Synthesis of silicon-germanium axial nanowire heterostructures in a solvent vapor growth system using indium and tin catalysts.

Here we describe a relatively facile synthetic protocol for the formation of Si-Ge and Si-Ge-Si1-xGex axial nanowire heterostructures. The wires are grown directly on substrates with an evaporated catalytic layer placed in the vapour zone of a high boiling point solvent with the silicon and germanium precursors injected as liquids sequentially. We show that these heterostructures can be formed using either indium or tin as the catalyst seeds which form in situ during the thermal anneal. There is a direct correlation between growth time and segment length allowing good control over the wire composition. The formation of axial heterostructures of Si-Ge-Si1-xGex nanowires using a triple injection is further discussed with the alloyed Si1-xGex third component formed due to residual Ge precursor and its greater reactivity in comparison to silicon. It was found that the degree of tapering at each hetero-interface varied with both the catalyst type and composition of the NW. The report shows the versatility of the solvent vapour growth system for the formation of complex Si-Ge NW heterostructures.

Oral health of children born small for gestational age.

We sought to evaluate the oral health status of children born small for gestational age (SGA). Children now aged 4-8 years who were born SGA (birth weight < -2 SDS) were examined using standardised criteria. The parents completed a structured oral health questionnaire. Twenty females and 25 males, mean age 72.1 months, and mean birth weight 2.1 kg, participated in the study. Poor appetite was a concern; 32 (71%) children snacked between meals and 14 (30%) used carbonated beverages more than 3 times daily. Erosion was present in 9 (20%) children. Dental decay occurred in 22 (47%) children with 92% being untreated. Eight children had more than 5 decayed teeth. It is essential that clinicians working with children born SGA include oral health within the general health surveillance and refer these children for a dental assessment within the first 2 years to support parents in establishing safe feeding patterns for their children.

Effects of VEGF and FGF2 on the revascularization of severed human dental pulps.

The long-term outcome of replanted avulsed permanent teeth is frequently compromised by lack of revascularization, resulting in pulp necrosis. The purpose of this study was to evaluate the effects of vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF-2) on the revascularization of severed human dental pulps. Tooth slices were prepared from non-carious human molars and treated with 0-50 ng/mL rhVEGF(165) or rhFGF-2 for 7 days in vitro. Both angiogenic factors enhanced pulp microvessel density compared with untreated controls (p < 0.05). Tooth slices were also treated with 0 or 50 ng/mL rhVEGF(165) for one hour prior to implantation into the subcutaneous space of immunodeficient mice. Treatment with rhVEGF(165) increased pulp microvessel density in vivo (p < 0.05). These results demonstrate that rhVEGF(165) enhanced neovascularization of severed human dental pulps and suggest that topical application of an angiogenic factor prior to replantation might be beneficial for the treatment of avulsed teeth.

Three phosphor plate systems and film compared for imaging root canals.

AIM: The aim of this study was to compare three phosphor plate intraoral imaging systems (Digora (DA), Digident (DT), Denoptix (DX)) and E-speed conventional film (CF) for the imaging of root canals. METHODOLOGY: Sixty extracted permanent teeth were exposed using CF, DA, DT and DX. The length of root canal visible from its most apical extent to a line drawn at the level of the cementoenamel junction was measured and this was expressed as a percentage of the distance between the radiographic apex and the cementoenamel line. All images were examined concurrently by two examiners. Films were viewed under standardized conditions and DA, DT and DX images were viewed directly from the monitor screen. The images on the monitor were enhanced to give the subjectively clearest image. RESULTS: The mean percentage of canal visible on CF was 90%, DA 78%, DT 81% and DX 83%. The difference was significant for CF-DA (P < 0.001) and CF-DT (P = 0.001). There was no statistically significant difference for CF-DX or between any of the three phosphor plate imaging systems. CONCLUSIONS: It is concluded that a greater length of root canal was visible on conventional film than on three phosphor plate imaging systems and that this may be of clinical significance.