The effectiveness of enzymic irrigation in removing a nutrient‐stressed endodontic multispecies biofilm

Abstract

Niazi SA, Clark D, Do T, Gilbert SC, Foschi F, Mannocci F, Beighton D. The effectiveness of enzymic irrigation in removing a nutrient-stressed endodontic multispecies biofilm. International Endodontic Journal.Aim To establish a nutrient-stressed multispecies model biofilm and investigate the dynamics of biofilm killing and disruption by 1% trypsin and 1% proteinase K with or without ultrasonic activation. Methodology Nutrient-stressed biofilms (Propionibacterium acnes, Staphylococcus epidermidis, Actinomyces radicidentis, Streptococcus mitis and Enterococcus faecalis OMGS 3202) were grown on hydroxyapatite discs and in prepared root canals of single-rooted teeth in modified fluid universal medium. The treatment groups included trypsin, proteinase K, 0.2% chlorhexidine gluconate and 1% sodium hypochlorite (NaOCl) (with and without ultrasonics). NaOCl and chlorhexidine were the positive controls and untreated group, and sterile saline was the negative control. The 3 biofilms were investigated using confocal laser scanning microscopy (CLSM) with live/dead staining and quantitative microbial culture.Results Nutrient stress in the multispecies biofilm was apparent as the medium pH became alkaline, glucose was absent, and serum proteins were degraded in the supernatant. The CLSM showed the percentage reduction in viable bacteria at the biofilm surface level due to nutrient starvation. On the disc model, trypsin and proteinase K were effective in killing bacteria; their aerobic viable counts were significantly lower (P < 0.01) than the negative control and chlorhexidine. NaOCl was the most effective agent (P < 0.001). In the tooth model, when compared to saline, trypsin with ultrasonics caused significant killing both aerobically and anaerobically (P < 0.05). Chlorhexidine (1.46 AE 0.42), trypsin (3.56 AE 1.18) and proteinase K (4.2 AE 1.01) with ultrasonics were significantly effective (P < 0.05) in reducing the substratum coverage as compared to saline with ultrasonics (12% AE 4.9). Conclusion Trypsin with ultrasonic activation has a biofilm killing and disrupting potential.

Synergistic effect of 2% chlorhexidine combined with proteolytic enzymes on biofilm disruption and killing

“…The viable counts after the use of NaOCl in an experimental set‐up similar to the one used in the present study (Niazi et al . ) were around or below 0.5 (log 10 CFU), which was <2.8–3.7 (log 10 CFU) achieved with the combination of trypsin, CHX and ultrasonic irrigation. In the present study, the log 10 CFU of untreated control was 7.67 and the combination of trypsin, CHX and ultrasonic irrigation achieved an effective reduction of about 5 log.…”

“…Even though their antibacterial properties were not as effective as NaOCl, they did have a degree of biofilm‐disrupting ability (Niazi et al . ).…”

“…It was decided to include bacteria such as P. acnes and S. epidermidis, because these were recently found to be predominant and identified as opportunistic pathogens in biofilm associated with both primary and secondary endodontic infections (Niazi et al . , Zakaria et al . ).…”

“…An in vitro nutrient‐stressed endodontic multispecies biofilm model has been used in previous studies (Niazi , Niazi et al . ). The biofilm model is not only multispecies, but also subjects the microorganisms to nutritional stress, thus altering their morphology and surface making them more resistant to the effects of disinfection (Bowden & Li , Siqueira ).…”

Effectiveness of different auxiliary chemical substances in the rapid disinfection of gutta-percha points - an in vitro study

“…This is due to the broad-spectrum antimicrobial activity of sodium hypochlorite 7,23 and chlorhexidine 8,24 . Our findings are in agreement with previous studies 17,18 where the same chemical auxiliary substances were effective in promoting the rapid sterilization of gutta-percha points.…”