25 September 2019

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Sodium Hypochlorite or Chlorhexidine digluconate as canal irrigant during endodontic retreatment?

Massimo Gagliani

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In the field of the endodontic treatment, retreatments are increasing in number. Several studies compared the outcome of these type of root canal therapies and, along these last years, they didn’t come to definitive results. The average percentage of success is nearly to 80%, but the different clinical setting, i.e. presence of periapical radiolucency, dimensions of the periapical pathosis and root canal previous instrumentation may lead to different clinical landscapes.

In the study presented in this paper the Authors compared the clinical and radiographic outcome of endodontic retreatment of teeth with apical periodontitis in which they used as irrigants either 1% sodium hypochlorite (NaOCl) or 2% chlorhexidine digluconate (CHX). The influence of residual infection detected by a molecular method on the outcome was also examined.

MATERIALS AND METHODS 
Fifty-two root-filled teeth with apical periodontitis were randomly assigned into 2 groups according to the irrigant used during retreatment. Root canal microbiological samples taken before (S1) and after (S2) preparation using either NaOCl or CHX irrigation and after calcium hydroxide medication (S3) were subjected to 16S ribosomal RNA gene-based real-time quantitative polymerase chain reaction (qPCR) to quantify total bacteria. The periapical status was scored using the periapical index and dichotomized as healed (<3) or not healed (≥3) at the 1- and 4-year follow-up. 

RESULTS 
Forty-five (NaOCl, n = 20; CHX, n = 25) and 33 teeth (NaOCl, n = 16; CHX, n = 17) were available at the 1- and 4-year follow-up, respectively. After 1 year, 65% in the NaOCl group and 64% in the CHX group healed, with no differences between them (P > .05). At the later follow-up, the corresponding figures were 81% and 82%, respectively (P > .05). Canals that yielded qPCR-negative results in S3 had a higher healing rate (79%) than qPCR-positive canals (45%, P < .05). The mean bacterial load increased from S2 to S3 in half of the unhealed cases (P < .05). All S3-positive canals containing <3.12 × 103 bacterial cell counts healed. Increasing the apical level of the root canal filling influenced the outcome (P < .05).

CONCLUSIONS
No significant differences in the clinical outcome between 1% NaOCl and 2% CHX were found. Bacterial persistence at the time of filling as detected by qPCR significantly affected the outcome. The only concern in this study is related to the concentration of NaOCl as several studies revealed a different clinical efficacy of different concentration of this irrigant solution; the presence of bacteria should be detected with faster and precise procedures up to now not available in clinical setting.  

(Photo credit: Prof. Massimo Gagliani)

For additional informations: 
Outcome of Endodontic Retreatment Using 2 Root Canal Irrigants and Influence of Infection on Healing as Determined by a Molecular Method: A Randomized Clinical Trial