[Influence of natural fluoride concentration in drinking water on dental health of first class pupils in an area with enhanced fluoride content at the beginning of the 21st century]. / Auswirkung des Trinkwasserfluoridgehalts auf die Zahngesundheit von Erstklässlern in einem Gebiet mit natürlich erhöhter Fluoridkonzentration zu Beginn des 21. Jahrhunderts.

BACKGROUND: Since the end of the first half of the 20 (th) century it is well-known that fluoride concentrations in drinking water of about 1 ppm reduce the prevalence of dental caries by about 40-60%. This knowledge led to the fluoridation of drinking water during the second half of the 20 (th) century in many countries, including East Germany. Although the natural F (-) content in drinking water in Germany is usually very low, the eastern Eifel is one of the few larger areas in Germany with (nearly) optimal (0.7-1.0 ppm) or moderately enhanced (0.3-0.7 ppm) natural fluoride concentrations in drinking water. 30 years ago, in 1977, the caries prevalence of children of various age groups in the fluoride-rich areas of the eastern Eifel was established by Einwag to be about 40% lower than in adjacent fluoride-poor regions (0.1 ppm). Meanwhile fluoride has become available from many different sources for children of any age: e. g., toothpaste (with 500 ppm fluoride even for very young children who just got the first tooth), fluoridated salt, professional fluoride applications (paid by health insurances), the rising consumption of mineral waters (many of which have a fluoride content >0.3 ppm). This poses the question of the current influence of enhanced natural drinking water fluoride concentrations on caries prevalence in children. METHOD AND RESULTS: The results of the dental examinations of 9 555 pupils (6 or 7 years old) of the first classes of all 63 primary schools in the Landkreis Mayen-Koblenz from 5 years (2004/2005-2008/2009) are compared to the fluoride content of the drinking water. The data show no obvious correlation between dental health and fluoride concentration for any of the dental health parameters investigated. However, in spite of the low geographic resolution of social parameters, there was a notable connection between dental health status and sociodemographic indicators for the respective region. DISCUSSION: 30 years after the study by Einwag in the same region, the natural fluoride content of drinking water either had no influence on dental health at all, or this influence is so diminutive that it is exceeded by far by sociodemographic factors. Obviously there is much more fluoride available from other sources nowadays compared to 30 years ago. The results may also have implications for the administration of fluoride tablets and support the recommendations of the DGZMK (Deutsche Gesellschaft für Zahn-, Mund- und Kieferheilkunde) from the year 2000, restricting the administration of fluoride tablets to special situations following an individual anamnesis of fluoride uptake.

Laser scanning microscopy study on adsorption of biologically relevant proteins on implant materials.

The adsorption of proteins at implant surfaces plays a key role in osseointegration and is therefore of great importance in biomaterial science. Laser scanning microscopy (LSM) is described, a method that is used here for the first study of the adsorption of proteins on implant surfaces. These LSM measurements provide information on the surface morphology, and the spatial distribution of adsorbed proteins can be deduced.

[Caries prevalence and state of treatment in the case of Koblenz children in the first school class with reference to district-related social indicators]. / Kariesprävalenz und -sanierung bei Koblenzer Erstklässlern in Bezug zu stadtteilbezogenen Sozialindikatoren.

The findings of the dental medical examinations of the school years 1996/1997 and 1997/1998 in the first classes of primary schools in Koblenz have been associated with district-related social indicators given in the social report for Koblenz, and more especially the "proportion of recipients of social welfare assistance among the 0-13 year-olds" indicator. The caries prevalence indices as well as the treatment deficits, the proportion of those needing treatment and the proportion of children with increased risk of caries clearly increased parallel with the proportion of social welfare assistance amongst the children although the greatest difference was seen in the case of districts with average social welfare assistance density and such with high/very high social welfare assistance density. Even at individual school levels a close connection could be established between the proportion of social welfare assistance recipients amongst the 0-13 year-olds in the school district and a) the proportion of children with increased caries risk in accordance with DAJ (Deutsche Arbeitsgemeinschaft für Jugendzahnpflege) criteria (r(s) = + 0.881) as well as b) a multi-factorial "first school class dental health index" (EZI) (which covered both prevalence and treatment parameters and also findings below the risk threshold of the DAJ criteria) developed for comparing the schools with each other (r(s) = + 0.825). The six "risk schools" (from 22 primary schools) determined by a) the proportion of children with increased caries risk according to DAJ criteria, b) the multi-factorial EZI and c) the social welfare assistance proportion amongst the 0-13 year-olds in the school district, are identical. In comparison with the complex multi-factorial first school class dental health index (EZI), the study confirms the general suitability of the "proportion of children with increased caries risk" for the identification of schools with above-average deficit in dental health care. However, at the same time such "risk schools" - at least in the towns with documented social differentiation of the resident population in the various town districts - can also be determined by the district-related social indicators. This may be significant in such cases where there are no dental examination results (determined according to uniform criteria) available for all schools in one town or region, but specific measures (for example examinations, prevention, fluoridation) should be concentrated on schools with greater need for such measures.

Discontinuous single electrode voltage-clamp measurements: assessment of clamp accuracy in Vicia faba guard cells.

The use of a discontinuous single electrode voltage-clamp (dSEVC) offers an attractive alternative to the patch-clamp technique, since whole-cell measurements can be performed with a single sharp electrode. Comparison of current-voltage relations, however, revealed a weaker voltage dependence of channels measured with the dSEVC compared to patch clamp. The accuracy of the dSEVC was tested on Vicia faba guard cells impaled with double-barrelled electrodes. The actual clamp potential was measured independently of the dSEVC, at the second barrel. The weaker voltage dependence of ion channels appeared to be due to an overestimation of the clamp potential by the dSEVC. The deviation between the intended and actual clamp potential showed a linear relationship with the injected current; on average a 126 mV deviation was found for a clamp current of 1 nA. The deviation was probably caused by a slow settling capacity at the electrode, not compensated by the dSEVC amplifier. It is concluded that the dSEVC method in its current state is only suited for the study of small ion conductances in plant cells.

Single guard cell recordings in intact plants: light-induced hyperpolarization of the plasma membrane.

Guard cells are electrically isolated from other plant cells and therefore offer the unique possibility to conduct current- and voltage-clamp recordings on single cells in an intact plant. Guard cells in their natural environment were impaled with double-barreled electrodes and found to exhibit three physiological states. A minority of cells were classified as far-depolarized cells. These cells exhibited positive membrane potentials and were dominated by the activity of voltage-dependent anion channels. All other cells displayed both outward and inward rectifying K+-channel activity. These cells were either depolarized or hyperpolarized, with average membrane potentials of -41 mV (SD 16) and -112 mV (SD 19), respectively. Depolarized guard cells extrude K+ through outward rectifying channels, while K+ is taken up via inward rectifying channels in hyperpolarized cells. Upon a light/dark transition, guard cells that were hyperpolarized in the light switched to the depolarized state. The depolarization was accompanied by a 35 pA decrease in pump current and an increase in the conductance of inward rectifying channels. Both an increase in pump current and a decrease in the conductance of the inward rectifier were triggered by blue light, while red light was ineffective. From these studies we conclude that light modulates plasma membrane transport through large membrane potential changes, reversing the K+-efflux via outward rectifying channels to a K+-influx via inward rectifying channels.

KAT1 is not essential for stomatal opening.

It is generally accepted that K(+) uptake into guard cells via inward-rectifying K(+) channels is required for stomatal opening. To test whether the guard cell K(+) channel KAT1 is essential for stomatal opening, a knockout mutant, KAT1En-1, was isolated from an En-1 mutagenized Arabidopsis thaliana population. Stomatal action and K(+) uptake, however, were not impaired in KAT1-deficient plants. Reverse transcription-PCR experiments with isolated guard cell protoplasts showed that in addition to KAT1, the K(+) channels AKT1, AKT2/3, AtKC1, and KAT2 were expressed in this cell type. In impalement measurements, intact guard cells exhibited inward-rectifying K(+) currents across the plasma membrane of both wild-type and KAT1En-1 plants. This study demonstrates that multiple K(+) channel transcripts exist in guard cells and that KAT1 is not essential for stomatal action.

Dynamics of ionic activities in the apoplast of the sub-stomatal cavity of intact Vicia faba leaves during stomatal closure evoked by ABA and darkness.

Stomatal movement is accomplished by changes in the ionic content within guard cells as well as in the cell wall of the surrounding stomatal pore. In this study, the sub-stomatal apoplastic activities of K+, Cl-, Ca2+ and H+ were continuously monitored by inserting ion-selective micro-electrodes through the open stomata of intact Vicia faba leaves. In light-adapted leaves, the mean activities were 2.59 mM (K+), 1.26 mM (Cl-), 64 microM (Ca2+) and 89 microM (H+). Stomatal closure was investigated through exposure to abscisic acid (ABA), sudden darkness or both. Feeding the leaves with ABA through the cut petiole initially resulted in peaks after 9-10 min, in which Ca2+ and H+ activities transiently decreased, and Cl- and K+ activities transiently increased. Thereafter, Ca2+, H+ and Cl- activities completely recovered, while K+ activity approached an elevated level of around 10 mM within 20 min. Similar responses were observed following sudden darkness, with the difference that Cl- and Ca2+ activities recovered more slowly. Addition of ABA to dark-adapted leaves evoked responses of Cl- and Ca2+ similar to those observed in the light. K+ activity, starting from its elevated level, responded to ABA with a transient increase peaking around 16 mM, but then returned to its dark level. During stomatal closure, membrane potential changes in mesophyll cells showed no correlation with the K+ kinetics in the sub-stomatal cavity. We thus conclude that the increase in K+ activity mainly resulted from K+ release by the guard cells, indicating apoplastic compartmentation. Based on the close correlation between Cl- and Ca2+ changes, we suggest that anion channels are activated by a rise in cytosolic free Ca2+, a process which activates depolarization-activated K+ release channels.

[Academic recommendations on the need for treating carious deciduous molars and canine teeth in elementary school children--results of a survey of university dental clinics]. / Lehrmeinungen zur Behandlungsnotwendigkeit kariäoser Milchmolaren und -eckzähne im Grundschulalter--Ergebnisse einer Umfrage bei Universitätszahnkliniken.

Supplying recommendations for dental treatment to primary school children with decayed deciduous molars and canines by the Public Health Service may cause conflicts. An inquiry by letter was performed to look for a consensus concerning the degree of necessity of the treatment of decayed deciduous teeth. The German dental clinics who answered the questions unanimously disapproved the "Retaining" of decayed deciduous molars and canines without treatment; most of them recommended a conservative therapy until shortly before they become physiologically defunct, or, alternatively, the removal of the decayed teeth.

[Ossifying fibroma of the bone]. / Das ossifizierende Knochenfibrom (OF).

In the spectrum of the fibroosseous bone tumours the ossifying fibroma of the bone (OF) is situated as a not yet clearly defined entity with many names. The present paper deals with the question wether a term innovation brings elucidation to clinical management. Therefore 811 previously published and 16 additional cases have been analysed with respect to their clinical and radiological behavior. In addition a simplificated histological reclassification was performed on 284 well documented literature cases. It was found that there are no great differences between these tumours according to their localisation, their clinical behavior, and their prognosis. All tumours of this group are suitable to different categories of histological maturation of the same tumour best called "ossifying fibroma".