Avaliação da dureza superfi cial de cimentos de ionômero de vidro reforçados por nanotubos de carbono
Evaluation of surface hardness of glass ionomer reinforced cements by carbon nanotubes
Santos, Mayra Manoella Perez Reis dos; Mathias, Ingrid Fernandes; Diniz, Michele Baffi; Bresciani, Eduardo
Resumo
Introdução: Os cimentos de ionômero de vidro (CIV) são materiais com baixa resistência à tração e ao cisalhamento, mostrando-se, portanto, contraindicados para áreas sujeitas às grandes cargas oclusais. Objetivo: Avaliar o efeito da incorporação de nanotubos de carbono em CIV por meio de dureza superficial Knoop. Material e método: Foram confeccionados 48 espécimes, divididos em quatro grupos, de acordo com o tipo de CIV (n=12) – convencional ou de alta viscosidade, incorporados ou não de nanotubos de carbono (NC) a 2%: (A) Vidrion R; (B) Vidrion R + NC 2%; (C) Vitro Molar, e (D) Vitro Molar + NC 2%. Os espécimes foram preparados utilizando-se seringa Centrix, para inserção do material em moldes plásticos, e armazenados em água deionizada por 24 horas. Após polimento, realizou-se o teste de dureza superficial com penetrador do tipo Knoop. Foram realizadas cinco endentações em cada espécime, distanciadas entre si em 100 μm. Resultado: Os valores médios de dureza foram 58,96 ± 8,29 (A), 34,81 ± 5,78 (B), 60,84 ± 4,91 (C) e 41,97 ± 5,45 (D). O teste ANOVA detectou diferenças estatisticamente significantes para os dois parâmetros estudados, tipo de material (p=0,016) e inclusão de NC (p<0,0001). Pelo teste de Tukey, observou-se que os grupos A e C foram estatisticamente semelhantes (p>0,05), enquanto os grupos B e D apresentaram diferenças significativas (p<0,05). Ao comparar o fator incorporação ou não de NC, observou-se diferença significativa entre os grupos A e B, e entre os grupos C e D (p<0,05). Conclusão: A incorporação de nanotubos de carbono influenciou negativamente os valores de dureza superficial para os dois tipos de CIV utilizados.
Palavras-chave
Abstract
Introduction: Glass ionomer cements (GIC) are materials with low tensile and shear bond strength and therefore contraindicated in areas subjected to high occlusal stress loads. Aim: To evaluate the effect of incorporation of carbon nanotubes in GICs, conventional or indicated for the Atraumatic Restorative Treatment (ART), through the superficial microhardness test. Material and method: Forty-eight specimens were prepared and divided into 4 groups according to the type of GIC (n=12): conventional or high viscosity, embedded or not with 2% carbon nanotubes (CN): (A) Vidrion R, (B) Vidrion R + 2% CN, (C) Vitro Molar and (D) Vitro Molar + 2% CN. The specimens were inserted into plastic molds with Centrix syringe and stored in deionized water for 24 hours. After polishing, the superficial hardness was performed with a Knoop indenter. Five indentations were made on each specimen, with distance of 100 micrometers between indentations. Result: The average hardness values were 58.96 ± 8.29 (A) 34.81 ± 5.78 (B) 4.91 ± 60.84 (C) 41.97 ± 5.45 (D). ANOVA detected significant difference for the two varibales, material (p=0,016) and CN inclusion (p<0,0001). Tukey test revealed that the groups A and C were statistically similar (p>0.05), while the B and D groups showed significant differences (p<0.05). When comparing the incorporation or not of factor CN, there was significant difference between groups A and B and between C and D groups (p<0.05). Conclusion: The incorporation of CNTs negatively influenced the values of surface hardness for the two types of GIC used.
Keywords
References
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