Pro-inflammatory mediators expression by pulp cells following tooth whitening on restored enamel surface.

This paper aimed to assess the influence of adhesive restoration interface on the diffusion of hydrogen peroxide (H2O2), indirect toxicity, and pro-inflammatory mediators expression by odontoblast-like cells, after in-office tooth whitening. Dental cavities prepared in bovine enamel/dentin discs were adhesively restored and subjected or not to hydrolytic degradation (HD). A whitening gel with 35% H2O2 (WG) was applied for 45 min onto restored and non-restored specimens adapted to artificial pulp chambers giving rise to the groups: SD- intact discs (control); SD/HP- whitened intact discs; RT/HP- restored and whitened discs; and RT/HD/HP- restored and whitened discs subjected to HD. The extracts (culture medium + WG components diffused through enamel/dentin/restoration interface) were collected and applied to odontoblast-like MDPC-23 cells. The study evaluated the amount of H2O2 in the extracts, as well as the cell viability (CV), cell morphology (CM), and gene expression of inflammatory mediators (TNF-α and COX-2) by the pulp cells exposed to the extracts (ANOVA and Tukey tests; 5% significance). All whitened groups presented lower CV than SD (control; p<0.05). The highest CV reduction and gene expression of TNF-α and COX-2 was observed in the RT/HD/HP group in comparison with SD/HP and RT/HP (control; p<0.05). CM alterations occurred in all whitened groups. The intensity of these cell side effects was directly related with the amount of H2O2 in the extracts. We concluded that adhesive restoration of dental cavity increases the H2O2 diffusion after in-office whitening, enhancing the indirect toxicity of this therapy and trigger pro-inflammatory overexpression by MDPC-23 cells.

Pro-inflammatory mediators expression by pulp cells following tooth whitening on restored enamel surface

Abstract This paper aimed to assess the influence of adhesive restoration interface on the diffusion of hydrogen peroxide (H2O2), indirect toxicity, and pro-inflammatory mediators expression by odontoblast-like cells, after in-office tooth whitening. Dental cavities prepared in bovine enamel/dentin discs were adhesively restored and subjected or not to hydrolytic degradation (HD). A whitening gel with 35% H2O2 (WG) was applied for 45 min onto restored and non-restored specimens adapted to artificial pulp chambers giving rise to the groups: SD- intact discs (control); SD/HP- whitened intact discs; RT/HP- restored and whitened discs; and RT/HD/HP- restored and whitened discs subjected to HD. The extracts (culture medium + WG components diffused through enamel/dentin/restoration interface) were collected and applied to odontoblast-like MDPC-23 cells. The study evaluated the amount of H2O2 in the extracts, as well as the cell viability (CV), cell morphology (CM), and gene expression of inflammatory mediators (TNF-α and COX-2) by the pulp cells exposed to the extracts (ANOVA and Tukey tests; 5% significance). All whitened groups presented lower CV than SD (control; p<0.05). The highest CV reduction and gene expression of TNF-α and COX-2 was observed in the RT/HD/HP group in comparison with SD/HP and RT/HP (control; p<0.05). CM alterations occurred in all whitened groups. The intensity of these cell side effects was directly related with the amount of H2O2 in the extracts. We concluded that adhesive restoration of dental cavity increases the H2O2 diffusion after in-office whitening, enhancing the indirect toxicity of this therapy and trigger pro-inflammatory overexpression by MDPC-23 cells.

Resumo Este trabalho teve como objetivo avaliar a influência da interface de uma restauração adesiva na difusão do peróxido de hidrogênio (H2O2), toxicidade indireta e expressão de mediadores pró-inflamatórios por células odontoblastóides, após clareamento dental em consultório. Cavidades dentárias preparadas em discos de esmalte / dentina foram restauradas com adesivo e submetidas ou não à degradação hidrolítica (HD). Um gel clareador com 35% H2O2 (WG) foi aplicado por 45 min em discos restaurados e não restaurados adaptados às câmaras pulpares artificiais dando origem aos grupos: SD- discos intactos (controle); SD / HP - Discos intactos clareados; RT / HP - discos restaurados e clareados; e RT / HD / HP - discos restaurados, clareados e submetidos a HD. Os extratos (meio de cultura + componentes WG difundidos através da interface esmalte/dentina/restauração) foram coletados e aplicados em células odontoblastóides MDPC-23. Foi avaliada a quantidade de H2O2 nos extratos, bem como a viabilidade (CV), morfologia (CM) e expressão gênica de mediadores inflamatórios (TNF-α e COX-2) pelas células pulpares expostas aos extratos (ANOVA e testes de Tukey; 5% de significância). Todos os grupos clareados apresentaram menor CV do que SD (controle; p <0,05). A maior redução CV e expressão gênica de TNF-α e COX-2 foi observada no grupo RT / HD / HP em comparação com SD / HP e RT / HP (controle; p <0,05). Alterações na CM ocorreram em todos os grupos clareados. A intensidade desses efeitos celulares teve relação direta com a quantidade de H2O2 nos extratos. Concluímos que a presença de uma cavidade contendo restauração adesiva aumenta a difusão de H2O2 após o clareamento em consultório, o que, por sua vez, aumenta a toxicidade indireta dessa terapia e desencadeia a expressão de mediadores pró-inflamatórios pelas células pulpares MDPC-23.

Strategy for reducing cytotoxicity and obtaining esthetic efficacy with 15 min of in-office dental bleaching.

OBJECTIVES: Evaluate in vitro the esthetic efficacy and cytotoxicity of a bleaching gel containing 35% hydrogen peroxide (BG-35%H2O2), applied for different time intervals, on enamel coated or not with polymeric biomaterials. MATERIALS AND METHODS: Nanofiber scaffolds (NSc) and a primer catalyst (PrCa) were used to coat the bovine enamel/dentin discs before the application of BG-35%H2O2, according to the following groups: G1-negative control (NC, without treatment); G2, G3, and G4-BG-35%H2O2 applied for 3 × 15, 2 × 15, and 15 min; G5, G6, and G7-BG-35%H2O2 applied on enamel coated with NSc and PrCa for 3 × 15; 2 × 15, and 15 min, respectively. The culture medium with components of gel diffused through the discs was applied on MDPC-23 cells, which were evaluated regarding to viability (VB), integrity of the membrane (IM), and oxidative stress (OxS). The quantity of H2O2 diffused and esthetic efficacy (ΔE/ΔWI) of the dental tissues were also analyzed (ANOVA/Tukey; p < 0.05). RESULTS: Only G7 was similar to G1 regarding VB (p > 0.05). The lowest value of H2O2 diffusion occurred in G4 and G7, where the cells exhibited the lowest OxS than G2 (p < 0.05). Despite G5 showing the greatest ΔE regarding other groups (p < 0.05), the esthetic efficacy observed in G7 was similar to G2 (p > 0.05). ΔWI indicated a greater bleaching effect for groups G5, G6, and G7 (p < 0.05). CONCLUSION: Coating the dental enamel with polymeric biomaterials reduced the time and the cytotoxicity of BG-35%H2O2. CLINICAL SIGNIFICANCE: Coating the dental enamel with polymeric biomaterials allows safer and faster BG-35%H2O2 application.

Polymeric biomaterials maintained the esthetic efficacy and reduced the cytotoxicity of in-office dental bleaching.

Evaluate the kinetics of hydrogen peroxide (H2 O2 ) degradation, esthetic efficacy and cytotoxicity of a bleaching gel with 35%H2 O2 applied on enamel previously covered or not with polymeric nanofibrillar scaffold (SNan), polymeric primer catalyst (PPol), and both. Standardized enamel/dentin discs (n = 128) obtained from bovine teeth were adapted to pulp chambers. After covering enamel with the polymeric products, the bleaching gel was applied for 45 min, establishing the following groups: G1: no treatment (negative control); G2: 35%H2 O2 (positive control); G3: SNan; G4: PPol; G5: SNan + PPol; G6: SNan + 35%H2 O2 ; G7: PPol + 35%H2 O2 ; G8: SNan + PPol + 35%H2 O2 . The kinetics of H2 O2 degradation (n = 8), bleaching efficacy (ΔE/ΔWI; n = 8), trans-amelodentinal cytotoxicity (n = 8), and cell morphology (n = 4) were assessed (ANOVA/Tukey test; p < 0.05). Greater H2 O2 degradation occurred in G7 and G8. Bleaching efficacy (ΔE) was higher in G6, G7, and G8 in comparison with G2 (p < 0.05). However, no difference was observed for ΔWI (p > 0.05). G8 presented the lower level of trans-amelodentinal diffusion of H2 O2 , oxidative stress, and toxicity to the MDPC-23 cells (p < 0.05). Polymeric biomaterials increased the kinetics of H2 O2 decomposition, as well as maintained the esthetic efficacy and minimized the cytotoxicity caused by a bleaching gel with 35%H2 O2 . CLINICAL SIGNIFICANCE: Application of a bleaching gel with 35%H2 O2 on enamel previously covered by polymeric biomaterials maintains the esthetic efficacy and reduces the cytotoxicity caused by a single session of in-office dental bleaching.

Evaluation of the aesthetic effect, enamel microhardness and trans-amelodentinal cytotoxicity of a new bleaching agent for professional use containing trimetaphosphate and fluoride.

This study evaluated the effects of calcium gluconate (CaGlu), sodium fluoride (NaF), sodium trimetaphosphate (TMP), and NaF/TMP when added to a 35% hydrogen peroxide (H2O2) bleaching gel on the color change, enamel hardness, penetration and cytotoxicity trans-amelodentinal. Bovine enamel/dentin disks (n = 288) were divided according to the bleaching gel: 35% H2O2; 35% H2O2 + 0.05% NaF; 35% H2O2 + 0.25% TMP; 35% H2O2 + 0.05% NaF + 0.25% TMP; 35% H2O2 + 0.1% NaF + 1% TMP and 35% H2O2 + 2% CaGlu. The bleaching gels were applied thrice (40 min/session) at 7-day intervals between each application. Then, the color change, percentage of surface hardness loss (%SH), cross-sectional hardness (ΔKHN), trans-amelodentinal penetration of H2O2, cell viability and morphology (MDPC-23 odontoblast-like cells), alkaline phosphatase activity (ALP) and deposition of mineralization nodules were determined. The data were submitted to ANOVA, followed by the Student-Newman-Keuls test (p < 0.05). All bleaching gels showed significant color changes after treatment (p < 0.001). Mineral loss (%SH and ΔKHN) and H2O2 penetration were lower for 35% H2O2/0.1% NaF/1% TMP; 35% H2O2/2% CaGlu, meanwhile, showed higher values, compared to the other groups (p < 0.001). Cell viability was around 9%, except for the bleaching gel containing 35% H2O2/0.1% NaF/1% TMP with 12.8% (p < 0.05). ALP was higher for groups containing TMP compared to other whitening gels (p < 0.05). The formation of mineralization nodules was greater for gels containing NaF/TMP or CaGlu (p < 0.05). The alterations of cell morphology were intense for all bleaching gels. It was concluded that the addition of NaF/TMP in-office bleaching did not interfere in bleaching efficacy, reduced enamel demineralization, H2O2 penetration and cytotoxicity.

Molecular design aided by random forests and synthesis of potent trypanocidal agents as cruzain inhibitors for Chagas disease treatment.

Cruzain is an established target for the identification of novel trypanocidal agents, but how good are in vitro/in vivo correlations? This work describes the development of a random forests model for the prediction of the bioavailability of cruzain inhibitors that are Trypanosoma cruzi killers. Some common properties that characterize drug-likeness are poorly represented in many established cruzain inhibitors. This correlates with the evidence that many high-affinity cruzain inhibitors are not trypanocidal agents against T. cruzi. On the other hand, T. cruzi killers that present typical drug-like characteristics are likely to show better trypanocidal action than those without such features. The random forests model was not outperformed by other machine learning methods (such as artificial neural networks and support vector machines), and it was validated with the synthesis of two new trypanocidal agents. Specifically, we report a new lead compound, Neq0565, which was tested on T. cruzi Tulahuen (ß-galactosidase) with a pEC50 of 4.9. It is inactive in the host cell line showing a selectivity index (SI = EC50cyto /EC50T. cruzi ) higher than 50.

Esthetic rehabilitation of anterior teeth with molar-incisor hypomineralization and dental fluorosis: a case report.

This case report describes the treatment of a patient who had molar-incisor hypomineralization associated with dental fluorosis, a diagnosis established through a comprehensive review of the clinical record, an intraoral clinical examination, and assessment of photographic records. First, dental hypersensitivity was treated with fluoride varnish, which was applied separately to each dental quadrant. Subsequently, the functional and esthetic reconstruction of the permanent maxillary central incisors was completed in a single session through the placement of direct composite resin veneers. After the treatment, the patient was reexamined monthly for 12 months to evaluate the durability of the restorations. At the 12-month follow-up, no fractures or pigmentations were observed, and only a slight loss of brightness of the restorations was noted. The dental hypersensitivity had been eliminated. When an adhesive restorative technique with composite resin is well executed, it is possible to obtain satisfactory and long-lasting esthetics and relief of painful symptoms.

Increased whitening efficacy and reduced cytotoxicity are achieved by the chemical activation of a highly concentrated hydrogen peroxide bleaching gel.

OBJECTIVE: This study was designed for the chemical activation of a 35% hydrogen peroxide (H2O2) bleaching gel to increase its whitening effectiveness and reduce its toxicity. METHODOLOGY: First, the bleaching gel - associated or not with ferrous sulfate (FS), manganese chloride (MC), peroxidase (PR), or catalase (CT) - was applied (3x 15 min) to enamel/dentin discs adapted to artificial pulp chambers. Then, odontoblast-like MDPC-23 cells were exposed for 1 h to the extracts (culture medium + components released from the product), for the assessment of viability (MTT assay) and oxidative stress (H2DCFDA). Residual H2O2 and bleaching effectiveness (DE) were also evaluated. Data were analyzed with one-way ANOVA complemented with Tukey's test (n=8. p<0.05). RESULTS: All chemically activated groups minimized MDPC-23 oxidative stress generation; however, significantly higher cell viability was detected for MC, PR, and CT than for plain 35% H2O2 gel. Nevertheless, FS, MC, PR, and CT reduced the amount of residual H2O2 and increased bleaching effectiveness. CONCLUSION: Chemical activation of 35% H2O2 gel with MC, PR, and CT minimized residual H2O2 and pulp cell toxicity; but PR duplicated the whitening potential of the bleaching gel after a single 45-minute session.

Positive influence of simvastatin used as adjuvant agent for cavity lining.

OBJECTIVES: To assess the biological, antimicrobial, and mechanical effects of the treatment of deep dentin with simvastatin (SV) before application of a glass-ionomer cement (GIC). MATERIALS AND METHODS: Dentin discs were adapted to artificial pulp chambers and SV (2.5 or 1.0 mg/mL) was applied to the occlusal surface, either previously conditioned or not with EDTA (±EDTA). The extracts (culture medium + SV that diffused through dentin) was obtained and then applied to cultured odontoblast-like MDPC-23 cells. Cell viability, alkaline phosphatase (ALP) activity, and mineralization nodule (MN) deposition were evaluated. Untreated discs were used as control. The antibacterial activity of SV (2.5 or 1.0 mg/mL) against Streptococcus mutans and Lactobacillus acidophilus, as well as the bond strength of GIC to dentin in the presence of SV 2.5 mg/mL (±EDTA) were also assessed. The data were analyzed by ANOVA/Tukey tests (α = 5%). RESULTS: EDTA + SV 2.5 mg/mL significantly enhanced the ALP activity and MN deposition in comparison with the control, without changing in the cell viability (p < 0.05). The association EDTA + SV 2.5 mg/mL + GIC determined the highest ALP and MN values (p < 0.05). SV presented intense antimicrobial activity, and the EDTA dentin conditioning followed by SV application increased bond strength values compared with SV treatment alone (p < 0.05). CONCLUSION: SV presents antimicrobial activity and diffuses across conditioned dentin to biostimulate odontoblast-like pulp cells. CLINICAL SIGNIFICANCE: The use of SV as adjuvant agent for indirect pulp capping may biostimulate pulp cells thus preserving vitality and function of the pulp-dentin complex.

Increased whitening efficacy and reduced cytotoxicity are achieved by the chemical activation of a highly concentrated hydrogen peroxide bleaching gel

Abstract Objective This study was designed for the chemical activation of a 35% hydrogen peroxide (H2O2) bleaching gel to increase its whitening effectiveness and reduce its toxicity. Methodology First, the bleaching gel - associated or not with ferrous sulfate (FS), manganese chloride (MC), peroxidase (PR), or catalase (CT) - was applied (3x 15 min) to enamel/dentin discs adapted to artificial pulp chambers. Then, odontoblast-like MDPC-23 cells were exposed for 1 h to the extracts (culture medium + components released from the product), for the assessment of viability (MTT assay) and oxidative stress (H2DCFDA). Residual H2O2 and bleaching effectiveness (DE) were also evaluated. Data were analyzed with one-way ANOVA complemented with Tukey's test (n=8. p<0.05). Results All chemically activated groups minimized MDPC-23 oxidative stress generation; however, significantly higher cell viability was detected for MC, PR, and CT than for plain 35% H2O2 gel. Nevertheless, FS, MC, PR, and CT reduced the amount of residual H2O2 and increased bleaching effectiveness. Conclusion Chemical activation of 35% H2O2 gel with MC, PR, and CT minimized residual H2O2 and pulp cell toxicity; but PR duplicated the whitening potential of the bleaching gel after a single 45-minute session.

Análise da citotoxicidade de um gel clareador com 10% de peróxido de hidrogênio sobre células odontoblastóides de acordo com a espessura do substrato dental / Analysis of the cytotoxicity of a 10% hydrogen peroxide bleaching gel to odontoblast-like cells according to the thickness of dental substrate

Objetivo: Avaliar a citotoxicidade de um gel clareador contendo 10% de peróxido de hidrogênio (H2O2), aplicado sobre discos de esmalte/dentina simulando diferentes espessuras dentais. Material e método: Discos com 2,3; 3,5; e 4,0 mm de espessura foram obtidos para simular incisivos centrais inferiores, incisivos centrais superiores e segundos pré-molares superiores, respectivamente. Para cada espessura, o gel com 10% de H2O2 foi aplicado sobre o esmalte por 3x 15 min, 1x 15 min ou 1x 5 min. O protocolo 35% H2O2 3x 15 min foi empregado como controle positivo (CP), e nenhum tratamento foi realizado no controle negativo (CN). Células odontoblastóides MDPC-23 foram expostas por 1 h aos componentes da difusão trans-amelodentinária coletados imediatamente após o clareamento, sendo realizada análise da viabilidade celular, estresse oxidativo, deposição de nódulos de mineralização, bem como a quantificação da difusão de H2O2 pelos discos. Resultados: O gel com 10% de H2O2 não promoveu redução significativa da viabilidade celular em relação ao CN para todos os protocolos e espessuras testadas, resultando em valores de difusão de H2O2 significativamente inferiores ao CP. Apenas o protocolo 10% 3x 15 min aplicado sobre os discos simulando incisivos promoveu aumento no estresse oxidativo e reduziu a deposição de nódulos de mineralização em relação ao CN; porém, estes efeitos foram significativamente inferiores ao CP. Conclusão: De acordo com a metodologia usada neste estudo, foi possível concluir que, independente da espessura dental, a aplicação de um gel clareador com 10% de H2O2 por 5-45 min sobre o esmalte causa limitado efeito citotóxico sobre células pulpares.

Objective: To evaluate the cytotoxicity of a bleaching gel with 10% hydrogen peroxide (H2O2) applied onto enamel/dentin discs simulating different dental thicknesses. Material and methods: Discs with 2.3; 3.5; and 4.0 mm thickness were obtained to simulate low central incisors, upper central incisors and upper second pre-molars, respectively. For each thickness, the 10% H2O2 gel was applied for 3x 15 min, 1x 15 min or 1x 5 min. A gel with 35% H2O2 applied for 3x 15 min was used as positive control (PC) and no treatment was performed in negative control (NC). Odontoblast- like MDPC-23 cells were exposed for 1 h to the transenamel and trans-dentinal components collected immediately after bleaching. Cell viability, oxidative stress and mineralized nodule deposition were assessed as well as the quantification of H2O2 diffused through the discs. Results: The 10% H2O2 gel did not promote significant reduction on cell viability in comparison to NC for all tested protocols and thicknesses, resulting in H2O2 diffusion values significantly lower than PC. Only the protocol 10% H2O2 3x 15 min applied onto discs simulating incisors increased significantly the oxidative stress and reduced mineralized nodule deposition compared to NC; however, these effects were significantly lower than PC. Conclusion: According to the methodology employed in this laboratorial study, the application of a bleaching gel with 10% H2O2 for 5-45 min onto dental structure featured limited cytotoxicity to pulp cells, disregarding the enamel/dentin thicknesses.

Influência do gluconato de cálcio sobre a citotoxicidade trans-amelodentinária de um agente clareador com 20% de peróxido de hidrogênio / Influence of calcium gluconate on the trans-enamel and trans-dentinal cytotoxicity of a bleaching agent with 20% hydrogen peroxide

Objetivo: Avaliar a citotoxicidade de um agente clareador contendo 2% de gluconato de cálcio (GC) sobre células pulpares humanas (HDPCs). Materiais e Métodos: Discos de esmalte-dentina adaptados em câmaras pulpares artificiais (CPAs) foram posicionados em compartimentos de forma que a dentina permaneceu imersa em meio de cultura, enquanto que o esmalte foi submetido ao clareamento com géis a 20% de H2O2 contendo ou não GC, durante 1x 45, 1x15 ou 1x5 minutos. No controle positivo foi realizado clareamento com 35% de H2O2 aplicado por 1x 45 minutos, sendo que no controle negativo nenhum tratamento foi realizado sobre o esmalte. A viabilidade celular (teste do MTT) e a difusão trans-amelodentinária de H2O2 (violeta leuco- -cristal/peroxidase) foram avaliadas (ANOVA/Tukey α = 5%; n = 8). Resultados: Foi observada redução significativa na viabilidade celular em todos os grupos clareados quando comparados ao controle negativo (p < 0,05); no entanto, os grupos expostos aos géis contendo 20% de H2O2, com ou sem GC, apresentaram valores de viabilidade celular significativamente superiores ao controle positivo (p < 0,05). A redução da viabilidade celular e a difusão de H2O2 residual para os grupos clareados com 20% de H2O2 foi proporcional ao tempo de contato dos produtos com a superfície dental, sendo que a presença de GC resultou em minimização significativo do efeito tóxico/difusão de H2O2 para os protocolos 1x 15 e 1x 5 min (p < 0,05). Conclusão: A presença de 2% de GC nos géis com 20% de H2O2 resulta em redução da difusão de H2O2 residual pela estrutura dental e do efeito citotóxico sobre células pulpares humanas, quando o produto é aplicado por curtos períodos sobre a superfície dental.

Objective: To evaluate the cytotoxicity of a bleaching agent containing 2% calcium gluconate (CG) on human pulp cells (HDPCs). Materials and Methods: Enamel-dentin disks adapted in artificial pulp chambers (CPAs) were placed in compartments so that dentin remained immersed in culture medium, while the enamel was subjected to bleaching with 20% H2O2 gels containing or not CG for 1x 45, 1x15 or 1x5 minutes. In the positive control, bleaching was performed with 35% H2O2 applied for 1x 45 minutes, and in the negative control no treatment was performed on the enamel. Cell viability (MTT test) and transenamel and trans-dentinal diffusion of H2O2 (leuco-crystal violet / peroxidase) were evaluated (ANOVA / Tukey α = 5%, n = 8). Results: A significant reduction in cell viability was observed in all bleached groups when compared to the negative control (p <0.05); However, groups exposed to gels containing 20% H2O2, with or without CG, had significantly higher values of cell viability than the positive control (p <0.05). The reduction of cell viability and the diffusion of residual H2O2 to the bleached groups with 20% H2O2 was proportional to the contact time of the products with the dental surface, and the presence of CG resulted in a significant minimization of the toxic /diffusion effect of H2O2 For the 1x15 and 1x5min protocols (p <0.05). Conclusion: The presence of 2% GC in gels with 20% H2O2 results in reduction of residual H2O2 diffusion by dental structure and cytotoxic effect on human pulp cells when the product is applied for short periods on the dental surface.

Bioestimulação de células pulpares humanas expostas a sinvastatina / Biostimulation of human pulp cells exposed to simvastatin

O objetivo desse estudo foi avaliar o potencial bioativo da sinvastatina (SV), aplicada por diferentes períodos sobre células da polpa dental humana (HDPCs). Para isto, HDPCs em 80% de confluência (n=6) foram tratadas com meio osteogênico suplementado com 0,01 µM de SV pelos períodos de 24 h, 72 h ou continuamente por até 21 dias. No controle negativo, as células foram mantidas em meio osteogênico. A viabilidade celular (MTT) foi avaliada em períodos de 1, 3, 7, 14 e 21 dias, e a deposição de matriz mineralizada (alizarin red) após 14 e 21 dias de cultivo celular. Os dados foram submetidos aos testes ANOVA e Tukey (α=5%). Foi observado que nos períodos de 1, 3, 7 e 14 dias não houve diferença significativa na viabilidade das células submetidas aos tratamentos com SV em comparação ao controle (p<0,05); no entanto, redução tardia foi observada aos 21 dias para as células tratadas com SV por 72 h ou de modo contínuo (p<0,05). Em contrapartida, aumento na deposição de matriz mineralizada foi observado para o tratamento contínuo com SV aos 21 dias, quando comparado ao controle (p<0,05). Foi possível concluir que o tratamento contínuo de células pulpares humanas com 0,01µM de SV foi capaz de bioestimular a deposição de matriz mineralizada in vitro.

The objective of this study was to evaluate the bioactive potential of simvastatin (SV), applied during different periods on human dental pulp cells (HDPCs). For this, HDPCs at 80% confluency (n = 6) were treated with osteogenic medium supplemented with 0.01 µM SV for periods of 24 h, 72 h or continuously up to 21 days. In the negative control group, the cells were cultivated in osteogenic medium. The cell viability (MTT) was evaluated after 1, 3, 7, 14 and 21 days, and the mineralized matrix deposition (alizarin red) was assessed at 14 and 21 days of cell culture. Data were submitted to ANOVA and Tukey's test (α=5%). No significant difference in cell viability was observed at 1, 3, 7 and 14 days for the cells exposed to SV compared to negative control (p<0.05); however, significant reduction was observed at 21 days for cells treated with SV during 72 h or continuously (p<0.05). On the other hand, increase in mineralized matrix deposition at 21 days was observed for cells treated continuously with SV when compared to control (p<0.05). It was possible to conclude that the continuous treatment of human pulp cells with 0.01 µM of SV was able to biostimulate mineralized matrix deposition in vitro.

Bleaching effectiveness, hydrogen peroxide diffusion, and cytotoxicity of a chemically activated bleaching gel.

OBJECTIVES: The objective of this study was to evaluate the bleaching effectiveness, hydrogen peroxide diffusion (H2O2), and cytotoxicity of a bleaching gel with 35 % H2O2 either associated with ferrous sulfate (FeSO4) or not. MATERIALS AND METHODS: Enamel/dentin discs adapted to artificial pulp chambers were placed in compartments containing a culture medium (Dulbecco's Modified Eagle's Medium (DMEM)) and distributed into the following groups: G1-no treatment (negative control), G2-10 % carbamide peroxide (one application for 4 h), G3-35 % H2O2 (three applications for 15 min), and G4-35 % H2O2 + 0.004 g FeSO4 (three applications for 15 min). After treatments, the extracts (DMEM + bleaching components that diffused across enamel and dentin) were applied on human dental pulp cells (HDPCs) and odontoblast-like cells (MDPC-23). Cell viability (MTT assay, Kruskal-Wallis and Mann-Whitney, α = 5 %), quantification of H2O2 diffusion, and color change of the enamel/dentin discs (Commission Internationale de I'Eclairage L*a*b* system) were assessed (analysis of variance and Tukey's tests, α = 5 %). RESULTS: For both cells, a significant reduction in cell viability was observed for G3 and G4 compared with G1 and G2. No statistical difference was observed between G3 and G4. The rate of H2O2 diffusion was significantly higher in G3 compared with that in G2 and G4. The ΔE value for G4 was statistically higher than that of the other groups. CONCLUSIONS: Chemical activation of H2O2 by FeSO4 improves the bleaching effectiveness. However, this metal ion has no significant protective effect against pulp cell cytotoxicity. CLINICAL RELEVANCE: Although the chemical activation of H2O2 by adding FeSO4 to the bleaching agent improved the bleaching effectiveness, this metal ion has no significant protective effect against pulp cell cytotoxicity.

Influence of adhesive restorations on diffusion of H2O2 released from a bleaching agent and its toxic effects on pulp cells.

PURPOSE: To assess the influence of adhesive restorations on hydrogen peroxide (H2O2) diffusion through enamel and dentin and its cytotoxicity to pulp (MDPC-23) cells. MATERIALS AND METHODS: Sound and resin-restored enamel/dentin disks were stored in water for 24 h or 6 months and adapted to artificial pulp chambers. Bleaching gels with 20% or 35% H2O2 were applied to the enamel surface for 45 min, and a culture medium in direct contact with the dentin surface (extract) was applied for 1 h to the MDPC-23 cells. Cell metabolism (MTT assay) and cell morphology (SEM) were assessed. The amount of H2O2 in the extracts was also quantified (peroxidase/leuco-crystal violet reaction). RESULTS: A significant reduction in cell metabolism was observed between the group bleached with the 35% gel and the control group (sound, nonbleached) (p < 0.05). The H2O2 diffusion was directly related to its concentration in the bleaching gel. The variables "presence of restoration" and "time of water storage" did not significantly influence H2O2 diffusion or cell metabolism for either of the bleaching gels (p > 0.05). All bleached groups presented alterations in cell morphology related to the concentration of H2O2 in the bleaching gel. CONCLUSION: The reduction in cell metabolism and the changes in cell morphology were H2O2-concentration dependent, having no relationship with the presence of either new or aged adhesive restorations on teeth subjected to bleaching therapies.