Estudo in vitro da dissolução eletroquímica de limas endodônticas fraturadas em canais radiculares e de seus efeitos sobre a microestrutura dentinária e viabilidade celular

Abstract

Several techniques have been proposed for the removal of fractured nickel-titanium files from inside the root canals, however, these methods present clinical limitations that may jeopardize the endodontic treatment. The aim of the present study was to investigate the electrochemical dissolution of fragments of endodontic files from inside the root canal of extracted teeth, using the [NaF 12 g/L + NaCl 1 g/L] solution, and the effects of this solution and its product containing NiTi on the microhardness and topography of the dentine and cell viability. The fragments of endodontic files were partially dissolved in the middle third of the root canals, enabling the possibility to bypass the fragment and recover the original path of the root canals. The elctrochemical dissolution induced a signigicant reduction on the volume of the fragments inside the root canals, when compared with the control group (p<0,01). The [NaF 12 g/L + NaCl 1 g/L] solution used on the electrochemical dissolution process did not change the dentine microhardness and the mean area of the dentine tubules, when compared with the EDTA solution (p<0,05). The [NaF 12 g/L + NaCl 1 g/L] solution and the dissolution product containing NiTi ions, presented a lower levels of cytotoxicity when compared with the sodium hypochlorite, at the 25 % and 50 % dilutions (p<0.01). The techinique proposed in the present study is promising and with a great clinical relevance to bypass fractured endodontic files from inside the root canals.