Mechanisms of vascular damage by systemic dissemination of the oral pathogen Porphyromonas gingivalis

Several studies have shown a clear association between periodontal disease and increased risk of cardiovascular disease. Porphyromonas gingivalis (Pg), a key oral pathogen, and its cell surface-expressed gingipains, induce oedema in a zebrafish larvae infection model although the mechanism of these vascular effects is unknown. Here, we aimed to determine whether Pg-induced vascular damage is mediated by gingipains. In vitro, human endothelial cells from different vascular beds were invaded by wild-type (W83) but not gingipain-deficient (ΔK/R-ab) Pg. W83 infection resulted inincreased endothelial permeability as well as decreased cell surface abundance of endothelial adhesion molecules PECAM-1 and VE-cadherin compared to infection with ΔK/R-ab. In agreement, when transgenic zebrafish larvae expressing fluorescently labelled PECAM-1 or VE-cadherin were systemically infected with W83 or ΔK/R-ab, a significant reduction in adhesion molecule fluorescence was observed specifically in endothelium proximal to W83 bacteria through a gingipain-dependent mechanism. Furthermore, this was associated with increased vascular permeability in vivo when assessed by dextran leakage microangiography. These data are thefirst to show that Pg directly mediates vascular damage in vivo by degrading PECAM-1 and VE-cadherin. Our data provide a molecular mechanism by which Pg might contribute to cardiovascular disease

The Relationship of Surface Characteristics and Antimicrobial Performance of Pulp Capping Materials

Pulp capping materials need to be able to protect the pulp but also bond to the overlying restorative materials. Light-curable pulp capping materials bond better to restorative materials and are easier to place than most water-based cements. The aim of this study was to characterize new light-curable tricalcium silicate-based pulp capping materials and compare their surface and antimicrobial properties with clinically available Theracal (Bisco, Schaumburg, IL) and Biodentine (Septodont, Saint-Maur-des-Fossés, France). The surface characteristics of 3 light-curable pulp capping materials based on a resin and filled with tricalcium silicate and tantalum oxide radiopacifier and Theracal and Biodentine were assessed by scanning electron microscopy, X-ray diffraction, and contact angle measurement. The radiopacity was measured following ISO 6876 standards. The antimicrobial activity was determined by the direct contact test and the antibiofilm activity by the adenosine triphosphate assay and the confocal laser scanning Live/Dead assay (Invitrogen, Eugene, OR) using a polymicrobial culture. The surface characteristics of the materials varied with the unfilled resin and Biodentine exhibiting a hydrophobic surface. Biodentine showed significantly higher antimicrobial properties in the direct contact test, but this property was absent in the antibiofilm activity tests. The resins filled with tricalcium silicate and Theracal showed higher antimicrobial activity than Biodentine in the adenosine triphosphate and live/dead assays. The surface characteristics of a material affect its antimicrobial properties. The experimental resin-modified materials exhibited comparable antimicrobial properties with other light-curable pulp capping agents. Further long-term studies on the materials' antimicrobial activity are required to assess whether they can result in better clinical outcomes

Standardization of antimicrobial testing of dental devices

Objective: Dental device is a very broad term that can be used to include any foreign material or product that is introduced in the host oral cavity to replace missing tissues. These devices are subjected to different environments which include dental hard tissues, tissue fluids, blood and saliva. All dental devices are continuously challenged microbiologically and a number of failures in clinical management are related to microbial colonization. Thus, the assessment of the antimicrobial properties of dental devices are extremely important. In this paper, a classification of dental devices is being proposed. This classification distinguishes the devices based on whether they are implantable or not, and also sub-classified based on their specific application and the substrate receiving the device. Methods and Results A literature search was conducted to identify how dental devices have been tested with relation to the microbial strains used and whether the testing has been performed in isolation or reported with other relevant tests such as material characterization and biological activity. The results of the literature review were analyzed and recommendations for antimicrobial testing of dental devices are proposed. These recommendations include the need for the setting up of pre-testing parameters such as ageing and the details of the pre-testing sterilization procedures, as these may affect the material chemistry and the specification for antimicrobial testing to be done with specific single strains or polymicrobial that are native to the region where the device is located are also suggested. Testing can be undertaken in vitro, ex vivo and in vivo. Since the antimicrobial and biological activities influence/condition one another and the material chemistry may affect both the antimicrobial and biological testing this document also makes recommendations regarding biological assessment which can be carried out in isolation or integrated with the microbiological testing and also material testing methods including chemical and physical characterization of bulk, surface, eluted and degraded materials as well as physical characterization methods. Significance The level of standardization of antimicrobial testing for the dental devices needs to be based on the device location and host interaction in order to increase the clinical applicability of the mentioned tests

Use of in vitro and in vivo zebrafish infection models to investigate the role of oral microorganisms in cardiovascular disease

Increasing evidence links periodontal pathogens with several systemic diseases, including cardiovascular disease, atherosclerosis, diabetes and Alzheimer’s disease. A well-established example is the association between periodontal disease that affects over 300 million people worldwide, and cardiovascular disease. Several periodontal pathogens have been detected in atherosclerotic plaques and patient vascular samples. These pathogens can enter the bloodstream through recurrent bleeding, disseminating systemically resulting in transient bacteraemia. However, little is known about how periodontal pathogens interact with the vasculature and which molecular mechanisms and virulence factors are responsible for initiation or potentiation of cardiovascular disease. Most research has focused on the oral pathogen Porphyromonas gingivalis (Pg), at the exclusion of other oral microorganisms identified in the circulation and atherosclerotic plaques, including Fusobacterium nucleatum (Fn) and Tanerella forsythia (Tf). Pg has been termed a ‘keystone pathogen’ and produces several virulence factors including cysteine proteases, gingipains and outer membrane vesicles (OMV). This study investigated the role of Pg gingipains in whole cell bacteria, as well as from OMV, in mediating endothelial damage assessed through cell adhesion molecule degradation and endothelial permeability in vitro and in vivo using a zebrafish larvae systemic infection model. In addition, since periodontitis is a polymicrobial infection, effects of Fn and Tf single species as well as multispecies endothelial infections with Pg were also assessed

Effect of sterilization techniques prior to antimicrobial testing on physical properties of dental restorative materials

Objectives: The aim of this study was to investigate any changes to the microstructure and surface properties of selected dental materials after sterilization carried out prior to sub- jecting them to antimicrobial testing. Initial microbial contamination on the material, as well as other possible sources of contamination were also assessed. Methods: The materials investigated included dentine replacement materials Chemfil Superior1, Ionoseal1, Dyract Extra1 and SDR1. The materials were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The test materials were sterilized using alcohol, steam, ultraviolet light (UV) and ethylene oxide and any changes to these materials were then assessed by SEM, microhardness testing and Fourier transform infrared (FT-IR) spectroscopy. Material microbial levels before treatments were assessed by plate counting technique and turbidity tests. Possible contamination through dispensers was assessed by analysing the CFU/sample. Results: Ethylene oxide affected the microstructure of the Chemfil, Ionoseal and Dyract, resulting in flattening of the Si–O stretching vibrations and deposition of chlorine and calcium respectively in Chemfil and Dyract. Varied contamination was demonstrated on all materials when incubated in anaerobic conditions. Conclusions: The different sterilization techniques affected the microstructure of the mate- rials under investigation. Samples of materials produced in sterile conditions could also be contaminated with bacteria, either from the material itself or through the dispensing apparatus. Clinical significance: Results of antimicrobial studies cannot be extrapolated clinically as the material sterilization treatment results in changes to material chemistry and microstruc- ture, which could in turn affect the materials’ antimicrobial activity.peer-reviewe