Nanoneedle-like zinc oxide as a filler particle for an experimental adhesive resin

Aim: The aim of this study was to develop an experimental adhesive resin with nanoneedle-like zinc oxide (N-ZnO), an inorganic filler, that could avoid particle agglomeration and lead to a homogeneous stress distribution within the material and characterize it. Materials and Methods: N-ZnO particles obtained by a thermal evaporation technique were characterized regarding size and surface area and added at 0 (control), 1, 2, 5, and 10 wt%, to an experimental adhesive resin. The following experimental adhesive resins' properties were assessed: radiopacity, contact angle to conditioned enamel and dentin, color, degree of conversion, flexural strength, resistance to degradation, and cytotoxicity. Statistical analysis was performed using one-way ANOVA and Tukey's post hoc test and paired Student's t-test. Results: Particles presented a mean particle size of 40 nm and a specific surface area of 16 m2/g. N-ZnO10%showed an increased radiopacity when compared to N-ZnO0%. Contact angles were significantly higher for N-ZnO10%at enamel and N-ZnO2%, N-ZnO5%, and N-ZnO10%at dentin. All groups showed color change when compared to N-ZnO0%. Higher the N-ZnO concentration, lower the degree of conversion. There were no significant differences between the groups for flexural strength and resistance to degradation. The addition of N-ZnO showed no difference in cytotoxicity when compared to positive control, N-ZnO0%, and all groups showed higher values than negative control. Conclusions: N-ZnO possibly exceeded potential limitations due to particles' agglomeration and improved the transference and distribution of stress within the material. It could be effectively used as a filler for adhesive resins.

Triazine Compound as Copolymerized Antibacterial Agent in Adhesive Resins

Abstract The aim of this study was to formulate and evaluate an experimental adhesive resin with the addition of 1,3,5-triacryloylhexahydro-1,3,5-triazine at different concentrations. Experimental adhesive resins were obtained by mixing 50% wt bisphenol A glycol dimethacrylate (BisGMA), 25% wt triethylene glycol dimethacrylate (TEGDMA), 25% wt 2-hydroxyethyl methacrylate (HEMA) and photoinitiator system. The triazine compound was added in 1, 2.5 and 5% wt to a base adhesive resin and one group remained with no triazine as control group. The experimental adhesive resins were analyzed for antibacterial activity (n=3), degree of conversion (n=3) and softening in solvent (n=3). Data distribution was evaluated by Kolmogorov-Smirnov test, paired t test, one-way ANOVA and Tukey’s with a 0.05 level of significance. All groups with added triazine compound showed antibacterial activity against Streptococcus mutans (p<0.05). All groups achieved more than 70% degree of conversion, but there was no difference in this chemical property (p>0.05). The initial Knoop hardness was higher in 2.5 and 5% wt groups (p<0.05) and both groups present lower percentage variation of Knoop hardness after solvent degradation. The present study formulated an antibacterial adhesive resin with a non-releasing agent able to copolymerize with the comonomeric blend, improving the restorative material’s properties.

Resumo O objetivo desse estudo foi desenvolver e avaliar a adição de 1,3,5-triacryloylhexahydro-1,3,5-triazine a uma resina adesiva experimental em diferentes concentrações. Resinas adesivas experimentais foram obtidas a partir da mistura de 50% em peso de bisphenol A glycol dimethacrylate (BisGMA), 25% em peso de triethylene glycol dimethacrylate (TEGDMA), 25% em peso de hidroxietil metacrilato (HEMA) e sistema fotoiniciador. O composto de triazina foi adicionado em proporções de 1; 2,5 e 5% em peso a resina adesiva base e um grupo permaneceu sem a adição do composto de triazina como grupo controle. As resinas adesivas experimentais foram analisadas por atividade antibacteriana (n=3), grau de conversão (n=3) e degradação em solvente (n=3). A distribuição dos dados foi avaliada por teste de Kolmogorov-Smirnov, teste t pareado, ANOVA de uma via e Tukey, considerando nível de significância de 5%. Todos os grupos com adição de composto de triazina demonstraram atividade antibacteriana contra Streptococcus mutans (p<0,05). Todos os grupos atingiram mais de 70% de grau de conversão, mas não houve diferença estatística para essa propriedade química (p>0,05). A dureza Knoop inicial foi maior para os grupos com 2,5 e 5% de triazina (p<0,05) e ambos os grupos apresentaram menor variação percentual de dureza Knoop após degradação em solvente. No presente estudo, foi produzida uma resina adesiva antibacteriana com agente sem liberação para o meio, capaz de copolimerizar com a blenda comonomérica, melhorando as propriedades do material restaurador.