Preformed metal crowns for decayed primary molar teeth

BackgroundPreformed metal crowns (PMCs) are recommended by the British Society of Paediatric Dentistry (BSPD) for restoring badly broken down primary molar teeth. However, few dental practitioners adopt this technique in clinical practice, citing cost and clinical difficulty as reasons for this. Whilst there is a subjective impression by clinical academics that PMCs provide a more durable restoration than filling materials, there appears to be little evidence within the literature to support this.ObjectivesThe primary aim of this systematic review was to compare clinical outcomes for primary molar teeth restored using PMCs compared to those restored with filling materials.Search methodsThe literature was searched using: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2005, Issue 3); MEDLINE (1966 to August 2005); EMBASE (1980 to August 2005); System for Information on Grey Literature in Europe (SIGLE) (1976 to August 2005). Relevant publications' reference lists were reviewed for relevant articles. The most recent search was carried out on 24 August 2005.Selection criteriaRandomised controlled trials (RCTs) that assessed the effectiveness of PMCs compared with filling materials or where there had been no treatment in children with untreated tooth decay in one or more primary molar teeth.Data collection and analysisTwo review authors independently assessed the title and abstracts for each article from the search results to decide whether it was likely to be relevant. Full papers were obtained for relevant articles and all three review authors studied these.Main resultsForty‐seven records were retrieved by the search strategies of which some were duplicates. Of these, 14 studies were scrutinised. No studies met the inclusion criteria and six studies were excluded from the review as they were either retrospective in design or reported as prospective outcomes but not randomised. No data were available for extraction and analysis and therefore, no conclusion could be made as to whether PMCs were more successful than filling materials for restoring primary molar teeth.Authors' conclusionsNo RCTs were available for appraisal. Whilst this technique is recommended by the BSPD for use in clinical practice, the evidence to support this is not strong, consisting mainly of case reports and uncontrolled studies. It is important that the absence of evidence for PMCs is not misinterpreted as evidence for their lack of efficacy.There is a strong need for prospective RCTs comparing PMCs and fillings for managing decayed primary molar teeth. The lower levels of evidence that have been produced, however, have strength in that the clinical outcomes are consistently in favour of PMCs, despite many of the studies placing PMCs on the most damaged of the pair of teeth being analysed

Spectral evolution and the onset of the X-ray GRB afterglow

Based on light curves from the Swift Burst Analyser, we investigate whether a `dip' feature commonly seen in the early-time hardness ratios of Swift-XRT data could arise from the juxtaposition of the decaying prompt emission and rising afterglow. We are able to model the dip as such a feature, assuming the afterglow rises as predicted by Sari & Piran (1999). Using this model we measure the initial bulk Lorentz factor of the fireball. For a sample of 23 GRBs we find a median value of Gamma_0=225, assuming a constant-density circumburst medium; or Gamma_0=93 if we assume a wind-like medium.Comment: 4 pages, 3 figures. To appear in the proceedings of GRB 2010, Annapolis November 2010. (AIP Conference proceedings

High voltage planar multijunction solar cell

A high voltage multijunction solar cell is provided wherein a plurality of discrete voltage generating regions or unit cells are formed in a single generally planar semiconductor body. The unit cells are comprised of doped regions of opposite conductivity type separated by a gap or undiffused region. Metal contacts connect adjacent cells together in series so that the output voltages of the individual cells are additive. In some embodiments, doped field regions separated by a overlie the unit cells but the cells may be formed in both faces of the wafer

Method of making a high voltage V-groove solar cell

A method is provided for making a high voltage multijunction solar cell. The cell comprises a plurality of discrete voltage generating regions, or unit cells, which are formed in a single semiconductor wafer and are connected together so that the voltages of the individual cells are additive. The unit cells comprise doped regions of opposite conductivity types separated by a gap. The method includes forming V-shaped grooves in the wafer and thereafter orienting the wafer so that ions of one conductivity type can be implanted in one face of the groove while the other face is shielded. A metallization layer is applied and selectively etched away to provide connections between the unit cells

High voltage v-groove solar cell

A high voltage multijunction solar cell comprises a number of discrete voltage generating regions, or unit cells, which are formed in a single semiconductor wafer and are connected together so that the voltages of the individual cells are additive. The unit cells comprise doped regions of opposite conductivity types separated by a gap. The method includes forming V-shaped grooves in the wafer and orienting the wafer so that ions of one conductivity type can be implanted in one face of the groove while the other face is shielded. A metallization layer is applied and selectively etched away to provide connections between the unit cells

Rules for transition rates in nonequilibrium steady states

Just as transition rates in a canonical ensemble must respect the principle of detailed balance, constraints exist on transition rates in driven steady states. I derive those constraints, by maximum information-entropy inference, and apply them to the steady states of driven diffusion and a sheared lattice fluid. The resulting ensemble can potentially explain nonequilibrium phase behaviour and, for steady shear, gives rise to stress-mediated long-range interactions.Comment: 4 pages. To appear in Physical Review Letter

HLA-B27 Positivity: associated health implications

HLA-B27 positivity makes the onset of autoimmune diseases such as uveitis, ankylosing spondylitis and Crohn's disease more likely to occur. Ankylosing spondylitis and Crohn's disease are two types of HLA-B27 positive diseases that demonstrate a direct association with uveitis. Although the possession of HLA-B27 positivity is not mandatory for autoimmune diseases such as uveitis to occur, HLA-B27 positivity not only makes it more likely but may modify the clinical picture in which a patient presents. In relation to assessment and diagnosis it is imperative that the medical history of patients is thoroughly examined to ensure pathological sequelae are appropriately treated. Nurses play an important role in assessing patients that have uveitis and should suspect ankylosing spondylitis or Crohn's disease may be present