[Evaluation of the professional dentists' ability to determine the tooth shade guide: a pilot study]. / Evaluation de la capacité des professionnels en odontologie à déterminer la couleur des teintiers: étude pilote.

BACKGROUND: During its clinical practice, the dentist is often faced with issues concerning the determination of teeth shade. This step is considered sensitive by numerous clinicians and dental laboratories. The objective of this study was to test the ability of professional dentists to visually determine the teeth color. MATERIAL AND METHODS: Eleven dentists classified 35 unmarked samples according to their hue, chroma and value from 2 standardized tooth shade guides Ivoclar-Vivadent (Chromascop) et Vita (3D Master). The ratio between the number of matching samples and the total amount of samples from each group was calculated and converted to a score between 0 and 10. RESULTS: Better scores were obtained for value and chroma with the 3D Master shade guide than with the Chromascop shade guide (p < 0.001). The opposite result was obtained for the hue (p < 0.05). Globally, better results were obtained for the value and chroma, the hue being the most difficult item to evaluate. A satisfying "color perception" was observed in 69% of the cases. CONCLUSION: The results of this study argue in favor of a specific training for tooth shade determination in Odontology.

Influence of gamma-irradiation sterilization on the structural defects of sapphire single crystals (alpha-Al(2)O(3)).

The influence of sterilization by gamma rays on the structure and the electrical behaviour of sapphire single crystal (alpha-Al(2)O(3)) was studied successively by thermoluminescence, by cathodoluminescence and by observation of the scanning electron microscope mirror effect. The mirror method allowed us to measure the capacity of an insulating material to trap electrons. The structural analysis of the alpha-Al(2)O(3) showed that there were oxygen vacancies, as well as chromium and titanium impurities. It was possible to demonstrate that these defects, especially the oxygen vacancies, are in a different state after a 30 kilogray irradiation. The valency state changes of these defects and the presence of trapped charges are accompanied by a deformation of the crystalline lattice which results in a modification of its electrical properties. At room temperature, the irradiated alpha-Al(2)O(3), unlike non irradiated alpha-Al(2)O(3), is capable of trapping electrons. It can be concluded that gamma-ray sterilization modifies the cohesive energy of alpha-Al(2)O(3), which could lead to mechanical changes (surface charge, friction, wear, fracture strength, em leader) in this material.

An image analysis method for the study of cell adhesion to biomaterials.

This fluorescence image analysis method for the quantitative determination of cell adhesion on biomaterials allows bone cells labelled with propidium iodide to be counted automatically, directly on their support. The reliability of the estimation by fluorescence image analysis was validated by comparison with visual counting and with results obtained by an electronic particle counter. In this way it was possible to demonstrate that the adhesive properties of bone cells are dependent on the type of substrate--enstatite (MgO, SiO2, CaO-P2O5-Al2O3), Thermanox (modified polyethyleneterephthalate), or glass. In contrast, the spread of the cell cytoplasm, labelled with fluorescein isothiocyanate and measured by image analysis, does not vary significantly according to the substrate. The characterisation by SKIZ tessellation of the spatial cell arrangement shows that the bone cells have a random organisation on Thermanox and glass, whereas they form aggregates on enstatite.

Strategies to promote breast-feeding among adolescent mothers.

OBJECTIVE: To identify characteristics of adolescent mothers who bottle-feed who considered breast-feeding their infants and strategies to promote breast-feeding within this special group. DESIGN: Adolescents completed an hour-long interview within 48 hours of delivery that elicited factors considered important to the mother's feeding decision and indices of mental health. SETTING: Postpartum ward of university hospital. SUBJECTS: A total of 693 adolescents 18 years old or younger (mean age, 16.7 years) from African American, Mexican American, or white race or ethnicity; 27% of Mexican American participants spoke little or no English. MAIN OUTCOME MEASURES: Factors associated with breast-feeding decision. RESULTS: Those who chose bottle-feeding (hereafter, bottle-feeders) who had considered breast-feeding were first compared with bottle-feeders who had not considered breast-feeding and then with adolescents who breast-fed. After controlling for ethnicity, bottle-feeders who had considered breast-feeding were more likely than those who had not considered breast-feeding to be impoverished (adjusted odds ratio [AOR] = 4.8), to have delayed their feeding decision until the later stages of pregnancy (AOR = 4.6), to have been encouraged to breast-feed (AOR = 4.5), to have friends who breast-fed (AOR = 2.3), and to have experienced low financial, tangible, emotional, or informational support from their families (AOR = 1.6). They were more likely to cite barriers associated with breast-feeding while returning to school or work (AOR = 2.0) and less likely to state that bottle-feeding was healthier (AOR = 0.3) as reasons for bottle-feeding. Compared with those who chose breast-feeding (hereafter, breast-feeders), this group was more likely to have made the feeding decision alone rather than relying on advice (AOR = 4.6), to have made this decision in the later stages of pregnancy (AOR = 4.4), to report fewer breast-feeding role models (AOR = 1.8) and fewer significant others who encouraged breast-feeding (AOR = 2.8), and to report at least 2 significant others who encouraged bottle-feeding (AOR= 3.2). They were also less likely to have attempted to breast-feed a previous child (AOR = 3.3). CONCLUSIONS: A subgroup of adolescent mothers who had considered breast-feeding but ultimately chose to bottle-feed may be identified in the late stages of gestation by collecting information on financial status, family support, perceived barriers to breast-feeding and attending school or working, timing of the feeding decision, prior breast-feeding experience, breast-feeding role models, and encouragement to breast-feed. We speculate that strategies to promote breast-feeding should focus on role modeling and facilitation.

Effects of new machinable ceramic on behavior of rat bone cells cultured in vitro.

The behavior of cultured rat bone cells growing on modified polyethylene terephthalate (mPET), glass, and machinable ceramic substrates containing enstatite (MgO, SiO2) and glass (CaO-P2O5-Al2O3) was studied. Cell attachment was measured directly on the substrates using an image analysis system. Electron microscopy observations and the MTT test revealed that cells are able to spread and proliferate on the material surface, keeping a healthy ultrastructure on all materials tested in the present study. After having colonized the surface of the materials, as shown by immunocytochemistry, the cells synthesize an osteoid-like matrix composed of osteocalcin, type I collagen, and fibronectin fibrils. The titration of alkaline phosphatase activity showed that the cells grown on the ceramic exhibit a greater osteogenic activity than those grown on controls (glass and mPET). This osteogenic activity results in a mineralization of the extracellular matrix in cultures on ceramic or plastic whereas only few calcium phosphate crystallite traces were revealed by Von Kossa staining on glass. Enstatite constitutes, therefore, an environment compatible with in vitro bone cell life.

Racial/ethnic differences in the decision to breastfeed among adolescent mothers.

OBJECTIVE: To identify racial/ethnic differences in prevalence and the factors that influence decisions to breastfeed among adolescent mothers. METHODS: A total of 696 Mexican-American, African-American, and Caucasian adolescent mothers