Propriedades antibacterianas, físicas e mecânicas de uma resina composta modificada com nanopartículas de ZnO e TiO2, puras e decoradas com prata, obtidas por diferentes sínteses
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Data
2017-08-24
Autores
Dias, Hércules Bezerra [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Estudos recentes relatam que resinas compostas contendo nanopartículas (NPs) de óxidos metálicos, tais como óxido de zinco (ZnO) e dióxido de titânio (TiO2) têm potencial antibacteriano e podem controlar a formação do biofilme oral cariogênico. O objetivo desse estudo foi avaliar a capacidade antibacteriana de uma resina composta modificada por NPs de óxido de zinco e dióxido de titânio puras e decoradas com prata (ZnO, ZnO/Ag, TiO2 e TiO2/Ag), bem como, avaliar as propriedades de resistência à compressão e à tensão diametral, estabilidade de cor, rugosidade superficial e grau de conversão após modificação da resina composta com as NPs. As NPs foram sintetizadas pelos métodos dos precursores poliméricos e hidrotermal assistido por micro-ondas, e caracterizadas por DRX, área de superfície BET, FTIR e MET. A resina FiltekTM Z350XT modificada com 0,5; 1 e 2% (em massa) foi testada sobre Streptococcus mutans por meio do teste do contato direto (UFC/mL) para determinação da menor concentração inibitória e então avaliada em biofilme de 7 dias por meio decontagem das unidades formadoras de colônias (UFC/mL). As resistências à compressão e à tração diametral da resina composta modificada (n=40) foram avaliadas utilizando-se máquina de ensaio universal (EMIC). O grau de conversão (n=25) foi realizado por análise em FTIR e a leitura da rugosidade superficial (n=50) foi realizada utilizando-se rugosímetro portátil. A estabilidade de cor (n=180) foi avaliada por leitura espectrofotométrica após imersão dos espécimes em solução de café e saliva artificial. Os dados foram analisados utilizando-se o software IBM SPSS Statistics 20.0 (SPSS Inc. Chicago, EUA) por ANOVA a um fator para a atividade antibacteriana e testes mecânicos; ANOVA a dois fatores e teste de Tukey para o grau de conversão; ANOVA de medidas repetidas e pós teste com ajuste de Bonferroni para estabilidade de cor e teste de rugosidade superficial, com nível de significância de 5%. A inclusão de 2% (em massa) de NPs de ZnO e TiO2 puros e decorados com Ag na resina composta inibiu o crescimento do biofilme de S. mutans, sem drásticas alterações nas propriedades mecânicas e físicas. Melhora nas propriedades mecânicas foi alcançada após a inclusão de TiO2/Ag. O grau de conversão permaneceu inalterado após a modificação da resina com todas os NPs testadas e a rugosidade superficial não foi significativamente alterada após a inclusão de TiO2/Ag (PREC POL). A estabilidade de cor da resina foi afetada após a inclusão das nanopartículas, especialmente quando armazenada em solução de café e após 90 dias. O desenvolvimento de um material restaurador dental antibacteriano que iniba a formação do biofilme de S. mutans sobre sua superfície sem sacrificar suas propriedades mecânicas e físicas poderia evitar a progressão de cáries secundárias.
Different methods to inhibit biofilm formation on dental restorative materials have been studied for decades and recent studies report that composite resins containing metal oxide nanoparticles (NPs), such as zinc oxide (ZnO) and titanium dioxide (TiO2), have antibacterial potential and can control the formation of cariogenic oral biofilm. In this way, the purpose of this study was to evaluate the antibacterial capacity of a resin modified by pure and silver decorated ZnO and TiO2 (ZnO, ZnO/Ag, TiO2 and TiO2/Ag) NPs and to evaluate the compressive and diametral tensile strength, color stability, surface roughness and degree of conversion after modification of the composite resin with the NPs. The NPs were synthesized by polymeric precursor and microwave-assisted hydrothermal methods, characterized by XRD, BET surface area, FTIR and MET. The direct contact test with Filtek ™ Z350XT modified with 0.5; 1 and 2% (by mass) of NPs against Streptococcus mutans was performed in order to choose the minor concentration to perform the other tests. The modified resin was tested against the 7- days S. mutans biofilm. The compressive strength and diametral tensile strength of the modified composite resin (n = 40) was tested using a universal test machine (EMIC). The degree of conversion (n = 25) was performed by FTIR analysis and the surface roughness reading (n = 50) was performed using a portable surface roughness tester. The color stability (n=180) was evaluated by spectrophotometric readings after storage in coffee solution and artificial saliva. The data was analyzed using the software IBM SPSS Statistics 20.0 (SPSS Inc. Chicago, USA). One-way ANOVA were performed to antibacterial and mechanical tests data, two-way ANOVA for degree of conversion and a mixed model repeated measurements ANOVA and a post hoc test for repeated measures with adjustment of Bonferroni were performed for surface roughness and color stability test. All tests were performed at 5% significance level. The inclusion of 2% (wt%) of ZnO and ZnO/Ag NPs from different synthesis provide S. mutans biofilm formation control without sacrificing of mechanical and physical properties of the composite resin, when the inclusion of pure and Ag decorated TiO2 into the composite resin can decrease S. mutans biofilm formation over the resin surface. An enhancement of mechanical properties was achieved after inclusion of TiO2/Ag. The degree of conversion remains unchanging after resin modification with all tested NPs and the surface rougnhess was not significantly increased after inclusion of TiO2/Ag (PREC POL). Regarding the color stability, after inclusion of nanoparticles, the color stability was affected, especially when stored in coffee solution after 90 days. The development of an antibacterial dental restorative material that hind S. mutans biofilm without sacrificing mechanical and physical properties could decrease the progression of secondary caries.
Different methods to inhibit biofilm formation on dental restorative materials have been studied for decades and recent studies report that composite resins containing metal oxide nanoparticles (NPs), such as zinc oxide (ZnO) and titanium dioxide (TiO2), have antibacterial potential and can control the formation of cariogenic oral biofilm. In this way, the purpose of this study was to evaluate the antibacterial capacity of a resin modified by pure and silver decorated ZnO and TiO2 (ZnO, ZnO/Ag, TiO2 and TiO2/Ag) NPs and to evaluate the compressive and diametral tensile strength, color stability, surface roughness and degree of conversion after modification of the composite resin with the NPs. The NPs were synthesized by polymeric precursor and microwave-assisted hydrothermal methods, characterized by XRD, BET surface area, FTIR and MET. The direct contact test with Filtek ™ Z350XT modified with 0.5; 1 and 2% (by mass) of NPs against Streptococcus mutans was performed in order to choose the minor concentration to perform the other tests. The modified resin was tested against the 7- days S. mutans biofilm. The compressive strength and diametral tensile strength of the modified composite resin (n = 40) was tested using a universal test machine (EMIC). The degree of conversion (n = 25) was performed by FTIR analysis and the surface roughness reading (n = 50) was performed using a portable surface roughness tester. The color stability (n=180) was evaluated by spectrophotometric readings after storage in coffee solution and artificial saliva. The data was analyzed using the software IBM SPSS Statistics 20.0 (SPSS Inc. Chicago, USA). One-way ANOVA were performed to antibacterial and mechanical tests data, two-way ANOVA for degree of conversion and a mixed model repeated measurements ANOVA and a post hoc test for repeated measures with adjustment of Bonferroni were performed for surface roughness and color stability test. All tests were performed at 5% significance level. The inclusion of 2% (wt%) of ZnO and ZnO/Ag NPs from different synthesis provide S. mutans biofilm formation control without sacrificing of mechanical and physical properties of the composite resin, when the inclusion of pure and Ag decorated TiO2 into the composite resin can decrease S. mutans biofilm formation over the resin surface. An enhancement of mechanical properties was achieved after inclusion of TiO2/Ag. The degree of conversion remains unchanging after resin modification with all tested NPs and the surface rougnhess was not significantly increased after inclusion of TiO2/Ag (PREC POL). Regarding the color stability, after inclusion of nanoparticles, the color stability was affected, especially when stored in coffee solution after 90 days. The development of an antibacterial dental restorative material that hind S. mutans biofilm without sacrificing mechanical and physical properties could decrease the progression of secondary caries.
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Palavras-chave
Nanotecnologia, Nanoestruturas, Resinas compostas, Produtos com ação antimicrobiana, Nanotechnology, Nanostructures, Composite resins, Products with antimicrobial action