Abstract
Enterococcus faecalis is the most frequent species present in post-treatment disease and plays a significant role in persistent periapical infections following root canal treatment. Its ability to persist in stressful environments is inter alia, due to its ability to form biofilms. The presence of certain D-amino acids (DAAs) has previously been shown to reduce formation of Bacillus subtilis biofilms. The aims of this investigation were to determine if DAAs disrupt biofilms in early and late growth stages for clinical E. faecalis strains and to test their efficacy in disrupting E. faecalis biofilms grown in sub-minimum inhibitory concentrations of commonly used endodontic biocides. From thirty-seven E. faecalis strains, the ten “best” biofilm producers were used to test the ability of a mixture containing D-leucine, D-methionine, D-tyrosine and D-tryptophan to reduce biofilm growth over a period of 24, 72 and 144 hours and when compared to their cognate L-Amino Acids (LAAs). We have previously shown that sub-MIC levels of tetracycline and sodium hypochlorite promotes biofilm growth in clinical strains of E. faecalis. DAAs were therefore tested for their effectiveness to reduce biofilm growth in the presence of sub-minimal concentrations of sodium hypochlorite (NaOCl-0.031%) and Odontocide™ (0.25% w/v), and in the presence of Odontopaste™ (0.25% w/v). DAAs significantly reduced biofilm formation for all strains tested in vitro, while DAAs significantly reduced biofilm formation compared to LAAs. The inhibitory effect of DAAs on biofilm formation was concentration dependent. DAAs were also shown to be effective in reducing E. faecalis biofilms in the presence of Odontopaste™ and sub-MIC levels of NaOCl and Odontocide™. The results suggest that the inclusion of DAAs into current endodontic procedures may reduce E. faecalis biofilms.
Highlights
The invasion by bacteria and their by-products into the pulp and periapical tissues respectively give rise to pulpal necrosis and apical periodontitis [1]
The most common reason for root canal treatment failure and the persistence of apical periodontitis is the presence of intra-radicular bacteria that had not been eliminated during endodontic therapy [2]
To exclude the possibility that D-amino acids (DAAs) had a negative effect on the growth rate and biofilm forming ability, 25mM D-Leu, D-Met and D-Trp and 0.25mM D-Tyr was added to the growth medium (THB) and growth was monitored over 6 hours during incubation
Summary
The invasion by bacteria and their by-products into the pulp and periapical tissues respectively give rise to pulpal necrosis and apical periodontitis [1]. It is the bacterial biofilms that are the most likely etiological agent of primary and post-treatment apical periodontitis [2]. The chemo-mechanical preparation of a root canal is not sufficient to completely eliminate bacteria from the root canal. The use of an intra-canal medicament placed in-between appointments has been suggested to achieve the maximum reduction of bacterial load prior to obturation [3]. The most common reason for root canal treatment failure and the persistence of apical periodontitis is the presence of intra-radicular bacteria that had not been eliminated during endodontic therapy [2]. The use of calcium hydroxide as an intra-canal medication has been associated with periradicular healing and high antibacterial efficacy [4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
