Made available in DSpace on 2015-04-11T13:55:49Z (GMT). No. of bitstreams: 1 Thiago Mendes de Lima.pdf: 1095985 bytes, checksum: af3d342d9c71734320c0b651931b5083 (MD5) Previous issue date: 2014-02-21 / Fundação de Amparo à Pesquisa do Estado do Amazonas / A utilização de agentes antioxidantes tem sido proposta para melhorar a resistência adesiva após clareamento dental. O presente estudo in vitro avaliou o efeito do hidrogel de ascorbato de sódio a 10% (AS), aplicado após o clareamento com peróxido de hidrogênio a 35% (PH), na resistência adesiva em esmalte de uma resina composta (RC). Foram selecionados 50 dentes bovinos e aleatoriamente divididos em cinco grupos experimentais (n=10) subdividindo-os em grupos testados tardiamente (7 dias) e após envelhecimento (3 meses): Grupo 1 (G1: 7 dias/ G1A: 3 meses) - sem clareamento (grupo controle) + RC; G2/G2A PH + RC; G3/G3A PH + 14 dias + RC; G4/G4A PH 35% + AS 10% (30 min) + RC; G5/G5A PH + 14 dias + AS (30 min) + RC. Foram obtidos palitos de resina-adesivo-esmalte (1mm x1mm) e submetidos ao tese de resistência à microtração em uma máquina de ensaio universal EMIC DL2000 (100N a 0,5mm/min). Os tipos de falhas foram analisados em microscopia digital (40x) e eletrônica de varredura, classificado-as como coesiva, adesiva, mista. Os valores (Mpa) de resistência adesiva à microtração foram avaliados estatisticamente através da Análise de Variância a dois critérios (ANOVA) e do teste de Tukey para comparações das médias, com significância 1%. Os resultados foram: G1: 20,09Aab ± 5,33 / G1A: 24,09Abc ± 5,12; G2: 17,14Aa ± 4,94 / G2A: 20,84Aab ± 5,21; G3: 20,36Aab ± 5,30 / G3A: 22,76Abc ± 5,40; G4: 22,18Aabc ± 5,30 / G4A: 30,22Ad ± 8,05; G5: 21,92Aab ± 5,90 / G5A: 27,25Ac ± 7,12. Pode-se concluir que, o uso do ascorbato de sódio a 10% interfere positivamente na resistência adesiva de restaurações envelhecidas em 3 meses, aumentando os valores de resistência adesiva.

The complicated problem of efficient stimulation of elastic fiber production in already developed human tissues has not yet been solved. The present study introduces sodium ascorbate (SA) as a stimulator of elastogenesis in cultures of different cell types including fibroblasts isolated from patients with elastopathy genetic diseases. We then elucidated mechanisms of elastogenic action of SA. SA exercises its net elastogenic effect only after being actively transported into the cell interior through two separate mechanisms. These are the “fast effect,” which reflects the greater stability of intracellular tropoelastin, and the “late effect,” which reflects the true enhancement of the elastin gene expression occurring after SA-induced activation of c-src tyrosine kinase and the consecutive phosphorylation of IGF-1 receptor, which triggers the downstream signals leading to activation of the elastin gene expression. In conclusion, for the first time we have established that SA is a potent stimulator of elastic fiber production.

The complicated problem of efficient stimulation of elastic fiber production in already developed human tissues has not yet been solved. The present study introduces sodium ascorbate (SA) as a stimulator of elastogenesis in cultures of different cell types including fibroblasts isolated from patients with elastopathy genetic diseases. We then elucidated mechanisms of elastogenic action of SA. SA exercises its net elastogenic effect only after being actively transported into the cell interior through two separate mechanisms. These are the “fast effect,” which reflects the greater stability of intracellular tropoelastin, and the “late effect,” which reflects the true enhancement of the elastin gene expression occurring after SA-induced activation of c-src tyrosine kinase and the consecutive phosphorylation of IGF-1 receptor, which triggers the downstream signals leading to activation of the elastin gene expression. In conclusion, for the first time we have established that SA is a potent stimulator of elastic fiber production.