Efetividade do EDTA 17% na remo??o da smear layer e da medica??o intracanal de hidr?xido de c?lcio das paredes dos canais radiculares: parte II / Effect of 17% EDTA on removal of canal wall smear layer and calciumhydroxide dressing: part II

RESUMO

Objective: the aim of this study was to evaluate, by scanning electron microscopy, the effectiveness of 17% EDTA on removal of canal wall smear layer and calcium hydroxide dressing in different thirds of root canal. Methods: Ttwenty-four premolars were instrumented in the cervical and middle thirds using Gates-Glidden drills. At the working length, the canal was widened up to # 35 file, followed by scaling up to file # 50. After instrumentation, the teeth were divided into four groups according to the treatment received GI - irrigation performed with 5 ml of NaOCl 2.5 % ; GII - irrigation with 5 ml of 17% EDTA for 2 and a half minutes , submitted to agitation with file # 15, followed by irrigation with 5 ml of 2.5% NaOCl ; GIII - irrigation with 5 ml of NaOCl 2.5% , drying , application of temporary dressing of Ca (OH )2 with propylene glycol and sealing. After 5 days , removing the sealing irrigation with 5 ml of 17% EDTA for 2 and a half minutes , submitted to agitation with file # 15, followed by a final flush with 5 ml of 2.5% NaOCl ; GIV - irrigation with 5 ml of 17% EDTA for 2 and a half minutes , submitted to agitation with file # 15 , followed by irrigation with 5 ml of 2.5% NaOCl , drying and after use of the medication in Ca (OH )2 with the sealing and propylene glycol which was removed after 5 days performing the irrigation with 5 ml of 17% EDTA for 2 and a half minutes , submitted to agitation with file # 15, followed by using 5 ml 2.5% NaOCl . Next, the teeth were prepared and taken to the scanning electron microscope. Results: The images revealed Group I - a marked presence of smear layer in all three thirds, Group II - removal of almost all of the smear layer in the cervical third and removal of large quantity in the middle third, whereas in the apical third a large quantity of smear layer still remained however, in comparison with the other groups, this was shown to be cleaner; Group III - in the three thirds, the presence of smear layer was observed, which was shown to be much less compacted than that observed in Group 1; Group IV- in all the thirds there was reduction of smear layer and Ca(OH)2-based medication, and presence of several unobstructed dentinal tubules could be observed, demonstrating the second best result observed. Conclusion: It could be concluded that the use of 17% EDTA favored removal of the smear layer and intracanal medication residues in all thirds of the root canal.