The response of dual-species bacterial biofilm to 2% and 5% NaOCl mixed with etidronic acid: A laboratory real-time evaluation using optical coherence tomography.

AIM: The addition of etidronic acid (HEDP) to sodium hypochlorite (NaOCl) could increase the antibiofilm potency of the irrigant, whilst maintaining the benefits of continuous chelation. Studies conducted so far have shown that mixing HEDP with NaOCl solutions of relatively low concentration does not compromise the antibiofilm efficacy of the irrigant. However, the working lifespan of NaOCl may decrease resulting in a reduction of its antibiofilm efficacy over time (efficiency). In this regard, continuous irrigant replenishment needs to be examined. This study investigated the response of a dual-species biofilm when challenged with 2% and 5% NaOCl mixed with HEDP for a prolonged timespan and under steady laminar flow. METHODOLOGY: Dual-species biofilms comprised of Streptococcus oralis J22 and Actinomyces naeslundii T14V-J1 were grown on human dentine discs in a constant depth film fermenter (CDFF) for 96 h. Biofilms were treated with 2% and 5% NaOCl, alone or mixed with HEDP. Irrigants were applied under steady laminar flow for 8 min. Biofilm response was evaluated by means of optical coherence tomography (OCT). Biofilm removal, biofilm disruption, rate of biofilm loss and disruption as well as bubble formation were assessed. One-way anova, Wilcoxon's signed-rank test and Kruskal-Wallis H test were performed for statistical analysis of the data. The level of significance was set at a ≤.05. RESULTS: Increasing NaOCl concentration resulted in increased biofilm removal and disruption, higher rate of biofilm loss and disruption and increased bubble formation. Mixing HEDP with NaOCl caused a delay in the antibiofilm action of the latter, without compromising its antibiofilm efficacy. CONCLUSIONS: NaOCl concentration dictates the biofilm response irrespective of the presence of HEDP. The addition of HEDP resulted in a delay in the antibiofilm action of NaOCl. This delay affects the efficiency, but not the efficacy of the irrigant over time.

Effects of curcumin-mediated antimicrobial photodynamic therapy associated to different chelators against Enterococcus faecalis biofilms.

BACKGROUND: The aim of this study was to evaluate curcumin-mediated antimicrobial photodynamic therapy (aPDT) action combined or not with ethylenediaminetetraacetic acid (EDTA) and hydroxyethylidene bisphosphonate (HEBP) on Enterococcus faecalis biofilms. METHODS: Enterococcus faecalis biofilms were grown on dentin bovine discs in brain heart infusion (BHI) medium with 1% glucose, in aerobic conditions at 37°C for 7 days. Then, they were randomly distributed to one of experimental conditions, as follows: control, 75 J.cm-2 LED, 600 µmol.L-1 curcumin, 17% EDTA, 18% HEBP, 600 µmol.L-1 curcumin plus 75 J.cm-2 LED, 600 µmol.L-1 curcumin plus 17% EDTA, 600 µmol.L-1 curcumin plus 18% HEBP, 600 µmol.L-1 curcumin plus 17% EDTA and 75 J.cm-2 LED or 600 µmol.L-1 curcumin plus 18% HEBP and 75 J.cm-2 LED. The viability of microorganisms and the vitality of biofilms were determined by colony forming unit counts and confocal scanning laser microscopy (CSLM), respectively. Statistical analysis was conducted by Kruskal Wallis and Dunn's post-hoc tests (α = 0.05). RESULTS: The results showed that all combinations of aPDT with chelators significantly reduced the viability of microbial cells and the vitality of biofilms in comparison to control, even when considering deeper layers of biofilms. CONCLUSION: The combination of curcumin with EDTA and HEBP similarly improved the effect of aPDT on E. faecalis biofilms.

Effects of bisphosphonates on osteogenesis and osteoclastogenesis signaling during the endochondral ossification of growing rats.

Osteoclasts and chondroclasts are necessary, during endochondral ossification, for the resorption of primary bone and calcified cartilage septa, respectively. The bisphosphonates inhibit mineralized tissue resorption by various mechanisms according to the different types of this drug, which can affect bone remodeling during skeletal growth. The objective of the present study is to analyze the way that alendronate (ALN) and etidronate (ETN) can affect osteoclastogenesis and bone formation during endochondral ossification of the long bones of growing rats. Newborn Wistar rats were treated daily with ETN, ALN, or sterile saline solution (control) for 21 days. Their femur and tibiae epiphyses were radiographed and analyzed by light, scanning and transmission electron microscopy. The expression of genes related to osteogenesis and to osteoclast differentiation and activity were analyzed by real-time quantitative polymerase chain reaction. The ETN group presented reduced body weight, disorganized growth plate and an extended area of cartilage in the ossification zone with little bone matrix; in the ALN group, this area was not altered. The ALN presented latent TRAP-positive cells, whereas in the ETN group, they were activated. The expression of NFκB1 and 2, OPG, Spp1 and Runx2 in the ossification zone was reduced by both bisphosphonates. RANKL expression was reduced by ETN, whereas ALN decreased the expression of RANK. The results also indicated that, in addition to the anti-resorptive effect of the drugs, disturbances in bone deposition occurred concomitantly with the reduced expression of osteogenesis-related genes.