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International audience; Reconstruction of endodontically treated posterior teeth use now dual or chemical cure core build-up materials. Core build-up materials have mechanical properties still unknown. These properties have consequences on survival of reconstruction and on the tooth. For the same material family, the operator feelings may be very different depending on resin flowability. The aim of this study was to evaluate the viscosity (processing properties) and some mechanical properties (in service properties) of different resins. For example: If the resin is very viscous it is difficult to fill the root canal If the resin is very flowable, injection is facilitated but what about the mechanical properties (stiffness, yield stress, hardness, …)? The resins properties were obtained from shear rheometry, flexural vibration analysis, micro-indentation and micro-hardness.

International audience; The aim of this study was to compare and to observe the microleakage of an experimental cement (RD94), at present marketed (Biodentin, Septodont) used as dentin substitute in the " opened sandwich " technic for the restoration of cavities of class II with regard to that of a resin modified glass ionomer cement (RMGIC, Fuji II LC, GC).

The current study compared the marginal adaptation of Class II open-sandwich restorations with a RMGIC versus a dual-cure composite as dentin substitute. Class II cavities were prepared on 50 extracted human third molars. The teeth were randomly assigned to two groups of 25 teeth to compare one dual cure composite (MultiCore Flow) with one resin-modified glass-ionomer cement (Fuji II LC) in open-sandwich restorations recovered with a light cure composite. The teeth were thermomechanocycled (2000 cycles, 5 degrees C to 55 degrees C; 100,000 cycles, 50 N/cm2). The specimens were then sealed with a 1 mm window around the cervical margin interface. Samples were immersed in a 50% w/v ammoniacal silver nitrate solution for two hours and exposed to a photo-developing solution for six hours. The specimens were sectioned longitudinally and silver penetration was directly measured using a light microscope. The results were expressed as a score from 0 to 3. The data were analyzed with a non-parametric Kruskal and Wallis test. The degree of leakage significantly increased with MultiCore Flow (median 2) compared to Fuji II LC (median 1). Resin-modified glassionomer cements remain the best intermediate material when open-sandwich restorations are indicated. A comparison of the degradation of these materials over time remains a topic to be investigated by future studies.

National audience; The black soils of Limagne (Terres Noires de Limagne Massif-Central-France) are classified as chernozems, brunizems and vertisols, according to French soil taxonomy. Study of the mineralogical composition of the clay fraction in these soils shows the constant presence of smectite, becoming widely prevalent in the vertisolic soil facies. X-ray diffraction figures, as well as thermo-differential and thermo-ponderal analysis, showed special behaviour related to the presence of a smectite-organic matter complex. A characterization of the complex was made and a hypothesis is proposed on the localization of organic matter in relation to the layers and the tactoids.; Les Terres noires de Limagne rassemblent des sols qui, sur le plan génétique, sont à rattacher aux chernozems, aux brunizems et aux vertisols. L’étude de la composition minéralogique de la phase argileuse de ces différents sols révèle la présence constante d’une smectite, qui devient largement dominante dans le faciès vertisolique. La diffraction des rayons X et les analyses thermiques révèlent que cette smectite présente des propriétés particulières qui sont à relier à l’existence d’un complexe smectite-matière organique. Après avoir essayé de caractériser ce complexe par différentes méthodes, des hypothèses sont avancées sur la localisation de la matière organique par rapport aux feuillets et aux tactoïdes des smectites.

A pedogenesis of f ersial litic type is developed, by generalized way, on basalts of the Massif Central, in the Middle and Upper Miocene , between 21 and 6,5 millions of years. Its main characteristics can been summarized as follows : ochre or red in color in the whole profile, intense désintégration of parent rock, .occurrence of 2/1 and 1/1 clays in < 2 yx phases, and more or less wheathered primary minerals in the 2-50 p fraction, saturation higher than 50 % in all horizons, almost complete leaching of cations Ca, Mg, К and Na. These results exclude their connection with the ferrallitic domain and are compatible with an evo¬ lution of fersiallitic type., Une pédogénèse de type fersialitique s'est développée d'une manière généralisée sur les basaltes du Massif Central au Miocène moyen et terminal entre 21 et 6,5 millions d'années. Ses caractéristiques essentielles sont les suivantes : teinte ocre à rouge sur l'ensemble des profils, ameublissement plus ou moins intense de la roche mère, présence d'argiles 2/1 et 1/1 dans les phases < 2 pm. et de minéraux primaires plus ou moins altérés dans les fractions 2-50pm taux de saturation supérieur à 50 % dans tous les horizons, évacuation quasi totale des cations Ca, Mg, К et Na. Ces données excluent l'appartenance de ces sols au domaine ferrallitique et sont compatibles avec une évolution fersiallitique ., Chesworth W., Dejou Jean, De Kimpe C., Macias -Vasquez F., Cantagrel J.M., Larroque P., Garcia-Paz C., Garcia-Rodeja E. Importance de la fersiallitisation sur les basaltes miocènes du Massif Central : principales caractéristiques de cette pédogenèse. In: Pétrologie des altérations et des sols. Vol. III : Pédologie. Pétrologie appliquée aux substances utiles. Colloque international du CNRS, Paris 4-7 juillet 1983. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1983. pp. 53-62. (Sciences Géologiques. Mémoire, 73)

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