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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. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study is to investigate the use of 15% carbamide peroxide in combination with fluoro calcium phosphosilicate desensitizing dentifrice during bleaching to evaluate postoperative dentinal tubule occlusion. Materials and Methods: Premolars which were extracted and bleached using 15% carbamide peroxide with fluoro calcium phosphosilicate dentifrice were used in this investigation, and the shade change was assessed. They were subsequently divided into sections and examined with scanning electron microscope. The quantity of open tubules, fully obstructed as well as moderately obstructed tubules, was recorded for each specimen. The statistical analysis of shade changes was conducted using the paired t-test. The tubule numbers were statistically evaluated after being assigned a mean and standard deviation. Results: The mean values between test and control groups in completely blocked tubules are 81.370 ± 1.989 and 42.586 ± 11.316, respectively. In partially blocked tubules, the mean values were found to be 13.219 ± 1.747 and 32.264 ± 11.554, respectively. In open tubules, the mean values are 5.398 ± 1.260 and 25.149 ± 8.781. The mean values of shade comparison for test group and control group are 1.95 ± 2.78 and 3.40 ± 2.83, respectively. Conclusions: According to the findings of the study, dentinal tubules were blocked when fluoro calcium phosphosilicate dentifrice was administered with 15% carbamide peroxide, but the bleaching process was unaffected. The potential clinical advantage of using a single paste system for both bleaching and desensitizing was also emphasized. [ABSTRACT FROM AUTHOR]

Background: This study investigated the contact between adult dental pulp stem cells (DPSCs) and carbamide peroxide (CP), a bleaching agent that is a popular choice for at-home whitening products, using an in vitro model. Objectives: The aim of this study was to evaluate the impact of exposure to different concentrations and timings of a commonly used peroxide-based home tooth-whitening product on DPSCs. Materials and methods: Human DPSCs obtained from impacted third molars were cultured and exposed to various concentrations of carbamide peroxide (0.1%, 0.5%, and 1%). The effects of CP on DPSC proliferation and apoptosis were investigated by MTT assay and flow cytometry. Migration was investigated by micrographs of wound healing. An enzyme-linked immunosorbent assay (IL-6 and IL-8) was used to investigate the CP-stimulated cytokine production of DPSCs. Each experiment was performed three times with independent batches of DPSCs. Statistical analysis of the collected data was performed using one-way and two-way ANOVAs with the significance threshold set at p < 0.05. Tukey's post hoc multiple comparison test was used to identify differences between groups. Results: Cell viability and adherence were lower in the CP-exposed cells compared to the non-stimulated cells, probably due to increased cell death (** p ≤ 0.01, **** p ≤ 0.0001). CP-stimulated DPSCs exhibited a dose-dependent release of IL-6 and IL-8 (**** p ≤ 0.0001). CP did not affect wound healing at any concentration tested. Conclusions: Human DPSCs were able to sense CP. Consequently, CP contributed significantly to cell apoptosis and local inflammatory responses through cytokine release. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the change in color, hardness, and roughness produced by carbamide peroxide (CP) at two different concentrations on two resins. The 16% or 45% CP was applied to 66 resin discs with and without Bis-GMA. The color was measured with a spectrophotometer, and ΔEab and ΔE00 were calculated. Microhardness tester and SEM were used. In both composites, the a* and b* coordinates tended to be red and yellow, respectively, and were significant in the Bis-GMA group (p < 0.05). The ΔEab and ΔE00 were higher in the composite with Bis-GMA, regardless of the treatment received (p < 0.05). The microhardness was reduced in both composites regardless of the PC concentration compared to the control (p < 0.05). The 45% CP reduced the microhardness in the resin group with Bis-GMA compared to 16% CP (p < 0.001) but was not significant in the resin without Bis-GMA (p = 1). An increase in roughness was directly proportional to the concentration of CP, and it was more notable in the composite without Bis-GMA. The composite with Bis-GMA showed a greater tendency to darken than the one without Bis-GMA. The surface hardness of the composite was reduced in both composites and was not influenced by CP concentration in the composite without Bis-GMA. Bleaching is a common procedure nowadays. It is important to know how CP affects composites to establish a prognosis of the treatments in terms of color change, roughness, and hardness. [ABSTRACT FROM AUTHOR]

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 oC, 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.

This systematic review examines studies focusing on tooth bleaching and its effects on healthy enamel or incipient caries and bacterial adhesion. The aim is to explore the impact of different bleaching agents on incipient caries lesions and healthy enamel. Clinical studies, in vitro studies, and observational studies that compared at least two groups were included. A search strategy was used to select studies from the MEDLINE via Pubmed and Scopus databases. Two evaluators performed data extraction, screening, and quality assessment independently. Only studies written in English were included. From 968 initial records, 28 studies were selected for a full-text evaluation. Of these, 7 studies were classified as cluster 1 (bacterial adherence on teeth), 12 studies as cluster 2 (no bacteria involved), 4 studies as cluster 3 (no teeth deployment), and 5 clinical studies were cluster 4. Of the selected studies, 6 (21.4%) supported increased bacterial attachment capacity and cariogenic dynamics, 4 (14.3%) decreased adhesion and cariogenic activity, 7 (25%) showed no difference, and 11 (39.3%) followed a different methodological approach and could not be categorized. The risk of bias appeared to be high, mainly because of the different methodologies in the studies, so we cannot reach a confident conclusion. Nevertheless, as far as carbamide peroxide bleaching is concerned, there does not seem to be a clinically significant alteration, neither in microorganism counts nor in enamel microstructure. [ABSTRACT FROM AUTHOR]

Resin infiltration is an effective method to mask vestibular white spots. If needed, external bleaching is usually recommended before infiltration, whilst in clinical practice, this sequence may not always be feasible. This in vitro study evaluated the effect of bleaching after resin infiltration regarding surface roughness and color using bovine incisors. Unlike for the untreated specimens (control, n = 25), artificial caries lesions were created within the test group (n = 25) using a demineralization solution at 37 °C for five days (pH = 4.95). The lesions were subsequently infiltrated using a resin infiltrant (Icon, DMG, Hamburg, Germany), followed by polishing. Afterwards, all specimens were bleached with a 10% carbamide peroxide gel (Opalescence, Ultradent, South Jordan, UT, USA) for 8 h/day over a ten-day period. Between bleaching treatments, specimens were stored in an opaque container with moistened paper tissues at 37 °C. Surface roughness was measured using a profilometer, and color in the L*a*b* space was assessed spectrophotometrically before and after bleaching. Bleaching increased the L*-values of both infiltrated (mean ± SD; ΔL* = 3.52 ± 1.98) and untreated (control) specimens (ΔL* = 3.53 ± 2.30) without any significant difference between the groups (p = 0.983). Bleaching also induced a significant increase in the mean surface roughness of both infiltrated (p < 0.001) and untreated (p = 0.0134) teeth. In terms of clinical relevance; it can be concluded that bleaching resin-infiltrated enamel is as effective as bleaching sound enamel. [ABSTRACT FROM AUTHOR]

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 oC, 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. [ABSTRACT FROM AUTHOR]

ABSTRACT 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

IntroductionTraditionally, 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 methodsThe 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% H2O2 and physiological saline) for 1 week.ResultsGranules release between 21.5% and 35.2% (wt/wt) of H2O2 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% H2O2 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

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.

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. [ABSTRACT FROM AUTHOR]

Internal bleaching is a conservative treatment applied to a darkened endodontically treated tooth to restore its original colour, either as a single treatment or as a treatment prior to a subsequent prosthetic phase. The aim of this study was to objectively measure and compare using an experimental model the expansive capacity of four bleaching groups: carbamide peroxide 37% (CP 37%), hydrogen peroxide 30% (HP 30%), HP 30% mixed with sodium perborate (SP) and SP mixed with distilled water. A total of 150 lower incisors (n = 30 in each group) were prepared for the Walking Bleach technique and a glass tube with oil was introduced into the coronal access cavity to measure the expansive capacity through oil displacement, due to the reaction that occurs when bleaching agents interact with dental tissues. The results after 10 days were analysed with the Games–Howell post hoc test to compare the samples. Significant higher expansion was observed with HP 30% (p < 0.05) and lower expansion with SP (p < 0.05) compared to the other groups. No significant differences were observed between CP 37% (p > 0.05) and HP 30% + SP (p > 0.05). This provides significant and observable information on the behaviour of each bleaching group and its evolution after 10 days. [ABSTRACT FROM AUTHOR]

This study aimed to compare changes in oral health-related quality of life (OHRQoL) resulting from three vital tooth bleaching protocols. 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. 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). 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. [ABSTRACT FROM AUTHOR]

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The basis of modern tooth whitening systems is the use of a whitening gel, which usually contains hydrogen peroxide or carbamide peroxide. The study included 81 patients aged 22 to 35 years with a tooth color A2 and a darker color on the Vita Classic scale. The purpose of our research was to identify a new approach to whitening teeth to improve safety and gentleness. To perform this, we assessed the effect of the tooth whitening procedure on the mineral composition of the oral fluid. A new approach to the teeth whitening procedure was to use a mouth retractor and a tool for aspirating the whitening gel, which we developed. Before the procedure, a protective film-forming aerosol, which included sodium ascorbate, was applied. After the tooth whitening procedure, the enamel was remineralized with a sealing liquid for 14 days. The concentrations of calcium and phosphorus in the oral fluid were determined using a spectrophotometer with a set of reagents (Human). The results obtained indicate that the new approach to the teeth whitening procedure contributed to less pronounced changes in the concentrations of calcium (+29.07, p < 0.001) and phosphorus (−14%, p < 0.001) in the oral fluid immediately after the procedure and in combination with the standard procedure for teeth whitening; immediately after this procedure, the calcium concentration increased by 74.4% (p < 0.001), and the phosphorus concentration decreased by 23.07% (p < 0.001). The use of remineralizing agents led to a faster recovery of the initial levels of calcium and phosphorus in the oral fluid. [ABSTRACT FROM AUTHOR]

Abstract 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). Conclusion Therefore, PBMT associated with CPP‐ACPF paste can reduce TS without compromising the efficacy of TW.

Abstract Objectives This study aimed to analyze the cost-effectiveness of whitening toothpastes and at-home bleaching for the treatment of tooth discoloration. Methodology A cost-effectiveness economic analysis was conducted, and eight randomized clinical trials were selected based on the whitening agent product used: blue covarine dentifrices (BCD), hydrogen peroxide dentifrices (HPD), dentifrices without bleaching agents (CD, negative control), and 10% carbamide peroxide (CP10, positive control) for at-home bleaching. The consumer/patient perspective was adopted, macro-costing techniques were used and a decision tree model was performed considering the costs in the American and Brazilian markets. The color change evaluation (ΔE*ab) was used to calculate the effectiveness of tooth bleaching. A probabilistic analysis was performed using a Monte Carlo simulation and incremental cost-effectiveness ratios were obtained. Results CP10 resulted in the highest cost-effectiveness compared to the use of dentifrices in both markets. In Brazil, HPD was more cost-effective than BCD and CD. In the US, the increased costs of HPD and BCD did not generate any whitening benefit compared to CD. Conclusions CP10 was more cost-effective than BCD and HPD for tooth bleaching from the perspectives of the Brazilian and American markets. Decision-making should consider the use of CP10 for treating tooth discoloration.

Composite materials used in dental restorations are considered resistant, long-lasting and aesthetic. As the wear of restorations is an important element in long-term use, the aim of this study was to evaluate the surface condition of nanohybrid and microfilled composite resins, after being subjected to the erosive action of dental bleaching protocols. This paper reflects a comparative study between one nanofilled composite and three microfilled composites used in restorations. For each composite, three sets of samples (under the form of composite discs) were created: a control group, an "office bleach" group with discs bleached with 40% hydrogen peroxide gel, and a "home bleach" group with discs bleached with 16% carbamide peroxide gel. Wear was numerically determined as the trace and the coefficients of friction obtained using a tribometer, the ball-on-disk test method, and two balls: alumina and sapphire. For all composite groups, there were statistically significant differences between the wear corresponding to the control and bleaching groups, for both testing balls. Regarding the composite type, the largest traces were recorded for GC Gradia direct anterior, for all groups, using the alumina ball. In contrast, for the sapphire ball, 3M ESPE Filtek Z550 was characterized by the largest traces. With respect to the friction coefficients, the "office bleach" group recorded the largest values, no matter the composite or the ball type used. The 3M ESPE Valux Plus composite recorded the largest friction coefficients for the alumina ball, and 3M ESPE Filtek Z550 for the sapphire ball. Overall, the "office bleach" group was characterized by higher composite wear, compared to the "home bleach" protocol or control group. Nanofilled composite resins showed superior wear resistance to microfilled resins after undergoing a bleaching protocol. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the present research was to analyse the effects of two bleaching agents, on the enamel crystallography by means of X-ray diffraction. Material and Methods: Twelve human sound posterior teeth, were collected for the present study (n = 12) and from each tooth two enamel slabs were obtained and randomly assigned to one of two different bleaching protocols. The first protocol involved an in-office bleaching agent (hydrogen peroxide 37.5%/SDI Polaoffice+), and the second an at-home whitening product (carbamide peroxide 16%/PHILIPS Zoom! NiteWhite). X-ray diffraction readings were made before and after applying the treatments in order to analyse the peak intensity and crystal domain size. Additionally, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were carried out to identify the composition correctly. Statistical analysis included repeated measures analysis of variance (p = 0.05). Results: Peak intensity in spectra obtained by X-ray diffraction had a tendency to diminish, mostly in the at-home bleaching group. The analysed data approximate a decrease in the crystal domain size among the samples treated for longer periods of time. Statistical analysis depicted no statistically significant differences among the experimental groups (p = 0.05). Conclusions: Crystal domain size had a tendency to decrease, mostly when the enamel was treated by bleaching gels that had to be applied by prolonged periods of time. [ABSTRACT FROM AUTHOR]

Objective To study the influence of procyanidins on the bonding strength of dentin bleached by carbamide peroxide to composite resin. Methods By applying different treatments to dentin bonding interfaces, 120 human third molars were randomly divided into 12 groups (n = 10): W group (no bleaching+deionized water), Wa group (no bleaching+deionized water+aging), WT1 group (no bleaching+5% procyanidins for 1 min), WT1a group (no bleaching+5% procyanidins for 1 min+aging), WT2 group (no bleaching+5% procyanidins for 5 min), WT2a group (no bleaching+5% procyanidins for 5 min+aging), C group (carbamide peroxide+deionized water), Ca group (carbamide peroxide+deionized water+aging), CT1 group (carbamide peroxide+5% procyanidins for 1 min), CT1a group (carbamide peroxide+5% procyanidins for 1 min+aging), CT2 group (carbamide peroxide+5% procyanidins for 5 min), and CT2a group (carbamide peroxide+5% procyanidins for 5 min+aging). The bond strength to composite resin was measured by universal mechanical testing machine, microstructure and the nanoleakages were measured by scanning electron microscope immediately or after the thermal cycling aging test. Results The immediate bond strength of the bleached groups pretreated with procyanidins for 1 min (P

Background: This study investigated the contact between adult dental pulp stem cells (DPSCs) and carbamide peroxide (CP), a bleaching agent that is a popular choice for at-home whitening products, using an in vitro model. Objectives: The aim of this study was to evaluate the impact of exposure to different concentrations and timings of a commonly used peroxide-based home tooth-whitening product on DPSCs. Materials and methods: Human DPSCs obtained from impacted third molars were cultured and exposed to various concentrations of carbamide peroxide (0.1%, 0.5%, and 1%). The effects of CP on DPSC proliferation and apoptosis were investigated by MTT assay and flow cytometry. Migration was investigated by micrographs of wound healing. An enzyme-linked immunosorbent assay (IL-6 and IL-8) was used to investigate the CP-stimulated cytokine production of DPSCs. Each experiment was performed three times with independent batches of DPSCs. Statistical analysis of the collected data was performed using one-way and two-way ANOVAs with the significance threshold set at p < 0.05. Tukey’s post hoc multiple comparison test was used to identify differences between groups. Results: Cell viability and adherence were lower in the CP-exposed cells compared to the non-stimulated cells, probably due to increased cell death (** p ≤ 0.01, **** p ≤ 0.0001). CP-stimulated DPSCs exhibited a dose-dependent release of IL-6 and IL-8 (**** p ≤ 0.0001). CP did not affect wound healing at any concentration tested. Conclusions: Human DPSCs were able to sense CP. Consequently, CP contributed significantly to cell apoptosis and local inflammatory responses through cytokine release.

Purpose: Resin infiltration may be a barrier for bleaching gels. The aim of this study was to compare dental bleaching effectiveness using low-concentration gels on heavily or mildly stained teeth that were or were not treated with resin infiltration agents.Materials and Methods: Forty bovine enamel surfaces were submitted to demineralisation, after which two staining protocols were performed. Twenty specimens were immersed in a staining broth for 24 h (Lab 1) or 7 days (Lab 2). Ten specimens of each group received resin infiltrant application following the manufacturer's recommendation. All specimens were bleached using 15% carbamide peroxide gel for 14 days (8 h daily). Colour measurement was performed using a reflectance spectrophotometer at three time points: baseline, after staining, and after bleaching. Data (CIEDE00) were analysed using Student's t-test (p < 0.05).Results: No statistically significant differences were observed in Lab 1 (p = 0.560). For Lab 2, statistically significant differences were detected (p = 0.031). Once bleaching was achieved to some degree (Lab 2), the resin infiltrant may have behaved as a semipermeable barrier to the carbamide peroxide gels.Conclusion: Bleaching treatment was effective on mildly pigmented tooth surfaces. On the other hand, in comparison to the control group, the heavily pigmented surfaces bleached less in the presence of the resin infiltrant, possibly due to the lack of free radicals penetrating into the substrate. [ABSTRACT FROM AUTHOR]

Abstract The effectiveness of at-home dental bleaching treatments depends on the time that bleaching products are in contact with the teeth surface and, consequently, on the adequate use of associated custom acetate trays. Objective This randomized single-blinded trial aimed to analyze if the daily usage time of these products influences the patient’s compliance behavior when submitted to monitored at-home dental bleaching. Secondary outcomes were color change and tooth sensitivity. Methodology Sixty-six volunteers were randomly distributed into three groups (n=22): patients were instructed to use the trays for 2 (G2), 4 (G4), and 8 (G8) hours daily. The daily dental bleaching compliance behavior was measured using a microsensor inserted into the trays. Subjective and objective color evaluation assessments were adopted at baseline (T0), one (T1), two (T2), and three weeks (T3) after the beginning of the bleaching treatment, as well as two weeks after the treatment (T4). Tooth sensitivity was analyzed using the VAS scale, ranging from T1 to T4. Results G2 showed a greater degree of cooperation than G8 and cooperation was inversely proportional to the recommended usage time. Significantly higher color change was observed in the upper arch for G8 when compared to G2 in subjective analysis, from T1 to T4. There were no statistical differences between the groups in objective analysis. Conclusion Shorter recommended usage time of the bleaching product may improve the patient's compliance with at-home dental bleaching treatments. However, increased daily usage time may promote better subjective color change. Bleaching sensitivity was more significant in the first week for a longer time of use.

Background: Dental aesthetic procedures aim to rectify flaws in dental elements' shape, alignment, or overly dark color. One of the most common dental aesthetic procedures is tooth whitening. This study attempts to introduce key aspects of bleaching and describe the different techniques and the mechanism of action of bleaching agents, focusing on the clinical implications in orthodontic and on composite restorations. Methods: The research was performed on PubMed, Web of Science, and Science Direct databases for articles on our topic published between 2017 and 2023, and we found a total of 1512 studies. In total, 57 papers were considered for the qualitative analysis in the review. Results: This study found that both carbamide peroxide and hydrogen peroxide were clinically effective, although patients' level of tooth sensitivity seemed to be lessened by the latter. However, the latter appears to be more effective at reducing patient-experienced tooth sensitivity. Conclusion: Carbamide and hydrogen peroxide based whitening techniques were shown to be equally successful at treating tooth discoloration after bracket composite removal, with no discernible differences between them. To increase the effectiveness of whitening on composites, more research is needed. To achieve the desired results and avoid the negative effects of whitening gels on teeth and soft tissue, a patient-specific approach is advised. [ABSTRACT FROM AUTHOR]

Introduction. Bleach-shade composite resins were recently introduced to the market due to the high demand of patients for whiter teeth. This study sought to compare four stain removal methods for bleach-shade composite resins. Materials and Methods. Seventy-two discs were fabricated from each of the Filtek Z350 XT and Gradia XBW composite resins and immersed in coffee or sour cherry juice staining solutions. Each group was then divided into four subgroups to assess the efficacy of four stain removal methods (finishing with soft-lex disk "brush with pumice" bleaching with carbamide peroxide 16%, bleaching with hydrogen peroxide 40%). The color of each specimen was measured by Easyshade spectrophotometer, and data were analyzed using SPSS 25 statistical package for social sciences. Results. The home-bleaching technique was more effective than the office-bleaching and pumice for the removal of sour cherry juice stain (ΔE = 1.93) and coffee stain (ΔE = 3.32) from Gradia composite discs, almost returning the baseline original color. The Sof-Lex discs were more effective than the pumice for the removal of sour cherry juice stain (ΔE = 4.11) and coffee stain (ΔE = 4.93) from Z350 composite discs but not return the baseline original color. Conclusions. Filtek Z350 had more discoloration than Gradia Direct. The different materials and solutions reacted differently to the four stain removal methods. In GCJ group after all stain removal methods, ΔE reduced to a clinically acceptable level. [ABSTRACT FROM AUTHOR]

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/mm2 to 2.2 ± 0.29 N/mm2) 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. [ABSTRACT FROM AUTHOR]

Recently, the use of antioxidants before the bonding of bleached enamel was considered effective for reversing the reduction in the bond strength. This article aimed to assess the influence of different sodium ascorbate (SA) presentations (liquid, gel, and semi-gel) on the composite resin–enamel bond strength after a bleaching protocol. Sound human anterior teeth were collected, cleaned, prepared for a bond strength test, and randomly allocated into groups according to the bonding procedure. Group 1 acted as a control, without bleaching treatment, and without applying an antioxidant agent. In groups 2–6, specimens were bleached using 10% carbamide peroxide. In groups 3, 4 and 5, 10% wt% SA was applied for 10 min as an antioxidant in the form of a liquid, gel, and semi-gel, respectively. In group 6, samples were bleached and immersed in fresh human saliva for 14 days. After the bleaching process, the materials were restored by means of an adhesive system and a resin composite material. The analysis revealed that the differences between the shear bond strength (SBS) between the different groups were statistically significant (p = 0.0469). The highest SBS was achieved for the group where the 10 wt% SA liquid was applied before the bonding procedures. The application of liquid 10 wt% SA might reverse the negative impact that bleaching has on the bond strength of a resin composite and enamel. [ABSTRACT FROM AUTHOR]

Background and Objectives: Tooth whitening is a relatively conservative and effective option to treat discolored teeth. However, questions remain whether in-office or at-home tooth whitening products with short treatment durations are as effective and stable as products with longer treatment durations. Materials and Methods: Forty human third molars with intact enamel surfaces were divided into four groups of ten each, subjected to discoloration challenges with coffee for 60 h, and they were treated with four professional tooth whitening systems: two for take-home use—6% hydrogen peroxide for 30 min/d for a total of 7 h in 14 days (HP6), 10% carbamide peroxide for 10 h/d for 140 h in 14 days (CP10), as well as two for in-office use—35% HP for 10 min × 3 (HP35) for a total of 30 min and 40% HP for 20 min × 3 (HP40) for a total of 60 min. Teeth colors were assessed in the CIE L*a*b* color space with a spectrophotometer immediately and six months after whitening treatments. Surface roughness (Sa) for the treated and untreated enamel surfaces of the teeth in all groups were evaluated with a three-dimensional laser scanning microscope after six months. Results: No significant differences were found between HP6 and CP10 groups immediately after whitening (∆E 10.6 ± 1.6 vs. 11.4 ± 1.7, p > 0.05) and at six months after treatments (∆E 9.0 ± 1.9 vs. 9.2 ± 2.5, p > 0.05), or between HP35 and HP40 groups immediately after whitening (∆E 5.9 ± 1.2 vs. 5.3 ± 1.7, p > 0.05) and at six months after treatments (∆E 7.2 ± 1.6 vs. 7.7 ± 1.3, p > 0.05). The two at-home whitening systems achieved significantly better whitening outcomes than the two in-office products immediately after whitening (p < 0.05). However, at six months after treatments, the differences between at-home and in-office treatments had narrowed significantly (p > 0.05). There were no statistically significant differences with respect to the Sa values between the treated and untreated surfaces (p > 0.05). Conclusions: Tooth whitening products in the same product category have similar whitening efficacies, despite significant differences in treatment durations (7 vs. 140 h, and 30 min vs. 60 min, respectively). Take-home products achieved better whitening outcomes than in-office products, but they needed 14 to 280 times longer treatment durations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background and Aim: Discoloration is an unfavorable side effect of regenerative endodontic procedures using mineral trioxide aggregate (MTA). The efficacy of home bleaching of discolored teeth with carbamide peroxide has not been well investigated, and the minimum required duration of home bleaching is still unclear. This study aimed to compare the effects of different durations of home bleaching on tooth discoloration caused by MTA. Materials and Methods: This in vitro, experimental study used 16 tooth blocks of bovine central incisors. To cause discoloration, white MTA was applied for 40 days in cavities drilled in blocks. The color parameters were measured at baseline and at 14, 28, and 42 days after the application of 20% carbamide peroxide using a spectrophotometer. Data were analyzed by repeated measures ANOVA and Tukey’s post-hoc test. Results: The color change (∆E) value was 22.9±10, 26.3±10.9, and 27.03±11 at 14, 28, and 42 days after bleaching, respectively. Significant color change occurred at 2, 4, and 6 weeks after the application of carbamide peroxide (P

Abstract Background The aim of this study was to evaluate the effect of bioactive glass (BAG) 45S5 paste on colour change and tooth sensitivity (TS) when used in combination with 20% carbamide peroxide (CP) during at-home vital tooth bleaching. Methods Twenty-four patients were selected and assigned into two experimental groups (n = 12) in a double-blind study design. Each patient received 20% CP followed by the application of either BAG paste or non-active placebo paste. The shade evaluation was performed using a digital spectrophotometer based on the CIE L*a*b* colour space system at different time points and the overall colour changes ΔE were calculated. TS was evaluated using visual analogue scale (VAS). The values of ΔE and TS were statistically analysed using paired t-test. The level of statistical significance was established at p = 0.05. Results The overall colour changes (ΔE) between baseline and each time point showed no significant differences between BAG and placebo groups (p > 0.05). The use of BAG paste significantly decreased TS reported by the participants. Conclusions The association of BAG paste with at-home bleaching treatment presents a promising method as it decreased TS and did not deteriorate bleaching efficacy. Trial registration This study was approved and registered in the Australian New Zealand Clinical Trials Registry (ANZCTR) under Registration number: ACTRN12621001334897.

The most frequently used bleaching materials are hydrogen and carbamide peroxide materials with specific concentration and techniques. The disadvantages of these materials range of sensitivity to bone inflammation and resorption processes. Therefore, it is desirable to employ alternative natural materials with little to no negative effects on the enamel, pulp and oral mucosa. This article reviews recently developing materials like papain, bromelain, chlorine dioxide, sodium chloride and sodium bicarbonate and a combination of peroxide and natural substances. In studies employing bromelain and papain in comparison to peroxide bleaching materials, the peroxide materials evolved to show better stain removal than the natural alternatives. It is worth mentioning that the concentrations of natural materials used were 20 times lesser compared to the peroxide materials. Chlorine dioxide was found to improve bleaching efficacy by virtue of the warmth that was created on application of light, leading to dryness of teeth. This material needs further research and improvement to match its conventional alternatives in efficacy. The newer alternatives considered in this line-up are sodium chloride and sodium bicarbonate. There was no slod scientific support to back this material's efficacy to conclusively compare it against peroxide materials. Finally, combination materials including lactoperoxidase along with hydrogen and carbamide peroxide showed to increase after 8 hours of contact than the system without lactoperoxidase. It can be concluded by saying that further research is required to find better alternatives to peroxide materials with better efficacy. Nanoparticles, off late, have found extensive purpose in modern day dentistry. The application of nanoparticles in bleaching is through hydroxyapatite nanoparticles. These nanoparticles concentration dependent whitening in comparison with carbamide peroxide. Recent developments including reduced graphene oxide has also been tried as an alternative to conventional bleaching methods. This material provided significant results and prove to be promising alternatives to peroxide tooth bleaching materials. This article reviews the developments and efficacy of non-peroxide bleaching materials. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate and compare the tooth-whitening potential of five over-the-counter (OTC), peroxide-free dental bleaching methods as well as an experimental tooth-whitening solution containing 0.1% hydrogen peroxide complexed with doping agents with a gold standard (positive control) containing 16% carbamide peroxide. Material and Methods: Eighty permanent bovine incisor teeth were randomly allocated to eight different groups. Two teeth from each group were immerged into five staining solutions represented by coffee, tea, red wine, and curry mixed in warm oil or distilled water (control group) and stored at 37 °C for 28 days in an incubator. The teeth were then reallocated to the eight groups, resulting in ten samples per group, and each group was matched with a bleaching product. The bleaching procedures were executed following the manufacturer's recommendations. The color of each sample was assessed over a white and black background using a quantitative numerical measurement approach with a calibrated spectrophotometer. Spectrophotometric measurements were performed after exposing the teeth to the bleaching agent for 60 min (T2), 100 min (T3), and 200 min (T4), and ΔE00 was calculated. Results: When analyzed over a white background, the mean ΔE00 values ranged from 2.14 (placebo) to 6.32 (Opalescence PF). When analyzed over a black background, the mean ΔE00 values ranged from 2.31 (placebo) to 5.78 (Opalescence PF). Statistically significant ΔE00 color changes over time for the eight groups and five staining solutions at T1 and T4 were assessed for both backgrounds using repeated ANOVA followed by Fisher's LSD post hoc test (p-value < 0.01). Conclusions: All tested over-the-counter whitening kits except one exhibited positive color variation. However, the individual performance differed vastly from one brand to the other, and the overall performance was less effective compared to the conventional carbamide-peroxide-based positive control. [ABSTRACT FROM AUTHOR]

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Composite resins are commonly used in dentistry for direct restorations. The color stability of these materials still represents a major concern for both the clinician and the patient. In recent years, ozone therapy has been extensively used in dentistry to manage wounds healing, dental caries, oral lichen planus, gingivitis and periodontitis, halitosis, osteonecrosis of the jaw, post-surgical pain, plaque and biofilms, root canal treatment, dentin hypersensitivity, temporomandibular joint disorders, and teeth whitening. To date, several studies have evaluated the bleaching effect exerted by ozone on natural teeth, but no studies have been conducted to determine the effect on the color of composite resins. The aim of the present study is to determine whether ozonized oils/gels could determine a color change on composite resin. A total of 40 discs of an A3 shade restorative composite were divided into two groups, respectively exposed to a pigmentation treatment consisting of 10 applications of 10 min each of a 1% chlorhexidine-based gel (trial group) and to storage into physiological solution (control group). The samples of both groups were respectively subdivided into four subgroups which underwent four different protocols, three of which were based on the exposure to different ozonized products and the latter representing the control. A colorimetric analysis with the CIELAB method was conducted with the following timing: after 24 h of storage in physiological solution (before the experimental procedures) (T0), after the subdivision into groups A and B (corresponding to the pigmentation for samples of group A and storage in physiological solution for samples of group B) (T1), and after subdivision into subgroups 1–4 (corresponding to the application of the ozonized products vs. control) (T2). No statistically significant difference was found between the samples at T0. The 20 samples of group A, exposed to the colorant agent, underwent a color change from T0 to T1, whereas the 20 samples exposed to the physiologic solution did not undergo any significant color change. A positive but moderate influence was assessed for E and L values, whereas no significant change occurred for A and B values. Therefore, dental ozonized oils/gels could be valuable in restorative dentistry as bleaching agents of resin composites exposed to discoloration, an alternative to the traditional hydrogen peroxide and carbamide peroxide, but further studies are required to confirm these findings. [ABSTRACT FROM AUTHOR]

Objective: To assess the effect of bleaching on surface roughness and gloss of different CAD/CAM ceramic materials. Methods: The ceramic materials included IPS e.max CAD (lithium disilicate), VITA ENAMIC (polymer infiltrated ceramic), and Celtra Duo CAD (zirconia reinforced lithium silicate). Samples of each material were randomly divided into four groups (n = 10); a control group immersed in distilled water, the second and third groups were treated with 20% carbamide peroxide (20% CP) and 35% carbamide peroxide (35% CP) bleaching agents for 4 h/day and 60 min/day respectively for 7 days. The fourth group was treated with 40% hydrogen peroxide (40% HP) applied twice, each turn for 20 min. After treatment, the surface roughness (using 3D non-contact profilometry) and surface gloss were assessed followed by imaging with a scanning electron microscope. The data were analyzed using multiple linear regression and Kruskal-Wallis one-way ANOVA tests (α = 0.05). Results: The surface roughness (p = 0.157) and gloss (p = 0.073) of IPS e.max CAD were not significantly affected by the different bleaching treatments. Similarly, no significant effect on surface roughness (p = 0.162) and gloss (p = 0.965) were shown for Celtra Duo CAD. On the other hand, VITA ENAMIC was significantly affected when treated with 20% CP and 35% CP showing increased roughness (p = 0.001) and gloss (p = 0.008). Conclusions: Home bleaching treatments (20% CP and 35% CP) significantly affected the surface roughness and gloss of VITA ENAMIC while IPS e.max CAD and Celtra Duo CAD were not affected by the different bleaching treatments. [ABSTRACT FROM AUTHOR]

The optical qualities of cutting-edge aesthetic dental ceramics are crucial for great aesthetics and may be impacted by various bleaching methods. The objectives of this study were to evaluate how home bleaching affected the translucency parameter (TP), contrast ratio (CR), total color difference (ΔE), and surface roughness (Ra) of various aesthetic dental ceramics, including innovative ultra-translucent zirconia. The three varieties of ceramics that were tested—IPS e.max-Press (IPS); classic zirconia with feldspathic layering (LZr); and translucent zirconia (TZr)—were each represented by seven samples. The samples were bleached at home using 15% carbamide peroxide for six hours a day for seven days. Each specimen's pre- and post-bleaching CIE L*a*b* values were measured using a spectrophotometer, and the TP, CR, and ΔE were determined. Ra values were measured via 3D profilometry. In comparison to the pre-stage results, statistical analysis showed a significant decrease in TP and increase in CR for LZr and TZr in the post-stage (p < 0.05), but not for IPS (p = 0.398). The results also showed substantial variations in ΔE for the three ceramics (p = 0.020). Ra readings during the post-stage were noticeably greater than those at the pre-stage (p = 0.018). Home bleaching had an impact on the optical characteristics and surface texture of the dental ceramics. Additionally, IPS had greater color stability than LZr and TZr. [ABSTRACT FROM AUTHOR]

Coupling dual-phase nickel selenides with N -doped carbon optimized number of catalytic active sites, reaction activation energy, electrical conductivity and improves the desorption of CO 2 , ultimately boosting UOR performance. [Display omitted] Electrochemical urea oxidation reaction (UOR) is urgently in demand for diverse energy conversion and storage device coupled with pollution treatment because of its favorable thermodynamic potential (0.37 V vs RHE) and wide distribution nature of urea, but simultaneously gravely limited by the sluggish reaction dynamics and poisoning of catalyst. Herein, dual-phased Ni 0.85 Se/NiSe 2 coupling with N doped carbon (Ni 0.85 Se/NiSe 2 @NC-2) in situ is prepared by a solvothermal-selenization pathway. Benefiting from the collective promotion of the dual-phased composition and the NC support, Ni 0.85 Se/NiSe 2 @NC provides abundant active sites, enhanced electrical conductivity. It delivers a current density of 252 mA cm−2 at 1.6 V vs RHE with a small Tafel slop of 64.4 mV dec-1 and gets a lower reaction barrier. Moreover, it requires a cell voltage of 1.46 V to approach 50 mA cm−2, about 250 mV less than that of water electrolysis, confirming the less energy consumption. Notably, the N doped carbon protects Ni 0.85 Se/NiSe 2 nanocrystals from aggregation leading to a faster CO 2 desorption from Ni sites, which endow the Ni 0.85 Se/NiSe 2 @NC-2 a much better working stability. The direct urea hydrogen peroxide fuel cell (DUHPFC) achieves a maximum power density of 9.09 mW cm−2 at 20 °C. This work extends highly efficient dual-phased structure loading in NC catalysts system for urea-assisted energy conversion. [ABSTRACT FROM AUTHOR]