Application of Rotating Magnetic Fields Increase the Activity of Antimicrobials Against Wound Biofilm Pathogens

Infective complications are a major factor contributing to wound chronicity and can be associated with significant morbidity or mortality. Wound bacteria are protected in biofilm communities and are highly resistant to immune system components and to antimicrobials used in wound therapy. There is an urgent medical need to more effectively eradicate wound biofilm pathogens. In the present work, we tested the impact of such commonly used antibiotics and antiseptics as gentamycin, ciprofloxacin, octenidine, chlorhexidine, polihexanidine, and ethacridine lactate delivered to Staphylococcus aureus and Pseudomonas aeruginosa biofilms in the presence of rotating magnetic fields (RMFs) of 10–50 Hz frequency and produced by a customized RMF generator. Fifty percent greater reduction in biofilm growth and biomass was observed after exposure to RMF as compared to biofilms not exposed to RMF. Our results suggest that RMF as an adjunct to antiseptic wound care can significantly improve antibiofilm activity, which has important translational potential for clinical applications.

The in vivo T helper type 17 and regulatory T cell immune responses to Aggregatibacter actinomycetemcomitans

The periodontal pathogen Aggregatibacter actinomycetemcomitans is known to elicit a systemic immune response in the infected host, and occasionally causes non-oral infections. Detailed information on its immunopathological responses and the involvement of bacterial virulence factors remains to be elucidated. The aim of this study was to assess the systemic immune response to A. actinomycetemcomitans oral infection. We used an animal model that simulates systemic dissemination of the bacteria by injecting live wild-type (WT) D7S-1 and a double knockout mutant of leukotoxin and cytolethal distending toxin (ΔltxΔcdt) A. actinomycetemcomitans strains in rat oral mucosa. Draining lymph nodes were examined for regulatory T (Treg) and T helper type 17 (Th17) cell subsets and their associated mediators. An increase in the proportion of Th17 cells and a decrease in Treg cells over the experimental period of 3 weeks were similarly observed for rats challenged with WT and ΔltxΔcdt. Significant upregulation and downregulation of proinflammatory cytokines in the Th17 gene pathway was noted, as well as several qualitative differences between WT and ΔltxΔcdt. Furthermore, we observed differential fold regulation in key genes associated with a proinflammatory response in ΔltxΔcdt-inoculated rats relative to D7S-1 group. This suggests that although the knockout of these two virulence factors (ΔltxΔcdt) may suppress certain proinflammatory genes, it causes similar over-expression of other genes compared with D7S-1, indicating a common factor that still remains in the pathogenicity of A. actinomycetemcomitans.

Evaluation of a nonthermal plasma needle to eliminate ex vivo biofilms in root canals of extracted human teeth

AIM

To evaluate the efficacy of a nonthermal plasma (NTP) at atmospheric pressure on ex vivo biofilm in root canals of extracted teeth.

METHODOLOGY

Intracanal contents from three teeth with root canal infections were collected, pooled and grown in thirty-five microCT-mapped root canals of extracted and instrumented human teeth. One group of teeth was treated with NTP, another with 6% NaOCl and one set was left untreated. The intracanal contents from twenty-seven teeth (nine teeth in each group) were plated on agar and colony forming units were determined. Parametric test of one-way analysis of variance (anova) was used to analyse statistical significance. The remaining teeth were cut open, stained with LIVE/DEAD(®) and examined with confocal laser scanning microscopy.

RESULTS

The untreated root canals were covered with biofilm of varying thickness. Treatment with nonthermal plasma decreased the number of viable bacteria in biofilms by one order of magnitude, whilst the NaOCl control achieved a reduction of more than four magnitudes. Both the NTP and the NaOCl treatment results were significantly different from the negative control (P < 0.05).

CONCLUSION

The nonthermal plasma displayed antimicrobial activity against endodontic biofilms in root canals, but was not as effective as the use of 6% NaOCl.

Intracranial physiological calcifications evaluated with cone beam CT

OBJECTIVES

The purpose of this study was to evaluate cone beam CT (CBCT) scans for the presence of physiological and pathological intracranial calcifications.

METHODS

CBCT scans from male and female patients that met our ascertainment criteria were evaluated retrospectively (n=500) for the presence of either physiological or pathological intracranial calcifications.

RESULTS

Out of the 500 patients evaluated, 176 had evidence of intracranial physiological calcification (35.2% prevalence), and none had evidence of pathological calcification. There was a 3:2 male-to-female ratio and no ethnic predilection; the ages of affected patients ranged from 13 years to 82 years with a mean age of 52 years. The majority of calcifications appeared in the pineal/habenular region (80%), with some also appearing in the choroid plexus region bilaterally (12%), and a smaller subset appearing in the petroclinoid ligament region bilaterally (8%).

CONCLUSIONS

Intracranial physiological calcifications can be a common finding on CBCT scans, whereas pathological intracranial calcifications are rare.

Non-exposed bisphosphonate-related osteonecrosis of the jaw: a critical assessment of current definition, staging, and treatment guidelines

Non-exposed bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a newly reported complication arising from bisphosphonate therapy that presents with atypical symptoms and no apparent mucosal fenestration or exposure of necrotic bone. The clinical observation of the presence of necrotic bone underneath normal epithelial coverage was not conclusive for the diagnosis of BRONJ based on current guidelines established by the American Association of Oral and Maxillofacial Surgeons (AAOMS) and the American Society for Bone and Mineral Research (ASBMR), which specify the presence of clinically exposed necrotic bone for more than 8 weeks. Hence, the purpose of this review is to critically assess the current guidelines for diagnosis and management of BRONJ and propose a modified staging system and treatment guidelines to properly address the non-exposed variant of BRONJ lesions.

Evaluation of student and faculty perceptions of the PBL curriculum at two dental schools from a student perspective: a cross-sectional survey

Problem-based learning (PBL) research has primarily highlighted issues related to medical education and less evaluation has been reported from the field of dental education. Furthermore, literature reports tend to focus mainly on PBL from a pedagogic and curriculum constructional view and up to this date, studies from a student perspective are lacking. The aim of this study was to approach the evaluation of student and staff perceptions of PBL curricula from a student perspective at two separate schools: the Faculty of Odontology at the University of Malmö, Sweden and the dental school of the University of Southern California, School of Dentistry (USCSD), Los Angeles, CA, USA. The study was initiated and conducted by two of the authors, at the time senior students at the Faculty of Odontology in Malmö, Sweden. The study was comprised of a literature search, a 2 week field trip to USCSD, USA, survey distribution to students and faculty in both schools, analysis of the data and a written report for oral defence. The results from the survey were intended to provide feedback on student and faculty perceptions regarding the PBL curriculum. The results indicate a general student and faculty satisfaction with the PBL curriculum. Perhaps, surprisingly their perceptions did not differ significantly despite differences in geography, culture and implementation of PBL pedagogy.