Репозиторий Университета

© 2018 by the authors. The aim of the study was to investigate the effects of several decalcifying agents used as irrigant solutions in endodontic treatment on collagen and mineral components of dentin. Coronal dentin discs from five caries-free human third molars with a smear layer were treated for one minute with a chelating solution (1% Ethylenediaminetetraacetic acid (EDTA), 10% EDTA, 17% EDTA, 10% citric acid). Mineralization degree (Ca/N and P/N atomic ratios, IR Iapatite/Iamide II and I1410(carbonate)/I554(phosphate) spectroscopic ratios) and possible collagen rearrangements (collagen infrared (IR) amide II e III shifts) were evaluated by environmental scanning electron microscopy (ESEM)/energy dispersive X-ray spectroscopy (EDX) and IR spectroscopy before and after treatment (T0) and after ageing (T24h and T2m) in simulated body fluid (SBF). At T0, analysis showed that the highest demineralizing effect was achieved using a 10% citric acid solution and 10% EDTA, while the smallest effect was observed when using 17% EDTA. No significant collagen modifications were detected upon treatment with 1% EDTA, while subtle changes were observed after the other treatments. At T24h or T2m, analyses showed the highest remineralization values for 1% EDTA and the lowest for 10% citric acid, mainly at T2m. The samples treated with 17% EDTA showed slight collagen rearrangements upon remineralization. In conclusion, the highest demineralizing effect was observed for 10% EDTA and 10% citric acid. Collagen rearrangement was found for all the treatments except for 1% EDTA. The highest remineralization capability in SBF values was recorded for 1% EDTA and the lowest for 10% citric acid. A slight collagen rearrangement upon remineralization was still present in 17% EDTA-treated samples. Clinical use as a chelating agent in the endodontic therapy of citric acid and concentrated EDTA solutions should be reconsidered.

© 2018 BMSTU. We studied the dependence of the rate of dissolution of d-elements oxides (cobalt and copper oxides) in acidic media with EDTA additives from different factors. Increase in EDTA concentration enhances the cobalt and copper oxides dissolution, while the copper oxide dissolution is inhibited. Within the research we determined the orders by hydrogen ions and EDTA: For cobalt oxide it is 0.5 ± 0.1; for copper oxide it is nH=0,6, and by EDTA it is∼-0.6. The peculiarity of the studied kinetics in EDTA is that the rate of cobalt oxides dissolution passes through a maximum at pH =-1, for copper oxide in the presence of chelating agent EDTA the dissolution rate first decreases, and then it increases at pH from 5 to 8. The activation energy of the process is Ea (H2SO4) = = 70 kJ/mol, Ea (EDTA) = 60 kJ/mol, for copper oxide the activation energy is 73 ± 0.5 kJ/mol. The simulation of the processes showed that the surface particle, which determines the rate of dissolution is eOH+ in mineral acids, and in the chelating agent it is HY.