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.

Objetivo: Avaliar atrav?s de Microscopia Eletr?nica de Varredura, a efic?cia do EDTA a 17% na remo??o da smear layer e da medica??o de hidr?xido de c?lcio nos diferentes ter?os do canal radicular. M?todos: Vinte e quatro pr?-molares foram instrumentados nos ter?os cervical e m?dio utilizando-se brocas Gates-Glidden. No comprimento de trabalhorealizou-se o alargamento at? a lima #35 seguido do escalonamento at? a lima #50. Ap?s, os dentes foram divididos em quatro grupos de acordo como tratamento recebido: GI - irriga??o realizada com 5 ml de hipoclorito de s?dio a 2,5%; GII - irriga??o com 5 ml de EDTA 17%, durante 2 minutose meio, submetidos a agita??o com a lima #15, seguidos de uma irriga??o com 5 ml de NaOCl a 2,5%; GIII - irriga??o com 5 ml de hipoclorito des?dio a 2,5%, secagem, aplica??o de medica??o intracanal de Ca(OH)2 associado ao propilenoglicol e selamento, ap?s 5 dias, remo??o do selamento, irriga??o com 5 ml de EDTA 17%, durante 2 minutos e meio, submetidos a agita??o com a lima #15, seguida de irriga??o final com 5 ml de NaOCl a 2,5%; GIV - irriga??o com 5 ml de EDTA 17%, durante 2 minutos e meio, submetidos a agita??o com a lima #15, seguidos de uma irriga??o com 5 ml de NaOCl a 2,5%, secagem e ap?s o uso da medica??o intracanal de Ca(OH)2 associado ao propilenoglicol e selamento que foi removido ap?s 5 dias realizando-se a irriga??o com 5 ml de EDTA 17%, durante 2 minutos e meio, submetidos a agita??o com a lima #15, seguida da utiliza??o de 5 ml de NaOCl a 2,5%. A seguir, os dentes foram preparados e levados ao microsc?pio eletr?nico de varredura. Resultados: As imagens revelaram: grupo I - presen?a marcante de smear layer nos tr?s ter?os; grupo II - nota-se a menor quantidade de smear layer no ter?ocervical e m?dio enquanto no apical h? presen?a mais marcante; grupo III- no ter?o cervical e apical h? presen?a de smear layer compactada nas paredes do canal e o aspecto mais disperso da medica??o enquanto no ter?o m?dio nota-se presen?a da medica??o no interior dos canal?culos; grupo IV- em todos os ter?os houve redu??o da smear layer e da medica??o e a presen?a de v?rios canal?culos dentin?rios desobstru?dos.Conclus?o: Pode-se concluir que o uso do EDTA a 17% favoreceu a remo??o da lama dentin?ria e dos res?duos da medica??o intracanal em todos os ter?os do canal radicular.