤ .05). No statistically significant differences were found between Groups A and B (P > .05). The study concluded that 16% carbamide peroxide was equally effective when applied with either protocol and obtained the same results, but the 48-hour application protocol produced less sensitivity than the 24-hour application protocol.

Objective: This in vitro study aimed to evaluate the effects of different whitening toothpastes on a composite resin during at-home bleaching with 10% carbamide peroxide., Materials and Methods: Sixty samples (7 mm × 2 mm) were used for color and roughness analyses, while another 60 samples (3 mm × 2 mm) were utilized to assess microhardness. The factors analyzed included toothpaste, for which 5 options with varying active agents were tested (distilled water; conventional toothpaste; whitening toothpaste with abrasive agents; whitening toothpaste with abrasive and chemical agents; and whitening toothpaste with abrasive, chemical, and bleaching agents). Brushing and application of whitening gel were performed for 14 days. Surface microhardness (SMH), surface roughness (Ra), and color (∆L*, ∆a*, ∆b, ∆E* ab , and ∆E 00 ) were analyzed. The Ra and SMH data were analyzed using mixed generalized linear models for repeated measures, while the color results were assessed using the Kruskal-Wallis and Dunn tests., Results: Between the initial and final time points, all groups demonstrated significant increases in Ra and reductions in SMH. No significant differences were found between groups for SMH at the final time point, at which all groups differed from the distilled water group. Conventional toothpaste exhibited the lowest Ra, while whitening toothpaste with abrasive agent had the highest value. No significant differences were observed in ∆L*, ∆a*, and ∆b., Conclusions: While toothpaste composition did not affect the color stability and microhardness of resin composite, combining toothbrushing with whitening toothpaste and at-home bleaching enhanced the change in Ra., Competing Interests: Conflict of Interest: No potential conflict of interest relevant to this article was reported., (Copyright © 2023. The Korean Academy of Conservative Dentistry.)

Objective To compare and evaluate the efficacy of tooth bleaching with prior application of two different desensitizing agents such as sodium fluoride and 5% potassium nitrate. Materials and methods A total of 108 extracted human maxillary central incisors were stained in black coffee solution and stored in artificial saliva for colour stabilization. The specimens were randomly divided into three groups (n = 36) according to the following protocols: (a) bleaching without desensitizer, (b) bleaching with prior application of sodium fluoride, and (c) bleaching with prior application of 5% potassium nitrate. After fabricating customized trays, desensitizers were applied for 10 minutes followed by 16% carbamide peroxide bleaching gel, which was in contact with the teeth for three hours. The bleaching efficacy was evaluated at baseline (after staining), 3rd day, 7th day, and 14th day using a digital spectrophotometer. Results There was an increase in the overall colour change (∆E) from baseline to 14th day, which was statistically significant at cervical, middle, and incisal thirds of the teeth between the three groups with the sodium fluoride group showing decreased ∆E. Conclusions Carbamide peroxide (16%) showed improved whitening efficacy from baseline to the 14th day with increasing median values at all time periods. The sodium fluoride group showed decreased ∆E value when compared to other groups., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Parthasarathy et al.)

The effect of annual at-home bleaching on the color, translucency, and whiteness properties of computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic materials requires investigation. The aim of the present in vitro study was to evaluate the effect of simulated annual at-home bleaching (consisting of daily applications for 10 hours a day for 14 days), for up to 3 years, on susceptibility to staining (ΔE00), translucency (ΔTP00), and whiteness (ΔWID) variations and on topography of CAD-CAM monolithic materials. Disks from the Lava Ultimate (LU), Vita Enamic (VE), IPS Empress CAD (EMP), and IPS e.max CAD (EMAX) were allocated as follows: 1) nonbleached or 2) bleached with 10% carbamide peroxide. After reading the CIE L*a*b* coordinates at baseline (R0), specimens were bleached or not and subsequently immersed for a 1-year simulated period in coffee before the next reading (R1). This process was repeated two more times, resulting in R2 and R3. The ΔE00, ΔTP00, and ΔWID between R1, R2, and R3 in relation to R0 were calculated. The surface topography was analyzed by scanning electron microscopy. In general, bleaching increased the staining susceptibility of all materials when compared to the nonbleached groups and that of the LU, VE, and EMAX over the years. Bleaching decreased the translucency of the VE in all years and over the years. When compared to the nonbleached groups, bleaching decreased the whiteness of the LU and EMAX and increased the whiteness of the EMP, while the VE was not affected. In the LU, the whiteness decreased over the years in both treatments, whereas the other materials were not affected with time. All materials showed progressive topographic changes over the years. The simulated annual at-home bleaching with 10% carbamide peroxide adversely affected the topography and the optical and/or colorimetric properties of the evaluated materials., (©Operative Dentistry, 2023.)

Purpose: This study evaluated enamel with early-stage erosion/abrasion following bleaching with 20% and 45% carbamide peroxide (CP) gels containing fluoride (F) and irradiated with violet LED (LED)., Methods: Enamel blocks were immersed in 1% citric acid (5 min) and artificial saliva (120 min) three times to produce early-stage enamel erosion. Simulated toothbrushing was performed only after the first saliva immersion, to provoke enamel abrasion. The erosive/abraded enamel samples were submitted to (n=10): LED/CP20, CP20, LED/CP20&#95;F, CP20&#95;F, LED/CP45, CP45, LED/CP45&#95;F, CP45&#95;F, LED, and control (without treatment). The pH of the gels was assessed, and color (ΔE 00 ) and whiteness index (ΔWI D ) changes were calculated after cycling (T 1 ), and 7 days from bleaching (T 2 ). Enamel surface roughness average (Ra) and Knoop microhardness (kg/mm 2 , %SHR) were evaluated at baseline (T 0 ) at T 1 and T 2. Scanning electron microscopy evaluated the enamel surface morphology at T 2 ., Results: The gels' pH was neutral and CP20 and CP45 exhibited no differences in ΔE 00 and ΔWI D (p>0.05) but LED increased these parameters for CP20&#95;F and CP45. Erosion/abrasion significantly decreased mean kg/mm 2 , and the LED group was the only one not increasing microhardness after bleaching (p>0.05). None of the groups fully recovered the initial microhardness. All groups exhibited %SHR similar to the control (p>0.05) and the increase in Ra was detected only after erosion/abrasion. CP20&#95;F groups exhibited a more preserved enamel morphology., Conclusion: Light irradiation combined with low-concentrated CP gel promoted a bleaching effect comparable to the high-concentrated CP. The bleaching protocols did not adversely impact the surface of early-stage eroded/abraded enamel., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: Dental color change and the temperature of the pulp chamber and of the buccal surface were evaluated during bleaching with 37% carbamide peroxide (CP) with continuous vs fractionated violet LED light protocols., Methodology: Bovine incisors received in-office bleaching for 30 min using different light protocols (Bright Max Whitening, MMOptics). Teeth were separated into groups (n = 10): HP) 35% hydrogen peroxide (Whiteness HP, FGM)/no light; CP) 37% carbamide peroxide (Whiteness SuperEndo, FGM)/no light; CP10) CP+10 min of continuous light; CP20) CP+20 min of continuous light; CP30) CP+30 min of continuous light; CPF) CP+20 cycles of 60 s light / 30 s no light (fractionated). Color evaluations were performed at different times. Evaluations of pulp and buccal surface temperatures were performed before and throughout the 30 min of bleaching., Results: Generalized linear models for repeated measures over time were applied to the data (α=5%). After the 1st session, CP20 and CP30 had significantly lower b* values ​​than CP and CP10 (p = 0.0071). For ΔE ab and ΔE 00 , CPF, CP20 and CP30 showed the highest color change among the treatments after the third bleaching (p<0.05). For temperature evaluations, CP30 showed higher pulp and buccal surface temperatures than the other protocols (p<0.0001) after 20 min., Conclusion: Fractionated or continuous application of violet LED for 20 or 30 min leads to greater effectiveness of color change. All protocols with the application of LED led to an increase in pulp and buccal surface temperatures during bleaching, although the fractionated application appeared to be safer than the use of continuous light., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The interaction of bleaching technique (in-office or at-home) and solutions (deionized distilled water with and without sugar, red wine with and without sugar, coffee with and without sugar) on the effectiveness of in vitro dental bleaching was evaluated. Hydrogen peroxide (HP) 37.5% gel was used for in-office bleaching, 3 applications of 8 min each, 3 sessions with an interval of 7 days. At-home bleaching was performed with 10% Carbamide peroxide (CP), 2 h/day, for 30 days. The enamel vestibular surfaces (n = 72) were subjected daily to test solutions for 45 min, washed with distilled water for 5 min and stored in artificial saliva. The enamel color analysis was performed with a spectrophotometer through color variation (ΔE) and luminosity variation (ΔL). Roughness analysis was performed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Enamel composition was determined by energy dispersive X-ray spectrometry (EDS). The results were submitted to one-way analysis of variance (ANOVA) for ΔE, ΔL and EDS and two-way for AFM. For ΔE and ΔL there was no statistically significant difference. An increase in roughness was observed on the surface when exposed to a sugar-water solution for at-home bleaching and a lower concentration of Ca and P in the deionized water solution with sugar. Solutions containing or not sugar did not influence the bleaching potential, however the presence of sugar in the water solution increased the surface roughness with CP., 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 © 2023 Elsevier Ltd. All rights reserved.)

Background and Objectives: This study aimed to evaluate the surface roughness evolution of several finished and polished composites when bleaching materials are applied. The research was conducted on four microhybrid or nanofilled composites that are used in dental restorations. Materials and Methods: For each composite type, 5 samples were selected for control, 5 samples were subjected to the bleaching protocol "office bleach" with 40% hydrogen peroxide, and 5 other samples were subjected to the "home bleach" protocol with 16% carbamide peroxide, resulting in a total number of 60 samples. The surfaces of all the samples were tested for roughness, and the values of the most relevant parameter (Ra), were collected. Comparisons between composites and samples were performed using one-way ANOVA (in Statistical Package for Social Sciences). Results: After the bleaching protocol with 40% hydrogen peroxide gel, it was found that the roughness of the group increased considerably compared to the control group, so the highest roughness was found at GC Gradia direct anterior group, and the lowest value was registered for the 3M ESPE Valux Plus group. Following the bleaching protocol with 16% carbamide peroxide (home bleach), it was noted that the sample surfaces were not as affected. In this case, the lowest roughness was found at 3M ESPE Valux Plus group, and the highest roughness was registered for the GC G-aenial anterior group. Following the interpretation of the results, all four types of dental composites tested showed significant surface roughness differences between the groups subjected to bleaching protocols and those kept as control ( p < 0.05). Conclusions: The surfaces of the samples were affected by the bleaching protocols by increasing the roughness compared to the control samples.

The high aesthetic demands of patients have increased their requests to align their teeth using clear aligners, including Invisalign. Patients also want to have their teeth whitened for the same purpose; the use of Invisalign as a bleaching tray at night has been reported in few studies. However, whether 10% carbamide peroxide affects the physical properties of Invisalign is unknown. Therefore, the objective of this study was to evaluate the effect of 10% carbamide peroxide on the physical properties of Invisalign when used as a bleaching tray at night. Twenty-two unused Invisalign aligners (Santa Clara, CA, USA) were used to prepare 144 specimens to test their tensile strength, hardness, surface roughness, and translucency. The specimens were divided into four groups: a testing group at baseline (TG1), a testing group after application of bleaching material at 37 °C for 2 weeks (TG2), a control group at baseline (CG1), and a control group after immersion in distilled water at 37 °C for 2 weeks (CG2). Statistical analysis was conducted using a paired t-test, Wilcoxon signed rank test, independent samples t-test, and Mann-Whitney test to compare samples in CG2 to CG1, TG2 to TG1, and TG2 to CG2. Statistical analysis showed no statistically significant difference between the groups for all physical properties, except for hardness ( p -value < 0.001) and surface roughness ( p -value = 0.007 and p -value < 0.001 for the internal and external surface roughness, respectively), which revealed a reduction in hardness values (from 4.43 ± 0.86 N/mm 2 to 2.2 ± 0.29 N/mm 2 ) and an increase in surface roughness (from 1.6 ± 0.32 Ra to 1.93 ± 0.28 Ra and from 0.58 ± 0.12 Ra to 0.68 ± 0.13 Ra for the internal and external surface roughness, respectively) after 2 weeks of dental bleaching. Results showed that Invisalign can be used for dental bleaching without excessive distortion or degradation of the aligner material. However, future clinical trials are required to further assess the feasibility of using Invisalign for dental bleaching.

Background This study was designed to evaluate the efficacy of standard at-home bleaching agents in comparison to new over-the-counter (OTC) products on human enamel regarding color change, color stability, and surface roughness. Methodology A total of 80 extracted adult human maxillary central incisors were prepared and arbitrarily divided into the following four equal groups (N =20): group A: at-home opalescence boost containing 15% carbamide peroxide (CP); group B: crest whitening strips containing 6% hydrogen peroxide (HP); group C: light-emitted diode (LED) home tray with 20% CP + 4% HP; and group D: white and black toothpaste containing active charcoal components. Tooth color was measured using a spectrophotometer. Enamel surface roughness using a three-dimensional optical profilometer was measured before and after the bleaching procedure. To assess color stability, each bleached group was further subdivided into two equal subgroups (n = 10) according to the immersion media of either coffee or tea. Finally, the color was measured after 24 hours of immersion. Results All groups showed improvement in color from the baseline. The crest whitening strips group showed the lowest color improvement in comparison to all other groups. After staining, group C showed the lowest mean color change value ∆E2. No statistically significant difference was noted in surface roughness among all groups. Conclusions All OTC bleaching products as well as at-home bleaching improve teeth color and increase roughness on the enamel surface. Staining media has an adverse effect on the teeth after bleaching. The LED home tray showed a better whitening effect and color stability after bleaching., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Basheer et al.)

After ozone therapy for bleaching, it is important to evaluate enamel surface properties, to ensure that bleaching provides adequate conditions for sound dental substrate. Aim: The aim of this in vitro study was to evaluate the effects of a bleaching treatment with 10% carbamide peroxide (CP), with or without ozone (O), on the microhardness, roughness and micromorphology of the enamel surface., Materials and Method: Bovine enamel blocks were planed and distributed among the following three bleaching treatment groups (n=10): CP - 1 hour per day/14 days (Opalescence PF 10%/ Ultradent); O - 1 hour per day every 3 days/3 sessions (Medplus V Philozon, 60 mcg/mL and oxygen flow rate of 1 L/min); and OCP - CP with O, 1 hour per day every 3 days/3 sessions. Enamel surface microhardness (Knoop), roughness (Ra), and micromorphology by scanning electron microscopy (5,000x magnification) were determined before and after the treatments., Results: ANOVA and Tukey-Kramer’s test showed that enamel microhardness remained unchanged by treatment with O and OCP (p=0.0087), but decreased by treatment with CP. Treatment with O promoted higher enamel microhardness than the other groups (p=0.0169). Generalized linear mixed models for repeated measures over time indicated treatment with CP increased enamel roughness more than OCP or O (p=0.0003). CP produced slight irregularities in enamel micromorphology after the whitening treatment. O, with or without CP, maintained the mechanical and physical properties of microhardness and enamel surface micromorphology, and either maintained or reduced surface roughness, compared to the conventional tray-delivered CP bleaching treatment., Conclusions: Treatment with 10% carbamide peroxide in trays promoted greater changes in enamel surface properties than treatments with ozone and with 10% ozonized carbamide peroxide in the office., Competing Interests: The authors declare no potential conflicts of interest regarding the research, authorship, and/or publication of this article.

Most of the existing oxidation denitrification methods need longer residence time to obtain higher NOx removal efficiency. In this study, urea peroxide (CO(NH 2 ) 2 ·H 2 O 2 ) was first used for removing SO 2 and NOx on diesel engine bench. The addition of ferrous sulfate can enhance the oxidant capacity of the solution. The better removal efficiency and lower nitrate content in liquid can be achieved in short exhaust gas residence time. The raw gas flow and residence time contained the actual application situation in ships and have high reference value. The removal efficiency decreased with the increase of gas flow, and the reaction temperature, urea peroxide concentration, liquid-gas ratio were the main factors. The optimal Fe 2+ concentration of 50 mmol/L and pH value of 4 were determined. The urea peroxide concentration, reaction temperature, and liquid-gas ratio were 9%, 70 ℃, and 10 L/m 3 respectively. The maximum gas treatment capacity was about 100 L/min, and residence time was close to 10 s for the scrubber. The pre-agglomerating method were used to improve the particle capturing efficiency combined with spray technology. The composited method can realize the synchronous and efficient removal of multiple pollutants in a single scrubber. The possibility of application on ship was further increased., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The objective of this study was to synthesize a novel choline hydroxide ionic liquid-based tooth bleaching gel. Ionic liquid-based gels were synthesized and characterized using FTIR along with pH testing. Tooth sample preparation was carried out in line with ISO 28399:2020. The effects of synthesized gels on tooth samples were tested. Tooth samples were stained and grouped into three experimental groups: EAI (22% choline hydroxide gel), EAII (44% choline hydroxide gel), and EB (choline citrate gel) and two control groups: CA (commercial at-home 16% carbamide peroxide gel) and CB (deionized water). The tooth color analysis, which included shade matching with the Vitapan shade guide ( n = 2), and digital colorimetric analysis ( n = 2) were evaluated. The surface characteristics and hardness were analyzed with 3D optical profilometry, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and Microhardness testing ( n = 3), respectively. The tooth color analysis (Vitapan shade guide) revealed that all the tooth samples treated with synthesized choline citrate gel (EB) showed an A1 shade as compared to the other four groups, giving a range of shades. An analysis of the ΔE values from digital colorimetry; EAI, EAII, CA, and CB showed ΔE values in a range that was clinically perceptible at a glance. However, EB showed the highest value of ΔE. The mean microhardness values for the five groups showed that the effects of three experimental gels i.e., 44% choline hydroxide, 22% choline hydroxide, and choline citrate, on the microhardness of the tooth samples were similar to that of the positive control, which comprised commercial at-home 16% carbamide peroxide gel. SEM with EDX of three tested subgroups was closely related in surface profile, elemental composition, and Ca/P ratio. The roughness average values from optical profilometry of four tested subgroups lie within approximately a similar range, showing a statistically insignificant difference ( p > 0.05) between the tested subgroups. The synthesized novel experimental tooth bleaching gels displayed similar tooth bleaching actions without any deleterious effects on the surface characteristics and microhardness of the treated tooth samples when compared with the commercial at-home tooth bleaching gel.

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.)

Objective: Assess the effects of activated charcoal-based products on whitening and changes on dental enamel surface., Material and Methods: Fifty-two blocks of bovine dental enamel were randomly distributed in four groups (n = 13): brushing with activated charcoal-based powder (PW); brushing with activated charcoal-based dentifrice (AC); brushing with a conventional dentifrice containing 1450 ppm of fluoride (CD); and whitening with 10% carbamide peroxide (CP). Color, microhardness, and surface alteration were analyzed at baseline and after 14 days of treatment. Three samples per group were randomly selected and examined using scanning electron microscopy (SEM) to analyze the morphology., Results: PW exhibited greater color change for the ΔE 00 , ΔWID, Δb* and ΔL* parameters than other groups (p < 0.05). After treatment, microhardness decreased in AC and CP groups (p < 0.05). Also, PW and AC groups showed more surface alteration than CD and CP (p < 0.001). Changes in the morphology of dental enamel were observed by SEM in PW and AC groups., Conclusion: Activated charcoal-based products showed a lower whitening effect than 10% carbamide peroxide. These products also influenced dental enamel microhardness, resulting in greater surface alteration., Clinical Significance: Activated charcoal-based products promoted minimum whitening effects with significant enamel surface alteration. The 10% carbamide peroxide was more effective for whitening and caused slight enamel surface alteration., (© 2022 Wiley Periodicals LLC.)