Antibacterial Effect of Endodontic Disinfections on Enterococcus Faecalis in Dental Root Canals-An In-Vitro Model Study

A 12-month randomized controlled trial to assess the efficacy of revitalization of retreated mature incisors with periapical radiolucency in adolescents

The use of regenrative endodontics is restoring the health status of the root canals of retreated mature teeth is a novel approach. Therefore, the current trial aimed to compare the effectiveness of regenerative endodontic procedures (REPs) to non-surgical root canal retreatment (NS-RCR) in reducing periapical radiolucency over one year for the retreatment of mature incisors with periapical periodontitis. The secondary purpose was to assess clinical success and regain pulp sensibility. A parallel randomized controlled trial, 66 mature incisors with periapical radiolucencies were randomly divided into two equal groups and retreated with either REPs or NS-RCR. At baseline and after 6 and 12 months, teeth were assessed clinically and radiographically using a periapical index (PAI). The Mann-Whitney test was used to analyze nonparametric PAI scores. The Electric pulp test readings were analyzed using the repeated measure analysis of variance (ANOVA). Over the follow-up intervals, there was no significant intergroup difference in the PAI medians, the majority of the teeth displayed a reduction in periapical radiolucency. At the end of the follow-up period, the clinical successes for the REP and NS-RCR groups were 93.9% and 97%, respectively (p = 0.555). Positive pulp sensibility was recorded in 54.54% of cases in the REPs after 12 months. Both approaches showed a comparable diminishing of periapical radiolucencies and equivalent clinical results. A conventional, non-surgical endodontic retreatment may not always be necessary.

Antimicrobial Efficacy of Saline, Chlorhexidine, and Zataria Multiflora and Mentha Piperita Essential Oils in Root Canal Irrigation of Primary Molars

Objectives: This study aimed to compare the antimicrobial efficacy of saline, 0.5% and 2% Zataria multiflora (Z. multiflora) essential oil, 0.5% and 2% Mentha piperita (M. piperita) essential oil, and 0.2% chlorhexidine (CHX) as root canal irrigants for primary molar teeth. Materials and Methods: A total of 64 primary molars were used in this in vitro study. The teeth were randomly assigned to six groups (N=10). The root canals were prepared up to file #35, and all teeth were sterilized before contamination with Enterococcus faecalis (E. faecalis; ATCC 29212) suspension. After 48 hours of incubation, the root canals in each group were irrigated with the respective irrigants. Sterile paper points were then used to collect microbial samples from the root canals. A colony counter was used to count the number of colony-forming units (CFUs). Data were analyzed by SPSS version 20 (alpha=0.05). Results: The colony count was significantly different among the groups (P<0.001), and 2% M. piperita (P=0.009), 0.5% Z. multiflora (P=0.021), and 0.2% CHX (P=0.002) were significantly more effective than saline in elimination of E. faecalis. The ascending order of microbial count after irrigation was as follows: saline > 0.5% M. piperita > 0.2% CHX > 2% M. piperita > 0.5% Z. multiflora. Conclusion: The current study showed the optimal antibacterial activity of 0.5% Z. multiflora essential oil and 2% M. piperita essential oil against E. faecalis, and indicated their possible efficacy for use as an irrigant for root canal irrigation of primary molars.

Lusutrombopag as a Repurposing Drug in Combination with Aminoglycosides against Vancomycin-Resistant Enterococcus

Due to the widespread abuse of antibiotics, drug resistance in Enterococcus has been increasing. However, the speed of antibiotic discovery cannot keep pace with the acquisition of bacterial resistance. Thus, drug repurposing is a proposed strategy to solve the crises. Lusutrombopag (LP) has been approved as a thrombopoietin receptor agonist by the Food and Drug Administration. This study demonstrated that LP exhibited significant antimicrobial activities against vancomycin-resistant Enterococcus in vitro with rare resistance occurrence. Further, LP combined with tobramycin exhibited synergistic antimicrobial effects in vitro and in vivo against Enterococcus. No in vitro or in vivo detectable toxicity was observed when using LP. Mechanism studies indicated that the disrupted proton motive force may account for LP's antimicrobial activity. In summary, these results demonstrate that LP has the previously undocumented potential to serve as an antibacterial agent against refractory infections caused by Enterococcus.

Photodynamic Suppression of Enterococcus Faecalis in Infected Root Canals with Indocyanine Green, TroloxTM and Near-Infrared Light

Recently, our group showed that additional supplementation of Trolox™ (vitamin E analogue) can significantly enhance the antimicrobial photodynamic effect of the photosensitizer Indocyanine green (ICG). Up to now, the combined effect has not yet been investigated on Enterococcus faecalis in dental root canals. In the present in vitro study, eighty human root canals were inoculated with E. faecalis and subsequently subjected to antimicrobial Photodynamic Therapy (aPDT) using ICG (250, 500, 1000 µg/mL) and near-infrared laser light (NIR, 808 nm, 100 Jcm-2). Trolox™ at concentrations of 6 mM was additionally applied. As a positive control, irrigation with 3% NaOCl was used. After aPDT, root canals were manually enlarged and the collected dentin debris was subjected to microbial culture analysis. Bacterial invasion into the dentinal tubules was verified for a distance of 300 µm. aPDT caused significant suppression of E. faecalis up to a maximum of 2.9 log counts (ICG 250 µg/mL). Additional application of TroloxTM resulted in increased antibacterial activity for aPDT with ICG 500 µg/mL. The efficiency of aPDT was comparable to NaOCl-irrigation inside the dentinal tubules. In conclusion, ICG significantly suppressed E. faecalis. Additional application of TroloxTM showed only minor enhancement. Future studies should also address the effects of TroloxTM on other photodynamic systems.

Therapeutic Potential of Chlorhexidine-Loaded Calcium Hydroxide-Based Intracanal Medications in Endo-Periodontal Lesions: An Ex Vivo and In Vitro Study

Endo-periodontal lesions are challenging clinical situations where both the supporting tissues and the root canal of the same tooth are infected. In the present study, chlorhexidine (CHX)-loaded calcium hydroxide (CH) pastes were used as intracanal medications (ICMs). They were prepared and tested on pathogens found in both the root canal and the periodontal pocket. Exposure to 0.5% and 1% CHX-loaded ICMs decreased the growth of Porphyromonas gingivalis and was effective in eradicating or inhibiting an Enterococcus faecalis biofilm. CH was injected into the root canal of extracted human teeth immersed in deionized water. CHX-loaded ICMs resulted in the transradicular diffusion of active components outside the tooth through the apex and the lateral dentinal tubules, as shown by the release of CHX (from 3.99 µg/mL to 51.28 µg/mL) and changes in pH (from 6.63 to 8.18) and calcium concentrations (from 2.42 ppm to 14.67 ppm) after 7 days. The 0.5% CHX-loaded ICM was non-toxic and reduced the release of IL-6 by periodontal cells stimulated by P. gingivalis lipopolysaccharides. Results indicate that the root canal may serve as a reservoir for periodontal drug delivery and that CHX-based ICMs can be an adjuvant for the control of infections and inflammation in endo-periodontal lesions.

Cytocompatibility and antimicrobial activity of a novel endodontic irrigant combining citric acid and chlorhexidine

OBJECTIVES

This study aimed to evaluate the antibacterial ability and cytocompatibility of a new irrigant solution for endodontic treatment composed of 10% citric acid (CA) and 1% chlorhexidine (CHX).

METHODS

Thirty-five extracted single-canal human teeth were selected and de-crowned. Canal systems (n = 7/group) were infected with Enterococcus faecalis for 4 weeks and subject to irrigation with 1% CHX; 10% CA; irrigating solution 10% CA associated with 1% CHX (CACHX); 2.5% NaOCl or sterile water (control). Microbiological samples were collected immediately and 18 h after irrigation (enriched samples). The canals were filled with culture medium post irrigation to verify the bacterial presence/absence qualitatively and quantitatively through colony counting (log₁₀ CFU/mL). A multiparametric assay was performed after exposure of human periodontal ligament fibroblasts (HPdLF) to the test solutions. The Kruskal-Wallis test with Dunn´s post-test and Fisher's exact test were employed at the 95% confidence level to compare differences among groups.

RESULTS

All tested solutions were cytocompatible with human periodontal ligament fibroblasts. No difference was observed on antibacterial activity between 1% CHX, 10% CA, CACHX and 2.5% NaOCl (p > 0.05). Eighteen hours after irrigation, CACHX samples were the only that did not present E. faecalis in the root canal system.

CONCLUSIONS

The demonstrated good in vitro biocompatibility and elimination of E. faecalis suggest a potential use of 10% CA associated with 1% CHX as a solution for microbiological control during endodontic treatment.

CLINICAL RELEVANCE

Irrigants play an essential role during endodontic therapy. This irrigating solution, based on the association of 10% citric acid with 1% chlorhexidine, seems viable for clinical procedures.

Antimicrobial Effect of Calcium Hydroxide Combined with Electrolyzed Superoxidized Solution at Neutral pH on Enterococcus faecalis Growth

Objective

To evaluate the effect of the combination of calcium hydroxide (Ca(OH)₂) and a novel electrolyzed superoxidized solution at neutral pH, known as OxOral® on Enterococcus faecalis growth in root canals.

Methods

Sixty human teeth were used, from which root canals were infected and randomly divided into the following treatment groups: saline solution, saline solution plus Ca(OH)₂, OxOral®, and OxOral® plus Ca(OH)₂.

Results

A permanent reduction in bacterial growth was observed at days 1, 6, 12, and 18 after OxOral® plus Ca(OH)₂ treatment from 4.4 ± 0.074 log₁₀ CFU/mL to 0.0 ± 0.001 log₁₀ CFU/mL. In addition, alkaline conditions maintenance was observed from application time (pH = 12.2 ± 0.033) to 18 d posttreatment (pH = 12.6 ± 0.083).

Conclusion

The combination of OxOral® and Ca(OH)₂ provides an alkaline pH and inhibits E. faecalis growth into the root canals. Our study opens the possibility for further research on the use of OxOral® in endodontic therapy.