Periodontal surgery in furcation-involved maxillary molars revisited—an introduction of guidelines for comprehensive treatment

Maxillary molars with interradicular loss of periodontal tissue have an increased risk of additional attachment loss with an impaired long-term prognosis. Since accurate clinical analysis of furcation involvement is not feasible due to limited access, morphological variations and measurement errors, additional diagnostics, e.g., with cone-beam computed tomography, may be required. Surgical treatment options have graduated from a less invasive approach, i.e., keeping as much periodontal attachment as possible, to a more invasive approach: (1) open flap debridement with/without gingivectomy or apically repositioned flap and/or tunnelling; (2) root separation; (3) amputation/trisection of a root (with/without root separation or tunnel preparation); (4) amputation/trisection of two roots; and (5) extraction of the entire tooth. Tunnelling is indicated when the degree of root separation allows for opening of the interradicular region. Alternatively, root separation is performed particularly in root-canal treated teeth with reduced coronal tooth substance requiring crown restorations. As soon as the attachment of one or two roots in maxillary molars is severely reduced, root removal is indicated and performed either as amputation or trisection including the corresponding part of the clinical crown. While the indication for regenerative measures in maxillary molars with furcation involvement is very limited, extraction and replacement with implants is restricted, particularly in sites requiring complex alveolar ridge augmentation and sinus elevation. A systematic approach for decision making in furcation-involved maxillary molars is described in this overview, including what constitutes accurate diagnosis and what indications there are for the different surgical periodontal treatment option

2D sense for faster 3D MRI

Sensitivity encoding in two spatial dimensions (2D SENSE) with a receiver coil array is discussed as a means of improving the encoding efficiency of three-dimensional (3D) Fourier MRI. it is shown that in Fourier imaging with two phase encoding directions, 2D SENSE has key advantages over one-dimensional parallel imaging approaches. By exploiting two dimensions for hybrid encoding, the conditioning of the reconstruction problem can be considerably improved, resulting in superior signal-to-noise behavior. As a consequence, 2D SENSE permits greater scan time reduction, which particularly benefits the inherently time-consuming 3D techniques. Along with the principles of 2D SENSE imaging, the properties of the technique are discussed and investigated by means of simulations. Special attention is given to the role of the coil configuration, yielding practical setups with four and six coils. The in vivo feasibility of the two-dimensional approach is demonstrated for 3D head imaging, permitting four-fold scan time reductio

Brushing without brushing?—a review of the efficacy of powered toothbrushes in noncontact biofilm removal

Objectives: The aim of the present review was to analyze the impact of the hydrodynamic effects created by powered toothbrushes on biofilm removal in vitro. Materials and methods: A MEDLINE search was performed for publications published by 20 May 2012; this search was complemented by a manual search. The study selection, data preparation, and validity assessment were conducted by two reviewers. Results: Sixteen studies were included. The studies differed with respect to the methods of biofilm formation and brushing protocols. Eighteen different powered toothbrush models were evaluated. Toothbrushes with side-to-side action demonstrated biofilm removal without direct bristle contact to biofilms ranging from 38 to 99%. Most studies found biofilm removal exceeding 50%. Biofilm reduction using multidimensional toothbrushes was significantly lower than by those with the side-to-side mode. Detachment forces due to hydrodynamic phenomena, passing air-liquid interfaces, and acoustic energy transfer were suggested to cause reduction of the biofilm. Conclusion: Noncontact biofilm reduction was obtained by the hydrodynamic effects of some powered toothbrushes in vitro. Clinical relevance: Powered toothbrushes may have the potential to simplify self-performed oral hygiene. However, additional beneficial effects of higher amounts of noncontact biofilm removal in vitro have not been shown clinically, ye

Phosphorylation of BK channels modulates the sensitivity to hydrogen sulfide (H2S)

Introduction: Gases, such as nitric oxide (NO), carbon monoxide (CO) or hydrogen sulfide (H2S), termed gasotransmitters, play an increasingly important role in understanding of how electrical signaling of cells is modulated. H2S is well known to act on various ion channels and receptors. In a previous study we reported that H2S increased calcium-activated potassium (BK) channel activity. Aims: The goal of the present study is to investigate the modulatory effect of BK channel phosphorylation on the action of H2S on the channel as well as to recalculate and determine the H2S concentrations in aqueous sodium hydrogen sulfide (NaHS) solutions.Methods: Single channel recordings of GH3, GH4 and GH4 STREX cells were used to analyze channel open probability, amplitude and open dwell times. H2S was measured with ananion selective electrode. Results: The concentration of H2S produced from NaHS was recalculated taking pH, temperature salinity of the perfusate and evaporation of H2S into account. The results indicate that from a concentration of 300 µM NaHS, only11-13%, i.e. 34-41 µM is effective as H2S in solution. GH3, GH4 and GH4 STREX cells respond differently to phosphorylation. BK channel open probability (Po) of all cells lines used was increased by H2S in ATP containing solutions. PKA prevented the action of H2S on channel Po in GH4 and GH4 STREX, but not in GH3 cells. H2S, high significantly increased Po of all PKG pretreated cells. In the presence of PKC, which lowers channel activity, H2S increased channel Po of GH4 and GH4 STREX, but not those of GH3 cells. H2S increased open dwell times of GH3 cells in the absence of ATP significantly. A significant increase of dwell times with H2S was also observed in the presence of okadaic acid.Conclusions: Our results suggest that phosphorylation by PKG primes the channels for H2S activation and indicate that channel phosphorylation plays an important role in the response to H2S

Isothermal microcalorimetry provides new insights into biofilm variability and dynamics

The purpose of this study was to investigate a three-species in vitro biofilm with peri-implantitis-related bacteria for its variability and metabolic activity. Streptococcus sanguinis, Fusobacterium nucleatum, and Porphyromonas gingivalis were suspended in simulated body fluid containing 0.2% glucose to form biofilms on polished, protein-coated implant-grade titanium disks over 72 h using a flow chamber system. Thereafter, biofilm-coated disks were characterized by scanning electron microscopy and fluorescence in situ hybridization/confocal laser scanning microscopy. To assess metabolic activity within the biofilms, their heat flow was recorded for 480 h at 37 °C by IMC. The microscopic methods revealed that the total number of bacteria in the biofilms varied slightly among specimens (2.59 × 104 ± 0.67 × 104 cells mm−2), whereas all three species were found constantly with unchanged proportions (S. sanguinis 41.3 ± 4.8%, F. nucleatum 17.7 ± 2.1%, and P. gingivalis 41.0 ± 4.9%). IMC revealed minor differences in time-to-peak heat flow (20.6 ± 4.5 h), a trend consistent with the small variation in bacterial species proportions as shown by microscopy. Peak heat flow (35.8 ± 42.6 µW), mean heat flow (13.1 ± 22.0 µW), and total heat over 480 h (23.5 ± 37.2 J) showed very high variation. These IMC results may be attributed to differences in the initial cell counts and relative proportions of the three species, their distribution and embedment in exopolysaccharide matrix on the test specimens. The present results provide new insights into variability and dynamics of biofilms on titanium disks, aspects that should be explored in future studies of dental surface

Quantification of vital adherent Streptococcus sanguinis cells on protein-coated titanium after disinfectant treatment

The quantification of vital adherent bacteria is challenging, especially when efficacy of antimicrobial agents is to be evaluated. In this study three different methods were compared in order to quantify vital adherent Streptococcus sanguinis cells after exposure to disinfectants. An anaerobic flow chamber model accomplished initial adhesion of S. sanguinis on protein-coated titanium. Effects of chlorhexidine, Betadine®, Octenidol®, and ProntOral® were assessed by quantifying vital cells using Live/Dead BacLight™, conventional culturing and isothermal microcalorimetry (IMC). Results were analysed by Kruskal-Wallis one-way analysis of variance. Live/dead staining revealed highest vital cell counts (P0.05), indicating equivalent numbers of bacteria were created and disinfectants delayed growth but did not eliminate it. In conclusion, contrary to culturing, live/dead staining enables detection of cells that may be viable but non-cultivable. Microcalorimetry allows unique evaluation of relative disinfectant effects by quantifying differences in time delay of regrowth of remaining vital cell