Aux bords de l'institution policière. Les délégués à la cohésion police-population (DCPP) en recherche de crédibilité

National audienc

Prevalence of Apical Bone Defects and Evaluation of Associated Factors Detected with Cone-beam Computed Tomographic Images.

INTRODUCTION: Cone-beam computed tomographic (CBCT) imaging has been shown to be accurate for detecting apical bone defects (ABDs). Medium field of view CBCT imaging may provide apical images of the whole oral cavity at a resolution that is sufficient to allow ABDs to be located and measured. The aim of the work presented was to calculate the prevalence of ABDs from CBCT images as well as to assess some associated factors and their measurement. METHODS: One hundred CBCT data sets with a voxel size of 0.2 mm were analyzed by 2 evaluators according to a standardized reading protocol. The number of maxillary and mandibular teeth, the presence of endodontic treatment, and the presence of ABDs associated with endodontic treatment were identified, and the presence of intraradicular posts was documented. The size of ABDs detected was measured, and they were classified according to the Cone Beam Computed Tomography Periapical Index. RESULTS: A total of 2368 teeth and 100 subjects were analyzed. The prevalence of ABDs in subjects was 78%; in 8.6% of the sample teeth, ABDs were present, and 38.2% of endodontically treated maxillary molars were affected by it. Endodontic treatment was significantly associated with an increased risk for the presence of an ABD (P = .0001); 40.8% of endodontically treated teeth were associated with an ABD. This rate increased to 85.9% in endodontically treated maxillary molars. Placement of a post was significantly associated with the presence of an ABD (P = .003). The most frequent lesions were those with diameters between 2 and 4 mm (39.2%). CONCLUSIONS: There are only few studies on the prevalence of ABDs using CBCT analysis. This study in a French population shows a high prevalence of ABDs, especially on endodontically treated molars. The most effective way to exhaustively detect such defects is with CBCT imaging. Moreover, CBCT images show details of the extent of bone loss, thus providing information valuable for the therapeutic decision and details that could help with the prognosis

Fine and hyperfine excitation of NH and ND by He: On the importance of calculating rate coefficients of isotopologues

International audienceThe NH and ND molecules play an important role in interstellar nitrogen chemistry. Accurate modeling of their abundance in space requires the calculation of rates for collisional excitation by the most abundant interstellar species. We calculate rate coefficients for the fine and hyperfine excitation of NH and ND by He. State-to-state rate coefficients between the first levels of NH and ND were obtained for temperatures ranging from 5 to 150 K. Fine structure resolved rate coefficients present a strong propensity rule in favor of Δj = ΔN transitions, as expected from theoretical considerations. The Δj = ΔF1 = ΔF propensity rule is observed for the hyperfine transitions of both isotopologues. The two sets of fine structure resolved rate coefficients are compared in detail and we find significant differences between the two isotopologues. This comparison shows that specific calculations are necessary for the deuterated isotopologues of any hydride. The new rate coefficients will help significantly in the interpretation of NH and ND terahertz spectra observed with current and future telescopes, and enable these molecules to become a powerful astrophysical tool for studying the nitrogen chemistry