Antimicrobial Orthodontic Wires Coated with Silver Nanoparticles

Abstract Conventional orthodontic treatment with the use of stainless steel may be detrimental to oral health by promoting demineralizing lesions appearance and increasing adhesion and formation of bacterial biofilm, inducing the development of cavities. An alternative that has been researched to reduce the side effects of orthodontic treatment is the coating of materials with antimicrobial nanoparticles. Nanometric- sized particles increase their surface area and contact with the microbial membrane, consequently intensifying their bacteriostatic and bactericidal effect. In this work, hydrothermal synthesis, a "green" process was used to attach silver nanoparticles (AgNPs) to the surface of two different brands of orthodontic wires. The coated materials were analyzed for their physicochemical properties by scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC), which showed the distribution of AgNPs along the wires without modifying their properties. In the microbiological test, one of the brands showed a statistically significant difference in microbial adhesion and biofilm formation by Staphylococcus aureus and Streptococcus mutans. Results lead to the conclusion that antimicrobial orthodontic wires coated with silver nanoparticles through hydrothermal synthesis is a promising material for the improvement of orthodontic treatment.

Caracterização e avaliação da citocompatibilidade de nanocompósitos baseados em celulose bacteriana e fibroína para aplicação em regeneração tecidual / Characterization and cytocompatibility evaluation of cellulose and fibroin based nanocomposites for tissue regeneration applications

A engenharia de tecidos tem como perspectiva desenvolver opções terapêuticas para quadros clínicos com prognóstico limitado, objetivando substituir ou regenerar os tecidos lesados por meio do uso de biomateriais. A metodologia baseia-se no cultivo de células sobre uma matriz ou scaffold que deve ser otimizado para minimizar o risco de infecções e permitir a liberação das moléculas bioativas no local pretendido. As propriedades dos diversos biomateriais são essenciais para o sucesso da metodologia e estes podem ser manipulados de forma a mimetizar a arquitetura da matriz nativa. Assim, nos propomos a desenvolver um novo biocompósito baseado em celulose bacteriana (CB)/ fibroína (FB) visando aplicações em regeneração tecidual na odontologia, em 3 concentrações diferentes (CB/FB25%, CB/FB50% e CB/FB75%). Estes foram caracterizados por análise termogravimétrica, Espectroscopia Vibracional na Região do Infravermelho (FT-IR), Difração de Raios-X, e Microscopia Eletrônica de Varredura (MEV), demonstrando boa estabilidade físico-química, inclusive resitência à degradação térmica em altas temperaturas. A investigação da citocompatibilidade foi conduzida por meio de testes in vitro apenas com as amostras de CB/FB50%. Os testes aplicados foram MTT, azul de tripano, adesão e proliferação celular. As análises estatísticas foram realizadas por meio do software Graph Prism 5.0. Os resultados demonstraram que o material desenvolvido é biocompatível e não citotóxico. As imagens de MEV revelaram um número muito maior de células aderidas à superfície dos scaffolds de CB/FB quando comparado ao de CB pura. Com base nos dados obtidos é possível sugerir que o nanocompósito baseados em CB/FB50% configura uma excelente alternativa como scaffold para a reparação de tecidos.

Tissue engineering has the purpose of developping therapeutic options especially designed to be used on limited clinical conditions, aiming to replace or regenerate damaged tissues applying biomaterials for that. The method is based on the cultivation of cells on a matrix or scaffold that should be optimized to offer minimum risk of infections and allow the release of bioactive molecules at the desired location. The success of the methodology depends on Biomaterials' properties that can be manipulated to mimic the three-dimensional architecture of native tissues extracellular matrix. Thus, we purpose to prepare a new nanocomposite based on bacterial cellulose (BC) / fibroin (SF) aiming at applications in the process of tissue regeneration in dentistry. Three different material's compositions were prepared (BC/SF 25 % BC/SF 50 % and BC/SF 75 %) and all of them were characterized by thermogravimetric analysis, Vibrational Spectroscopy in the Infrared Region (FT-IR), X-ray diffraction, and Scanning Electron Microscopy (SEM). The material showed good physical and chemical stability including resistance to thermal degradation at high temperatures. The investigation of the cytocompatibility was realized just using the samples BC/SF 50 % and the in vitro tests conducted were MTT, Trypan Blue, cell adhesion and proliferation assays. The statistical analysis was done applying the software Graph Pad Prism 5.0. The results showed that the developed nanocomposite is biocompatible and non-cytotoxic. SEM images revealed a greater number of cells attached to the scaffold CB / FB surface when compared to pure CB scaffolds. Based on the data obtained, it is possible to suggest that the nanocomposite based on CB/FB50% configures an excellent alternative as a scaffold for tissue repair