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ABSTRACT Objective Materials and Methods Results Conclusion Clinical Relevance 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).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 (ΔEab, ΔE00, and ΔWID). 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).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 ΔE00; p < 0.05), the color measurements of both groups exceeded the 50%:50% perceptibility/acceptability threshold.In‐office dental bleaching using 37% CP resulted in reduced risk and TS intensity, without prejudice to the BE.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 [ABSTRACT FROM AUTHOR]

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]

In the following research, meso‐tetrakis(4‐carboxyphenyl)porphyrinatomanganese (III) acetate (MnTCPP(OAc)) was immobilized onto the surface of two functionalized magnetic nanoparticles (MNPs) with different linker length via amide bond (Fe3O4@SiO2‐NH2‐MnTCPP(OAc) (A1) and Fe3O4@SiO2‐NHCO‐NH2‐MnTCPP(OAc) (A2)). The prepared catalysts were characterized by standard methods such as: atomic absorption spectroscopy (AAS), Ultra violet‐visible (UV‐Vis), Fourier‐transform infrared (FT‐IR), vibrating sample magnetometry (VSM), field emission scanning electron microscopy (FE‐SEM) and transmission electron microscopy (TEM) techniques and also the effect of the length of the linker on the catalytic activity of supported magnetic nanohybrids was investigated. The prepared magnetic nano‐catalysts with different linker lengths were participated in a comparative study of the clean oxidation of sulfides with urea hydrogen peroxide (UHP) in ethanol. The higher catalytic activity, selectivity and also reusability were achieved in the presence of the catalyst with longer linker length (A2) at ambient temperature. Moreover, the turnover number (TON) of catalytic reactions using A2 as catalyst was highly enough to consider the catalyst as an efficient material to oxidize various sulfides. Both A1 and A2 catalysts simply have accomplished 5 runs of recycling without significant decrease in the catalytic activity. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the bleaching efficacy and effects on enamel properties of experimental gels with carbamide peroxide (CP; 10%) or hydrogen peroxide (HP; 6%) containing calcium polyphosphate sub-microparticles (CaPPs). Methods: A total of 216 bovine tooth specimens were divided for microhardness and color analyses (n = 108) and block randomized into nine groups (n = 12): (G1) commercial CP (Whiteness Perfect, FGM; Brazil); (G2) experimental CP; (G3) CP-0.5%CaPPs; (G4) CP-1.5%CaPPs; (G5) commercial HP (Potenza Bianco, PHS; Brazil); (G6) experimental HP; (G7) HP-0.5%CaPPs; (G8) HP-1.5%CaPPs; (G9) artificial saliva. The gels' pH values were determined with a bench pH meter. Color (ΔE, ΔE00, ΔWID) and microhardness variation were evaluated before and after the therapy. Part of the specimens used for microhardness was submitted to the scanning electron microscopy (SEM) (n = 3) and energy-dispersive X-ray spectroscopy EDX (n = 3) analyses. Statistical analyses were performed in the R statistical software (α = 0.05). Linear mixed models for repeated measures in time were used to analyze microhardness and L* values. Generalized linear models were used to analyze the a*, b*, ΔE, ΔE00, and ΔWID, considering a group effect. The EDX data were analyzed using a one-way ANOVA with Tukey's test. Results: The gels' pH remained over 6,0. All gels effectively bleached the specimens and did not differ significantly. When compared to the control group, the hardness was significantly lower in the G1, G2, G6, and G7 groups. The G3, G4, G5, and G8 groups did not differ significantly (p > 0.05). Conclusion: The incorporation of CaPPs in low-concentration whitening gels reduces its negative effects on microhardness without interfering with their bleaching efficacy. [ABSTRACT FROM AUTHOR]

Background: Although several studies indicate the harmful effects of bleaching on pulp tissue, the demand for this procedure using high concentrations of hydrogen peroxide (HP) is high. Objectives: To investigate the influence of bleaching on the pulp tissue. Methods: Electronic searches were conducted (PubMed/MEDLINE, Scopus, Cochrane Library and grey literature) until February 2021. Only in vivo studies that evaluated the effects of HP and/or carbamide peroxide (CP) bleaching gels on the inflammatory response in the pulp tissue compared with a non‐bleached group were included. Risk of bias was performed according to a modified Methodological Index for Non‐Randomized Studies scale for human studies and the Systematic Review Centre for Laboratory Animal Experimentation's RoB tool for animal studies. Meta‐analysis was unfeasible. Results: Of the 1311 studies, 30 were eligible. Of these, 18 studies evaluated the inflammatory response in animal models. All these studies reported a moderate‐to‐strong inflammatory response in the superficial regions of pulp, characterized by cell disorganization and necrotic areas, particularly during the initial periods following exposure to 35%–38% HP, for 30–40 min. In the evaluation of human teeth across 11 studies, seven investigated inflammatory responses, with five observing significant inflammation in the pulp of bleached teeth. In terms of tertiary dentine deposition, 11 out of 12 studies noted its occurrence after bleaching with 35%–38% HP in long‐term assessments. Additionally, three studies reported significant levels of osteocalcin/osteopontin at 2 or 10 days post‐treatment. Other studies indicated an increase in pro‐inflammatory cytokines ranging from immediately up to 10 days after bleaching. Studies using humans' teeth had a low risk of bias, whereas animal studies had a high risk of bias. Discussion: Despite the heterogeneity in bleaching protocols among studies, High‐concentrations of HP shows the potential to induce significant pulp damage. Conclusions: High‐concentrations of bleaching gel increases inflammatory response and necrosis in the pulp tissue at short periods after bleaching, mainly in rat molars and in human incisors, in addition to greater hard tissue deposition over time. However, further well‐described histological studies with long‐term follow‐up are encouraged due to the methodological limitations of these studies. Registration: PROSPERO (CRD42021230937). [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]

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]

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 ∆Eab, ∆E00 and WID 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. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate how tluoride- or chitosan-based toothpaste used during at-home bleaching affects enamel roughness, tooth color, and staining susceptibility. Methods: Bovine enamel blocks were submitted to a 14-day cycling regime considering a factorial design (bleaching agent x toothpaste, 2 x 3), with n= 10: (1) bleaching with 16% carbamide peroxide (CP) or 6% hydrogen peroxide (HP), and (2) daily exposure of a fluoride (1,450 ppm F-NaF) toothpaste (FT). chitosan-based toothpaste (CBT), or distilled water (control). Then, 24 hours after the last day of bleaching procedure the samples were exposed to a coffee solution. Color (AE.,b, AEoo, L: a*, b*) and roughness (Ra, kim) analyses were performed to compare the samples initially (baseline), after bleaching, and after coffee staining. The results were evaluated by linear models for repeated measures (L: a: b: and Ra), 2-way ANOVA (AE.,b and AEoo) and Tukey's test (a= 0.05). Results: After the at-home bleaching procedure (toothpaste vs. time, P< 0.0001), the toothpaste groups presented a statistically lower Ra than the control (CBT 0.05). After coffee exposure, CBT presented lower AEat, and AEoo values in the H P groups (toothpaste, P< 0.0001), and lower b* and a* values in the CP groups (toothpaste vs. time, P= 0 .004). [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

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.

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.

Aim: To find out which whitening techniques and products are currently used by dentists in two cities, Marrakech and Khouribga-Morocco. Methods: Study type: Descriptive cross-sectional survey; Study population: 347 dentists practicing in the private sector, including 276 dentists in Marrakech and 71 in Khouribga; Study design: a questionnaire was drawn up to collect the data required for the study; Statistical analysis: data were analyzed using SPSS software at the FMDC Community Health Laboratory of Epidemiology and Biostatistics. Results: 205 responses out of 347 questionnaires distributed. External whitening was most widely used in Khouribga, and internal whitening most widely used in Marrakech; 35.7% of dentists used hydrogen peroxide at 35% as an internal whitening product; 35.9% of dentists used carbamide peroxide at 15% as an at-home bleaching product; 67% of dentists made casts with reservoirs; 66% of dentists used 35% hydrogen peroxide in the dental office; 81.2% of practitioners used the light activation as a means of activation, while 37% used the whitening product for 30 minutes with the light activation. Conclusion: Dentists in Khouribga and Marrakech frequently employ the oldest high concentration whitening procedures. It is imperative that dentists in these two cities receive ongoing training. It must be regular, demanding and of high quality, as the therapeutics of each dyschromia and the specificities of internal and external bleaching protocols call for up-to-date knowledge. [ABSTRACT FROM AUTHOR]

Aim: To find out which whitening techniques and products are currently used by dentists in two cities, Marrakech and Khouribga-Morocco. Methods: Study type: Descriptive cross-sectional survey; Study population: 347 dentists practicing in the private sector, including 276 dentists in Marrakech and 71 in Khouribga; Study design: a questionnaire was drawn up to collect the data required for the study; Statistical analysis: data were analyzed using SPSS software at the FMDC Community Health Laboratory of Epidemiology and Biostatistics. Results: 205 responses out of 347 questionnaires distributed; External whitening was most widely used in Khouribga, and internal whitening most widely used in Marrakech; 35.7% of dentists used hydrogen peroxide at 35% as an internal whitening product; 35.9% of dentists used carbamide peroxide at 15% as an ambulatory whitening product; 67% of dentists made casts with reservoirs; 66% of dentists used 35% hydrogen peroxide for chairside whitening; 81.2% of practitioners used the lamp as a means of activation, while 37% used the whitening product for 30 minutes with the lamp. Conclusion: Dentists in Khouribga and Marrakech frequently employ the oldest high concentration whitening procedures. It is imperative that dentists in these two cities receive ongoing training. It must be regular, demanding and of high quality, as the therapeutics of each dyschromia and the specificities of internal and external bleaching protocols call for up-to-date knowledge. [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]

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 (ΔEab) and CIEDE2000 (ΔE00) 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 ΔEab 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 ΔE00. [ABSTRACT FROM AUTHOR]

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]

Objectives: This clinical trial evaluated the effects of red wine exposure on the effectiveness of at-home bleaching with 10% carbamide peroxide, degree of tooth sensitivity, and levels of periodontal inflammatory markers. Method and materials: Eighty participants were assigned to two groups, namely, those who drank red wine (experimental group), and those who did not drink red wine (control group). The experimental group participants rinsed their mouths with 25 mL of red wine four times a day during the bleaching period. Shade evaluation was assessed visually by using the Vita Classical and Vita Easyshade techniques. Tooth sensitivity was evaluated by the numeric and visual analog scales, and the salivary and gingival crevicular fluids were collected for assessment of nitric oxide (NO) levels, a marker of inflammation. Differences in color change were analyzed by oneway analysis of variance (ANOVA). The absolute risks of tooth sensitivity were compared by the Fisher exact test. Tooth sensitivity intensity data sets for both the visual analog scale and the numeric rating scale were compared using the Wilcoxon signed rank test (α = .05). Repeated measures and two-way ANOVA followed by the Bonferroni test were used to assess time-course and differences between groups in NO production. Results: The bleaching technique was effective regardless of wine consumption (P > .05). Tooth sensitivity was classified as mild, with no differences between groups (P > .05). Red wine reduced both the gingival crevicular fluid and salivary levels of NO (P < .05). Conclusion: Red wine does not interfere with the effectiveness and sensitivity of at-home teeth bleaching with 10% carbamide peroxide and protects against bleaching-induced inflammation. [ABSTRACT FROM AUTHOR]

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]

Carbamide Peroxide, an adduct of Urea and Hydrogen Peroxide (UHP) industrially used as a solid source of hydrogen peroxide, exhibits the behaviour of a tertiary explosive but a detailed performance characterisation is still lacking in the literature. In this work, we calculated a 20 % experimental TNT equivalence for brisance, i. e. the shattering effect from the shock wave transmitted from the detonating high explosive into adjacent materials, by experimental indirect measurement of UHP detonation pressure. We determined a 3.5 GPa detonation pressure for 5 kg unconfined UHP charges (0.87 g/cm3, 120 mm charge diameter) by measuring the attenuated shock wave velocity (ASV) in adjacent inert materials using passive optical probes. Particle velocity measurements at the interface of a PMMA impedance window carried out with Photonic Doppler Velocimetry on scaled‐down charges of 90 g UHP under heavy confinement (0.85 g/cm3, 30 mm charge diameter, 4 mm thick steel) are consistent with ASV results in the PMMA acceptors but further investigations are required to determine the detonation pressure, using a small‐scale experimental setup. The ASV method has proven reliable to assess the brisance of a non‐ideal explosive for risk assessment purposes. [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.

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.

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

A tungsten (VI) complex, [WO(O2)L(CH3OH)], L = (E)-N'-(2-hydroxy-3-methoxybenzylidene)isonicotinohydrazide has been synthesized by the action of WO3 with a ONO donor tridentate Schiff base using H2O2. The tungsten(VI) complex has been characterized by CHN, FT-IR, multinuclear (1H & 13C) NMR, and UV-Vis. spectroscopic methods. Theoretical calculations, using DFT at the B3LYP level of theory at the Def2-TZVP basis set, for the estimation of geometrical parameters like natural bond orbital (NBO), molecular electrostatic potential (MEP), and frontier molecular orbitals (FMOs) analysis of the synthesised compounds showed that the numerical results correspond to the actual findings. The catalytic activity of WO(O2)L(CH3OH) for the selective oxidation of benzylic alcohols to the corresponding aryl aldehydes was studied utilizing various factors, like the nature of the oxidant, the effect of solvent, and the amount of catalyst. The best results were obtained by using 2 mmol of urea hydrogen peroxide (UHP) as an oxidant in the presence of 1 mol% of the catalyst in CH3CN under reflux conditions. [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.

The present work revealed a novel one-pot synthesis of 2-oxo-1,2,3,4-tetrahydropyrimidines. It involved the use of methyl arenes as a surrogate of aldehydes, in situ generation of urea, and eco-friendly lactic acid as a green catalyst for the synthesis of the desired product in solvent-free conditions via the Biginelli reaction. The appealing characteristics of the proposed protocol include; environmentally benign mild reaction conditions, readily available and cost-effective chemicals as starting material, invaluable bio-based green catalyst, aerobic conditions, shorter reaction time, tolerance to distinct functional groups, and easy isolation of final product with high yield value even without the use of chromatographic separation technique. [ABSTRACT FROM AUTHOR]

Tooth color change is an alteration that varies in cause, location and severity, which may be related to extrinsic factors, intrinsic factors or a combination of both; For this reason, dental whitening is one of the procedures most requested from dentists; more and more patients are looking for a better image and smile without considering the possible consequences. This is due to the constant advertising in the media; in addition, it has led to the appearance of certain products on the market that are used by consumers without any control from the dentist. Therefore, the objective of this review is to know the advantages and disadvantages of dental whitening with 35% hydrogen peroxide (PH) (ultradent) in the office and 10% carbamide peroxide (PC) (ultradent) for home use, with the aim of in order to guarantee the comfort of patients during use and to avoid possible adverse effects. The academic Google search engine was reviewed, as well as databases: PubMed, SciELO, Medigraphic and ScienceDirect, in the period 2002 to 2020, using as keywords "hydrogen peroxide", "carbamide peroxide", "whitening", "clarification", "ph" and their similar in English. Two hundred fifty-four articles were obtained, of which 50 were selected and analyzed because they were related to the topic raised. It is concluded that, according to the instructions specified by the manufacturer, PH 35% and PC 10% are reliable agents for dentistry. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the correlation between the dental crown's color and the pulse oximeter result in healthy teeth before and after 30 days of the end bleaching procedures. Material and methods: The dental crown's color of 70 healthy maxillary central incisors were evaluated using a spectrophotometer and the oxygen saturation level of the pulp was recorded using a pulse oximeter. The bleaching was performed using the combined technique, with 35% hydrogen peroxide bleaching gel, in the office stage, and 10% carbamide peroxide, in the at-home, for 16 days. The variables symmetry was verified by the Kolmogorov Smirnov test, and the quantitative variables described by mean and standard deviation. The correlation between quantitative variables was established using Pearson's correlation coefficient. The significance level considered was 5%. Results: A significant change was observed between values recorded by the pulse oximeter before (85.0% ± 4.1) and after (86.4% ± 2.3) 30 days of the end. Thirty days after the end of the bleaching procedures, the dental crowns were lighter with the difference between L*s equal to 1.4, more greenish with a difference between a*s equal to 1.3, and more bluish with a difference between b*s equal to -7.2. There was no correlation between the values of coordinates L*, a* and b* and the results recorded by the pulse oximeter in the initial period, respectively, or 30 days after the bleaching procedures, respectively. Conclusion: Changes in pulse oximeter recordings did not correlate with the change in the dental crown's color promoted by bleaching procedures. [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]

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