Micro-CT assessment of internal morphology and root canal configuration of non C-shaped mandibular second molars

The root canal system morphology of the mandibular second molar was investigated by means of micro-computed tomography (µCT). The root canal configuration (RCC), foramina and accessory canals frequency of 93 mandibular second molars of an Egyptian sample were investigated by µCT scans. The RCC and main foramina number (MFN) are described by means of a four-digit system from coronal to apical. The most frequently observed RCCs in the mesial root were 2-2-1/1 (32.3%), 2-2-2/2 (28.0%), 1-1-1/1 (6.5%) and 2-1-1/1 (6.5%); an additional twelve different RCCs were also found here. In the distal root, the RCC 1-1-1/1 was observed in 81.7%; another ten different RCCs with a frequency of less than 5% were also observed in this root. Anastomoses be-tween the mesiobuccal and mesiolingual canals in the mesial root were witnessed in the coronal (20.5%), middle (19.4%) and apical (10.8%) thirds. Accessory canals were found in the coronal (mesiobuccal 15.0%, mesiolingual 12.9%, distobuccal 1.1%), middle (mesiobuccal 7.5%, mesiolingual 10.8%, distolingual 3.3%) and apical (mesiobuccal 19.3%, mesiolingual 16.2%, distolingual 10.8%, distobuccal 2.2%) thirds. The RCC of mandibular second molars showed a great variety. When compared with the first mandibular molar in a historical control from the same sample, the mandibular second molar presented less morphological diversifications. Yet, the mesial root canalsystem of the mandibular second molar showed more RCC variations, connecting and accessory canals than the distal root.

Surface modification of nanodiamond under Bingel-Hirsch conditions.

The Bingel-Hirsch reaction consists in the reaction of a bromomalonate with electron-poor π bonds, for example, of carbon materials, yielding cyclopropane derivatives. The reactive nucleophile is generated in situ from the respective malonate using CBr(4) and a base. The resulting cyclopropane moiety links the carbon material's surface atoms covalently with the functional side groups of the malonate. So far, the reaction was limited to fullerenes and carbon nanotubes. Herein, we report on the first application of this reaction type for the surface modification of diamond nanoparticles. The surface of thermally annealed nanodiamond consists of fullerene-like sp(2) carbon atoms which exhibit a similar reactivity as those in the all-sp(2) carbon nanomaterials. It was found that the reaction proceeds smoothly and enables the grafting of a large variety of functional groups to the surface of nanodiamond. The generated nucleophiles are also able to react with carbonyl species on the diamond. This reaction pathway enables the grafting of malonates even on oxidized nanodiamond without prior thermal annealing.

Saccharide-modified nanodiamond conjugates for the efficient detection and removal of pathogenic bacteria.

The detection and removal of bacteria, such as E. coli in aqueous environments by using safe and readily available means is of high importance. Here we report on the synthesis of nanodiamonds (ND) covalently modified with specific carbohydrates (glyco-ND) for the precipitation of type 1 fimbriated uropathogenic E. coli in solution by mechanically stable agglutination. The surface of the diamond nanoparticles was modified by using a Diels-Alder reaction followed by the covalent grafting of the respective glycosides. The resulting glyco-ND samples are fully dispersible in aqueous media and show a surface loading of typically 0.1 mmol g(-1). To probe the adhesive properties of various ND samples we have developed a new sandwich assay employing layers of two bacterial strains in an array format. Agglutination experiments in solution were used to distinguish unspecific interactions of glyco-ND with bacteria from specific ones. Two types of precipitates in solution were observed and characterized in detail by light and electron microscopy. Only by specific interactions mechanically stable agglutinates were formed. Bacteria could be removed from water by filtration of these stable agglutinates through 10 µm pore-size filters and the ND conjugate could eventually be recovered by addition of the appropriate carbohydrate. The application of glycosylated ND allows versatile and facile detection of bacteria and their efficient removal by using an environmentally and biomedically benign material.

Playing the surface game-Diels-Alder reactions on diamond nanoparticles.

Stable covalent C-C bonding of aromatic moieties has been achieved using Diels-Alder reactions on surface-annealed nanodiamond. Subsequent functionalisation leads to tunable surface properties and molecule-like behaviour.