Low dimensional ordering and fluctuations in methanol-β\beta-hydroquinone-clathrate studied by X-ray and neutron diffraction

Methanol-$\beta$-hydroquinone-clathrate has been established as a model system for dielectric ordering and fluctuations and is conceptually close to magnetic spin systems. In X-ray and neutron diffraction experiments, we investigated the ordered structure, the one-dimensional (1D) and the three-dimensional (3D) critical scattering in the paraelectric phase, and the temperature dependence of the lattice constants. Our results can be explained by microscopic models of the methanol pseudospin in the hydroquinone cage network, in consistency with previous dielectric investigations

Ethical reflection in dentistry: first steps at the Faculty of Dental Surgery of Toulouse.

International audienceThe goal of this work is to contribute to ethical reflection in the dental profession through the example of a survey of ethical reflection and ethical issues in dentistry conducted at the dental school of Toulouse. A written survey was given to the heads of departments and to the sixth-year students and also to the dental faculty at the hospital dental clinic in order to estimate their level of understanding and concern about these topics

Absence of Helicobacter pylori in the oral cavity of 10 non-dyspeptic subjects demonstrated by real-time polymerase chain reaction

Helicobacter pylori plays a significant role in gastric disease. However, the presence of this bacterium in the oral cavity remains controversial. The aim of the present study was to detect and quantify H. pylori in 29 different sites of the oral cavity in non-dyspeptic subjects by means of real-time polymerase chain reactions (PCR). Ten subjects without gastric symptoms were studied. Samples from unstimulated saliva, three sites of the tongue, oral mucosa, and 12 sites of both supragingival and subgingival plaque were collected from each subject. DNA was extracted from the oral samples and analysed for the presence of H. pylori by real-time PCR (LightCycler) using JW23/22 primers which targeted the 16S rRNA gene. DNA from H. pylori DSM 4867 was used as a positive control. Amplification efficiency for the LightCycler 2.0 runs ranged from 1.8 to 2.4. Melting curve analysis identified all the positive control capillaries, which contained H. pylori reference DNA, as a single and narrow peak at a melting temperature between 84.5 and 84.9 degrees C. All the negative control capillaries with no template control and the 29 oral samples from each subject showed either no melting peaks or broad melting peaks below 80 degrees C, which were considered as primer dimers. Therefore, H. pylori was not detected from any of the 290 oral samples. As a conclusion, H. pylori seems not to be permanently present in the oral cavity of a non-dyspeptic population

Pressure dependence of the dielectric loss in semi-conducting polypyrrole aged at room temperature

The effect of physical aging of semi-conducting polypyrrole at ambient temperature for two years duration on the dielectric loss at various pressures is investigated. Changes of the dielectric loss spectra and the modification of the values of the activation volume for relaxation are interpreted through the division of chain clusters into smaller components and the reduction of the size of the conductive grains.Comment: Synthetic Metals (in print

IMPACT OF TYPE 2 DIABETES ON THE DEVELOPMENT OF PERIODONTAL DISEASE IN THE MOUSE

Oral Communication presented at the ";;Forum des Jeunes Chercheurs";;, Brest (France) 2011

Effect of fixed orthodontic appliances on salivary microbial parameters at 6 months:a controlled observational study

Objective: The aim of this study was to assess the microbial changes in children with fixed orthodontic appliances compared with a control group of children without orthodontic treatment. Material and Methods: Ninety-five children, aged between 12 and 16 years, participated in this study. Forty-eight subjects were fitted with fixed orthodontic appliances and forty-seven were free of any such appliances. The follow-up was 6 months for all children. The association between orthodontic appliances and high levels of Streptococcus mutans and Lactobacillus spp was assessed with logistic regression models, taking age, sex, pH and buffer capacity into account. Results: Differences at baseline between the two groups were not statistically significant. We found that wearing a fixed orthodontic appliance was associated with high levels of Streptococcus mutans and Lactobacillus spp (adjusted OR: 6.65, 95% CI [1.98-22.37]; 9.49, 95% CI [2.57-35.07], respectively), independently of other variables. Conclusion: The originality of the present epidemiological study was to evaluate the evolution of salivary microbial parameters in a population of children with fixed orthodontic appliances. Our results show an increase of Streptococcus mutans and Lactobacillus spp values during the follow-up. The whole dental workforce should be aware that preventive measures are of paramount importance during orthodontic treatment

Comparaison des techniques de culture et d’immuno-fluorescence dans l’étude de Bacteroides à pigmentation noire

The aim of that study was to compare culture and immunofluorescence (IF) methods to determine whether B.gingivalis and other B.P.B. can be detected in subgingival plaque of children.Samples were collected from the lingual sulcus of mandibular incisors, dispersed and diluted from 1 to 10-5; 15 µl of each dilution were plated on Trypticase soja agar and Todd-Hewitt agar supplemented with blood, Vit K 1 and hemin. The same dilutions were smeared on glass slides for indirect IF using an species-specific polyclonal rabbit whole cell antiserum to B.gingivalis ATCC 33 277. Representative colonies producing brown-to-black pigment were isolated, purified and further characterized.Using culture, BPB were detected in 46% of children (19/41). B.gingivalis was cultured from 6 children.Using immuno-fluorescence test (Fluotec*), 90% of 309 children 3 years old and more harbour detectable B.P.B., but B.gingivalis don’t react with that test. B.gingivalis were detected by immuno-fluorescence in 72% of children (30/41) in the incisor plaque.L’objectif de cette étude est de comparer les techniques de culture et d’immuno-fluorescence dans leurs capacités à retrouver B.gingivalis et les autres B.P.N. dans la plaque sous gingivale de l’enfant.Les échantillons sont recueillis au niveau du sulcus lingual des incisives mandibulaires, dispersés et diluís de 1 à 10-5; 15 µl de chaque dilution sont étalés sur milieux gélose Trypticase-soja et Todd-Hewitt enrichis de sang, de Vit K 1 et d’hémine. Les mêmes dilutions sont déposées sur lames de verre pour immunofluorescence indirecte en utilisant des antisérum cellules entières polyclonaux spécifiques contre B.gingivalis ATCC 33 277. Les colonies représentatives à coloration brun-noire sont isolées, purifiées et identifiées.Par culture, BPN est retrouvé chez 46% des enfants (19/41). B.gingivalis est cultivé à partir de 6 enfants.Par un test d’immuno-fluorescence (Fluotec*), 90% de 309 enfants de 3 ans et plus présentent des B.P.N., mais B.gingivalis n’est pas retrouvé par ce test. B.gingivalis est retrouvé par immuno-fluorescence chez 72% des enfants (30/41) dans la plaque des incisives

Maternal periodontitis and the causes of preterm birth: the case-control Epipap study.

International audienceAIM: To analyse the association between maternal periodontitis and preterm birth ( or =37 weeks) at six French maternity units were included. Periodontal examinations after delivery identified localized and generalized periodontitis. Cases were classified according to four causes of preterm birth. Polytomous logistic regression analysis was used to control for confounders (maternal age, parity, nationality, educational level, marital status, employment during pregnancy, body mass index before pregnancy, smoking status) and the examiner. RESULTS: Localized periodontitis was identified in 129 (11.6%) cases and in 118 (10.8%) control women and generalized periodontitis in 148 (13.4%) and 118 (10.8%), respectively. A significant association was observed between generalized periodontitis and induced preterm birth for pre-eclampsia [adjusted odds ratio 2.46 [95% confidence intervals (95% CI)1.58-3.83]. Periodontitis was not associated with spontaneous preterm birth or preterm premature rupture of membranes or with the other causes. CONCLUSION: Maternal periodontitis is associated with an increased risk of induced preterm birth due to pre-eclampsia

Effect of voxel size on the accuracy of 3D reconstructions with cone beam CT.

OBJECTIVES: The various types of cone beam CT (CBCT) differ in several technical characteristics, notably their spatial resolution, which is defined by the acquisition voxel size. However, data are still lacking on the effects of voxel size on the metric accuracy of three-dimensional (3D) reconstructions. This study was designed to assess the effect of isotropic voxel size on the 3D reconstruction accuracy and reproducibility of CBCT data. METHODS: The study sample comprised 70 teeth (from the Institut d\u27Anatomie Normale, Strasbourg, France). The teeth were scanned with a KODAK 9500 3D® CBCT (Carestream Health, Inc., Marne-la-Vallée, France), which has two voxel sizes: 200 µm (CBCT 200 µm group) and 300 µm (CBCT 300 µm group). These teeth had also been scanned with the KODAK 9000 3D® CBCT (Carestream Health, Inc.) (CBCT 76 µm group) and the SCANCO Medical micro-CT XtremeCT (SCANCO Medical, Brüttisellen, Switzerland) (micro-CT 41 µm group) considered as references. After semi-automatic segmentation with AMIRA® software (Visualization Sciences Group, Burlington, MA), tooth volumetric measurements were obtained. RESULTS: The Bland-Altman method showed no difference in tooth volumes despite a slight underestimation for the CBCT 200 µm and 300 µm groups compared with the two reference groups. The underestimation was statistically significant for the volumetric measurements of the CBCT 300 µm group relative to the two reference groups (Passing-Bablok method). CONCLUSIONS: CBCT is not only a tool that helps in diagnosis and detection but it has the complementary advantage of being a measuring instrument, the accuracy of which appears connected to the size of the voxels. Future applications of such measurements with CBCT are discussed