Effectiveness of Different Irrigation Regimes on the Removal of Smear Layer in the Middle And Apical Thirds of Root Canals – A Scanning Electron Microscopic Study

Aim: To evaluate the effectiveness of four different irrigation regimes on removal of smear layer and smear plugs at the tubular apertures in the middle and apical thirds of the root canals by using Scanning Electron Microscopy(SEM). Settings and Design: In vitro material science study. Materials and methods: Twenty human mandibular first premolars were used for this study. The teeth were divided into 4 groups-Group I,0.9% physiological saline, Group II ,5.25% alternate use of sodium hypochlorite and 3% hydrogen peroxide, Group III, 5.25% sodium hypochlorite, 3% hydrogen peroxide and ethylene diamine tetraacetic acid (EDTA) and Group IV,5.25% sodium hypochlorite, 3% hydrogen peroxide and ethylene glycol-bis (β-amino ethyl ether) -N’N’N’, N-tetraacetic acid (EGTA). The split halves of the root surfaces were examined under a SEM and the images were analyzed for the amount of smear layer using a three score system. Results: There was a significant difference in the effectiveness of different irrigation regimes in removing the smear layer at the middle and apical thirds. Groups III and IV differed significantly from Groups I and II, but did not differ in their ability to remove smear layer, although Group III showed a lower score in the apical third. Conclusion: Though the use of EGTA effectively removed smear layer from the root canals without inducing erosion of the tubules, the most effective irrigation regime was the use of EDTA in combination with NaOCl and H2O2, as it completely removed the smear layer from both the middle and the apical thirds.