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1.
Arq. neuropsiquiatr ; 76(9): 603-608, Sept. 2018. graf
Article in English | LILACS | ID: biblio-973951

ABSTRACT

ABSTRACT The neuropeptide orexin-A and its receptors are widely distributed in both hippocampal circuitry and pain transmission pathways. Objective: Involvement of the CA1 orexin 1 receptor (OX1R) on the modulation of orofacial pain and pain-induced changes in hippocampal expression of cyclooxygenase-2 (COX-2) and brain-derived neurotrophic factor (BDNF) was investigated. Methods: Orofacial pain was induced by an intra-lip injection of capsaicin (100 μg). Reverse transcription polymerase chain reaction and immunoblot analysis were used to indicate changes in hippocampal BDNF and COX-2 expression, respectively. Results: Capsaicin induces a significant pain response, which is not affected by either orexin-A or SB-334867-A, an OX1R antagonist. However, an increased expression of COX-2 and decreased expression of BDNF was observed in the hippocampus of animals that received capsaicin or SB-334867-A (80 nM) plus capsaicin. Meanwhile, orexin-A (40 pM) attenuated the effects of capsaicin on the expression of COX-2 and BDNF. Conclusions: CA1 OX1R activation moderates capsaicin-induced neuronal inflammation and neurotrophic deficiency.


RESUMO O neuropeptídeo orexina-A e seus receptores estão amplamente distribuídos nos circuitos do hipocampo e nas vias de transmissão da dor. Objetivo: O envolvimento do receptor de orexina 1 CA1 (OX1R) na modulação da dor orofacial e alterações induzidas pela dor na expressão do hipocampo de ciclooxigenase-2 (COX-2) e fator neurotrófico derivado do cérebro (BDNF) foi investigado. Métodos: A dor orofacial foi induzida por injeção intra-labial de capsaicina (100 μg). A reação em cadeia da polimerase de transcrição reversa e a análise de imunotransferência foram utilizadas para indicar alterações na expressão de BDNF e COX-2 no hipocampo, respectivamente. Resultados: A capsaicina induz uma resposta significativa à dor, que não é afetada pela orexina-A ou pelo SB-334867-A, um antagonista do OX1R. No entanto, uma expressão aumentada de COX-2 e uma expressão diminuída de BDNF foi observada no hipocampo de animais que receberam capsaicina ou SB-334867-A (80 nM) mais capsaicina. Enquanto isso, a orexina A (40 pM) atenuou os efeitos da capsaicina na expressão de COX-2 e BDNF. Conclusões: A ativação de CA1 OX1R modera a inflamação neuronal induzida por capsaicina e a deficiência neurotrófica.


Subject(s)
Animals , Male , Rats , Facial Pain/metabolism , Brain-Derived Neurotrophic Factor/metabolism , Cyclooxygenase 2/metabolism , Orexin Receptors/metabolism , Orexins/pharmacology , Hippocampus/metabolism , Urea/analogs & derivatives , Urea/pharmacology , Benzoxazoles/pharmacology , Capsaicin , Rats, Wistar , Reverse Transcriptase Polymerase Chain Reaction , Disease Models, Animal , Hippocampus/drug effects , Naphthyridines , Neurons/drug effects , Neurons/metabolism
2.
J. appl. oral sci ; 26: e20170573, 2018. tab, graf
Article in English | LILACS | ID: biblio-954500

ABSTRACT

Abstract Objectives A single-blinded, randomized, parallel clinical trial evaluated the use of 37% carbamide peroxide (CP) on bleaching effectiveness and tooth sensitivity reported by patients undergoing in-office tooth bleaching, in comparison with the results of using 35% hydrogen peroxide. Material and Methods Forty patients were allocated to receive two sessions of in-office tooth bleaching using either 35% hydrogen peroxide (HP) or 37% CP. Each patient's sensitivity level was evaluated during and up to 24 h after bleaching. The effectiveness of the bleaching procedures was evaluated with a spectrophotometer one week after each session and 30 days after the last session. The impact of tooth bleaching on the patients' perceptions regarding smile changes, in addition to the bleaching procedures and their results, were also recorded. Absolute and relative sensitivity risks were calculated. Data on sensitivity level were analyzed using the Mann-Whitney or T-test, and data from the color evaluation were subjected to 2-way repeated measures ANOVA. Results The use of CP reduced the risk and level of tooth sensitivity to values close to zero, whereas the difference between the bleaching agents disappeared after 24 h. An increased bleaching effect was observed for HP, mainly due to an improved reduction of redness and yellowness. Participants perceived improved tooth bleaching for HP and reduced sensitivity for CP, but no differences regarding the comfort of the techniques were noted. Conclusions In our study, 37% CP resulted in reduced tooth sensitivity but decreased the tooth bleaching effectiveness. However, both bleaching agents resulted in high levels of patient satisfaction.


Subject(s)
Humans , Male , Female , Adult , Young Adult , Peroxides/administration & dosage , Tooth Bleaching/methods , Urea/analogs & derivatives , Dentin/drug effects , Dentin Sensitivity/prevention & control , Tooth Bleaching Agents/administration & dosage , Hydrogen Peroxide/administration & dosage , Peroxides/adverse effects , Time Factors , Tooth Bleaching/adverse effects , Urea/administration & dosage , Urea/adverse effects , Single-Blind Method , Reproducibility of Results , Risk Factors , Analysis of Variance , Treatment Outcome , Statistics, Nonparametric , Risk Assessment , Dentin Sensitivity/chemically induced , Tooth Bleaching Agents/adverse effects , Visual Analog Scale , Carbamide Peroxide , Hydrogen Peroxide/adverse effects
3.
J. appl. oral sci ; 26: e20170284, 2018. tab, graf
Article in English | LILACS | ID: biblio-893698

ABSTRACT

Abstract Objective The objective of this study was to evaluate dental sensitivity using visual analogue scale, a Computerized Visual Analogue Scale (CoVAS) and a neurosensory analyzer (TSA II) during at-home bleaching with 10% carbamide peroxide, with and without potassium oxalate. Materials and Methods Power Bleaching 10% containing potassium oxalate was used on one maxillary hemi-arch of the 25 volunteers, and Opalescence 10% was used on the opposite hemi-arch. Bleaching agents were used daily for 3 weeks. Analysis was performed before treatment, 24 hours later, 7, 14, and 21 days after the start of the treatment, and 7 days after its conclusion. The spontaneous tooth sensitivity was evaluated using the visual analogue scale and the sensitivity caused by a continuous 0°C stimulus was analyzed using CoVAS. The cold sensation threshold was also analyzed using the TSA II. The temperatures obtained were statistically analyzed using ANOVA and Tukey's test (α=5%). Results The data obtained with the other methods were also analyzed. 24 hours, 7 and 14 days before the beginning of the treatment, over 20% of the teeth presented spontaneous sensitivity, the normal condition was restored after the end of the treatment. Regarding the cold sensation temperatures, both products sensitized the teeth (p<0.05) and no differences were detected between the products in each period (p>0.05). In addition, when they were compared using CoVAS, Power Bleaching caused the highest levels of sensitivity in all study periods, with the exception of the 14th day of treatment. Conclusion We concluded that the bleaching treatment sensitized the teeth and the product with potassium oxalate was not able to modulate tooth sensitivity.


Subject(s)
Humans , Male , Female , Adolescent , Adult , Young Adult , Peroxides/adverse effects , Tooth Bleaching/adverse effects , Urea/analogs & derivatives , Pain Measurement/methods , Dentin Sensitivity/diagnosis , Dentin Sensitivity/chemically induced , Tooth Bleaching Agents/adverse effects , Orotic Acid/therapeutic use , Peroxides/chemistry , Time Factors , Urea/adverse effects , Urea/chemistry , Severity of Illness Index , Analysis of Variance , Treatment Outcome , Pain Threshold , Visual Analog Scale , Carbamide Peroxide
4.
J. appl. oral sci ; 25(2): 234-242, Mar.-Apr. 2017. tab, graf
Article in English | LILACS | ID: biblio-841184

ABSTRACT

Abstract Regenerative endodontic procedure (REP) has been proposed as a new approach to treat immature permanent teeth. However, materials used in REP for root canal disinfection or cervical sealing may induce tooth discoloration. Objectives To assess tooth crown’s color after intracanal treatment with triple antibiotic paste (TAP) or calcium hydroxide (CH); cervical sealing with glass ionomer cement (GIC) or mineral trioxide aggregate (MTA); and bleaching with carbamide peroxide. Material and Methods After pulp removal and color spectrophotometer measurement, 50 bovine incisors were divided into 4 experimental groups and one control (untreated). Experiments were performed in phases (Ph). Ph1: TAP (ciprofloxacin, metronidazole, minocycline), TAPM (ciprofloxacin, metronidazole, amoxicillin), DAP (ciprofloxacin, metronidazole), or CH treatment groups. After 1 and 3 days (d); 1, 2, 3 weeks (w); and 1, 2, 3 and 4 months (m), color was measured and medications were removed. Ph2: GIC or MTA cervical sealing, each using half of the specimens from each group. Color was assessed after 1d, 3d; 1w, 2w, 3w; 1m and 2m. Ph3: Two bleaching sessions, each followed by color measurement. Data were analyzed with ANOVA and post-hoc Holm-Sidak method. Results Ph1: Specimens of TAP group presented higher color alteration (ΔE) mean than those of TAPM group. No significant difference was found among TAP or TAPM and CH, DAP or Control groups. Ph2: cervical sealing materials showed no influence on color alteration. Ph3: Different ΔE means (from different groups), prior to bleaching, became equivalent after one bleaching session. Conclusions TAP induces higher color alteration than TAPM; color alteration increases over time; cervical sealing material has no influence on color alteration; and, dental bleaching was able to recover, at least partially, the tooth crown’s color.


Subject(s)
Animals , Cattle , Anti-Bacterial Agents/chemistry , Root Canal Filling Materials/chemistry , Root Canal Irrigants/chemistry , Root Canal Therapy/methods , Tooth Bleaching Agents/chemistry , Tooth Crown/drug effects , Tooth Discoloration/chemically induced , Aluminum Compounds/chemistry , Calcium Compounds/chemistry , Calcium Hydroxide/chemistry , Drug Combinations , Glass Ionomer Cements/chemistry , Materials Testing , Oxides/chemistry , Peroxides/chemistry , Prosthesis Coloring , Reference Values , Reproducibility of Results , Silicates/chemistry , Spectrophotometry , Time Factors , Tooth Bleaching/methods , Urea/analogs & derivatives , Urea/chemistry
5.
J. appl. oral sci ; 24(5): 509-517, Sept.-Oct. 2016. tab, graf
Article in English | LILACS | ID: lil-797983

ABSTRACT

ABSTRACT Tooth bleaching is a technique of choice to obtain a harmonious smile, but bleaching agents may damage the dental pulp. Objective: This study evaluated the inflammatory responses of human dental pulp after the use of two bleaching techniques. Material and Methods: Pulp samples were collected from human third molars extracted for orthodontic reasons and divided into three groups: control - no tooth bleaching (CG) (n=7); at-home bleaching with 15% carbamide peroxide (AH) (n = 10), and in-office bleaching with 38% hydrogen peroxide (IO) (n=12). Pulps were removed and stained with hematoxylin-eosin for microscopic analysis of inflammation intensity, collagen degradation, and pulp tissue organization. Immunohistochemistry was used to detect mast cells (tryptase+), blood vessels (CD31+), and macrophages (CD68+). Chi-square, Kruskal-Wallis, and Mann Whitney tests were used for statistical analysis. The level of significance was set at p<.05. Results: The inflammation intensity and the number of macrophages were significantly greater in IO than in AH and CG (p<0.05). The results of CD31+ (blood vessels per mm2) were similar in CG (61.39±20.03), AH (52.29±27.62), and IO (57.43±8.69) groups (p>0.05). No mast cells were found in the pulp samples analyzed. Conclusion: In-office bleaching with 38% hydrogen peroxide resulted in more intense inflammation, higher macrophages migration, and greater pulp damage then at-home bleaching with 15% carbamide peroxide, however, these bleaching techniques did not induce migration of mast cells and increased the number of blood vessels.


Subject(s)
Humans , Pulpitis/chemically induced , Tooth Bleaching/adverse effects , Dental Pulp/drug effects , Tooth Bleaching Agents/toxicity , Peroxides/toxicity , Pulpitis/pathology , Time Factors , Tooth Bleaching/methods , Urea/analogs & derivatives , Urea/toxicity , Blood Vessels/drug effects , Blood Vessels/pathology , Immunohistochemistry , Antigens, Differentiation, Myelomonocytic , Random Allocation , Antigens, CD , Cell Count , Collagen/drug effects , Statistics, Nonparametric , Platelet Endothelial Cell Adhesion Molecule-1 , Dental Pulp/pathology , Hydrogen Peroxide/toxicity
6.
JCPSP-Journal of the College of Physicians and Surgeons Pakistan. 2016; 26 (2): 83-86
in English | IMEMR | ID: emr-176238

ABSTRACT

Objective: To evaluate the effect of home-use bleaching agent containing 16% Carbamide Peroxide [CP] and in-office bleaching agent containing 38% Hydrogen Peroxide [HP] on enamel micro-hardness


Study Design: An in vitro experimental study


Place and Duration of Study: Department of Operative Dentistry and Science of Dental Materials at Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences and Material Engineering Department of NED University of Engineering and Technology, Karachi, from July to December 2014


Methodology: A total of 90 enamel slabs from 45 sound human 3rd molar were randomly divided into 3 groups. Each group contained 30 specimens [n=30]. Group 1 was kept in artificial saliva at 37[degree]C in incubator during the whole experiment. However, Groups 2 and 3 were treated with power whitening gel and tooth whitening pen respectively. After bleaching session, specimens were thoroughly rinsed with deionized water again for 10 seconds and then stored in artificial saliva at 37[degree]C in incubator. Artificial saliva was changed after every 2 days. The Vickers hardness tester [Wolpert 402 MVD, Germany] was adjusted to a load of 0.1 kg [100 gm] and dwell time of 5 seconds. Three Vickers were performed on each specimen using a hardness tester according to the ISO 6507-3:1998 specification. Micro-hardness measurements were performed before and after bleaching at day 1, 7 and 14


Results: In the control group, the baseline micro-hardness was 181.1 +/- 9.3 which was reduced after the storage on day 1, 7 and 14 [p = 0.104]. In Group 2, baseline micro-hardness was 180.4 +/- 10.1 which was reduced to 179.79 +/- 10.0 units after day 1. Whereas, on day 7 and 14, the values of micro-hardness were 179.8 +/- 10 and 179.7 +/- 10.29, respectively [p=0.091]. Furthermore, the baseline micro-hardness in Group 3 was 174.0 +/- 22.9 units which was reduced to 173 +/- 23 on day 1, 170 +/- 30 on day 7 and 173 +/- 23 on day 14 [p = 0.256]. The statistically insignificant difference was found among micro-hardness values of different bleaching agents [p = 0.118]


Conclusion: Bleaching with 38% Hydrogen Peroxide [HP] and 16% Carbamide Peroxide [CP] resulted in insignificant effect on surface micro-hardness of enamel


Subject(s)
Peroxides , Urea/analogs & derivatives , Hydrogen Peroxide , Dental Enamel , Hardness , Saliva, Artificial , In Vitro Techniques
7.
JCPSP-Journal of the College of Physicians and Surgeons Pakistan. 2016; 26 (1): 9-12
in English | IMEMR | ID: emr-175795

ABSTRACT

Objective: To evaluate the effect of home-use bleaching agent containing 16% Carbamide Peroxide [CP] and in-office bleaching agent with 38% Hydrogen Peroxide [HP] on surface micro-morphology of enamel


Study Design: An experimental study


Place and Duration of Study: The discs were prepared at Material Engineering Department of NED University of Engineering and Technology, Karachi, and surface morphology was analyzed at Centralized Science Laboratory of Karachi University, Pakistan. Duration of study was one year from January to December 2012


Methodology: Forty five sound human third molar crowns, extracted for periodontal reason, were included in the study. Longitudinal sections were made using diamond disks [0.2 mm] under water lubrication to obtain enamel slabs measuring [3 mm x 3 mm]. The slabs were embedded in polystyrene resin by using 2.0 cm diameter PVC molds, leaving the outer enamel surface uncovered by the resin. Ninety dental enamel slabs were prepared. The slabs were then randomly divided into 3 groups. Each group contained thirty specimens [n=30]. Group 1 was kept in artificial saliva at 37[degree]C in incubator [Memart, Germany] during whole experiment. Group 2 was treated with power whitening gel [White Smile 2011, Germany]. Group 3 was treated with tooth whitening pen [White Smile 2011, Germany]. The most central region or the region that was most representative of the entire surface area was used. The SEM [Jeol-Japan-JSM6380A, JAPAN] micrographs were examined to determine the type of surface presented. The enamel changes were classified as no or mild alteration, moderate alteration and severe altered surface


Results: Regarding micro-morphology, the enamel surface of control groups showed smooth surface in general with some scattered clear scratches due to the polishing procedure. The specimens bleached in group 2 and group 3, represented areas of mild erosion


Conclusion: Bleaching with 38% Hydrogen Peroxide [HP] and 16% Carbamide Peroxide [CP] resulted in mild changes in surface micro-morphology of enamel


Subject(s)
Bleaching Agents , Peroxides , Urea/analogs & derivatives , Hydrogen Peroxide , Dental Enamel
8.
J. appl. oral sci ; 23(6): 609-613, Nov.-Dec. 2015. tab
Article in English | LILACS | ID: lil-769821

ABSTRACT

ABSTRACT Objective The purpose of this in vitro study was to compare the efficacy of a bleaching toothpaste containing Blue Covarine vs. conventional tooth bleaching techniques using peroxides (both in-office and at-home). Material and Methods Samples were randomly distributed into five experimental groups (n=15): C - Control; BC – Bleaching toothpaste containing Blue Covarine; WBC – Bleaching toothpaste without Blue Covarine; HP35 - In-office bleaching using 35% hydrogen peroxide; and CP10 – At-home bleaching with 10% carbamide peroxide. The dental bleaching efficacy was determined by the color difference (ΔE), luminosity (ΔL), green-red axis (Δa), and blue-yellow axis (Δb). The CIELab coordinates were recorded with reflectance spectroscopy at different times: T0 - baseline, T1 – immediately after bleaching, T2 - 7 days, T3 - 14 days, and T4 - 21 days after the end of treatments. Data were analyzed by a repeated measures mixed ANOVA and post hoc Bonferroni test, with a significance level of 5%. Results No significant differences were found between the treatment groups C, BC, and WBC. The groups HP35 and CP10 showed significantly higher whitening efficacy than groups C, BC, and WBC. Conclusions There were no significant differences in the whitening efficacy between a Blue Covarine containing toothpaste, a standard whitening toothpaste, and a control. Neither of the whitening toothpastes tested were as effective as in-office or at-home bleaching treatments.


Subject(s)
Humans , Isoindoles/chemistry , Metalloporphyrins/chemistry , Tooth Bleaching Agents/chemistry , Tooth Bleaching/methods , Toothpastes/chemistry , Analysis of Variance , Color , Colorimetry , Hydrogen Peroxide/chemistry , Peroxides/chemistry , Reference Values , Reproducibility of Results , Single-Blind Method , Spectrophotometry , Statistics, Nonparametric , Time Factors , Toothbrushing , Urea/analogs & derivatives , Urea/chemistry
9.
Clinics ; 70(5): 333-338, 05/2015. graf
Article in English | LILACS | ID: lil-748272

ABSTRACT

OBJECTIVE: This study investigated the acute hemodynamic responses to multiple sets of passive stretching exercises performed with and without the Valsalva maneuver. METHODS: Fifteen healthy men aged 21 to 29 years with poor flexibility performed stretching protocols comprising 10 sets of maximal passive unilateral hip flexion, sustained for 30 seconds with equal intervals between sets. Protocols without and with the Valsalva maneuver were applied in a random counterbalanced order, separated by 48-hour intervals. Hemodynamic responses were measured by photoplethysmography pre-exercise, during the stretching sets, and post-exercise. RESULTS: The effects of stretching sets on systolic and diastolic blood pressure were cumulative until the fourth set in protocols performed with and without the Valsalva maneuver. The heart rate and rate pressure product increased in both protocols, but no additive effect was observed due to the number of sets. Hemodynamic responses were always higher when stretching was performed with the Valsalva maneuver, causing an additional elevation in the rate pressure product. CONCLUSIONS: Multiple sets of unilateral hip flexion stretching significantly increased blood pressure, heart rate, and rate pressure product values. A cumulative effect of the number of sets occurred only for systolic and diastolic blood pressure, at least in the initial sets of the stretching protocols. The performance of the Valsalva maneuver intensified all hemodynamic responses, which resulted in significant increases in cardiac work during stretching exercises. .


Subject(s)
Humans , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Benzodioxoles/pharmacology , Colonic Neoplasms/drug therapy , Isoquinolines/pharmacology , Protein Kinase Inhibitors/pharmacology , Thiophenes/pharmacology , Topoisomerase I Inhibitors/pharmacology , Urea/analogs & derivatives , DNA Replication/drug effects , Drug Synergism , Protein Kinases/metabolism , Protein-Serine-Threonine Kinases/metabolism , Urea/pharmacology
10.
Article in English | IMSEAR | ID: sea-158285

ABSTRACT

Aim: The aim of the study was to evaluate the microleakage on the marginal integrity of nanohybrid composite during bleaching with carbamide peroxide after applying a protective coating of G‑Coat plus (GC, Japan). Materials and Methods: Class V cavities were prepared and restored with nanohybrid composite restoration in 60 freshly extracted noncarious premolars extracted for orthodontic reasons. Then they were divided into 3 groups. Group 1 ‑ bleaching with carbamide peroxide without G coat plus (n = 20), Group 2 ‑ bleaching with carbamide peroxide with G‑Coat plus (n = 20), Group 3 ‑ without bleaching procedure (n = 20) (control group). In Group 2, G coat plus was applied over the restorative surface and margins. Then all teeth in Groups 1 and 2 were taken and mounted in dental stone. Bleaching trays were custom fabricated over the cast with the help of a heated vacuum‑forming machine. 10% carbamide peroxide (opalescence PF) was applied over the tooth, and the bleaching process was done for about 2 weeks. Then all samples underwent thermocycling and were then immersed in the 2% methylene blue solution for 24 h and observed under a stereomicroscope to evaluate the amount of dye penetration. Data were compared using Kruskal–Wallis test and Mann–Whitney test using SPSS Inc.; Chicago, IL, USA, Version 17.0. Results: Mann–Whitney test shows that the difference in microleakage between Group 1–Group 2 and Group 2–Group 3 is statistically significant (P < 0.05). Conclusion: Significant reduction in microleakage was seen in Group 2 when compared to other groups.


Subject(s)
Composite Resins , Glass Ionomer Cements , Peroxides , Surface Properties , Tooth Bleaching Agents , Urea/analogs & derivatives
11.
Braz. oral res. (Online) ; 29(1): 1-7, 2015. tab, ilus
Article in English | LILACS | ID: lil-777227

ABSTRACT

Dental bleaching has become one of the most frequently requested esthetic treatments in dental offices. Despite the high clinical success observed with this procedure, some adverse effects have been reported, including a potential for developing premalignant lesions, root resorption and tooth sensitivity, especially when misused. The aim of this study was to evaluate the genotoxic response using a micronucleus (MN) assay, after the application of two concentrations of carbamide peroxide. Thirty-seven patients were divided into two groups and randomly received either a 10% carbamide peroxide (CP) (19) or a 16% carbamide peroxide (18) concentration for 21 days in individual dental trays. Gingival margin cells were collected immediately before the first use (baseline), and then 15 and 45 days after baseline. The cells were placed on a histological slide, stained by the Feulgen technique, and evaluated by an experienced blinded examiner. One thousand cells per slide were counted, and the MN rate was determined. The two groups were analyzed by the Wilcoxon rank-sum test and the Kruskal-Wallis equality-of-populations rank test. A slight increase in MN was observed for both groups, in comparison with the baseline, at 15 days. However, no difference was observed between the two groups (10% and 16%), at either 15 or 45 days (p = 0.90). When bleaching is not prolonged or not performed very frequently, bleaching agents containing carbamide peroxide alone will not cause mutagenic stress on gingival epithelial cells.


Subject(s)
Adult , Female , Humans , Male , Young Adult , Gingiva/drug effects , Peroxides/adverse effects , Tooth Bleaching/adverse effects , Urea/analogs & derivatives , Epithelial Cells/drug effects , Micronucleus Tests , Mouth Mucosa/drug effects , Peroxides/administration & dosage , Random Allocation , Statistics, Nonparametric , Time Factors , Treatment Outcome , Tooth Bleaching/methods , Urea/administration & dosage , Urea/adverse effects
12.
Journal of Islamic Dental Association of Iran [The]-JIDA. 2015; 26 (4): 285-293
in Persian | IMEMR | ID: emr-167552

ABSTRACT

Tooth colored restorations are the commonly used current approach for aesthetic problems associated with brown spots. Considering the importance of conservative dentistry, the aim of this in vitro study was to evaluate the efficacy of color correction using casein phophopeptide amorphous calcium phosphate [CPP-ACP] and resin infiltration after using 20% carbamide peroxide for brown spots in esthetic areas. In this experimental study, 70 humans teeth samples with brown spots were collected. In the first step, 20% carbamide peroxide was applied and then samples were divided into two groups to be treated with CPP-ACP or resin infiltration. Color parameters of the samples were evaluated at baseline, after bleaching, after using infiltration resin and CPP-ACP. Any color shift was measured using spectrophotometer. The results were analyzed by SPSS version 20. For statistical analysis, paired t test, indeipendent t-test and repeated measures ANOVA were used. P value <0.05 was considered significant. After using 20% carbamide peroxide, L[asterisk] and b[asterisk] increased and a [asterisk] decreased significantly [p<0.001]. By using CPP-ACP, decreases in a [asterisk] and b[asterisk] were not significant [p>0.05] but L[asterisk] increased significantly [p<0.001]. Application of infiltration resin caused a significant decrease in a [asterisk] [p<0.001]; however, the decrease in L[asterisk] and the increase in b[asterisk] were not statistically significant [p>0.05]. Comparison of the two groups showed that the degree of color shift [delta E] in brown spots and adjacent sound enamel did not change significantly in the two subgroups [p>0.05]. The results show that for esthetically unfavorable brown spots, using 20% carbamide peroxide with CPP-ACP or resin infiltration can improve the appearance. In general, application of resin infiltration with carbamide peroxide is preferably recommended for improving translucency


Subject(s)
Humans , Resins, Synthetic , Peroxides , Urea/analogs & derivatives , Caseins , Esthetics, Dental , Spectrophotometry
13.
Rev. colomb. biotecnol ; 15(2): 38-46, jul.-dic. 2013. graf
Article in Spanish | LILACS | ID: lil-703335

ABSTRACT

Se comparó la eficiencia de sistemas de cultivos discontinuos alimentados versus cultivos discontinuos convencionales, en cuanto a concentración de nitrógeno, adicionando 0,2 mM de urea cada tres días al final de la fase exponencial, durante 21 días. Se realizaron cultivos con un volumen de 1500 mL a 15 y 35 UPS de salinidad, enriquecidos con medio ALGAL 8mM NaNO3, a 238 µmol q m-2 s-1, aireación constante, fotoperiodo 12:12 horas y temperatura de 29 ±3°C. Phormidium sp. posee la capacidad de hidrolizar la urea; mostrando una asimilación de 65±7,07% de la misma, con la mayor producción (p<0,05) de clorofila a, ficocianina y proteínas de 20,26±1,24; 203,47±12,83 y 707,87±28,47 µg mL-1en los cultivos alimentados. La producción de pigmentos vario en el tiempo, independientemente a la salinidad y sistema de cultivo, mientras que la producción de proteínas y carbohidratos totales fue directamente proporcional a la edad del cultivo, con valores máximos de 612,74 ± 5,41 µg mL-1 y 8,96±0,08 mg mL-1 respectivamente a los 31 días. La síntesis de lípidos y EPS fueron influenciadas (p<0,05) por la salinidad, presentando los máximos de lípidos a 15 UPS con 12,22±2,91µg mL-1, y los EPS se incrementaron a 35 UPS con 2,00 ± 0,26 y 2,03 ± 0,15 mg mL-1. Estos resultados determinan que los cultivos de Phormidium sp. alimentados con urea y a salinidades de 15 y 35 UPS, representan una alternativa económica para la producción de clorofila a, ficocianina y proteínas, incrementándose un 31,04; 40,72 y 31,94 % respectivamente en comparación con cultivos no alimentados.


Fed-batch system efficiency versus batch cultures was compared in relation to nitrogen concentration, adding 0,2mM urea at the end of the exponential phase, during 21 days. Cultures were carried out in 1500 mL to 1.5 and 3.5 UPS of salinity, enriched with Algal medium 8mM NaNO3, 238 mol q m-2 s-1, constant aeration, photoperiod 12:12 h. and 29 ±3°C. Phormidium sp. is able to hydrolyze urea; showing a total assimilation of 65±7.07%, with the highest (p< 0.05) chlorophyll a, phycocyanin and protein production of 20.26 ± 1.24, 203.47 ± 12.83 and 707.87 ± 28.47 µg mL-1 in the fed-batch cultures. On the other hand, pigment production varies in time, regardless salinity and culture system. Proteins and total carbohydrate production were directly proportional to the age of cultures, with maximum values of 612.74 ± 5.41 µg mL-1 and 8.96 ± 0.08 mg mL-1, respectively. Lipid and EPS were influenced (p< 0.05) by salinity, showing maximum of lipids at 15 UPS with 12.22±2.91 µg mL-1, and EPS at 15 and 35 UPS with 2.00 ± 0.26 and 2.03 ± 0.15 mg mL-1. These results determine that Phormidium sp. cultures fed with urea, to salinities of 15-35 UPS, represent an economic alternative for chlorophyll a, phycocyanin and protein production, with an increase of 31.04, 40.72 and 31.94% respectively in comparison with non-fed cultures.


Subject(s)
Cyanobacteria/classification , Cyanobacteria/growth & development , Cyanobacteria/chemistry , Salinity , Urea/administration & dosage , Urea/isolation & purification , Urea/analogs & derivatives , Urea/immunology , Urea/chemical synthesis , Urea , Chlorophyll , Phycocyanin , Proteins
14.
Braz. dent. j ; 24(5): 517-521, Sep-Oct/2013. tab, graf
Article in English | LILACS | ID: lil-697629

ABSTRACT

The aim of this study was to compare the effect of a 16% carbamide peroxide (CP) gel and a 10% CP gel on mineralized enamel content and morphology. Enamel blocks from bovine incisors were subjected to a 14-day treatment (8 h/day) with 10% or 16% CP gels. Knoop microhardness was evaluated before bleaching and at 1, 7 or 14 days after this treatment (50 g/15 s). Mineral content (energy-dispersive x-ray spectroscopy), surface roughness and topography (atomic force microscopy) were evaluated at the 14-day period. Data were analyzed statistically by two-way ANOVA and Tukey's test (α=0.05). Significant microhardness reduction was observed at the 7 th and 14 th days for 10% CP gel, and for all bleaching times for 16% CP gel (p<0.05). At the 14-day period, a significant decrease in Ca and P content, increase on surface roughness (p<0.05) as well as on picks and valleys distance were observed when both bleaching gels were used. These enamel alterations were more intense for 16% CP gel. It was concluded that both CP-based gels promoted loss of mineral structure from enamel, resulting in a rough and porous surface. However, 16% CP gel caused the most intense adverse effects on enamel.


O objetivo do presente estudo foi comparar o efeito de um gel com 16% de peróxido de carbamida (PC) sobre a estrutura mineral e morfologia do esmalte dental com os efeitos de um gel com 10% de PC. Blocos de esmalte provenientes de incisivos bovinos foram submetidos a 14 dias de tratamento (8 h/dia) com géis com 10 ou 16% de PC. A microdureza Knoop foi avaliada antes do clareamento e 1, 7 e 14 dias pós-tratamento (50 g/15 s). O conteúdo mineral (EDX), rugosidade de superfície e topografia (MFA) foram avaliados no período de 14 dias (ANOVA a dois critérios e teste de Tukey; α=0,05). Redução significante na microdureza foi observada nos períodos de 7 e 14 dias para o gel com 10% de PC, e em todos os períodos para o gel com 16% de PC (p<0,05). No período de 14 dias, uma diminuição significante no conteúdo de Ca e P, aumento na rugosidade de superfície (p<0,05), bem como na distância entre picos e vales foram observados para ambos os agentes clareadores usados. Estas alterações foram mais intensas para o gel com 16% de PC. Pôde-se concluir que ambos os géis à base de PC promoveram perda de estrutura mineral do esmalte, resultando em superfície mais rugosa e porosa. Porém, o gel com 16% de PC causou efeitos adversos mais intensos no esmalte dental.


Subject(s)
Humans , Dental Enamel/drug effects , Peroxides/adverse effects , Tooth Bleaching/methods , Tooth Demineralization/chemically induced , Urea/analogs & derivatives , Gels , Hardness Tests , Microscopy, Atomic Force , Peroxides/administration & dosage , Spectrometry, X-Ray Emission , Urea/administration & dosage , Urea/adverse effects
15.
Braz. oral res ; 27(4): 299-304, Jul-Aug/2013. tab
Article in English | LILACS | ID: lil-679220

ABSTRACT

We investigated the effect of sodium ascorbate (SA) on the microtensile bond strengths (MTBSs) of different composites to bovine enamel after vital bleaching with hydrogen peroxide (HP) or carbamide peroxide (CP). Thirty bovine incisors were randomly divided into five groups and treated with no bleaching application (control), 35% HP alone, 35% HP + 10% SA for 10 minutes (HP + SA), 16% CP alone, or 16% CP + 10% SA for 10 minutes (CP + SA). Specimens were restored with Silorane adhesive and Filtek Silorane composite (designated as S / group) or with Clearfil SE bond and Filtek Supreme XT (designated as F / group). Composite build-up was created on the enamel. Sectioned specimens (n = 10 per group; 1 mm2; cross-sectional area) were created and stressed in a universal testing machine at 1 mm/min crosshead speed. The application of 10% SA immediately after bleaching with 16% CP or 35% HP increased the enamel MTBS, regardless of the adhesive / composite resin used. The resulting MTBS values were similar to those of the control groups. Use of 16% CP and 35% HP alone decreased the enamel MTBS, regardless of the adhesive / composite resin used, with F / CP + SA = F / HP + SA = F / CP = S / CP + SA = S / HP + SA = S / C > S / CP = S / HP = F / CP = F / HP (p < 0.05). We concluded that the application of SA for 10 minutes immediately after vital bleaching increases the enamel BS for dimethacrylate- and silorane-based composites.


Subject(s)
Animals , Cattle , Antioxidants/pharmacology , Ascorbic Acid/pharmacology , Composite Resins/chemistry , Dental Bonding/methods , Methacrylates/chemistry , Silorane Resins/chemistry , Tooth Bleaching/methods , Dental Enamel/chemistry , Dental Enamel/drug effects , Dentin-Bonding Agents/chemistry , Hydrogen Peroxide/chemistry , Materials Testing , Peroxides/chemistry , Resin Cements/chemistry , Surface Properties/drug effects , Tensile Strength/drug effects , Urea/analogs & derivatives , Urea/chemistry
16.
Braz. dent. j ; 24(3): 263-266, May-Jun/2013. tab
Article in English | LILACS | ID: lil-681876

ABSTRACT

This study investigated the effect of 16% carbamide peroxide (Whiteness Perfect/FGM) on the Vickers microhardness and flexural strength of the restorative composites Filtek Z100 (hybrid), Filtek Z350 (nanofill), Brilliant (micro-hybrid) and Opallis (micro-hybrid). Disc-shaped (4x2 mm; n=5) and bar-shaped (12x2x1 mm; n=10) specimens of each restorative material were randomly divided into 2 groups: (G1) 16 weeks stored in distilled water; (G2) 16 weeks stored in distilled water, with 16% carbamide peroxide application during 6 h per day for the last 4 weeks. The mechanical properties were evaluated using a Vickers microhardness tester and a mechanical testing machine. Data were analyzed by two-way ANOVA and Tukey's (HSD) post-hoc test (α=0.05). Filtek Z100 presented the highest microhardness value, followed by Filtek Z350 and finally by Brilliant and Opallis (p=0.00). Filtek Z100 and Brilliant exhibited the highest flexural strength value, followed by Filtek Z350 and Opallis (p=0.00). Bleaching treatment decreased significantly microhardness of Brilliant and Opallis (p=0.00). The flexural strength of all studied materials was not affected by the home bleaching (p=0.28).


Este estudo investigou o efeito do peróxido de carbamida a 16% (Whiteness Perfect/FGM) na dureza Vickers e resistência à flexão dos compósitos restauradores Filtek Z100 (híbrida), Filtek Z350 (nanoparticulada), Brilliant (micro-híbrida) e Opallis (micro-híbrida). Espécimes em forma de disco (4x2 mm; n=5) e de barra (12x2x1 mm; n=10) de cada material restaurador foram distribuídos aleatoriamente em 2 grupos: (G1) 16 semanas em água destilada; (G2) armazenamento em água destilada durante 16 semanas, com aplicação do peróxido de carbamida a 16% por 6 h diárias nas últimas 4 semanas. As propriedades mecânicas foram avaliadas em microdurômetro Vickers e máquina de ensaios mecânicos. Os dados foram analisados por ANOVA a 2 critérios e teste de Tukey (α=0,05). Filtek Z100 apresentou o maior valor de dureza, seguido por Filtek Z350 e, finalmente, por Brilliant e Opallis (p=0,00). Filtek Z100 e Brilliant mostraram o maior valor de resistência à flexão, seguido por Filtek Z350 e Opallis (p=0,00). O clareamento diminuiu significantemente a dureza das resinas Brilliant e Opallis (p=0,00). A resistência à flexão dos materiais estudados não foi afetada pelo clareamento caseiro (p=0,28).


Subject(s)
Humans , Composite Resins/chemistry , Dental Materials/chemistry , Peroxides/chemistry , Tooth Bleaching Agents/chemistry , Urea/analogs & derivatives , Hardness , Materials Testing , Methacrylates/chemistry , Pliability , Polyethylene Glycols/chemistry , Polymethacrylic Acids/chemistry , Stress, Mechanical , Silicon Dioxide/chemistry , Time Factors , Urea/chemistry , Water/chemistry , Zirconium/chemistry
17.
Braz. dent. j ; 24(2): 121-127, Mar-Apr/2013. tab, graf
Article in English | LILACS | ID: lil-675665

ABSTRACT

The aim of this study was to evaluate the possibility of fluoride solutions applied to enamel to protect pulp cells against the trans-enamel and transdentinal cytotoxicity of a 16% carbamide peroxide (CP) bleaching gel. The CP gel was applied to enamel/dentin discs adapted to aicial pulp chambers (8 h/day) during 1, 7 or 14 days, followed by fluoride (0.05% or 0.2%) application for 1 min. The extracts (culture medium in contact with dentin) were applied to MDPC-23 cells for 1 h, and cell metabolism (MTT assay), alkaline phosphatase (ALP) activity and cell membrane damage (flow cytometry) were analyzed. Knoop microhardness of enamel was also evaluated. Data were analyzed statistically by ANOVA and Kruskal-Wallis tests (α=0.05). For the MTT assay and ALP activity, significant reductions between the control and the bleached groups were observed (p<0.05). No statistically significant difference occurred among bleached groups (p>0.05), regardless of fluoride application or treatment days. Flow cytometry analysis demonstrated 30% of cell membrane damage in all bleached groups. After 14 days of treatment, the fluoride-treated enamel presented significantly higher microhardness values than the bleached-only group (p<0.05). It was concluded that, regardless of the increase in enamel hardness due to the application of fluoride solutions, the treated enamel surface did not prevent the toxic effects caused by the 16% CP gel to odontoblast-like cells.


Resumo O objetivo do presente estudo foi avaliar o possível efeito protetor de soluções fluoretadas aplicadas sobre o esmalte dentário frente à citotoxicidade trans-amelodentinária de um gel clareador com 16% de peróxido de carbamida (PC). O gel de PC foi aplicado sobre discos de esmalte/dentina adaptados a câmaras pulpares aiciais (8 h/dia) durante períodos de 1, 7 ou 14 dias, seguido de aplicação de soluções fluoretadas (0,05% ou 0,2%) durante 1 min. Os extratos (meio de cultura em contato com a dentina) foram aplicados sobre células MDPC-23 durante 1 h, seguido de análise do metabolismo celular (teste do MTT), atividade de fosfatase alcalina (ALP) e danos à membrana celular (citometria de fluxo). A microdureza Knoop do esmalte dental foi avaliada. Os dados foram analisados pelos testes de ANOVA e Kruskal-Wallis. Para o teste do MTT e atividade de ALP, redução significante entre os grupos controle e clareados foram observados (p<0,05). Nenhuma diferença entre os grupos clareados foi observada (p>0,05), independente da aplicação das soluções fluoretadas ou tempo de tratamento. A análise por citometria de fluxo demonstrou lesão à membrana celular em torno de 30% para todos os grupos clareados. Após 14 dias de tratamento, os espécimes clareados e fluoretados apresentaram aumento significante na microdureza do esmalte (p<0,05). Pôde-se concluir que apesar do aumento na dureza do esmalte decorrente da aplicação das soluções fluoretadas, este tratamento não preveniu os efeitos tóxicos causados pelo gel com 16% de PC sobre as células odontoblastóides. .


Subject(s)
Animals , Cattle , Dental Enamel/drug effects , Dental Pulp/drug effects , Fluorides/pharmacology , Peroxides/toxicity , Protective Agents/pharmacology , Tooth Bleaching Agents/toxicity , Urea/analogs & derivatives , Alkaline Phosphatase/drug effects , Cell Line , Cell Membrane/drug effects , Cell Survival/drug effects , Coloring Agents , Dental Pulp Cavity/drug effects , Dental Pulp/cytology , Dentin/drug effects , Hardness , Odontoblasts/drug effects , Odontoblasts/metabolism , Propidium , Succinate Dehydrogenase/drug effects , Time Factors , Urea/toxicity
18.
Dental press j. orthod. (Impr.) ; 18(2): 61-68, Mar.-Apr. 2013. graf, tab
Article in English | LILACS | ID: lil-683185

ABSTRACT

OBJECTIVE: To evaluate the influence of bonding and debonding of orthodontic brackets on dental in-home bleaching, taking into account three different adhesive systems. METHODS: Forty-four bovine incisors were divided into four groups according to the primer system used for orthodontic bracket bonding. Following the debonding of orthodontic brackets, the teeth were stored in staining solution for 96 hours. Then, teeth were whitened using 10% carbamide peroxide for two weeks at a 6-hour-a-day regime. Standardized digital photographs were taken at the following intervals: T0 (initial); T1 (after debonding); T2 (after pigmentation); T3, T4 and T5 representing 1, 7, and 14 days of bleaching. Repeatability and stability tests were carried out to check the method accuracy. Images were analyzed using Adobe Photoshop 7.0 software considering (L*a*b*)color coordinate values and a modified color difference total (Δ;E'). RESULTS: The results of this study (ANOVA and Tukey; p < 0.01) demonstrated that after 7 days of bleaching, experimental groups showed significantly less teeth whitening compared to the control group. However, there were no significant color differences between the groups after 14 days, according to values of lightness (L*). CONCLUSIONS: Regardless of the adhesive primer system applied, bonding and debonding of orthodontic brackets alters the outcome of tooth whitening in the first 7 days of bleaching, however it has no influence on the whitening of the dental structure after 14 days of in-home dental bleaching with 10% carbamide peroxide.


OBJETIVO: o objetivo desse estudo foi avaliar a influência da colagem e descolagem de braquetes ortodônticos no clareamento caseiro, considerando três diferentes sistemas adesivos. MÉTODOS: quarenta e quatro incisivos bovinos foram divididos em quatro grupos, de acordo com o sistema adesivo utilizado para colagem dos braquetes. Após a descolagem dos braquetes, os dentes foram pigmentados por 96 horas e depois clareados com peróxido de carbamida a 10% por 6 horas diárias, durante duas semanas. Foram realizadas fotografias digitais padronizadas nos tempos: T0 (inicial); T1 (após descolagem); T2 (após pigmentação); T3, T4 e T5 representando 1, 7 e 14 dias de clareamento. Testes de repetitividade e de estabilidade foram realizados para avaliar a acurácia do método. As imagens foram avaliadas pelo software Adobe Photoshop 7.0, considerando os parâmetros de cor (L*a*b*) e a diferença total de cor adaptada para esse estudo (Δ;E'). RESULTADOS: os resultados do presente estudo (ANOVA e Tukey; p < 0,01) demonstraram que, após uma semana de clareamento, os grupos experimentais apresentaram uma resposta mais lenta ao clareamento que o grupo controle. Contudo, após 14 dias, não houve diferença cromática significativa entre os grupos, observada pelos valores de luminosidade (L*). CONCLUSÕES: independentemente do sistema adesivo utilizado, a colagem e descolagem de braquetes ortodônticos altera os resultados de obtenção de cor com sete dias de avaliação. Contudo, após 14 dias não se observa nenhuma diferença de cor na estrutura dentária clareada pela técnica caseira.


Subject(s)
Animals , Cattle , Dental Bonding/methods , Dental Cements/chemistry , Dental Debonding/methods , Orthodontic Brackets , Peroxides/chemistry , Tooth Bleaching Agents/chemistry , Tooth Bleaching/methods , Urea/analogs & derivatives , Analysis of Variance , Colorimetry , Urea/chemistry
19.
Braz. oral res ; 26(6): 536-542, Nov.-Dec. 2012. ilus, tab
Article in English | LILACS | ID: lil-656697

ABSTRACT

This study evaluated the influence of fluoride-containing carbamide peroxide (CP) bleaching agents and adhesive systems on bonded enamel interfaces that are part of the dynamic pH cycling and thermal cycling models. The buccal surfaces of 60 bovine incisors were restored with a composite resin and bonded with three- and two-step, etch-and-rinse, fluoride-containing adhesives, Optibond FL (FL) and Optibond Solo Plus (SP), respectively. Restored teeth were subjected to thermal cycling to age the interface. Both SP and FL adhesive-restored teeth were bleached (n = 10) with 10% CP (CP) and 10% CP + fluoride (CPF) or were left unbleached (control). Bleaching was performed for 14 days simultaneously with pH cycling, which comprised of 14 h of remineralization, 2 h of demineralization and 8 h of bleaching. The control groups (FL and SP) were stored in remineralizing solution during their bleaching periods and were also subjected to carious lesion formation. Parallelepiped-shaped samples were obtained from the bonded interface for microtensile bond strength (∝TBS) testing. The enamel ∝TBS of the FL and SP groups (control, not bleached) were higher (p < 0.05) than those of the bleached interfaces (FL > FL + CPF = FL + CP and SP > SP + CPF = SP + CP). The groups subjected to treatment with the fluoride-containing bleaching agents exhibited similar ∝TBS compared to regular bleaching agents. Bleaching agents, regardless of whether they contained fluoride, decreased enamel bond strength.


Subject(s)
Animals , Cattle , Dental Bonding/methods , Dental Enamel/drug effects , Fluorides/chemistry , Peroxides/chemistry , Resin Cements/chemistry , Tooth Bleaching Agents/chemistry , Urea/analogs & derivatives , Dental Restoration Failure , Dentin/drug effects , Tensile Strength , Time Factors , Tooth Demineralization , Urea/chemistry
20.
J. appl. oral sci ; 20(4): 435-443, July-Aug. 2012. ilus, graf, tab
Article in English | LILACS | ID: lil-650620

ABSTRACT

This study evaluated color change, stability, and tooth sensitivity in patients submitted to different bleaching techniques. MATERIAL AND METHODS: In this study, 48 patients were divided into five groups. A half-mouth design was conducted to compare two in-office bleaching techniques (with and without light activation): G1: 35% hydrogen peroxide (HP) (Lase Peroxide - DMC Equipments, São Carlos, SP, Brazil) + hybrid light (HL) (LED/Diode Laser, Whitening Lase II DMC Equipments, São Carlos, SP, Brazil); G2: 35% HP; G3: 38% HP (X-traBoost - Ultradent, South Jordan UT, USA) + HL; G4: 38% HP; and G5: 15% carbamide peroxide (CP) (Opalescence PF - Ultradent, South Jordan UT, USA). For G1 and G3, HP was applied on the enamel surface for 3 consecutive applications activated by HL. Each application included 3x3' HL activations with 1' between each interval; for G2 and G4, HP was applied 3x15' with 15' between intervals; and for G5, 15% CP was applied for 120'/10 days at home. A spectrophotometer was used to measure color change before the treatment and after 24 h, 1 week, 1, 6, 12, 18 and 24 months. A VAS questionnaire was used to evaluate tooth sensitivity before the treatment, immediately following treatment, 24 h after and finally 1 week after. RESULTS: Statistical analysis did not reveal any significant differences between in-office bleaching with or without HL activation related to effectiveness; nevertheless the time required was less with HL. Statistical differences were observed between the results after 24 h, 1 week and 1, 6, 12, 18 and 24 months (intergroup). Immediately, in-office bleaching increased tooth sensitivity. The groups activated with HL required less application time with gel. CONCLUSION: All techniques and bleaching agents used were effective and demonstrated similar behaviors.


Subject(s)
Adolescent , Adult , Humans , Color , Hydrogen Peroxide/therapeutic use , Peroxides/therapeutic use , Tooth Bleaching Agents/therapeutic use , Tooth Bleaching/methods , Urea/analogs & derivatives , Dentin Sensitivity , Dental Enamel/drug effects , Follow-Up Studies , Gels , Materials Testing , Time Factors , Treatment Outcome , Urea/therapeutic use
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