Reproductive effects of prepubertal exposure to 35 % carbamide peroxide in female Wistar rats

This clinical trial aimed to evaluate the influence of a purple repositioning silicone guide on color assessment before and after at-home tooth bleaching. Forty-five individuals received 10% carbamide peroxide at-home tooth bleaching using custom trays on both arches, 3 h per day for 2 weeks. Upper canines were evaluated with a spectrophotometer in two different ways: with and without (control) a purple silicone guide. Tooth color was assessed using the CIELab (ΔE*ab), CIEDE2000 (ΔE00), and the whitening index for dentistry (ΔWID) at baseline, 2 and 4 weeks after the beginning of treatment. Data were analyzed using paired t tests for dependent samples (p < 0.05). At all evaluation periods, the use of the purple silicone guide resulted in lower b* values and higher WID values (p < 0.001) compared with the control group. At 2 and 4 weeks, the repositioning guide resulted in lighter teeth (higher values of ΔE*ab, ΔE00, and ΔWID) than the group that did not use the guide (p < 0.04). The use of a purple repositioning guide with a spectrophotometer influenced the color measurement of upper canines before and after at-home tooth bleaching.

To assess the bleaching efficacy, tooth sensitivity, enamel surface morphology, and oral health-related quality of life (OHRQoL) of two at-home bleaching products with matched effective hydrogen peroxide (HP) concentrations: Beyke iWhite (8% carbamide peroxide) and Invisalign (3% hydrogen peroxide). A randomized, triple-blind, split-mouth clinical trial was conducted with 22 participants undergoing a two-week bleaching treatment. The gel was used daily for 6-8h. Tooth color and OHRQoL were assessed at baseline, post-bleaching, and 1-month follow-up. Tooth color was measured using a spectrophotometer (ΔE00), while OHRQoL was evaluated using psychological questionnaires (OHIP and PIDAQ questionnaires). Daily tooth sensitivity reports were collected, and enamel morphology was analyzed using scanning electron microscopy. An in vitro experiment tracked the initial pH values of gels and their 8h changes on bovine enamel. Statistical analysis included Wilcoxon Signed Rank tests for tooth sensitivity and questionnaires, paired t-tests for color change (ΔE00), and ANOVA for pH changes. Both products presented effective color change (ΔE00 = 5.39 ± 2.50 for 3% HP and ΔE00 = 4.75 ± 2.25 for 8% CP) after two weeks, exceeding clinical acceptability thresholds (ΔE00 >1.8). The 3% HP gel yielded a statistically greater color change than the 8% CP gel (p < 0.05). The 8% CP gel induced statistically lower tooth sensitivity (NRS/VAS, p < 0.05), while both reported mild sensitivity (0 < NRS < 1.5, 0 < VAS < 3). OHRQoL improved significantly (P < 0.05). Invisalign treatment led to more noticeable surface undulations than Beyke iWhite. The in vitro experiment indicated Beyke iWhite gel was initially alkaline, turning neutral, while Invisalign gel remained acidic. Both products effectively whitened teeth while inducing mild tooth sensitivity, and both had a positive socio-psychological impact. The 3% HP gel provided a bleaching efficacy advantage, while the 8% CP gel demonstrated lower sensitivity and less enamel alteration. Clinicians may consider at-home bleaching techniques with 3% HP and 8% CP to obtain effective bleaching results with slight side effects. Chinese Clinical Trial Registry ChiCTR2400092807, 24/11/2024, Retrospectively registered.

In vitro whitening performance of gold standard dental bleaching methods compared to trending alternatives from social media.

A standard cosmetic dentistry procedure that is designed to improve the appearance of stained teeth is external dental whitening. Age, dietary choices, cigarette usage, or teeth trauma are among some of the causes of teeth discoloration. The objective of this study is to study the effects of whitening gels on teeth color, duration of effects, and potential adverse effects. To find studies that satisfied the inclusion criteria, two independent reviewers searched electronic sources, including PubMed, Scopus, Web of Science, and the Cochrane Library, in July 2024, which was updated on August 1, 2024. Changes in tooth color before and after external bleaching were the key end measures for the studies that were chosen, and these changes were measured using either shade guide units (SGU) or a spectrophotometer/colorimeter (ΔE). The effectiveness of various bleaching gels was compared after combining the pertinent research in subgroup analysis. These substances comprise gels based on hydrogen peroxide, carbamide peroxide, and other substances frequently applied during teeth whitening procedures. The Cochran Q test and I2 statistic were used to evaluate statistical heterogeneity and ensure the results were reliable. The results of this systematic review summarize the most recent data on the effectiveness of various bleaching gels used in external teeth whitening. Regarding ΔE, carbamide peroxide gels performed better than hydrogen peroxide-based whitening gels, although their ΔSGU values were comparable. The quality of evidence for ΔE*, risk, and intensity of teeth sensitivity was graded as moderate in all types of whitening agents. Teeth that are stained can be significantly bleached by whitening gels such as hydrogen peroxide and carbamide peroxide. The greater concentration carbamide peroxide bleaching gel showed less tooth sensitivity than the higher concentration HP bleaching gel. This study protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) dated November 26, 2023, with the registration ID CRD42023483434.

The study addresses dental bleaching for restricted teeth as one of the most sought-after aesthetic procedures in modern dentistry, driven by the appreciation of appearance and self-esteem. The main objective is to understand the clinical limitations of bleaching, its techniques, benefits, risks, and necessary care. Bleaching has been practiced historically since Ancient Egypt, evolving into the modern use of hydrogen and carbamide peroxides, introduced in the 1980s. The study highlights two main techniques: supervised home bleaching and in-office bleaching, which offer similar functionality, differing only in the concentration of the bleaching agent, application time, and cost. The procedure is indicated for cases of dental darkening caused by extrinsic pigmentation (from food, beverages, and smoking) or intrinsic pigmentation (from trauma, disease, or medications). Although it is a safe and minimally invasive method, it can cause side effects such as dentin hypersensitivity and gum protection, which are generally temporary. Strategies such as the use of desensitizers, fluoride, and low-level laser help reduce these symptoms. The dentist plays a crucial role in evaluating and customizing treatment, taking into account oral health, the type of stain, and the integrity of the enamel. The success of whitening depends on proper indication, professional monitoring, and respect for biological limits. It can be concluded that tooth whitening is a safe, effective, and affordable procedure, as long as it is performed ethically and under supervision. In addition to the aesthetic benefits, it contributes to the patient's self-esteem and well-being, reinforcing the importance of ongoing scientific updating for dental professionals.

Background: Earwax impaction is common and can cause symptoms such as hearing loss, discomfort, tinnitus, vertigo, and chronic cough. Removing impacted cerumen often improves hearing. Many cerumen-removal products exist but have limited efficacy, often requiring multiple doses over days. Sodium bicarbonate (5%) and carbamide peroxide (6.5%) are two important cerumenolytics. This study aimed to compare their effects on different degrees of wax obstruction. Methods: This cross-sectional study at a tertiary ENT center included 148 adult patients with ≥50% bilateral ear canal occlusion (grades 3-4). Each patient received 5% sodium bicarbonate drops in one ear and 6.5% carbamide peroxide drops in the other, three times daily for four days. After 4 days, cerumen was removed by syringing and clearance outcomes were compared. Data were analyzed statistically with significance at p≤0.05. Results: The mean age was 54±12.8 years, with a male predominance. Hearing loss was the most common symptom. Sodium bicarbonate demonstrated significantly more effective cerumen dissolution and clearance than carbamide peroxide (p&lt;0.05). Complete clearance was achieved in 34.3% and 25.0% of ears treated with sodium bicarbonate and carbamide peroxide, respectively. Nearly half of sodium bicarbonate-treated ears (50.5%) were cleared with one syringing attempt, compared to about one-third with carbamide peroxide. Conclusions: Sodium bicarbonate is a more effective option than carbamide peroxide for treating cerumen impaction in the external ear canal. By reducing blockage and symptoms, its use can improve patients’ quality of life.

Introduction: The purpose of this study was to investigate the effects of 15% carbamide peroxide, orange juice, and Cola on the microhardness of composite resin restoration material. Materials and Methods: In this in vitro study, forty disk-shaped composite samples were prepared and randomly classified into four groups (n=10); the artificial saliva (control), bleaching agent (15% carbamide peroxide), orange juice, and Cola. Vickers microhardness was measured on the surface of the samples before and after immersion for 6 and 48 hours. Results: The microhardness values of the 15 % carbamide peroxide, Orange juice and Cola groups were significantly lower after 48 hours compared to the artificial saliva group (P=0.003, P=0.002, P=0.001, respectively). However, these differences were not statistically significant after 6 hours of immersion (P=0.068). When comparing the microhardness values of these groups over time, as expected, these measures significantly decreased, except for the 15 % carbamide peroxide group in which the mean microhardness value did not significantly decrease from baseline after 6 hours immersion (P=0.106). However, there was a significant difference after 48 hours compared to baseline and 6 hours immersion (P=0.001, P=0.004). Conclusion: This suggests that 15 % carbamide peroxide gel can be employed as a bleaching agent in cases with composite restorations for a limited amount of time without significant deterioration of the microhardness.

The effect of a 16% carbamide peroxide on the microhardness and compressive strength of a nano composite

Background: Clear aligners are widely used for orthodontic treatment, while dental bleaching remains a popular cosmetic procedure. Recently, aligners have been proposed as dual-function devices capable of simultaneously achieving tooth movement and whitening. Objective: To systematically review the literature supporting the hypothesis that clear aligners can serve as effective bleaching trays without compromising orthodontic efficacy. Methods: A systematic review was conducted following PRISMA 2020 guidelines. Searches were performed in PubMed, Scopus, and Web of Science up 2019 to April 2025. Studies evaluating the use of bleaching agents during clear aligner therapy were included. Two reviewers independently screened studies, extracted data, and assessed risk of bias. The PRISMA flow diagram, a summary table of characteristics, and a Risk of Bias plot were generated. Results: Fiveeen studies (9 clinical and 5 in vitro) were included. All reported positive whitening effects using 10–11% carbamide peroxide during aligner therapy. No significant adverse effects on tooth movement or aligner integrity were reported. Mild, transient sensitivity was noted in some studies. Risk of bias varied with study type. Conclusion: Current evidence supports the use of clear aligners as effective bleaching trays, enabling simultaneous orthodontic and whitening treatment. Future randomized controlled trials are warranted to optimize protocols and confirm long-term outcomes.

Aim: This in vitro study aimed to evaluate the color stability and surface roughness of different photoinitiator systems-based nanohybrid resin composites after staining and home or office bleaching. Materials and Methods: A total of 80 resin-based composite (RBC) discs with lucirin-TPO (Tetric EvoCeram, Ivoclar Vivadent) or champhoroquinon (CQ) (Grandio, Voco) were preperad (8x2mm). At baseline, post-coffee staining (12 days/37°C), and bleaching, color values (ΔE*Lab) using spectrophotometre and surface roughness (Ra) by profilometer were measured. Hydrogen peroxide gel 35% (Whiteness HP, FGM) for office bleaching and carbamide peroxide gel 16% (Whiteness Perfect, FGM) for home bleaching were used. One sample of each groups was evaluated under scanning electron microscopy. Statistical analyses were performed by one-way ANOVA with Tukey HSD, dependent t-test and non-parametric tests (p

Background and Objectives: Chairside bleaching can alter enamel morphology and mineral content. This in vitro study compared surface changes and elemental shifts after three in-office protocols using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Materials and Methods: Forty-two human premolars/molars were sectioned; matched halves served as control or received Opalescence Quick 45% carbamide peroxide (CP), Opalescence Boost 40% hydrogen peroxide (HP), or BlancOne Ultra+ 35% HP with light activation. Gels were applied per manufacturers’ instructions. SEM assessed topography (×500–×1100); EDS quantified atomic percent of O, Ca, P, C and trace elements. One-way ANOVA compared Ca and P between bleached groups (α = 0.05). Results: Controls showed compact surfaces with preserved Ca and P. After Quick, SEM revealed roughness, fissures and microcracks; Ca fell from 11.5 to 12.5 to 9.53–11.73 at% and P from 7.5 to 8.9 to 7.41–8.59 at%. Boost produced mild superficial restructuring and granular deposits with variable Ca 13.80–27.94 at% and P 7.32–14.65 at%. BlancOne Ultra+ caused diffuse erosion and loss of prismatic clarity with marked demineralization (Ca 1.42–7.85 at%, P 1.22–6.71 at%); C rose locally to 46.61 at%. Across bleached groups, Ca and P differed significantly (both p < 0.001). Oxygen remained dominant (~39–50 at%) in all spectra; occasional Al/Si/Cl/K likely reflected residues or preparation artifacts. Conclusions: All protocols produced surface and compositional alterations, with a severity gradient: BlancOne Ultra+ > Boost > Quick. High-concentration, light-activated HP yielded the largest Ca/P losses. Clinically, neutral-pH, non-activated or chemically activated regimens and immediate post-bleach remineralization should ideally be used when feasible, particularly before adhesive procedures.

This in vitro study aimed to evaluate the changes in surface integrity of dental enamel after bleaching using gels with different compositions followed by an erosive challenge. Bovine enamel specimens (4 × 4 × 2mm; n = 12/group) stored in artificial saliva were treated with bleaching gels containing carbamide peroxide (CP) or hydrogen peroxide (HP) with or without calcium polyphosphate (CaPP) followed by an erosive challenge. In Experiment 1, 10% commercial CP (CPC), CPC + 2% NaF, 10% manipulated CP (CPM), CPM + 2% NaF, 10% CP + 0.5 wt% CaPP, 10% CP + 1.5 wt% CaPP, manipulated gel without CP, or no bleaching were applied for 14days. In Experiment 2, CP was switched with 35% HP, and all gels were applied for two sessions. Thereafter, all samples were subjected to a 5-day erosive challenge using 1% citric acid (pH 3.5) for 120s. Enamel surface loss was assessed using contact profilometry and scanning electron microscopy (SEM). Statistical analysis was performed using a generalized linear model (α = 0.05). Compared with that in the CP + 0.5% CaPP and HP + 0.5% CaPP groups, enamel loss was significantly greater in the CPM and CPC groups and HPM and HPC groups in Experiments 1 and 2, respectively. SEM analysis revealed less surface degradation in the groups containing 0.5% CaPP, with greater preservation of the prismatic and interprismatic enamel structure. Both low- and high-concentration bleaching gels containing 0.5% CaPP improved enamel preservation after an erosive challenge compared to that with gels without CaPP. Thus, the addition of CaPP may help minimize enamel damage during bleaching by reducing mineral loss.

Effect of at-home agents and concentrations on bleaching efficacy: A systematic review and network meta-analysis.

Effect of at-home bleaching agents and concentrations on tooth sensitivity: A systematic review and network meta-analysis.

ABSTRACTBackground and Objective:The alteration of surface texture of lithium disilicate materials through the application of carbamide peroxide gels, which are frequently utilized as home bleaching agents, presents significant implications that remain contentious, and the enhancement of this phenomenon via polishing techniques is additionally subject to skepticism. The objective of the study was to systematically assess the impact of bleaching and polishing protocols on the surface roughness of lithium disilicate.Methods:A total of 28 IPS e.max press discs were systematically allocated to two distinct groups. Group A served as the control cohort, while Group B constituted the experimental cohort. In the case of Group B, the bleaching agent was administered for duration of 20 minutes daily over the course of 14 days. The surface roughness of each disc was quantified prior to and following the application of the bleaching agent, as well as subsequent to the polishing intervention.Results:In comparing the post-bleaching results of Group B to those of Group A, statistical evaluation indicated that while the roughness average (Ra) exhibited a marginal elevation following the bleaching cycles and after the polishing process, this observed increase did not achieve statistical significance (P > 0.05).Conclusion:The surface roughness of IPS e.max press discs was not significantly affected by home bleaching or polishing.

To assess the penetration of hydrogen peroxide (HP) into the pulp chamber and the bleaching efficacy on teeth with white spot lesions (WSLs) compared to sound teeth, when subjected to both in-office and at-home bleaching treatments. Forty premolars were allocated into four groups (n = 10 each): sound teeth and teeth with artificially induced WSLs, both subjected to at-home bleaching (16% carbamide peroxide) and in-office bleaching (35% hydrogen peroxide). WSLs were induced in half of the specimens using a 14-day pH-cycling protocol alternating between demineralizing and remineralizing solutions. HP permeability (µg/mL) and color parameters (L*, a*, b*, and WID) were quantitatively assessed using a Cary UV-Vis 100 spectrophotometer and a VITA Easyshade Advance 4.0 digital spectrophotometer, respectively. Statistical analyses were performed using two-way and three-way ANOVA, with post hoc comparisons by Tukey's, at a significance level of α = 0.05. WSLs subjected to in-office bleaching exhibited higher HP penetration compared to the other groups (p < 0.05). After bleaching, WSLs showed significantly lower L* and WID values than sound teeth, regardless of the bleaching protocol or time point (p < 0.05). For a*, higher values were observed in WSLs after at-home bleaching, while for b* values no significant differences were found (p > 0.05). No significant difference in WID was observed between bleaching methods for WSLs teeth (p > 0.05). White spot lesions exhibited greater HP permeability and less favorable optical outcomes compared to sound teeth, particularly after in-office bleaching. Teeth with white spot lesions are more susceptible to HP diffusion and present less favorable whitening results. At-home bleaching may be a safer and more esthetically favorable conservative treatment option for managing white spot lesions.

Background/Objectives: In-office bleaching commonly employs high concentrations of hydrogen peroxide (HP) or carbamide peroxide (CP), which may compromise enamel integrity. This in vitro paired-design study aimed to compare the chemical and mechanical effects of three commercial bleaching agents-Opalescence Boost (40% HP), Opalescence Quick (45% CP), and BlancOne Ultra+ (35% HP)-on human enamel. The null hypothesis assumed no significant differences between the control and treated samples. Given the ongoing debate over pH, active ingredients, and enamel impact, comparing whitening systems remains clinically important. Methods: Forty-two extracted teeth were assigned to three experimental groups (n = 14) with matched controls. Each underwent a single bleaching session per manufacturer protocol: Opalescence Boost (≤60 min), Opalescence Quick (15-30 min), and BlancOne Ultra+ (three light-activated cycles of 8-10 min). Enamel chemical changes were analyzed by Fourier transform infrared (FTIR) spectroscopy (phosphate and carbonate bands), and surface hardness by Vickers microhardness testing. Paired t-tests (α = 0.05) assessed statistical significance. Results: FTIR analysis revealed alterations in phosphate and carbonate bands for all agents, most notably for Opalescence Boost and BlancOne Ultra+. Microhardness testing showed significant reductions in enamel hardness for Opalescence Boost (control: 37.21 ± 1.74 Hv; treated: 34.63 ± 1.70 Hv; p = 0.00) and Opalescence Quick (control: 45.82 ± 1.71 Hv; treated: 39.34 ± 1.94 Hv; p < 0.0001), whereas BlancOne Ultra+ showed no significant difference (control: 51.64 ± 1.59 HV; treated: 51.60 ± 2.34 Hv; p = 0.95). Conclusions: HP-based agents, particularly at higher concentrations, caused greater enamel alterations than CP-based products. While clinically relevant, the results should be interpreted cautiously due to in vitro limitations and natural enamel variability.

Objective: The case reports 6-year follow-up of a lithium disilicate fragment luted on buccal surface of the right upper central incisor to restore an enamel hypoplasia lesion. Method: First, the tooth was whitened using at-home vital bleaching (i.e., daily use of 20% carbamide peroxide gel for 15 days) and enamel microabrasion using 6% hydrochloric acid in 5 cycles of 10 s each. The whitening techniques reduced the extension of the lesion, although without solving the unesthetic issue. Thus, a minimally invasive preparation on the remaining hypoplasia was carried out for partial restoration of the buccal surface with a glassy ceramic fragment reinforced by lithium disilicate IPS e.max Press. Results: The immediate clinical result showed that home bleaching added to microabrasion contributed to standardize the color of the hypoplastic enamel surface and to reduce the size of the opacity generated by hypoplasia. This allowed restoring the aesthetics and, consequently, the patient’s self-esteem, using a minimally invasive technique, with preparations confined to the enamel for adhesion of the ceramic fragment. Conclusion: After 6-years, the functional and aesthetic result of this treatment remained satisfactory and without structural and optical clinical changes associated with the adhered fragment.

To evaluate the efficacy of low and high-concentrated bleaching gels in both at-home and in-office techniques and their effects on enamel properties. Bovine enamel/dentin specimens were randomly allocated to five groups (n=12): deionized water (negative control - DW), 6% hydrogen peroxide (6HP), 40% hydrogen peroxide (40HP), 10% carbamide peroxide (10CP), and 45% carbamide peroxide (45CP). For 6HP and 40HP, the gel was applied 3x20 minutes in 1 day. For 10CP and 45CP, the bleaching gels were applied 1x/day for 8 hours and 1x/day for 30 minutes over 7 days, respectively. Before and after bleaching treatment, color (CIE L*a*b*), surface microhardness (SMH), roughness (Ra), and gloss (GU) were assessed. Alterations in color (ΔE₀₀ and ΔWID), SMH (%SMHalt), Ra (%Raalt) and GU (%GUalt) were calculated. Data were analyzed by one-way ANOVA and Tukey's test (α= 0.05). Significant differences were found for color alteration (P< 0.05). The group 10CP showed the highest color difference. The groups 40HP, 10CP, and 45CP exhibited similar values of ΔWID. No alteration in enamel microhardness and roughness was found (P> 0.05). Although significant differences were found for %GUalt between the groups (P< 0.05), they were not different from the negative control. The 10% carbamide peroxide resulted in the highest color alteration, while all tested bleaching gels were effective in producing color change that exceeded the acceptability threshold without causing damage to the enamel surface. All bleaching gels can be considered safe in the tested protocol, and the greatest color difference was promoted by 10% carbamide peroxide overnight.