Engineering of Injectable Antibiotic-laden Fibrous Microparticles Gelatin Methacryloyl Hydrogel for Endodontic Infection Ablation

This study aimed at engineering cytocompatible and injectable antibiotic-laden fibrous microparticles gelatin methacryloyl (GelMA) hydrogels for endodontic infection ablation. Clindamycin (CLIN) or metronidazole (MET) was added to a polymer solution and electrospun into fibrous mats, which were processed via cryomilling to obtain CLIN- or MET-laden fibrous microparticles. Then, GelMA was modified with CLIN- or MET-laden microparticles or by using equal amounts of each set of fibrous microparticles. Morphological characterization of electrospun fibers and cryomilled particles was performed via scanning electron microscopy (SEM). The experimental hydrogels were further examined for swelling, degradation, and toxicity to dental stem cells, as well as antimicrobial action against endodontic pathogens (agar diffusion) and biofilm inhibition, evaluated both quantitatively (CFU/mL) and qualitatively via confocal laser scanning microscopy (CLSM) and SEM. Data were analyzed using ANOVA and Tukey’s test (α = 0.05). The modification of GelMA with antibiotic-laden fibrous microparticles increased the hydrogel swelling ratio and degradation rate. Cell viability was slightly reduced, although without any significant toxicity (cell viability > 50%). All hydrogels containing antibiotic-laden fibrous microparticles displayed antibiofilm effects, with the dentin substrate showing nearly complete elimination of viable bacteria. Altogether, our findings suggest that the engineered injectable antibiotic-laden fibrous microparticles hydrogels hold clinical prospects for endodontic infection ablation.

Comparative evaluation of 5% sodium hypochlorite and Nd:YAG laser in reducing endotoxins level from infected root canals – An in vivo microbiological study

Objectives: Endodontic infection is one of the most challenging aspects of dental treatment which is primarily caused by Gram-negative anaerobic bacterial species. The primary objective in the management of endodontic treatment is eradication of bacteria, as well as elimination of endotoxin. The aim of this study was to compare the effectiveness of 5% sodium hypochlorite, a mixture of calcium hydroxide+2% chlorhexidine (CHX) gel and Nd:YAG lasers for decreasing the level of endotoxin in infected root canals. Material and Methods: Forty four patients in the age group of 18–50 years were carefully chosen for the study and divided into control (Group 1, n = 11) and experimental group (Group 2, n = 33). Experimental group was further split into three subgroups according to the medicaments used. Samples were collected after the access opening (pre-operative specimens), after the biomechanical preparation (intermediate samples), and after the application of intracanal medicament for 15 days. The concentration of endotoxin in each sample was measured using quantitative chromogenic limulus amebocyte lysate assay. The data collected were statistically analyzed using SPSS for Windows (Statistical Package for the Social Sciences, Inc., Chicago, IL,) Version 15.0 Statistical Analysis Software. The level of significance was set at 0.05 for all tests. Results: Pretreatment endotoxins level observed was 6.783EU/ml in Control group and 7.261EU/ml, 6.963EU/ml, 7.247EU/ml in experimental subgroups. After biomechanical preparation and use of medicaments endotoxins level reduced to 3.919EU/ml in Control group and 0.5222EU/ml (sodium hypochlorite) 1.164EU/ml (calcium hydroxide+chlorhexidine), 0.841EU/ml (laser). Conclusion: This study concluded after analyzing the data that use of 5% sodium hypochlorite and Nd:YAG laser was effective in decreasing the level of endotoxins and use of intracanal medicament (2% CHX+ calcium hydroxide) for 15 days further helps to reduce the endotoxin level.

Chitosan Enhances the Anti-Biofilm Activity of Biodentine against an Interkingdom Biofilm Model

Endodontic infection is a biofilm disease that is difficult to irradicate with current treatment protocols, and as such, persistent micro-organisms may lead to ongoing or recurrent disease. The potential for the use of enhanced filling materials to modify biofilm regrowth is a promising strategy. This current study aimed to evaluate the anti-biofilm efficacy of calcium silicate cements modified with chitosan. The development of mono-species and multi-species biofilms on ProRoot MTA, Biodentine and bovine dentine discs were explored using quantitative microbiology analysis. The effect on regrowth of biofilms was assessed following the addition of chitosan to each cement. In comparison to a dentine substrate, both materials did not show the ability to inhibit biofilm regrowth. Biodentine incorporated with chitosan displayed a dose-dependent reduction in multi-species biofilm regrowth, unlike MTA. Notably, interkingdom biofilms were shown to enhance bacterial tolerance in the presence of chitosan. This study demonstrates the potential to enhance the antimicrobial properties of Biodentine. The findings highlight the need for appropriate model systems when exploring antimicrobial properties of materials in vitro so that interspecies and interkingdom interactions that modify tolerance are not overlooked while still supporting the development of innovative materials.

Inhibitory effect of calcium hydroxide combined with Nigella sativa against Enterococcus faecalis

Background: Calcium hydroxide is the gold standard medicament for root canal treatment. Enterococcus faecalis, the primary cause of intraradicular persistent endodontic infection, is often identified even after endodontic treatment. Thymoquinone, an active ingredient of Nigella sativa, has an antimicrobial effect on both gram-negative and positive bacteria, including E. faecalis. Purpose: This study aimed to evaluate the inhibitory effect of calcium hydroxide combined with Nigella sativa extract and determine the best ratio for the combined material. Methods: This is an experimental study comprised of six groups (n = 4 per group) based on the material and its ratio, namely; (1) calcium hydroxide; (2) Nigella sativa extract; and groups of the combination of calcium hydroxide and Nigella sativa extract with a ratio (3) 70:30, (4) 50:50, (5) 30:70, (6) 10:90. The inhibitory effect against E. faecalis was evaluated by the agar well diffusion method in Muller–Hinton agar. Observation of the inhibitory zone was performed on the first, third, and seventh days. The collected data were analysed by a one-way ANOVA and LSD post hoc test. Results: Calcium hydroxide has the highest inhibitory effect, and the combination of Nigella sativa extract with calcium hydroxide ratio 50:50 was second. The inhibitory zone of these two groups was significantly higher than in any other group (p<0.05). Conclusion: Nigella sativa extract combine with calcium hydroxide did not enhance calcium hydroxide’s antimicrobial property against E. faecalis. An equal amount of Nigella sativa and calcium hydroxide is the best combination ratio, with a stable effect for up to seven days.

Activity of Two Antimicrobial Peptides against Enterococcus faecalis in a Model of Biofilm-Mediated Endodontic Infection

Enterococcus faecalis is a common cause of biofilm-associated opportunistic infections, which are often difficult to treat. The formation of E. faecalis biofilms on the dentinal walls of the root canal is frequently the cause of endodontic treatment failure and secondary apical periodontitis. In a preliminary work, two recognized antifungal peptides, KP and L18R, showed antibacterial activity against planktonic E. faecalis cells at micromolar concentrations. Moreover, L18R proved to reduce the biomass in the early stage of E. faecalis biofilm development on polystyrene plates, while a qualitative biofilm inhibition was demonstrated on hydroxyapatite disks by confocal laser scanning microscopy (CLSM). The aim of this study was to better characterize the effect of both peptides on E. faecalis biofilm. A reduction in metabolic activity after peptide treatment was detected by Alamar Blue assay, while a remarkable impairment in the architecture of E. faecalis biofilms on hydroxyapatite disks, along with a significant reduction in viable bacteria, was caused mostly by L18R, as assessed by CLSM and scanning electron microscopy. The lack of cytotoxicity of the investigated peptides against L929 murine fibroblasts was also determined. Obtained results suggest L18R as a promising candidate for the development of new strategies for endodontic infection control.

Cardiovascular Disease and Chronic Endodontic Infection. Is There an Association? A Systematic Review and Meta-Analysis

The aim of the present study was to systematically assess existing evidence on the possible association between chronic endodontic infections and cardiovascular disease (CVD). An electronic database search was implemented until 2 October 2020. The main outcome was risk of CVD diagnosis. Risk of bias was assessed through the ROBINS-I tool, while random effects meta-analyses were conducted. The quality of the evidence was assessed with the Grading of Recommendations Assessment, Development, and Evaluation. Twenty-one studies were eligible for inclusion, while 10 were included in the quantitative synthesis. Risk for CVD diagnosis in patients with chronic endodontic infection was 1.38 times those without infection (RR = 1.38; 95% CIs: 1.06, 1.80; p = 0.008). Risk of bias ranged from moderate to serious, while the quality of the evidence was graded as very low. Indications for an identified association between chronic endodontic infection and CVDs do exist; however, they are not grounded on high-quality evidence at present. Further research for an establishment of an association based on temporal sequence of the two entities and on unbiased well-conducted cohort studies would be highly valued.