Treatment of multiple traumatized anterior teeth associated with an alveolar bone fracture in a 15-year-old school boy: a 2.5-year follow up.

We report a case of multiple dental traumas in a 15-year-old school boy who was hit by a stone. Clinical examinations revealed the avulsion of teeth 21, 22, and 23, an uncomplicated crown fracture of tooth 41, and a complicated crown fracture (CCF) of teeth 11, 31, and 33. An alveolar bone fracture and a root fracture in the apical third of tooth 23 were as well noted on radiographs. The avulsed teeth were replanted and rigidly splinted after an extraoral dry time of 90 min. Endodontic treatments were performed on teeth with CCFs. The dental morphology was restored using polyethylene fiber-reinforced composite resin. Endodontic obturations were performed on replanted teeth after the arrest of external root resorptions by a long-term calcium hydroxide dressing. Esthetics and function were recovered with a 2.5-year follow-up period.

Microstructure and crystallographic texture of Charonia lampas lampas shell.

Charonia lampas lampas shell is studied using scanning electron microscopy and X-ray diffraction combined analysis of the preferred orientations and cell parameters. The Charonia shell is composed of three crossed lamellar layers of biogenic aragonite. The outer layer exhibits a 001 fibre texture, the intermediate crossed lamellar layer is radial with a split of its c-axis and single twin pattern of its a-axis, and the inner layer is comarginal with split c-axis and double twinning. A lost of texture strength is quantified from the inner layer outward. Unit-cell refinements evidence the intercrystalline organic influence on the aragonite unit-cell parameters anisotropic distortion and volume changes in the three layers. The simulation of the macroscopic elastic tensors of the mineral part of the three layers, from texture data, reveals an optimisation of the elastic coefficient to compression and shear in all directions of the shell as an overall.

Effect of high osmolarity acclimation on tolerance to hyperosmotic shocks in L929 cultured cells.

Application of abrupt, large hyperosmotic shocks induces in L929 cultured cells changes similar to those previously described in other cell types, notably a hypercondensation of the nuclear chromatin. This paper shows that; 1) this phenomenon is concomitant with a complete disappearance of deoxyribonucleic acid, as visualized by immunogold labelling, from the nucleoplasmic spaces; 2) acclimation to high osmolarities (600 mOsm) by addition to the culture medium of NaCl, sorbitol or proline protects the cells from these effects, which appear to be largely attenuated-acclimated cells also survive much better to the osmotic shock than do control cells and; 3) the best protection seems to be provided by sorbitol and NaCl. Proline acclimation is less effective. These effects are discussed in terms of increased tolerance to NaCl load induced at the level of different macromolecules by so-called 'compensatory' organic compounds.

Increased tolerance to large hyperosmotic shocks and compensatory solutes in mammalian cultured cells.

L929 and MDCK cells acclimated to sorbitol, proline or taurine media can tolerate a NaCl load that they would be unable to stand when cultured in normal conditions. The protecting effect is observed only at high concentrations, between 100 and 300 mM. In that range, the effect is increasing with increasing concentration. The presence of the compound is not necessary, in the extracellular medium, to induce tolerance. These results are discussed in the framework of the theory considering preferential interactions of proteins with solvent components to explain the protecting effect of such compounds.

An new concept for removal of dental fluorosis stains.

Bleaching has been suggested by several authors in order to treat the unaesthetic aspect of dental fluorosis. Many results are, however, unsatisfactory. A different method, based on the structural characteristics of the fluorotic tooth and the organic and exogenous nature of fluorotic enamel stains, includes three principal stages: 1--enamel etching with 12% HCl in order to eliminate the posteruptive calcified layer that covers the fluorotic enamel surface and to denude the microcavities containing the organic elements; 2--application of pure manufactured sodium hypochlorite to remove these organic stains; and 3--filling the chemically opened microcavities with a light-cured dental adhesive to provide the tooth with a smooth and even surface and to prevent restaining. To improve the aesthetic aspect of intensely discolored teeth, it is possible to use a variety of tints available in several composite resin kits. Teeth with a rough enamel surface react more positively than ones with a smooth surface. The enamel adhesives provide better results than the amelo-dentinal ones.

[Canal preparation of fluorotic teeth]. / La préparation canalaire sur dents fluorotiques.

This study compared the effectiveness of nine root-canal preparation techniques of fluorotic teeth. Seventy-three canal systems from 53 extracted human fluorotic teeth were instrumented. Pre-and postinstrumentation measurements were taken of the root canal systems in the cervical, middle and apical thirds; they proved the efficiency of the method using Rispi and Helifile. The results of this study were also extrapolated to the clinical situation.