Enhancing glass ionomer cement features by using the calcium phosphate nanocomposite

Abstract This study showed the synthesis of Glass ionomer cements (GIC) modified with calcium phosphate nanoparticles (nCaP). The nCaP/GIC were submitted to mechanical compression and diametral tensile tests. The biocomposite were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Cytotoxicity and cell viability tests were performed on the human bone marrow mesenchymal stem cells using a 3-(4,5-dimethylthiazol-2yl)2,5-diphenyl- tetrazolium-bromide assay and LIVE/DEAD assays. Statistically significant differences were observed for mechanical properties (Kruskal-Wallis, p<0.001), nCaP/GIC showed higher resistance to compression and diametral traction. The SEM analyses revealed a uniform distribution nCaP in the ionomer matrix. The EDX and XRD results indicated that hydroxyapatite and calcium β-triphosphate phases. The FTIR spectra revealed the asymmetric band of ν3PO43- between 1100-1030cm-1 and the vibration band associated with ν1PO43- in 963cm-1 associated with nCaP. The nCaP/GIC presented response to adequate cell viability and non-cytotoxic behavior. Therefore, the new nCaP/GIC composite showed great mechanical properties, non-cytotoxic behavior, and adequate response to cell viability with promising dental applications.

Resumo Este estudo apresenta a síntese de cimentos de ionômero de vidro (GIC) modificados com nanopartículas de fosfato de cálcio (nCaP). Os nCaP / GIC foram submetidos a ensaios mecânicos de compressão e tração diametral. Os biocompósitos foram caracterizados por microscopia eletrônica de varredura (MEV), espectroscopia de energia dispersiva de raios-X (EDX), difração de raios-X (XRD) e espectroscopia de infravermelho com transformada de Fourier (FTIR). Os testes de citotoxicidade e viabilidade celular foram realizados em células-tronco mesenquimais da medula óssea humana usando um ensaio de 3- (4,5-dimetiltiazol-2-il) 2,5-difeniltetrazólio-brometo e ensaios LIVE / DEAD. Diferenças estatisticamente significativas foram observadas para as propriedades mecânicas (Kruskal-Wallis, p <0,001), nCaP / GIC apresentou maior resistência à compressão e tração diametral. As análises de SEM revelaram uma distribuição uniforme de nCaP na matriz do ionômero. Os resultados de EDX e DRX indicaram fases de hidroxiapatita e β-trifosfato de cálcio. Os espectros de FTIR revelaram a banda assimétrica de ν3PO4 3- entre 1100-1030cm-1 e a banda de vibração associada a ν1PO4 3- em 963cm-1 associada a nCaP. O nCaP / GIC apresentou resposta adequada à viabilidade celular e comportamento não citotóxico. Portanto, o novo compósito nCaP / GIC apresentou ótimas propriedades mecânicas, comportamento não citotóxico e resposta adequada à viabilidade celular com promissoras aplicações odontológicas.

Addition of mechanically processed cellulosic fibers to ionomer cement: mechanical properties

In this study, conventional restorative glass ionomer cement (GIC) was modified by embedding it with mechanically processed cellulose fibers. Two concentrations of fibers were weighed and agglutinated into the GIC during manipulation, yielding Experimental Groups 2 (G2; 3.62 wt% of fibers) and 3 (G3; 7.24 wt% of fibers), which were compared against a control group containing no fibers (G1). The compressive strengths and elastic modulus of the three groups, and their diametral tensile strengths and stiffness, were evaluated on a universal test machine. The compressive and diametral tensile strengths were significantly higher in G3 than in G1. Statistically significant differences in elastic modulus were also found between G2 and G1 and between G2 and G3, whereas the stiffness significantly differed between G1 and G2. The materials were then characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Heterogeneously shaped particles were found on the G2 and G3 surfaces, and the cement matrices were randomly interspersed with long intermingled fibers. The EDS spectra of the composites revealed the elemental compositions of the precursor materials. The physically processed cellulosic fibers (especially at the higher concentration) increased the compressive and diametral tensile strengths of the GIC, and demonstrated acceptable elastic modulus and stiffness.

Avaliação anti-microbiológica do ácido peracético como desinfetante para moldes odontológicos / Anti-microbial evaluation of peracetic acid as a disinfectant for dental impressions

Objetivo: Esse estudo piloto avaliou a atividade desinfetante do ácido peracético a 0,2% em corpos de prova de hidrocolóide irreversível. Materiais e métodos: Sua ação antimicrobiana foi investigada comparativamente à solução de glutaraldeído 2%, à solução de hipoclorito de sódio 2,5% e ao digluconato de clorexidina agregado à fórmula de um hidrocolóide irreversível. Foram selecionadas cepas de quatro microrganismos, Escherichia coli, Staphylococcus aureus, Bacilus proteus e Candida albicans para inoculação nos meios de cultura. As amostras de hidrocolóide irreversível foram divididas aleatoriamente em cinco grupos...