Influence of Apical Enlargement and Complementary Canal Preparation with the Self-Adjusting File on Endotoxin Reduction in Retreatment Cases

E.J.N.L. Silva, V.M. Ferreira, C.C. Silva, D.R. Herrera, G. De-Deus, B.P. Gomes 

International Endodontic Journal. 2017. 50(7):646-651.


AIM: To compare the effectiveness of large apical preparations and complementary canal preparation with the Self Adjusting File (SAF) in removing endotoxins from the root canal of teeth with apical periodontitis.

METHODOLOGY: Ten single-rooted and single-canaled teeth with post-treatment apical periodontitis were selected. Endotoxin samples were taken after the removal of the root filling (S1), after chemomechanical preparation (CMP) using 2.5% NaOCl and an R25 file (S2), after CMP using 2.5% NaOCl and an R40 file (S3), and after complementary CMP using the SAF system (S4). Limulus amebocyte lysate (LAL) was used to measure endotoxin levels. The Friedman and Wilcoxon tests were used to compare endotoxin levels at each clinical intervention (P < .05).

RESULTS: After root filling removal, endotoxin was detected in 100% of the root canals (S1, 4.84 EU/mL). CMP with the R25 file was able to significantly reduce endotoxin levels (P <.05). Increased levels of endotoxin removal were achieved by apical preparation with the R40 file (P < .05). Complementary CMP with SAF did not significantly reduce endotoxin levels (P > .05) following the use of the R40 instrument.

CONCLUSION: Apical enlargement protocols were effective in significantly reducing endotoxin levels. Complementary preparation with the SAF system failed to eliminate residual endotoxin contents beyond those obtained with the R40 instrument.


Additional Info

  • ReDent Nova’s note:

    This research failed to use the SAF according to the clinical guidelines, and the results demonstrate that.

    Operation of a Reciproc R40 instrument, with an apical dimensions of #40/.08, is an excessive preparation prior to instrumentation with the SAF, and is likely to pack a lot of debris that cannot be removed, especially due to the reciprocal motion.

    Additionally, the operation of the SAF did not include the use of a gutta-percha softener (chloroform or other), and the irrigation protocol during the SAF operation did not sequence the use of NaOCl with the use of EDTA. This led to remaining gutta-percha and debris that was created by the reciprocal instrument, that could not be removed by the SAF and continued to harbor bacteria.

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  • View abstract on PubMed. PMID: 27400743