Objective: This study was designed for the chemical activation of a 35% hydrogen peroxide (H 2 O 2) 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 (H 2 DCFDA). 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.
The 17.5% H2O2 applied to tooth specimens for 5 min caused no alteration in the odontoblast-like cells. When this gel was applied for 45 or 15 min, a slight cytotoxicity, associated with alterations in phenotypic markers, was observed. However, cells were able to recover their functions up to 21 days post-bleaching.
Dental cavities restored with the RMGIC subjected to hydrolytic degradation allowed for more intense diffusion of H2O2 into the pulp chamber, intensifying the toxicity of a 35%-H2O2 bleaching gel to pulp cells.
Avaliou-se o efeito de diferentes agentes de limpeza (etanol 95% - E ou xilol - X) e momento do condicionamento ácido – CA (imediato – I ou após 7 dias – T) na interface de adesão e resistência de união do sistema adesivo condiciona-e-lava em dentina impregnada com cimentos à base de resina epóxi (R) e silicato de cálcio (S). Cem espécimes de coroas de incisivos bovinos (protocolo n.o 12/2014 CEUA/FOAr-UNESP) foram preparados e impregnados com os cimentos. Para avaliar a formação da camada híbrida, os espécimes foram restaurados com resina composta, tiveram suas imagens obtidas por meio de microscopia confocal (1024X) e mesuradas no Image J (Kruskal Wallis/Dunn - P0,05). Para a resistência de união, os espécimes foram igualmente preparados e submetidos ao teste de microcisalhamento (ANOVA/Tukey - P0,05). Para os espécimes impregnados com R, a extensão da camada híbrida apresentou-se reduzida para todos os protocolos e a maior resistência de união foi encontrada no protocolo de limpeza com X e CA T. Já para os espécimes impregnados com S, os maiores valores para extensão da camada híbrida e resistência de união foram observados para o protocolo de limpeza com E e CA T. Concluiu-se que para R, apesar da menor camada híbrida formada, a limpeza com X e CA T não interferiu na resistência de união. Já para S, a limpeza com E e CA T foi o protocolo que menos interferiu na interface adesiva e resistência de união do sistema adesivo.Palavras-chave: Dentina. Solventes. Adesivos Dentinários.
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