Investigação de um cimento de ionômero de vidro modificado por uma argila lamelar nanométrica do tipo hidróxido duplo lamelar fluoretado (HDL-F)

Abstract

Caries disease affects a large part of the world population and strategies aimed at the prevention and control of this disease have been intensively studied, such as the improvement of materials benefited by nanotechnology. In this sense, glass ionomer cement (GIC) is very well used in the technique of atraumatic restorative treatment (ART) and stands out for its good dental adhesion and fluoride release (F - ). However, it needs better physicochemical properties for better clinical efficacy. Thus, the objective of this study was to characterize and evaluate in vitro and ex vivo a GIC containing 1, 2, 5 and 10% by weight of a nanometric clay of the type fluoridated layered double hydroxide (LDHF). The groups were thus designated: GIC/LDH-F 1%; GIC/LDH-F 2%; GIC/LDH-F 5%, GIC/LDH-F 10% and the control group: GIC. Specimens were made, crushed and processed for characterization by X-ray diffraction (XRD), infrared spectroscopy with Fourier transform (FTIR) and energy dispersive X-ray fluorescence spectrometry (FSX). The mechanical evaluation was performed on the specimens through the axial compression test (CS), according to ISO 9917-1:2007. The release of F - was evaluated by specific electrode reading and the release profiles were evaluated using kinetic models: zero order, first order, Higuchi and Korsmeyer-Peppas with the help of software Statistic 13.3. Also, the area over the curve (UAC) was evaluated using the Graph pad Prism 7. The microleakage of the samples was analyzed using human teeth from the Tooth Bank – UFPB in a qualitative and quantitative way, using the software ImageJ. The data were submitted to the statistical test ANOVA, Tukey and Kruskal-Wallis post-hoc using the software SPSS 26.0 and significance level of 5% (p < 0.05). Structurally, the clay presented different crystalline control and modified products that followed an amorphous pattern. Spectral bands were observed in the FTIR characteristics of the materials studied. The elemental analysis of EDX revealed the predominance of magnesium and aluminum for clay and cement was seen calcium, silicon, aluminum, phosphorus and sodium. For the products, in addition to these, magnesium was present, characterizing the presence of clay in the composites. Axial compression analysis revealed less resistant hybrid products compared to control (37.80 MPa). The fluoride release revealed a slow and sustained release for the products and the kinetic model that best fit was the KorsmeyerPeppas with predominance of Fick formulations with slow diffusion through the outer layer of the material. The microleakage demonstrated efficiency of modified GIC’s, with reduced infiltration when compared to control. It was concluded that among the products analyzed, what stood out most was the GIC/LDH-F 5%, with a lower degree of infiltration in the toothrestoration interface, and may be indicated as a restorative material for clinical use. In addition, in vivo studies are suggested to better elucidate the use and clinical applicability of this material with a view to reducing initial and secondary caries lesions.