The impact of different irrigants on the quality of root canal walls

Abstract

Introduction: Root canal irrigation plays an important part in the endodontic therapy. Inadequate irrigation or instrumentation without irrigation increase the accumulation of debris on the cutting surfaces of instruments as well as debris and smear layer on root canal walls. Aim: The aim of this study was to evaluate smear layer removal after irrigation with saline, 5% NaOCl, 15% EDTA and the combination of 15% EDTA and 5% NaOCl. Materials and Methods: The study was conducted at the Clinic for Dentistry and Institute for biomedical research of the School of Medicine in Nis. Twenty five premolars, extracted from orthodontic reasons, were allocated to 5 groups (A-E) of 5 teeth. Root canals of all teeth were instrumented using hand K files. Samples from Group A were instrumented without irrigation (control group). In Group B, the irrigation was done using saline, in Group C 5% NaOCl, in Group D 15% EDTA and in Group E the combination of 15% EDTA and 5% NaOCl. After the treatment, all samples were prepared for scanning electron microscopy (SEM). Central parts of root canals were examined and photomicrographs were taken at different magnification. The amount of debris and smear layer was quantified and the data were statistically analyzed. Results: All four treatment modalities (B, C, D, E) induced changes in the appearance of dentinal walls and the amount of debris and the smear layer compared to the control group (A). The difference between the control group and Group B was statistically significant (p<0.01) and highly significant between the control group and Groups C, D and E (p<0.0001). The combined use of 15% EDTA and 5% NaOCl for irrigation and 1 min final rinse resulted in a complete elimination of the smear layer; the use of saline, 5% NaOCl or 15% EDTA alone failed to remove the debris and smear layer completely. Conclusion: The use of singular solutions for root canal irrigation significantly reduces the amount of debris and the smear layer whereas the combined use of NaOCl and EDTA results in the complete elimination of the smear layer from root canal walls.