Antibacterial substantivity of a new antibiotic-based endodontic irrigation solution

Rational design of a Nano-Antibiotic chitosan hydrogel for the bacterial infection Therapy: In vitro & ex vivo Assessments

In modern times, many antibiotics have become less effective as microorganisms develop resistance. Besides antibiotic resistance, another bacterial strategy that contributes to the capacity to withstand antimicrobials is biofilm formation. Because of these bacterial survival strategies, the desired response cannot be achieved with conventional treatment. Considering the limited discovery of new compounds, the most logical approach is to reconstruct existing antimicrobial molecules with nano-drug delivery systems. With this scientific approach, the aim of the study is to develop a novel nano-antibiotic hydrogel formulation containing silver nanoparticles, chitosan, and amoxicillin. Endodontic disease was used as a model of biofilm-mediated infection, and the antibacterial activity of nano-antibiotic hydrogel was evaluated with the E. faecalis standard bacterial strain. By adopting the Box-Behnken design for the optimisation of formulation variables, an innovative pharmaceutical formulation with antimicrobial and antibiofilm activity was successfully obtained. Further characterisation studies, including nanoparticle characterisation, in vitro cytotoxicity, and ex vivo activity studies, were carried out on dental samples using the optimised formulation. All results were compared with antimicrobial agents routinely used in endodontic treatment. The findings mainly conclude that the optimised nano-antibiotic hydrogel may be an alternative antimicrobial formulation since it is non-cytotoxic and exhibits high antibiofilm activity.

Comparative Evaluation of Residual Antibacterial Substantivity of Chlorhexidine, MTAD and Chitosan Against Enterococcus Faecalis in Human Root Dentin - An In vitro Study

Introduction

Complex anatomy of the root canal system results in incomplete debridement with mechanical instrumentation, leaving some areas or root canal walls untouched. There comes the significance of endodontic irrigants with residual antibacterial substantivity which prolongs the post-antibiotic effect, thereby improving the success and predictability of endodontic treatment.

Aim

To comparatively evaluate the residual antibacterial substantivity of 2% chlorhexidine, Biopure MTAD and 2% chitosan against Enterococcus faecalis at intervals of 1, 14 and 28 days.

Materials and Methods

Seventy-five therapeutically extracted permanent single rooted mandibular premolars teeth were selected. Dentin blocks of 4 mm thickness were prepared and enlarged to 1.6 mm. The autoclaved blocks were inoculated with 24-hour colonies of pure cultures of E. faecalis for 14 days. After the contamination period, canals of each dentin block were irrigated with 5 ml of sterile saline and dried with sterile paper points. A total of 75 dentin blocks were randomly divided into five groups as follows: Group A (21 specimens): 2% chlorhexidine, Group B (21 specimens): Biopure MTAD, Group C (21 specimens): 2% chitosan, Group D (6 specimens): positive control (infected dentin tubes) and Group E (six specimens): negative control (sterile dentin tubes). Then, the lumens of dentin blocks were irrigated with the respective irrigants for 10 mins and were dried using sterile paper points. The specimens were then incubated at 37°C for 28 days to maintain humidity. At experimental intervals of 1, 14 and 28 days, dentin shavings were removed from the canals of respective groups by circumferential filing with sterile no. 35 Hedstrom files. The powdered dentin samples obtained with each dentin block were observed for colony forming units (CFUs) using a Digital Colony counter and were expressed as CFUs/mL.

Result

All the irrigants in the study showed a significant decrease in CFUs from day 1 to day 28 indicating that they have residual antibacterial substantivity against E. faecalis. Group B (Biopure MTAD) showed significantly least mean CFUs compared to Group A (2% CHX) and Group C (2% chitosan) against E. faecalis at B1(day 1), B2(day 14) and B3(day 28). Group A (2% CHX) showed significantly higher mean CFUs than Group C (2% chitosan) at A1(day 1). Group C (2% chitosan) showed significantly higher mean CFUs compared to Group A (2% CHX) at C2(day 14) and C3 (day 28).

Conclusion

MTAD showed statistically higher residual antibacterial substantivity against E. faecalis at experimental periods of 1, 14 and 28 days. The residual antibacterial effect of 2% chitosan was better compared to 2% CHX at day 1. The residual antimicrobial substantivity of 2% CHX was higher compared to 2% chitosan at intervals of 14 and 28 days.

Feasibility of the crude extracts of Amorphophallus paeoniifolius and Colocasia esculenta as intracanal medicaments in endodontic therapy in comparison to the 940 nm diode laser: An in vitro antimicrobial study

Background/purpose

The elimination and debridement of intracanal bacteria are credited with long-term effectiveness in endodontic therapy. This study aimed to compare the antimicrobial efficacies of Amorphophallus paeoniifolius (Suran), Colocasia esculenta (Aravi) crude extracts as intracanal medicaments with calcium hydroxide (CH), 2% chlorhexidine (CHX) gel, and 940 nm diode laser.

Materials and methods

Fifty-eight intact, single-root, extracted human mandibular premolar teeth were prepared. The samples were sterilized, transferred into microcentrifuge tubes, and inoculated with E. faecalis. The samples were placed in an incubator for three weeks to allow the biofilm to grow. Then the samples were randomly divided into five experimental groups (n = 10), disinfected with Suran, Aravi crude extracts, CH, 2% CHX gel, and a 940 nm diode laser. The negative control group (n = 4) and the positive control group (n = 4). Then the samples were observed under light and scanning electron microscopy to monitor the E. faecalis biofilm. The sampling method was carried out in paper point (intracanal) and Peeso bur (intradentinal). Later the number of colony-forming units was counted and analyzed.

Results

Colony-forming units were significantly reduced in the 2% CHX gel in both sampling methods, while Suran showed lower colony-forming units compared to Aravi and CH. The differences between experimental groups were not statistically significant (P > 0.05) in both sampling methods.

Conclusion

This study showed that the application of Suran and Aravi crude extracts as intracanal medicaments leads to a significant reduction in the number of bacterial colonies compared to CH, 2% CHX gel, and 940 nm diode laser.

Efficacy of the photon-initiated photoacoustic streaming combined with different solutions on Enterococcus faecalis in the root canals

This study aimed to evaluate the efficacy of different irrigation solutions used in photon-initiated photoacoustic streaming (PIPS) or conventional needle irrigation (CNI) for eradication of Enterococcus faecalis from artificial root canals. Altogether, 240 artificial root canal samples were included. The models were split and incubated for 2 days to allow formation of E. faecalis biofilm. The models were randomly divided into two groups (n = 120): CNI and laser-activated irrigation (LAI). Each group was divided into six subgroups according to different irrigation solutions: distilled water, 1% sodium hypochlorite (NaOCl), 2% NaOCl, 5.25% NaOCl, MTAD, and chlorhexidine, respectively. After irrigation, half of the samples (n = 10) were assessed immediately, and the other half of the samples (n = 10) were incubated for 6 hr. Bacterial suspensions were obtained from all samples before and after irrigation, and after incubation, and were quantified adenosine 5'-triphosphate (ATP) assay kit. The biofilms were examined using fluorescent microscopy and analyzed by Image Pro Plus software. Significant reduction of ATP, average fluorescence density after irrigation, and growth after incubation was obtained in LAI group than in CNI group (p < .05). LAI can improve bacteriostasis effect of 2% NaOCl (p < .05). PIPS improved the antibacterial effect of the 2% NaOCl used in root canal therapy.

The Comparative Evaluation of the Post-Antimicrobial Effect of MTAD ® and 2% Chlorhexidine against Enterococcus faecalis of Permanent Teeth with Necrotic Pulp

AIM:

Enterococcus faecalis is one of the most resistant bacteria in necrotic teeth. That’s why the goal of this study was to determine the post-antibiotic effect of MTAD®& 2% Chlorhexidine® as root canal irrigating solution on clinical isolates of E. faecalis from infected root canals of permanent teeth, using the spectrophotometric technique.

MATERIAL AND METHODS:

The antibacterial efficacy of Chloramphenicol 30 mcg, Nitrofurantoin 300 mcg, Vancomycin 5 mcg, Amoxicillin/clavulanic acid 30 mcg and Ofloxacin 5 mcg against E. faecalis was compared using the Disc diffusion method. Patients were selected for this study with permanent necrotic teeth. The sterile paper point was inserted inside the infected root canal and left for 60 seconds; to obtain the microbiological sample. Postantibiotic effect of MTAD® and 2% Chlorohexidine® on E. faecalis was compared. The absorbance of bacterial growth was examined for both irrigating solutions during the first 10 hours with an hour interval, and then tested at 48, 72, 96 up to 240 hours.

RESULTS:

The results showed that during the first 10 hours, MTAD® showed immediate antibacterial effect and maintained its higher antibacterial activity than 2% chlorohexidine®. After 48, 72, 96 and 240 hours, both MTAD® and 2% chlorohexidine® showed the same prolonged action of post-antibiotic effect against E. faecalis with a non-significant difference. According to Antibiotic sensitivity, the results revealed MTAD® is the most effective antimicrobial drug, showing the highest zone of inhibition, followed by 2% Chlorhexidine and Nitrofurantoin 300 mcg which showed the same inhibitory activity

CONCLUSION:

From the current study, it can be concluded that MTAD® has a strong bactericidal effect against E. faecalis and showed the highest zone of inhibition.

A Review Over Benefits and Drawbacks of Combining Sodium Hypochlorite with Other Endodontic Materials

INTRODUCTION

As the root canal system considered to be complex and unpredictable, using root canal irrigants and medicaments are essential in order to enhance the disinfection of the canal. Sodium hypochlorite is the most common irrigant in endodontics. Despite its excellent antimicrobial activity and tissue solubility, sodium hypochlorite lacks some important properties such as substantivity and smear layer removing ability.

OBJECTIVE

The aim of this review was to address benefits and drawbacks of combining sodium hypochlorite with other root canal irrigants and medicaments.

DISCUSSION

According to the reviewed articles, NaOCl is the most common irrigation solution in endodontics. However, it has some drawbacks such as inability to remove smear layer. One of the drawbacks of NaOCl is its inability to remove the smear layer and lack of substantivity.

CONCLUSION

The adjunctive use of other materials has been suggested to improve NaOCl efficacy. Nevertheless, further studies are required in this field.

Influence of Mixed Additives on the Physicochemical Properties of a 5.25% Sodium Hypochlorite Solution: An Unsupervised Multivariate Statistical Approach

INTRODUCTION

This article reports for the first time the effects of multiple additives (polyethylene glycol 400, Triton X-100, benzalkonium chloride, and ethyl formate) on the surface tension, pH, and viscosity of 5.25% sodium hypochlorite (NaOCl) irrigant solution. Advanced statistical approaches based on unsupervised multivariate analysis (cluster analysis and principal component analysis) were used to quantify the variability of the physicochemical properties of the modified NaOCl solution for the first time in dentistry.

METHODS

Solutions of 5.25% NaOCl were modified with multiple additives in various concentrations, physicochemical parameters were measured at 22°C and 37°C, and the results were statistically analyzed to group the solutions and reveal the effects of additives.

RESULTS

Cluster analysis and principal component analysis revealed that pH and surface tension were the significant parameters (P < .05) for grouping the modified solutions. Four principal components, accounting for 90.6% of the total variance, were associated with flow characteristics (37.3%) determined by polyethylene glycol; the wetting property (22.5% and 10.5%), which was dependent on cationic and nonionic surfactant; and the antimicrobial effect (20.3%) influenced by ethyl formate. Varimax rotation of the principal components showed that the cationic surfactant (benzalkonium chloride) had significantly decreased surface tension compared with the nonionic surfactant (Triton-X). Although ethyl formate was introduced as an odor modifier, it had a significant effect on pH decrease and the occurrence of effervescence with O₂ and hypochlorous acid release.

CONCLUSIONS

The statistical results revealed that the 5.25% NaOCl irrigant solution should be modified with a mixture of 0.1% benzalkonium chloride, 1% ethyl formate, and 7% polyethylene glycol for obtaining a low pH and low surface tension.

Direct and indirect antibacterial effects of various concentrations of triple antibiotic pastes loaded in a methylcellulose system

We investigated the direct and indirect (residual) antibacterial effects of various concentrations of triple antibiotic paste (TAP) loaded into a methylcellulose system. Enterococcus faecalis (E. faecalis) was grown on sterilized dentin blocks (n = 60) and treated with clinically used TAP (1,000 mg/mL), low concentrations of methylcellulose-based TAP (100, 10, and 1 mg/mL), placebo paste, or 1.5% NaOCl (n = 10). The pastes were then removed, and biofilm disruption assays were performed. Additional dentin blocks (n = 120) were pretreated with the same experimental groups (n = 20). The pastes were rinsed off, and the samples were immersed independently in phosphate-buffered saline for 2 and 4 weeks (n = 10). E.faecalis was then grown on the dentin blocks, and biofilm disruption assays were performed. Fisher's Exact and Wilcoxon rank sum tests were used for statistical analyses. With regard to direct antibacterial effects, all treatment groups demonstrated complete eradication of biofilms in comparison to placebo paste, while 10 mg/mL of TAP or higher provided substantial residual antibacterial effects. However, dentin treated with 1 mg/mL of TAP or 1.5% NaOCl did not provide substantial residual antibacterial effects. Dentin pretreated with 10 mg/mL of TAP or higher exhibited extended residual antibacterial effects and can thus be used during endodontic regeneration.(J Oral Sci 58, 575-582, 2016).

Influence of Temperature on the Antibacterial Activity of Sodium Hypochlorite

Abstract The aim of this study was to compare the antimicrobial activity of 5.25% NaOCl, Hypoclean and Chlor-Xtra at 20 °C and 45 °C in bovine root dentin. One-hundred-and-seventy dentin tubes prepared from bovine maxillary incisors were infected for 21 days with Enterococcus faecalis. The specimens were divided into the following groups: 1. 5.25% NaOCl 20 °C; 2. Hypoclean 20 °C; 3. Chlor-Xtra 20 °C; 4. 5.25% % NaOCl 45 °C; 5. Hypoclean 45 °C; 6. Chlor-Xtra 45 °C; 7. positive control; 8. negative control. Dentin chips were collected with round burs into Brain Heart Infusion (BHI) broth. After culturing, the number of colony-forming units (CFU) was counted. Statistical analyses were performed using descriptive statistics (mean, standard deviation, median), Shapiro-Wilk test, ANOVA and Tukey test. Significance level was set at p<0.05. In all experimental groups, CFU was minimum after treatment (day 0) and the obtained results were significantly different from each other at any period (p<0.05). After treatment, the Hypoclean and Chlor-Xtra showed the lowest numbers of CFU at 20 °C and 45 °C, whereas 5.25% NaOCl showed the highest number of CFU at both temperatures. In each group, the number of CFUs increased significantly with time (p<0.05). The antibacterial activity of Hypoclean and Chlor-Xtra at 45 °C were significantly greater than other tested solutions.

Radiographic evaluation of root canal cleaning, main and laterals, using different methods of final irrigation

OBJECTIVE: To evaluate the efficacy of passive ultrasonic irrigation (PUI) using intermittent or continuous flushing and conventional manual irrigation (CMI) on the cleaning of main and simulated lateral root canals.MATERIAL AND METHOD: The root canals of 24 artificial teeth were prepared and simulated lateral canals were made in the medium and apical thirds of the root. The specimens were divided into three groups: G1- CMI, G2- PUI 1 (intermittent flushing) and G3- PUI 2 (continuous flushing). Root canals were filled with contrast solution and the roots were radiographed pre- and post-irrigation. The digital images were transferred to Image Tool 3.0 software and the areas of root canal completely filled with contrast, and after irrigation with contrast remnant, were measured to obtain percentage data. Statistical analysis between groups was performed by ANOVA and Tukey tests.RESULT: In the apical third, G2 and G3 (PUI) groups showed higher percentage of cleaning than G1 (CMI) (p<0.05).CONCLUSION: Passive ultrasonic irrigation using intermittent flushing promoted a higher cleaning of simulated lateral canals than conventional manual irrigation in the apical third. There were no differences between groups in the main root canal and the middle third.

Substantivity of three concentrations of tetraclean in bovine root dentin

In the present study, the residual antibacterial activity, or substantivity, of three concentrations of Tetraclean (Ogna Laboratori Farmaceutici, Muggiò, Italy) was assessed in bovine root dentin in vitro. One hundred ten dentin tubes prepared from bovine incisor teeth were infected in vitro for 14 days with Enterococcus faecalis. Thereafter, the specimens were divided into five groups as follows: 100% Tetraclean, 10% Tetraclean, 1% Tetraclean, sterile dentin tubes (negative control), and infected dentin tubes (positive control). Dentin chips were collected with round burs into tryptic soy broth and, after culturing, the number of colony-forming units (CFU) was counted. The number of CFU was minimal in the first cultures in all experimental groups, and the results obtained were significantly different in the different groups at all time periods (p<0.05). At all five experimental periods, the 100% Tetraclean group showed the most effective antibacterial action (p<0.05). In each group, the number of CFU increased significantly with time (p<0.05). There was a direct relationship between the concentration of Tetraclean and its substantivity. In conclusion, under the conditions of the study presented here, the substantivity of 100% Tetraclean was significantly higher than that of lower concentrations.