RESUMO
Objective: This study's aim was to quantify the hydrogen peroxide (HP) penetration into the pulp chamber of teeth submitted to different protocols of bleaching. Material and Methods: Ninety premolars were randomly divided into nine groups according to the bleaching agent protocol (n = 10): control (no bleaching), carbamide peroxide 10% [10% CP], carbamide peroxide 16% [16% CP], carbamide peroxide 22% [22% CP], hydrogen peroxide 4% [4% HP], hydrogen peroxide 6% [6% HP], hydrogen peroxide 7.5% [7.5% HP], hydrogen peroxide 10% [10% HP] and hydrogen peroxide 35% [35% HP]. The penetration of HP was measured via spectrophotometric analysis of the acetate buffer solution from the pulp chamber. The absorbance of the resulting solution was determined in a spectrophotometer and converted into equivalent concentration of HP (µg/ mL). To analyze the concentration of HP, the titration of bleaching agents with potassium permanganate was used. Data were subjected to ANOVA and Tukey's test for pairwise comparison (α = 0.05). Results: Higher concentration of HP in the pulp chamber was found in the HP 35% group (p < 0.0001). No significant difference between at-home protocols were observed (p = 0.64). Titration values showed that the concentration of the products was similar to that claimed by the manufacturer. Conclusion: It follows that the amount of HP that reaches the pulp chamber is not proportional to the concentration of whitening gels, but depends on the application time recommended by the manufacturers (AU)
Objetivo: o objetivo deste estudo foi quantificar a penetração do peróxido de hidrogênio (PH) na câmara pulpar dos dentes submetidos a diferentes protocolos de clareamento. Material e Métodos: Noventa pré-molares foram divididos aleatoriamente em nove grupos, de acordo com o protocolo do agente clareador (n = 10): controle (sem clareamento), peróxido de carbamida 10% [PC 10%], peróxido de carbamida 16% [PC 16%], peróxido de carbamida 22% [PC 22%], peróxido de hidrogênio 4% [PH 4%], peróxido de hidrogênio 6% [PH 6%], peróxido de hidrogênio 7,5% [PH 7,5%], peróxido de hidrogênio 10% [PH 10%] e peróxido de hidrogênio 35% [PH 35%]. A penetração de PH foi medida por análise espectrofotométrica da solução de tampão de acetato da câmara pulpar. A absorvância da solução resultante foi determinada em um espectrofotômetro e convertida em concentração equivalente de PH (µg / mL). Para analisar a concentração de PH, foi utilizada a titulação de agentes clareadores com permanganato de potássio. Os dados foram submetidos à ANOVA e teste de Tukey para comparação pareada (α = 0,05). Resultados: Foi encontrada maior concentração de PH na câmara pulpar no grupo PH 35% (p < 0,0001). Não foi observada diferença significativa entre os protocolos domiciliares (p = 0,64). Os valores de titulação mostraram que a concentração dos produtos era semelhante à reivindicada pelo fabricante. Conclusão: Conclui-se que a quantidade de PH que atinge a câmara pulpar não é proporcional à concentração de géis clareadores, porém depende do tempo de aplicação recomendado pelos fabricantes.(AU)
Assuntos
Clareamento Dental , Permeabilidade do Esmalte Dentário , Clareadores , Peróxido de Carbamida , Peróxido de HidrogênioRESUMO
To evaluate the effect of different in-office bleaching agents on the permeability, roughness and surface microhardness of human enamel. Methods: For evaluation of roughness and microhardness, 40 hemi-faces of 20 premolars were subjected to initial roughness (Ra parameter) and microhardness (VHN) measurements. Thirty-two premolar's crowns were used for permeability test. Then, all specimens were randomly divided into four groups: C - without bleaching (control), HP35 - bleaching with 35% hydrogen peroxide (HP), HPF38 - 38% HP+fluoride, HPC35 - 35% HP+calcium. Final roughness (FR) and microhardness (FM) measurements were evaluated. For permeability, the 32 crowns were immersed in 1% sodium hypochlorite (20 min) and silver nitrate solutions (2 h) and subjected to developing solution under fluorescent light (16 h). Three sections from the crowns were analyzed in light microscope (100x) to evaluate the scores of permeability: Score 0 - no tracer agent penetration; Score 1 - less than half the thickness of enamel penetration; Score 2 - tracer agent reaching half the enamel thickness; Score 3 - entire enamel depth penetration, without reaching dentin and Score 4 - tracer agent reaching dentin. For roughness and microhardness evaluation were used one-way ANOVA and Dunnet post-test for independent samples, and t test for paired samples. For permeability, the data were analyzed by Kruskal Wallis and Dunn tests. Results: A significantly higher permeability and surface roughness were observed in groups HP35, HPF38 and HPC35 compared to the C group, as well as decreased microhardness (p<0.05). Conclusions: All bleaching agents increased permeability and surface roughness, and decreased microhardness of human enamel; thus, the addition of fluoride or calcium was not beneficial...
Assuntos
Humanos , Masculino , Feminino , Clareadores Dentários/efeitos adversos , Esmalte Dentário , Permeabilidade do Esmalte Dentário , Peróxido de Hidrogênio/efeitos adversos , Peróxido de Hidrogênio/uso terapêutico , Propriedades de Superfície , Clareamento DentalRESUMO
OBJECTIVE: Resin infiltration is an innovative microinvasive measure, whereby hard tissues are preserved, that has been used to treat medium stages of caries. The aim of this study is to evaluate with Confocal laser scanning microscopy the indirect staining technique of resin infiltration in teeth with different degrees of fluorosis. METHODS: Twenty-four fluorosed human molars and premolars were infiltrated and light cured. Specimens were prepared and lesions, as well as penetration depth were analyzed using dual fluorescence method in confocal laser microscopy. RESULTS: Percentage penetration, was significantly higher in teeth with mild and very mild fluorotic lesions, unlike moderate and control group which was significantly lower (p < 0.05, Bonferroni test). However, there are no statistically significant differences between control and moderate groups neither between very mild and mild groups (p > 0.05, Bonferroni test). CONCLUSION: It can be concluded that resin penetration in mild and very mild fluorotic lesions is higher than in moderate lesions
OBJETIVO: La infiltración con resina es una innovadora técnica microinvasiva, donde los tejidos duros son preservados, que ha sido usada para tratar estadios medios de caries. El objetivo de este estudio es evaluar con microscopio laser confocal la técnica indirecta de tinción en dientes con diferentes grados de fluorosis. MÉTODOS: Veinticuatro molares y premolares humanos con fluorosis fueron infiltrados y fotocurados. Los especímenes fueron preparados y las lesiones (FDmax), así como la profundidad de penetración fueron analizadas usando el método de fluorescencia dual en el microscopio láser confocal. RESULTADOS: El porcentaje de penetración fue significativamente mayor en dientes con fluorosis leve y muy leve, a diferencia de los especímenes con fluorosis moderada y grupo control en los que el porcentaje de penetración fue significativamente menor (p < 0,05, test de Bonferroni). Sin embargo, no hubo diferencias significativas entre el grupo mode-rado y control, ni entre los grupos leve y muy leve (p > 0,05, test de Bonferroni). CONCLUSIÓN: Se puede concluir que la penetración de la resina en dientes con fluorosis leve y muy leve es mayor que en los dientes con lesiones moderadas
Assuntos
Humanos , Resinas Sintéticas , Resinas Sintéticas/uso terapêutico , Dente Pré-Molar , Microscopia Confocal , Permeabilidade do Esmalte Dentário , Ácido Clorídrico , Dente Molar , Fluorose DentáriaRESUMO
This study sought to quantify the concentration of hydrogen peroxide (HP) in the pulp chamber and evaluate changes on dental permeability after bleaching with 3 HP concentrations (10%, 35%, and 50%). This study was divided into 2 experiments and the bleaching treatments consisted of 3 applications of HP for 30 minutes during a single session. The first experiment tested HP penetration into the pulp chamber of 4 experimental groups (n = 10) of bovine crowns, which were divided by HP concentration: an unbleached control group (0% HP), 10% HP, 35% HP, and 50% HP. Acetate buffer solution was placed into the pulp chamber and after each application of HP. This solution was collected to determine spectrophotometrically the concentration of HP that reached the pulp chamber. The second experiment evaluated dental permeability. Bovine crowns were divided into 3 groups (n = 10). The crowns were connected to a permeability device and the initial permeability was measured at 10 psi. Three different concentrations of HP gels (10%, 35% and 50%) were applied to the buccal enamel surfaces and the dental permeability was measured after the first, second, and third applications of HP. The data were analyzed by 2-way ANOVA and Tukey test (P ≤ 0.05). All concentrations of HP reached the pulp chamber, although no significant differences were noted between the 3 concentrations tested (P > 0.05). However, the increase of dental permeability in the group that received 50% HP was significantly higher than the 10% HP group (P < 0.05). The results indicate that the HP bleaching treatments increased dental permeability.
Assuntos
Cavidade Pulpar/metabolismo , Peróxido de Hidrogênio/farmacocinética , Clareadores Dentários/farmacocinética , Permeabilidade Dentária/efeitos dos fármacos , Animais , Bovinos , Esmalte Dentário/efeitos dos fármacos , Esmalte Dentário/metabolismo , Permeabilidade do Esmalte Dentário/efeitos dos fármacos , Cavidade Pulpar/efeitos dos fármacos , Dentina/efeitos dos fármacos , Dentina/metabolismo , Permeabilidade da Dentina/efeitos dos fármacos , Corantes Fluorescentes , Violeta Genciana , Peróxido de Hidrogênio/administração & dosagem , Peróxido de Hidrogênio/farmacologia , Distribuição Aleatória , Espectrofotometria/métodos , Fatores de Tempo , Clareadores Dentários/administração & dosagem , Clareadores Dentários/farmacologia , Coroa do Dente/efeitos dos fármacos , Coroa do Dente/metabolismoRESUMO
OBJECTIVE: The aim of this in situ study was to analyze the influence of the Er:YAG, Nd:YAG, and CO(2) lasers on the enamel acid resistance of pits and fissures. BACKGROUND DATA: The laser tissue interaction has been studied as a method of preventing occlusal caries. METHODS: Thirteen volunteers wore palatal acrylic appliances containing human occlusal enamel blocks that were divided into four groups (G1, control; G2, Er:YAG; G3, Nd:YAG; G4, CO(2)). Each palatal acrylic appliance was used in the four studied groups and was used for 14 consecutive days. A sucrose solution was applied to the specimens six times per day. The specimens were then sectioned in half, and a microhardness test was applied. The other halves were analyzed using polarized light microscopy to measure the caries-like lesion areas, and a morphological analysis was conducted using a scanning electron microscope (SEM). RESULTS: For the statistical analysis of the data obtained from the microhardness test (Knoop hardness number. [KHN]) (α=5%), Fisher's exact test was performed, and the group means were as follows: G1, 247±71; G2, 258±70; G3, 272±73; and G4, 298±56. The results demonstrated that the control group was significantly different from G3 and G4, which presented higher microhardness values. The Wilcoxon signed-rank test was used to analyze the data obtained from the caries-lesion area measurements (mm(2)) (α=5%) (G1, 0.01±1.08; G2, 0.13±0.18; G3, 0.05±0.17; and G4, 0.09±0.22). The results no showed significant differences among the groups in this analysis. CONCLUSIONS: Based on the results from the present study, it may be concluded that the CO(2) and Nd:YAG lasers increased the enamel acid resistance in pits and fissures.
Assuntos
Esmalte Dentário/efeitos da radiação , Fissuras Dentárias/radioterapia , Lasers de Estado Sólido , Adulto , Cárie Dentária/radioterapia , Permeabilidade do Esmalte Dentário/efeitos da radiação , Feminino , Humanos , Masculino , Microscopia Eletrônica de Varredura , Adulto JovemRESUMO
This study aimed to test the hypothesis that organic volume is the main variable for explaining the optical properties and predictive degree of diffusion of enamel histological points at zones of natural enamel caries (NEC; surface layer, SL, n = 30, and body of the lesion, BL, n = 58) and normal enamel (NE, n = 131). Molars with either NEC or NE were quantitatively analyzed regarding the mineral, organic and water volumes (considered as effective pore volume), opacity (predicted in 94% of cases by water volume in NEC), and water volume more easily available for diffusion, αd (squared water volume divided by the nonmineral volume; related to permeability). NEC presented lower mineral volumes and higher organic volumes, effective pore volume and opacity than NE. External origin of organic volume in NEC was evidenced by an organic gradient decreasing from the surface inward (R2 = -0.7), which was not detected in teeth with NE only; αd values of the SL and NE were similar and both were lower (p < 0.0001) than that of the BL. Comparing the SL from both NEC and artificial enamel caries (AEC; published data; n = 71), with similar mineral volumes, against developing enamel (published data), AEC showed more effective pore volume (3 times higher), higher αd and opacity than NEC mainly due to differences in organic volumes. Our results reasonably matched widely known features of NEC histological zones, and confirmed the organic volume as the main variable for explaining optical properties and αd (related to permeability).
Assuntos
Cárie Dentária/patologia , Esmalte Dentário/química , Esmalte Dentário/patologia , Birrefringência , Cárie Dentária/diagnóstico por imagem , Esmalte Dentário/diagnóstico por imagem , Permeabilidade do Esmalte Dentário , Humanos , Processamento de Imagem Assistida por Computador , Microrradiografia , Minerais/análise , Compostos Orgânicos/análise , Fotografia Dentária , Porosidade , Estatísticas não Paramétricas , Água/análiseRESUMO
PURPOSE: To assess the trans-enamel and trans-dentin toxicity of a 10% hydrogen peroxide (HP) whitening strip to odontoblast-like cells (MDPC-23). METHODS: Enamel surfaces of enamel/dentin discs adapted to artificial pulp chambers were subjected to two 30-minute whitening strip applications to obtain indirect extracts (DMEM + bleaching components that diffused across enamel and dentin). The extracts were applied for 1 hour to the cells for 1 or 5 days. A bleaching gel with 35% HP was used as the positive control. Cell viability (MTT assay) and morphology (SEM) as well as the quantity of HP in the extracts were assessed. RESULTS: Discrete cell viability reduction (21.9%) associated with slight alterations in cell morphology occurred after application of the extracts for 5 days to the MDPC-23 cells (Tukey's test; P < 0.05). Lower enamel/dentin diffusion of HP was observed after the use of the whitening strip compared with the bleaching gel (Mann-Whitney; P < 0.05).
Assuntos
Polpa Dentária/efeitos dos fármacos , Peróxido de Hidrogênio/toxicidade , Odontoblastos/efeitos dos fármacos , Clareadores Dentários/toxicidade , Animais , Bovinos , Técnicas de Cultura de Células , Forma Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Corantes , Permeabilidade do Esmalte Dentário/efeitos dos fármacos , Polpa Dentária/citologia , Permeabilidade da Dentina/efeitos dos fármacos , Difusão , Peróxido de Hidrogênio/farmacocinética , Microscopia Eletrônica de Varredura , Saliva Artificial/administração & dosagem , Sais de Tetrazólio , Tiazóis , Fatores de Tempo , Técnicas de Cultura de Tecidos , Clareamento Dental/instrumentação , Clareadores Dentários/farmacocinéticaRESUMO
The aim of this study was to evaluate the amount of peroxide passage from the pulp chamber to the external enamel surface during the internal bleaching technique. Fifty bovine teeth were sectioned transversally 5 mm below the cemento-enamel junction (CEJ), and the remaining part of the root was sealed with a 2-mm layer of glass ionomer cement. The external surface of the samples was coated with nail varnish, with the exception of standardized circular areas (6-mm diameter) located on the enamel, exposed dentin, or cementum surface of the tooth. The teeth were divided into three experimental groups according to exposed areas close to the CEJ and into two control groups (n=10/group), as follows: GE, enamel exposure area; GC, cementum exposed area; GD, dentin exposed area; Negative control, no presence of internal bleaching agent and uncoated surface; and Positive control, pulp chamber filled with bleaching agent and external surface totally coated with nail varnish. The pulp chamber was filled with 35% hydrogen peroxide (Opalescence Endo, Ultradent). Each sample was placed inside of individual flasks with 1000 µL of acetate buffer solution, 2 M (pH 4.5). After seven days, the buffer solution was transferred to a glass tube, in which 100 µL of leuco-crystal violet and 50 µL of horseradish peroxidase were added, producing a blue solution. The optical density of the blue solution was determined by spectrophotometer and converted into microgram equivalents of hydrogen peroxide. Data were submitted to Kruskal-Wallis and Dunn-Bonferroni tests (α=0.05). All experimental groups presented passage of peroxide to the external surface that was statistically different from that observed in the control groups. It was verified that the passage of peroxide was higher in GD than in GE (p<0.01). The GC group presented a significantly lower peroxide passage than did GD and GE (p<0.01). It can be concluded that the hydrogen peroxide placed into the pulp chamber passed through the dental hard tissues, reaching the external surface and the periodontal tissue. The cementum surface was less permeable than were the dentin and enamel surfaces.
Assuntos
Cemento Dentário/metabolismo , Esmalte Dentário/metabolismo , Dentina/metabolismo , Peróxido de Hidrogênio/uso terapêutico , Peróxidos/farmacocinética , Clareadores Dentários/uso terapêutico , Clareamento Dental/métodos , Animais , Bovinos , Permeabilidade do Esmalte Dentário/efeitos dos fármacos , Cavidade Pulpar/metabolismo , Permeabilidade da Dentina/efeitos dos fármacos , Corantes Fluorescentes , Violeta Genciana , Umidade , Peróxido de Hidrogênio/administração & dosagem , Temperatura , Clareadores Dentários/administração & dosagemRESUMO
PURPOSE: This in vitro investigation assessed whether different dentifrices would be capable of controlling the enamel erosion progression caused by HCl. MATERIALS AND METHODS: Sixty bovine enamel slabs were covered with acid-resistant varnish, except for a 2.5-mm2 circular area on the labial surface. According to a complete block design, the experimental units were immersed in HCl solution (pH 1.2; 0.1M). After storage in artificial saliva for 1 h, specimens (n = 15) were exposed to different dentifrices: Sensodyne Cool Gel (1100 ppm F), Sensodyne ProNamel (1450 ppm F), and PrevDent 5000 (5000 ppm F). The control group was immersed in deionised water. Following five cycles of erosive challenge, the slabs were prepared for porosity evaluation using solutions of copper sulfate and rubeanic acid. RESULTS: ANOVA demonstrated no difference in the enamel porosity as a function of the dentifrice employed (P = 0.5494). CONCLUSION: The damage caused by a simulated intrinsic erosive challenge seems unable to be controlled by fluoridated dentifrices, even when this ion is found in elevated concentrations.
Assuntos
Dentifrícios/uso terapêutico , Ácido Clorídrico/efeitos adversos , Erosão Dentária/prevenção & controle , Animais , Cariostáticos/uso terapêutico , Bovinos , Corantes , Sulfato de Cobre , Esmalte Dentário/efeitos dos fármacos , Permeabilidade do Esmalte Dentário/efeitos dos fármacos , Progressão da Doença , Concentração de Íons de Hidrogênio , Imersão , Teste de Materiais , Porosidade , Distribuição Aleatória , Saliva Artificial/química , Fluoreto de Sódio/uso terapêutico , Tioamidas , Fatores de Tempo , Erosão Dentária/induzido quimicamenteRESUMO
AIM: To evaluate the transenamel and transdentinal cytotoxicity of bleaching gels based on carbamide peroxide (CP) on odontoblast-like cells after different contact times of the products with enamel. METHODOLOGY: Enamel/dentine discs were obtained from bovine incisors and placed in artificial pulp chambers. Bleaching gels containing 10% or 16% CP were applied for 8 h day(-1) on the enamel side of the discs during periods of 1, 7 or 14 days. Deionized water and artificial saliva served as controls. The extracts (culture medium plus bleaching gel products that diffused through the discs) were collected and applied on previously cultured MDPC-23 cells for 1 h. Cell metabolism was evaluated by the MTT assay, and the data were analysed statistically by one-way anova and Tukey's test (α=0.05). Cell morphology was analysed by SEM. RESULTS: There was no significant difference (P>0.05) between the controls and the groups bleached with 10% CP gel. In the groups bleached with 16% CP gel, however, cell metabolism decreased significantly (P<0.05) by 40.32%, 30.16% and 26.61% at 1, 7 and 14 days, respectively. There was no significant difference (P>0.05) between 1, 7 or 14 applications of the gels for either of the CP concentrations. CONCLUSION: Regardless of the number of applications on an enamel surface, the 10% CP bleaching gel did not cause transenamel and transdentinal cytotoxicity to the MDPC-23 cell cultures. However, diffusion of products from the 16% CP gel through enamel and dentine and cytopathic effects to the pulp cells occurred even after a single application of this product on enamel.
Assuntos
Esmalte Dentário/efeitos dos fármacos , Dentina/efeitos dos fármacos , Odontoblastos/efeitos dos fármacos , Peróxidos/toxicidade , Clareadores Dentários/toxicidade , Ureia/análogos & derivados , Análise de Variância , Animais , Peróxido de Carbamida , Bovinos , Células Cultivadas , Permeabilidade do Esmalte Dentário/efeitos dos fármacos , Relação Dose-Resposta a Droga , Géis , Peróxidos/farmacocinética , Estatísticas não Paramétricas , Fatores de Tempo , Clareadores Dentários/farmacocinética , Ureia/farmacocinética , Ureia/toxicidadeRESUMO
OBJECTIVE: This study aimed to investigate bleached enamel susceptibility to coffee and red-wine staining at different time periods after bleaching. BACKGROUND DATA: Although hydrogen peroxide is effective for dental bleaching, little is known regarding color stability immediately after bleaching. MATERIALS AND METHODS: Fifty-four standardized bovine enamel slabs were obtained and assigned to the following treatments (n = 9): (CO) control: sound enamel surface submitted only to bleaching with 35% hydrogen peroxide (HP); (C30') enamel submitted to HP and coffee immersion at 30 min after bleaching; (C150') enamel submitted to HP and coffee immersion at 150 min after bleaching; (W30') enamel submitted to HP and red-wine immersion at 30 min after bleaching; and (W150') enamel submitted to HP and red-wine immersion at 150 min after bleaching. The color of treated enamel was determined by means of photoreflectance spectroscopy at baseline (T(0)) and after the described treatments (T(f)), and data were statistically analyzed with ANOVA and Tukey tests (p < 0.05). RESULTS: No differences were observed between the exposure times of 30 and 150 min after bleaching for both beverages (p > 0.05). Although coffee did not stain the surface, red wine significantly darkened previously bleached enamel (p < 0.05). CONCLUSION: Bleached enamel was susceptible to red-wine staining at both 30 and 150 min after bleaching procedures, whereas coffee did not interfere with the bleaching process.
Assuntos
Café/efeitos adversos , Esmalte Dentário/efeitos dos fármacos , Animais , Bovinos , Permeabilidade do Esmalte Dentário/efeitos dos fármacos , Peróxido de Hidrogênio , Espectrofotometria , Fatores de Tempo , Clareamento Dental , Clareadores Dentários , Descoloração de Dente/etiologia , Vinho/efeitos adversosRESUMO
PURPOSE: The aim of the present study was to perform a review of the effects of infiltrants and sealers on the inhibition of enamel demineralisation. MATERIALS AND METHODS: The authors searched the Cochrane Library, Embase, PubMed and Web of Science (ISI) for papers published between January 1970 and September 2008. The main search terms were 'artificial caries' or 'caries treatment' or 'caries-like lesion' or 'white spot lesion' or 'enamel demineralisation' or 'natural caries' and 'enamel' and 'sealant' or 'resin infiltration'. The inclusion criteria were studies that produced artificial non-cavitated enamel lesions before the application of sealant in in vivo or in vitro studies. Studies excluded were those that had not produced artificial non-cavitated enamel lesions before the application of sealant; had evaluated the inhibition of enamel demineralisation around restorations, sealant and orthodontic bracket/bands; had not evaluated the inhibition of enamel demineralisation after the sealant application; and had not applied sealant materials. Selected papers were given scores, from A to C, according to predetermined criteria. RESULTS: Eighteen studies were identified and included in the project critical appraisal. Two papers were classified as Grade A, nine as Grade B and seven as Grade C. CONCLUSIONS: It can be concluded that while fissure sealing acts as a diffusion barrier on the top of the lesion surface, the infiltration technique creates a barrier inside the lesion by replacing the mineral lost with a low-viscosity light-curing resin.
Assuntos
Selantes de Fossas e Fissuras/uso terapêutico , Desmineralização do Dente/prevenção & controle , Ácidos/farmacologia , Animais , Bovinos , Esmalte Dentário/efeitos dos fármacos , Permeabilidade do Esmalte Dentário , Humanos , Técnicas In Vitro , Selantes de Fossas e Fissuras/farmacologia , Desmineralização do Dente/induzido quimicamenteRESUMO
PURPOSE: To quantify the amount of peroxide penetration from the pulp chamber to the external surface of teeth during the walking bleaching technique. METHODS: Seventy-two bovine lateral incisors were randomly divided over five experimental groups and one control (n = 12 per group): (1) 35% hydrogen peroxide (HP); (2) 35% carbamide peroxide (CP); (3) sodium perborate (SP); (4) (HP+SP); (5) (CP+SP) and (6) Control (CG), deionized water. All groups were treated according to the walking bleach technique. After 7 days at 37 degrees C in an acetate buffer solution, 100 microl violet leukocrystal coloring and 50 microl peroxidase was added, producing a blue stain that could be measured in a spectrophotometer and then converted into peroxide microg/ml. RESULTS: G5 exhibited the greatest penetration, while G2 and G3 produced the lowest values. All bleaching agents penetrated from the pulp chamber to the external root surface. There was a direct correlation between the presence of oxidative agents and penetration potential. Sodium perborate in distilled water was less oxidative and appeared to be the least aggressive bleaching agent.
Assuntos
Boratos/farmacocinética , Peróxido de Hidrogênio/farmacocinética , Oxidantes/farmacologia , Peróxidos/farmacocinética , Clareamento Dental/métodos , Colo do Dente/metabolismo , Ureia/análogos & derivados , Condicionamento Ácido do Dente , Animais , Boratos/administração & dosagem , Peróxido de Carbamida , Bovinos , Cemento Dentário/metabolismo , Permeabilidade do Esmalte Dentário , Permeabilidade da Dentina , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Peróxido de Hidrogênio/administração & dosagem , Oxirredução , Peróxidos/administração & dosagem , Distribuição Aleatória , Dente não Vital , Ureia/administração & dosagem , Ureia/farmacocinéticaRESUMO
PURPOSE: To evaluate the influence of two concentrations of bleaching agents applied over enamel surfaces on the dentin bonding at different depths. METHODS: Twenty-four bovine incisors were sectioned, obtaining three fragments per tooth (4x4 mm). Each fragment presented a 0.7 mm enamel thickness; and the dentin thickness varied according to the experimental group: 0.5 mm, 1 mm or 1.5 mm. Fragments from each dentin-thickness were allocated into three groups (n=8): G1: Control (no bleaching); G2: 16% carbamide peroxide (6 hours/14 days); G3: 35% hydrogen peroxide (three 15-minute treatments). 24 hours after enamel bleaching, the adhesive system was applied and dentin surfaces were restored with resin composite cylinders (2 mm diameter and 1 mm height). The micro-shear testing was performed immediately after restorative procedures, at a speed of 0.5 mm/minute until failure. Bond strength values, in MPa, were statistically analyzed (split-plot ANOVA/Tukey alpha=0.05). RESULTS: Means obtained were: G1-0.5 mm: 13.5, G1-1 mm: 9.48, G1-1.5 mm: 9.01; G2-0.5 mm: 9.64, G2-1 mm: 9.44, G2-1.5 mm: 9.27; G3-0.5 mm: 11.68, G3-1 mm: 11.64, G3-1.5 mm: 7.63. Regardless of the dentin thickness, bleached groups presented bond strengths similar to that of control groups. Nevertheless, significant differences among dentin depths were detected (P=0.02); and the lowest bond strength was observed on the deepest dentin (1.5 mm). The diffusion of bleaching agents through enamel surfaces did not affect the bond strength to dentin, which is highly dependent on the morphology/depth of the substrate.
Assuntos
Colagem Dentária , Dentina/efeitos dos fármacos , Clareamento Dental/efeitos adversos , Análise de Variância , Animais , Peróxido de Carbamida , Bovinos , Permeabilidade do Esmalte Dentário , Análise do Estresse Dentário , Dentina/anatomia & histologia , Difusão , Peróxido de Hidrogênio/efeitos adversos , Oxidantes/efeitos adversos , Peróxidos/efeitos adversos , Resistência ao Cisalhamento , Estatísticas não Paramétricas , Ureia/efeitos adversos , Ureia/análogos & derivadosRESUMO
OBJECTIVES: The aim of this study was to evaluate the effects of chemical activation of hydrogen peroxide (HP) gel on colour changes and penetration through the tooth structure. METHODS: One hundred and four bovine incisors were used. One dentine (CD) disc and one enamel-dentine (ED) disc were prepared from each tooth. They were positioned over artificial pulpal chambers and the bleaching was performed with an experimental 35% HP gel. Two control and six experimental groups were prepared. In the positive control group (PC) no chemical activator was used. In the negative control group (NC) the specimens did not receive any bleaching. Each experimental group received a different chemical activator (manganese gluconate-MG; manganese chlorite-MC; ferrous sulphate-FS; ferrous chlorite-FC; and mulberries root extract-MRE). After the bleaching procedure a sample of solution was collected from the artificial pulpal chamber and the HP concentration was measured. The data were analysed using ANOVA, Tukey's, and Dunnett's tests. RESULTS: The groups MG and FS showed a significantly lower penetration of HP than the PC group. For the parameter Delta E, all the groups, with the exception of the group MRE, showed a significantly higher means in relation to the PC group in ED colour. For dentine colour, just the groups MG and FS had significant differences in relation to PC. CONCLUSIONS: The addition of MG and FS decreases the penetration of HP. The chemical activation using metal salts tested was effective in increasing the bleaching effect.
Assuntos
Esmalte Dentário/efeitos dos fármacos , Dentina/efeitos dos fármacos , Peróxido de Hidrogênio/farmacologia , Espécies Reativas de Oxigênio/farmacologia , Clareadores Dentários/farmacologia , Animais , Bovinos , Cloretos/farmacologia , Cor , Esmalte Dentário/anatomia & histologia , Esmalte Dentário/metabolismo , Permeabilidade do Esmalte Dentário/efeitos dos fármacos , Dentina/anatomia & histologia , Dentina/metabolismo , Permeabilidade da Dentina/efeitos dos fármacos , Compostos Ferrosos/farmacologia , Géis , Gluconatos/farmacologia , Peróxido de Hidrogênio/farmacocinética , Compostos de Manganês/farmacologia , Morus , Extratos Vegetais/farmacologia , Espécies Reativas de Oxigênio/farmacocinética , Espectrofotometria/métodos , Fatores de Tempo , Clareadores Dentários/farmacocinéticaRESUMO
This aim of the present study was to evaluate the pulp chamber penetration of 35% hydrogen peroxide activated by LED (light-emitting diode) or Nd:YAG laser in bovine teeth, after an in-office bleaching technique. Forty-eight bovine lateral incisors were divided into four groups, acetate buffer was placed into the pulp chamber and bleaching agent was applied as follows: for group A (n = 12), activation was performed by LED; for group B (n = 12), activation was performed by Nd:YAG laser (60 mJ, 20 Hz); group C (n = 12) received no light or laser activation; and the control group (n = 12) received no bleaching gel application or light or laser activation. The acetate buffer solution was transferred to a glass tube and Leuco Crystal Violet and horseradish peroxidase were added, producing a blue solution. The optical density of this solution was determined spectrophotometrically and converted into microgram equivalents of hydrogen peroxide. The results were analysed using ANOVA and Tukey's test (5%). It was verified that the effect of activation was significant, as groups activated by LED or laser presented greater hydrogen peroxide penetration into the pulp chamber (0.499 +/- 0.622 microg) compared with groups that were not (0.198 +/- 0.218 microg). There was no statistically significant difference in the penetration of hydrogen peroxide into the pulp chamber between the two types of activation (LED or laser). The results suggest that activation by laser or LED caused an increase in hydrogen peroxide penetration into the pulp chamber.
Assuntos
Lâmpadas de Polimerização Dentária , Peróxido de Hidrogênio/farmacocinética , Lasers de Estado Sólido , Oxidantes/farmacocinética , Clareamento Dental/métodos , Animais , Bovinos , Permeabilidade do Esmalte Dentário , Cavidade Pulpar , Permeabilidade da Dentina , Peróxido de Hidrogênio/efeitos da radiação , Oxidantes/efeitos da radiação , Dente não VitalRESUMO
AIM: To evaluate the trans-enamel and trans-dentinal cytotoxic effects of a 35% H(2)O(2) bleaching gel on an odontoblast-like cell lines (MDPC-23) after consecutive applications. METHODOLOGY: Fifteen enamel/dentine discs were obtained from bovine central incisor teeth and placed individually in artificial pulp chambers. Three groups (n = 5 discs) were formed according to the following enamel treatments: G1: 35% H(2)O(2) bleaching gel (15 min); G2: 35% H(2)O(2) bleaching gel (15 min) + halogen light (20 s); G3: control (no treatment). After repeating the treatments three consecutive times, the extracts (culture medium + gel components that had diffused through enamel/dentine discs) in contact with the dentine were collected and applied to previously cultured MDPC-23 cells (50 000 cells cm(-2)) for 24 h. Cell metabolism was evaluated by the MTT assay and data were analysed statistically (alpha = 5%; Kruskal-Wallis and Mann-Whitney U-test). Cell morphology was analysed by scanning electron microscopy. RESULTS: Cell metabolism decreased by 92.03% and 82.47% in G1 and G2 respectively. G1 and G2 differed significantly (P < 0.05) from G3. Regardless of halogen light activation, the application of the bleaching gel on the cultured odontoblast-like cells caused significantly more severe cytotoxic effects than those observed in the nontreated control group. In addition, significant morphological cell alterations were observed in G1 and G2. CONCLUSION: After three consecutive applications of a 35% H(2)O(2) bleaching agent, the diffusion of the gel components through enamel and dentine caused severe toxic effects to cultured pulp cells.
Assuntos
Permeabilidade do Esmalte Dentário/efeitos dos fármacos , Permeabilidade da Dentina/efeitos dos fármacos , Peróxido de Hidrogênio/toxicidade , Odontoblastos/efeitos dos fármacos , Clareamento Dental/efeitos adversos , Administração Tópica , Animais , Bovinos , Células Cultivadas , Esmalte Dentário/efeitos dos fármacos , Dentina/efeitos dos fármacos , Esquema de Medicação , Peróxido de Hidrogênio/administração & dosagem , Luz , Odontoblastos/efeitos da radiação , Oxidantes/administração & dosagem , Oxidantes/toxicidade , Estatísticas não Paramétricas , Clareamento Dental/métodosRESUMO
The aim of this study was to evaluate the trans-enamel and trans-dentinal effects of a 35% hydrogen peroxide (H2O2) bleaching gel on odontoblast-like cells. Enamel/dentin discs obtained from bovine incisors were mounted in artificial pulp chambers (APCs). Three groups were formed: G1- 35% H2O2; G2- 35% H2O2 + halogen light application; G3- control. The treatments were repeated 5 times and the APCs were incubated for 12 h. Then, the extract was collected and applied for 24 h on the cells. Cell metabolism, total protein dosage and cell morphology were evaluated. Cell metabolism decreased by 62.09% and 61.83% in G1 and G2, respectively. The depression of cell metabolism was statistically significant when G1 and G2 were compared to G3. Total protein dosage decreased by 93.13% and 91.80% in G1 and G2, respectively. The cells in G1 and G2 exhibited significant morphological alterations after contact with the extracts. Regardless of halogen light application, the extracts caused significantly more intense cytopathic effects compared to the control group. After 5 consecutive applications of a 35% H2O2 bleaching agent, either catalyzed or not by halogen light, products of gel degradation were capable to diffuse through enamel and dentin causing toxic effects to the cells.
Assuntos
Permeabilidade do Esmalte Dentário/efeitos dos fármacos , Polpa Dentária/efeitos dos fármacos , Permeabilidade da Dentina/efeitos dos fármacos , Peróxido de Hidrogênio/toxicidade , Odontoblastos/efeitos dos fármacos , Oxidantes/toxicidade , Administração Tópica , Animais , Bovinos , Células Cultivadas , Esmalte Dentário/efeitos dos fármacos , Polpa Dentária/citologia , Cavidade Pulpar/efeitos dos fármacos , Dentina/efeitos dos fármacos , Odontoblastos/citologia , Clareamento Dental/efeitos adversosRESUMO
This study evaluated the influence of internal tooth bleaching with 38% hydrogen peroxide (H2O2) on the permeability of the coronal dentin in maxillary anterior teeth and premolars. Seventy teeth (14 per group) were used: central incisors (CI), lateral incisor (LI), canines (C), first premolars (1PM) and second premolars (2PM). Pulp chamber access and transversal sectioning at 2 mm from the cementoenamel junction were performed and the specimens were divided into 2 groups (n= 7): a) no treatment and b) bleaching with 38% H2O2. The bleaching agent was applied to the buccal surface and to the pulp chamber for 10 min. This procedure was repeated 3 times. The specimens were processed histochemically with copper sulfate and rubeanic acid, sectioned longitudinally, and digitalized in a scanner. The area of stained dentin was measured using Image Tool software. Data were analyzed statistically by ANOVA and Tukey's HSD test (alpha=0.05). There was statistically significant difference (p<0.001) among the untreated groups, CI (0.23 +/- 0.26) having the lowest permeability and LI (10.14 +/- 1.89) the highest permeability. Among the bleached groups, dentin permeability was increased in all groups of teeth except for 2PM. It may be concluded that bleaching with 38% H2O2 affected dentin permeability near the pulp chamber in maxillary anterior teeth and in first and second premolars.
Assuntos
Cavidade Pulpar/efeitos dos fármacos , Permeabilidade da Dentina/efeitos dos fármacos , Peróxido de Hidrogênio/farmacologia , Irrigantes do Canal Radicular/farmacologia , Clareamento Dental/métodos , Corantes/farmacologia , Cobre/farmacologia , Permeabilidade do Esmalte Dentário/efeitos dos fármacos , Humanos , Maxila , Oxidantes/farmacologia , Dente não VitalRESUMO
The aim of this study was to evaluate the trans-enamel and trans-dentinal effects of a 35 percent hydrogen peroxide (H2O2) bleaching gel on odontoblast-like cells. Enamel/dentin discs obtained from bovine incisors were mounted in artificial pulp chambers (APCs). Three groups were formed: G1- 35 percent H2O2; G2- 35 percent H2O2 + halogen light application; G3- control. The treatments were repeated 5 times and the APCs were incubated for 12 h. Then, the extract was collected and applied for 24 h on the cells. Cell metabolism, total protein dosage and cell morphology were evaluated. Cell metabolism decreased by 62.09 percent and 61.83 percent in G1 and G2, respectively. The depression of cell metabolism was statistically significant when G1 and G2 were compared to G3. Total protein dosage decreased by 93.13 percent and 91.80 percent in G1 and G2, respectively. The cells in G1 and G2 exhibited significant morphological alterations after contact with the extracts. Regardless of halogen light application, the extracts caused significantly more intense cytopathic effects compared to the control group. After 5 consecutive applications of a 35 percent H2O2 bleaching agent, either catalyzed or not by halogen light, products of gel degradation were capable to diffuse through enamel and dentin causing toxic effects to the cells.
O objetivo deste estudo foi avaliar os efeitos citotóxicos de um agente clareador com 35 por cento de peróxido de hidrogênio (H2O2) sobre células da linhagem odontoblástica. Foram confeccionados discos de esmalte/dentina obtidos de incisivos bovinos, os quais foram posicionados em câmaras pulpares artificiais (CPAs). Três grupos foram formados: G1: gel clareador; G2: gel clareador + luz halógena e G3: controle. Após 5 aplicações consecutivas do gel clareador sobre o esmalte, os extratos foram obtidos e aplicados por 24 h sobre as células. Foram realizadas avaliações do metabolismo celular, morfologia das células e expressão total de proteína. O metabolismo celular para G1 e G2 reduziu em 62,09 por cento e 61,83 por cento, respectivamente. A redução do metabolismo celular foi estatisticamente significante quando se comparou G1 e G2 com G3. A expressão de proteína total reduziu em 93,13 por cento e 91,80 por cento para G1 e G2, respectivamente. As células em G1 e G2 apresentaram importantes alterações morfológicas após contato com os extratos. Foi possível concluir que independente da catalização ou não do gel clareador por luz halógena, os componentes que se difundiram através dos tecidos duros do dente após sua quinta aplicação sobre o esmalte, causaram intensos efeitos citotóxicos para as células.