Antibiofilm potential over time of a tricalcium silicate material and its association with sodium diclofenac.

OBJECTIVES: The objectives of this study are to investigate, over time, the antimicrobial activity against polymicrobial biofilms and ability to inhibit biofilm formation, of Biodentine (BD) alone and with 5% and 10% sodium diclofenac (DC). MATERIAL AND METHODS: The antimicrobial activity of BD alone and modified with 5% and 10% DC against polymicrobial biofilm growth in dentin was determined by a modified direct contact test. The study groups were (1) BD; (2) BD + 5% DC; and (3) BD + 10% DC. The viability of microorganisms after 1 and 4 weeks was quantified by means of an ATP assay and flow cytometry. The antibiofilm efficacy of the materials, preventing polymicrobial biofilm formation over time, was assessed by confocal laser scanning microscopy (CLSM). RESULTS: The results obtained with both the ATP test and flow cytometry showed that BD alone and with 5% and 10% DC exerted antibiofilm activity with respect to the control, in the two evaluated times (p < 0.001). Comparison between groups showed a tendency of increased antimicrobial effect, both over time and depending on the DC concentration. These results coincide with those obtained in CLSM analysis, where efficacy increased with time and DC concentration. CONCLUSIONS AND CLINICAL RELEVANCE: Biodentine, over time, showed antimicrobial and antibiofilm efficacy on polymicrobial biofilms. The addition of 5% and 10% DC to BD enhanced this effect, in a concentration- and time-dependent manner.

A laboratory study of root canal and isthmus disinfection in extracted teeth using various activation methods with a mixture of sodium hypochlorite and etidronic acid.

AIM: To evaluate in a laboratory setting the antibiofilm activity of several irrigating protocols including conventional irrigation, ultrasonic activation and XP-endo Finisher, with a mixture of sodium hypochlorite and etidronic acid in infected isthmuses and root canals of extracted human mandibular molar teeth. METHODOLOGY: Fifty-six mesial roots of mandibular molars, half of them with a continuous isthmus from the cervical to the apical third between the two root canals (type 1), and the other half with a continuous isthmus from the cervical to the middle third and one canal in the apical third (type 2), were included. The root canals were contaminated for 7 days with an Enterococcus faecalis suspension. There were three experimental groups plus a control group (n = 7 per type of root canal anatomy). All the root canals, except for the control group that was not treated, were chemomechanically prepared and then assigned to one of the experimental groups according to the final adjunctive procedure: conventional irrigation, ultrasonic activation or XP-endo Finisher activation. The irrigating solution used was a combination of 2.5% sodium hypochlorite and 9% etidronic acid, and the final protocols were applied for three cycles of 30 s with a 3 mL volume. The antibiofilm activity was evaluated at each location (root canal and isthmus) and third (cervical, middle and apical) using confocal laser scanning microscopy and the live/dead technique. Statistical analysis was performed using SPSS (descriptive statistics) and SUDAAN (P-value calculations). RESULTS: Root canals had significantly lower biovolume values than the isthmuses (P < 0.05). The biovolume in the root canals was significantly reduced in all the experimental groups in all the thirds except for conventional irrigation in the apical third (P > 0.05). In the cervical and middle thirds, ultrasonic activation was associated with the lowest biovolumes (P < 0.05), followed by XP-endo Finisher. In the isthmus, disinfection was similar in all the thirds for all the protocols. Conventional irrigation was associated with intermediate values with no significant differences from the control group or from the activated protocols (P > 0.05), although the latter were significantly different from the control group (P < 0.05). No differences were found between ultrasonic activation and XP-endo Finisher in the middle and apical thirds (P > 0.05) in the isthmuses. CONCLUSIONS: In this laboratory study on extracted teeth, the isthmus was more difficult to disinfect than root canals. In the root canals, ultrasonic activation and XP-endo Finisher had a greater effectiveness than conventional irrigation. In the isthmuses, no differences were observed between the two activation techniques and conventional irrigation.

Influence of dentine debris and organic tissue on the properties of sodium hypochlorite solutions.

AIM: To determine the free available chlorine of 2.5% sodium hypochlorite (NaOCl) alone and combined with 9% etidronic acid (HEDP) in the presence of inhibitors, organic tissue and organic tissue plus dentine debris; to evaluate the influence of dentine debris on the tissue-dissolving capacity of both NaOCl solutions; and to determine the antimicrobial action of these solutions when in contact with organic tissue and organic tissue plus dentine debris. METHODOLOGY: The available chlorine of the solutions over time in the absence and presence of the inhibitors was measured using a titration method. The organic tissue dissolution by the solutions alone and in the presence of dentine powder was evaluated by weighing bovine tissue specimens before and after exposure to the solutions for 3 and 10 min. For the antimicrobial activity, biofilms of Enterococcus faecalis were exposed to the solutions for 3 min in the absence and presence of organic tissue and organic tissue + dentine debris. The biovolume and percentage of damaged membrane cells of the biofilm were measured by means of confocal microscopy and the live/dead technique. Nonparametric tests were used to determine statistical differences (P < 0.05). RESULTS: Both inhibitors consumed the free available chlorine of the solutions over time. The presence of dentine debris significantly reduced the tissue dissolution capacity of the NaOCl solutions (P < 0.05). The percentages of biovolume reduction were not affected by the presence of the inhibitors in the two NaOCl solutions, whereas the percentage of damaged membrane cells was significantly reduced (P < 0.001). Overall, a similar behaviour was observed in the NaOCl and NaOCl/HEDP groups. CONCLUSIONS: The presence of organic tissue and organic tissue + dentine debris favoured rapid consumption of the free chlorine of NaOCl and NaOCl/HEDP. This resulted in a decreased ability to dissolve organic tissue without affecting the short-term antimicrobial activity.

Efficacy of antimicrobial solutions against polymicrobial root canal biofilm.

AIM: To evaluate the antibiofilm activity of 2.5% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), 2% alexidine (ALX) and 0.2% cetrimide (CTR) alone and in combination on mature polymicrobial root canal biofilms on human dentine using confocal laser scanning microscopy (CLSM). METHODOLOGY: Twenty-eight human dentine specimens were infected for 21 days with microbial samples collected from infected root canals of three volunteers. Antibiofilm activity of the irrigating solutions was evaluated after 3 min of contact time under CLSM. For quantification purposes, bioimage_L software was used. The variables evaluated were the log10 of total biovolume (µm3 ) and percentage of live cells (green) population. Statistical analysis of both variables was performed using an anova test and a post hoc Duncan test to determine significant clusters amongst groups. The variable green population percentage was previously subjected to the normalized Anscombe transformation. RESULTS: The NaOCl group had a total biovolume and percentage of live cells significantly lower than the other groups (P Ë‚ 0.001). The addition of 0.2% CTR significantly increased the antimicrobial effect of 2% CHX (P Ë‚ 0.001). There were no significant differences between 0.2% CTR, 2% ALX and the combination of both (P Ë‚ 0.05). CONCLUSIONS: Overall, 2.5% NaOCl dissolved and killed bacteria significantly more efficiently when used against polymicrobial mature biofilm on human dentine. Cetrimide improved the antimicrobial activity of chlorhexidine and alexidine.

The effect of benzalkonium chloride additions to AH Plus sealer. Antimicrobial, physical and chemical properties.

OBJECTIVES: The aim of this study was to determine the antimicrobial and antibiofilm activities and physicochemical properties of AH Plus sealer mixed with different concentrations of benzalkonium chloride (BC). METHODS: AH Plus was tested alone and mixed with 1%, 2% and 3% of BC. The antimicrobial and antibiofilm activities of the sealers against Enterococcus faecalis were evaluated by the direct contact test (DCT) and by confocal laser scanning microscopy, respectively. Setting time, flow and solubility were assessed according to ANSI/ADA specifications. Microhardness and contact angle tests were also performed. The chemical changes of the sealers were evaluated by X-ray diffraction analysis, and both Fourier transform infrared spectroscopy (FT-IR) and attenuated total reflectance Fourier transform infrared (ATR FT-IR). RESULTS: AH Plus+3% BC was the only sealer to promote total elimination of E. faecalis and the biovolume in this group was significantly lower than in the rest of the sealers (p>0.05). The physical properties of the sealers were according to the ANSI/ADA specifications. The microhardness decreased significantly when BC was added and a significant reduction in contact angle was obtained when incorporating 2% and 3% BC (p<0.05). No phase changes were observed with the modified sealers. CONCLUSIONS: The addition of 2% or higher concentrations BC to AH Plus showed antimicrobial and antibiofilm activities without affecting the properties specified in ANSI/ADA standards. However, additives to the root canal sealer altered other physical and chemical properties that are not commonly found in the literature to evaluate filling materials. CLINICAL SIGNIFICANCE: The present study highlights that the antimicrobial properties of AH Plus can be significantly improved with the addition of BC. Testing beyond what is specified in standards may be indicated.

Antimicrobial activity of Chlorhexidine, Peracetic acid and Sodium hypochlorite/etidronate irrigant solutions against Enterococcus faecalis biofilms.

AIM: To evaluate the antimicrobial effect of 2.5% sodium hypochlorite alone (NaOCl) and associated with 9% HEBP (NaOCl/HEBP), 2% peracetic acid (PAA) and 2% chlorhexidine (CHX), on the viability of Enterococcus faecalis biofilms attached to dentine. METHODOLOGY: Biofilms of E. faecalis were grown on the surface of dentine blocks for 5 days and then exposed to the irrigating solutions for 3 min. Distilled water was used as the control. The total biovolume and the percentage of dead cells of the infected dentine were measured by means of confocal microscopy and the live/dead technique. Nonparametric tests were used to determine statistical differences (P < 0.05). RESULTS: NaOCl and the NaOCl/HEBP mixture were associated with a significantly greater percentage of dead cells, followed by PAA (P < 0.05). No significant antimicrobial effect of CHX was observed in comparison with the control group. Total biovolume decreased significantly in NaOCl, NaOCl/HEBP and PAA solutions in comparison with the CHX and control groups. CONCLUSIONS: NaOCl alone or associated with HEBP were the most effective irrigant solutions in dissolving and killing E. faecalis biofilms.

Reduction in Enteroccocus faecalis counts - a comparison between rotary and reciprocating systems.

AIM: To compare the chemomechanical reduction and regrowth of Enterococcus faecalis between rotary and reciprocating systems in root canal preparation. METHODOLOGY: Seventy-six single-rooted human mandibular premolars were selected and standardized to 15 mm in length. Root canals were enlarged up to a size 25 K-file and irrigated with distilled water and then were infected with E. faecalis for 4 weeks. The specimens were divided into 3 groups (n = 24) for instrumentation with Mtwo, Twisted File and WaveOne. Each group was further divided into two subgroups (n = 12) according to the irrigant used: distilled water or 5.25% sodium hypochlorite (NaOCl). Before and after rotary preparation, microbiological samples were collected using three sterilized paper points, and efficacy was expressed as reduction in percentage. The proportion of grown samples for 60 days was evaluated using nonparametric Kaplan-Meier survival analysis. Differences amongst groups were tested using the log-rank test at a significance level of 0.05. RESULTS: In the main root canal, the percentage reduction in the distilled water and 5.25% NaOCl groups ranged from 95.9% to 100%, with no significant differences amongst the three systems (P > 0.05). The bacterial regrowth in NaOCl groups revealed that Mtwo had the lowest number of samples regrown at 60 days, giving statistically significant differences with respect to Twisted File (P = 0.029) and WaveOne (P = 0.005). CONCLUSIONS: Reciprocating and rotary systems resulted in similar percentage reduction in E. faecalis when using either distilled water or 5.25% NaOCl solution. Over time, the Mtwo system was more effective regarding disinfection.