Elsevier

Journal of Endodontics

Volume 36, Issue 4, April 2010, Pages 697-702
Journal of Endodontics

Basic Research
The Self-adjusting File (SAF). Part 3: Removal of Debris and Smear Layer—A Scanning Electron Microscope Study

https://doi.org/10.1016/j.joen.2009.12.037Get rights and content

Abstract

Aim

The aim of this study was to evaluate the cleaning ability of the Self-Adjusting File (SAF) system in terms of removal of debris and smear layer.

Methodology

Root canal preparations were performed in 20 root canals using an SAF operated with a continuous irrigation device. The glide path was initially established using a size 20 K-file followed by the SAF file that was operated in the root canal via a vibrating motion for a total of 4 minutes. Sodium hypochlorite (3%) and EDTA (17%) were used as continuous irrigants and were alternated every minute during this initial 4-minute period. This was followed by a 30-second rinse using EDTA applied through a nonactivated SAF and a final flush with sodium hypochlorite. The roots were split longitudinally and subjected to scanning electron microscopy (SEM). The presence of debris and a smear layer in the coronal, middle, and apical thirds of the canal were evaluated through the analysis of the SEM images using five-score evaluation systems based on reference photographs.

Results

The SAF operation with continuous irrigation, using alternating irrigants, resulted in root canal walls that were free of debris in all thirds of the canal in all (100%) of the samples. In addition, smear layer–free surfaces were observed in 100% and 80% of the coronal and middle thirds of the canal, respectively. In the apical third of the canal, smear layer–free surfaces were found in 65% of the root canals.

Conclusions

The operation of the SAF system with continuous irrigation coupled with alternating sodium hypochlorite and EDTA treatment resulted in a clean and mostly smear layer–free dentinal surface in all parts of the root canal.

Section snippets

Selection of Teeth

Twenty-three single-rooted teeth were selected from a random collection of human teeth that were extracted within the last 3 months and stored in 10% buffered formalin until they were used. Each root was radiographed in buccolingual and mesiodistal projections to evaluate the shape of the root canal and to detect any possible obstruction. The inclusion criteria were single-rooted teeth with straight root canal and an intact pulp chamber, whereas the exclusion criteria were previous root canal

Examiner Agreement

Initial independent agreement of all three examiners was 78% and 58% for debris and smear layer scores, respectively. As for debris scoring, in an additional 17% of the cases, there was initial agreement between two examiners and in only 5% of the cases was there a difference between examiners by more than one level of scoring. When scoring smear layer, in an additional 22% of the cases, there was agreement between two examiners, and in no case was the difference between the examiners by more

Discussion

The SAF, as any mechanical device that is designed to remove dentin layers, produces a smear layer when operated in conjunction with sodium hypochlorite alone 15, 16. This occurred despite the continuous irrigation method used by the SAF (Fig. 2A). Nevertheless, the application of an irrigation protocol with alternating administration of 3% sodium hypochlorite and 17% EDTA rendered the root canal dentin surface free of the smear layer. Similar results could also be achieved in the coronal and

Conclusions

The SAF, operated with the continuous flow of irrigants alternating between sodium hypochlorite and EDTA, resulted in root canals that were free of debris and almost completely free of the smear layer.

The results were better than those previously published for the coronal and midroot portions of the root canal.

The difference was also pronounced in the apical third of the canal, in which previously published protocols failed to adequately clean the canal, whereas the SAF protocol resulted in

Acknowledgments

The excellent SEM work of Mr. Jacob Delarea from the Electron Microscopy Unit, Tel Aviv University, Tel Aviv, is gratefully acknowledged. In addition, the expert technical assistance of Mr. Eltanani Moshe was essential for this study and is gratefully acknowledged.

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  • Cited by (0)

    Dr. Ehud Teperovich, Dr. Raphaela Cohen, and Dr. Raviv Zary are employed by ReDent-Nova, manufacturer of the SAF file. Dr Zvi Metzger serves as a scientific consultant to the same company.

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