Antimicrobial activity, toxicity and accumulated hard-tissue debris (AHTD) removal efficacy of several chelating agents.

AIM: To evaluate the antimicrobial, toxicity and cleaning effectiveness of ethylenediaminetetraacetic acid (EDTA) and maleic acid (MA) alone and combined with cetrimide (CTR). METHODOLOGY: Cytotoxic and genotoxic effects were assessed on Chinese hamster cells V79 using the MTT, clonogenic and micronucleus assays, respectively. The bacterial inhibitory and bactericidal concentrations (MIC and MBC, respectively) were determined on a strain of Enterococcus faecalis. Antimicrobial tests were performed on a biofilm model after treatment with the chelating agents by using a biofilm eradication concentration (MBEC) and confocal laser scanning microscope (CLSM) assays. Quantification of cell biomass and percentage of live and dead cells in the biomass were assessed for each group. The percentage reduction of accumulated hard-tissue debris (AHTD) after root canal preparation and final irrigation protocols was evaluated by micro-CT. Statistical tests of one-way analysis of variance (anova), Bonferroni test, Kruskal-Wallis test, Dunn's multiple comparison test and Wilcoxon matched-pairs signed-rank tests were used. RESULTS: Cetrimide alone as well as in combination with EDTA and MA at dilutions of 1/10 and 1/100 was significantly more toxic as compared to untreated controls (P < 0.001). All tested mixtures were nontoxic at a dilution of 1/1000. EDTA retained a weak inhibitory and bactericidal effect against planktonic cells, whilst MA inhibited cells growth and killed 99.9% of the cells when diluted. CTR revealed the most prominent effect, being inhibitory and bactericidal, also when diluted. Cetrimide alone or combined with EDTA was able to remove, respectively, 40% (P < 0.01) and 60% (P < 0.001) of the entire biomass after 1 min. Conversely, MA alone and in combination with CTR did not have a significant effect on biomass reduction. After final irrigation, the AHTD volume was significantly decreased in all groups (P < 0.05). EDTA + CTR and MA + CTR were associated with a significant reduction in the percentage of AHTD on the entire root canal compared to the same solutions without surfactant. CONCLUSIONS: 7% MA was less cytotoxic in comparison with 17% EDTA. The addition of cetrimide to EDTA and MA removed accumulated hard-tissue debris effectively from the canal walls and increased their antimicrobial activity when compared to the same solutions without detergents.

Modulation of opportunistic species Corynebacterium diphtheriae, Haemophilus parainfluenzae, Moraxella catarrhalis, Prevotella denticola, Prevotella melaninogenica, Rothia dentocariosa, Staphylococcus aureus and Streptococcus pseudopneumoniae by intranasal administration of Streptococcus salivarius 24SMBc and Streptococcus oralis 89a combination in healthy subjects.

OBJECTIVE: Probiotics S. salivarius 24SMBc and S. oralis 89a comprised in the nasal spray Rinogermina are known to exert inhibition of harmful pathogens and ameliorate the outcome of patients with chronic upper airways infections. In this study, for the first time, the effect of this formulation on the modulation of the microflora of healthy subjects was evaluated, with particular interest on pathobionts and pathogens present. PATIENTS AND METHODS: Metagenomic identification and quantification of bacterial abundances in healthy subjects were carried out by means of Ion Torrent Personal Machine. In particular, nasal swabs were sampled one, two and four weeks after seven days of treatment with Rinogermina. RESULTS: The modulation of the abundance of pathobionts and pathogenic species (i.e., Corynebacterium diphtheriae, Haemophilus parainfluenzae, Moraxella catarrhalis, Prevotella denticola, Prevotella melaninogenica, Rothia dentocariosa, Staphylococcus aureus and Streptococcus pseudopneumoniae) was characterized and a significant temporary decrease in their presence was identified. CONCLUSIONS: The beneficial effects of S. salivarius 24SMBc and S. oralis 89a nasal intake was assessed but seemed to be restricted in specific temporal windows. Thus it would be interesting to evaluate also this positive impact of longer administration of this probiotic formulation.