Oral Biofilm Architecture on Natural Teeth

Periodontitis and caries are infectious diseases of the oral cavity in which oral biofilms play a causative role. Moreover, oral biofilms are widely studied as model systems for bacterial adhesion, biofilm development, and biofilm resistance to antibiotics, due to their widespread presence and accessibility. Despite descriptions of initial plaque formation on the tooth surface, studies on mature plaque and plaque structure below the gum are limited to landmark studies from the 1970s, without appreciating the breadth of microbial diversity in the plaque. We used fluorescent in situ hybridization to localize in vivo the most abundant species from different phyla and species associated with periodontitis on seven embedded teeth obtained from four different subjects. The data showed convincingly the dominance of Actinomyces sp., Tannerella forsythia, Fusobacterium nucleatum, Spirochaetes, and Synergistetes in subgingival plaque. The latter proved to be new with a possibly important role in host-pathogen interaction due to its localization in close proximity to immune cells. The present study identified for the first time in vivo that Lactobacillus sp. are the central cells of bacterial aggregates in subgingival plaque, and that Streptococcus sp. and the yeast Candida albicans form corncob structures in supragingival plaque. Finally, periodontal pathogens colonize already formed biofilms and form microcolonies therein. These in vivo observations on oral biofilms provide a clear vision on biofilm architecture and the spatial distribution of predominant species

Identifying Where REDD+ Financially Out Competes Oil Palm in Floodplain Landscapes Using a Fine-Scale Approach

Reducing Emissions from Deforestation and forest Degradation (REDD+) aims to avoid forest conversion to alternative land-uses through financial incentives. Oil-palm has high opportunity costs, which according to current literature questions the financial competitiveness of REDD+ in tropical lowlands. To understand this more, we undertook regional finescale and coarse-scale analyses (through carbon mapping and economic modelling) to assess the financial viability of REDD+ in safeguarding unprotected forest (30,173 ha) in the Lower Kinabatangan floodplain in Malaysian Borneo. Results estimate 4.7 million metric tons of carbon (MgC) in unprotected forest, with 64% allocated for oil-palm cultivations. Through fine-scale mapping and carbon accounting, we demonstrated that REDD+ can outcompete oil-palm in regions with low suitability, with low carbon prices and low carbon stock. In areas with medium oil-palm suitability, REDD+ could outcompete oil palm in areas with: very high carbon and lower carbon price; medium carbon price and average carbon stock; or, low carbon stock and high carbon price. Areas with high oil palm suitability, REDD + could only outcompete with higher carbon price and higher carbon stock. In the coarse-scale model, oil-palm outcompeted REDD+ in all cases. For the fine-scale models at the landscape level, low carbon offset prices (US $3 MgCO2e) would enable REDD+ to outcompete oil-palm in 55$27 million to secure these areas for 25 years. Higher carbon offset price (US $30 MgCO2e) would increase the competitiveness of REDD+ within the landscape but would still only capture between 69$380–416 million in carbon financing. REDD+ has been identified as a strategy to mitigate climate change by many countries (including Malaysia). Although REDD+ in certain scenarios cannot outcompete oil palm, this research contributes to the global REDD+ debate by: highlighting REDD+ competitiveness in tropical floodplain landscapes; and, providing a robust approach for identifying and targeting limited REDD+ funds

Endodontic drug delivery for root surface disinfection: a laboratory feasibility evaluation

OBJECTIVES This study aims to assess the potential of a mixture of three antibiotics (TreVitaMix, TVM) as an intracanal dressing to disinfect the outer root surface by applying a new in vitro model. MATERIALS AND METHODS Fifty freshly extracted bovine roots were endodontically treated. Forty samples were then thoroughly scaled, mounted to petri dishes, gas sterilized, and randomly allocated to four groups (n = 10/group) according to their intracanal medication: sterile saline (NaCl; control, A); the TVM carrier material alone, i.e., propylene glycol (PG; B); TVM (C); and calcium hydroxide (D). In an additional group (E), the cementum was not removed and TVM was placed. Petri dishes were filled with Fastidious Anaerobe Agar, inoculated with Fusobacterium nucleatum suspension and then anaerobically incubated during 48-h intervals at 37 °C up to 192 h. Inhibition zones around the roots were then measured after each incubation period (mm(2)). RESULTS Only teeth inoculated with the TVM dressing showed inhibition at all time points, whereas the other treatments showed no peri-radicular growing inhibition. Presence of cementum had no negative effect on disinfection (p = 0.9320). CONCLUSION TVM was able to penetrate through the dentine and inhibit the bacterial growth of F. nucleatum up to 192 h. CLINICAL RELEVANCE TVM might have the potential to sustainably disinfect the outer root surface in perio-endo lesions and serve as an adjunctive antimicrobial agent

E-government in a corporatist, communitarian society: The case of Singapore

10.1177/1461444806065661New Media and Society85707-73