Propriedades físico-químicas e antimicrobianas de compósito resinoso modificado pela incorporação de nanotubos de haloisita e triclosan

Abstract

One of the reasons for replacements of composite resin restorations is the occurrence of secondary caries. Thus, composite resin incorporated with antimicrobial agents were developed over time. Triclosan (TCN) is an antibacterial agent used in several products as dentifrices and mouthwashes, however it needs a carrier agent. Halloysite nanotubes (HNT) are natural aluminosilicates that can be used as a reinforcing agent, improving mechanical properties,such in the form of biologically safe reservoirs. Therefore, the present study evaluated in vitro the physicochemical and microbiological behavior of an experimental resin incorporated with 8% HNT/TCN (HNT/TCN-8%), an experimental resin without HNT/TCN (HNT/TCN-0%) and another nanoparticulate commercial resin. Degree of Conversion (GC), flexural modulus (FM), flexural strength (FS), roughness (RU), polymerization stress (PE), dynamic-mechanical analysis (ADM) thermogravimetry (TGA) microbiological (MS). The data of the mechanical properties were submitted to analysis of variance one way (Anova) as well as for analysis of antimicrobial effect, followed with post-test of Tukey. The level of significance was set at 5% and the program used was sigmastat (CA, USA). The DMA and TGA tests were analyzed in a descriptive way for characterization. The GC and RU of the composites were not altered by the incorporation of nanotubes, whereas the ME of the incorporated experimental resin was numerically higher when compared to the other groups, as well as the polymerization stress. RF of 8% HNT/TCN and Z350XT resin obtained statistically higher values when compared to HNT/TCN-0%. In ADM, HNT/TCN 8% showed a better load-to-matrix ratio than HNT/TCN-0%, in addition to a greater crosslinking of the polymer network than the other resins. The TGA curves showed a maximum temperature of 422ºc for HNT/TCN-0%, 418ºc for HNT/TCN-8% and 409ºc for comercial composite. Numerically, the microbiological assay showed that the HNT/TCN-8% resin presented smaller amount of colony-forming units in relation to the other groups. The incorporation showed a trend of improvement in the physical-chemical and antimicrobial properties of composites resins. The incorporation showed improvements in some physical-chemical and mechanical properties of composites resin, besides a tendency of antimicrobial activity against Streptococcus mutans.