Eur Endod J. 2017; 2(1): 30 | DOI: 10.5152/eej.2017.17022

Calcium Hydroxide Treatment Does Not Alter the Susceptibility of Enterococcus faecalis Biofilms to Sodium Hypochlorite

Suzette V. Van Der Waal¹, Johannes J. De Soet², Paul R. Wesselink³, Wim Crielaard^2
1Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam; Department of Cariology, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands
²Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands
³Department of Cariology, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands

Objective: To investigate the influence of calcium hydroxide (Ca(OH)2) on susceptibility to disinfection with sodium hypochlorite (NaOCl) of biofilm bacteria.
Methods: Monospecies biofilms of eight Enterococcus faecalis strains were subjected to a 2-h challenge with Ca(OH)2. After a recovery phase, the biofilms were treated with a concentration of NaOCl that was lower than the minimum inhibitory concentration. In a metabolic assay, the efficacy of NaOCl disinfection in Ca(OH)2-challenged biofilms and unchallenged biofilms was evaluated. The data were analyzed with Mann-Whitney U and Kruskall- Wallis tests. A P value of less than 0.05 was considered statistically significant.
Results: There were marginal differences in susceptibility to NaOCl among the E. faecalis strains. After the Ca(OH)2 challenge, seven strains remained equally susceptible to NaOCl disinfection whereas one strain be- came more resistant to NaOCl (P= 0.03).
Conclusion: After a Ca(OH)2 challenge, in general E. faecalis remained equally susceptible to disinfection with NaOCl.

Keywords: Biofilm, calcium hydroxide, canal medicaton, disinfection, endodontic, microbiology, irrigation

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