Are mutans streptococci detected in preschool children a reliable predictive factor for dental caries risk? A systematic review

Research suggests that mutans streptococci play an important role in cariogenesis in children but the usefulness of bacterial testing in risk assessment is unknown. Our objective was to summarize the literature assessing the association of mutans streptococci and dental caries in preschool children, (Pre)Medline (1966-2003), Embase (1980-2003), the Cochrane Register of Controlled Trials (2003, issue 3), and reference lists of included studies were searched. All abstracts found by the electronic searches (n = 981) were independently scrutinized by 2 reviewers. Minimal requirements for inclusion were assessment of preschool children without caries at baseline, reporting of mutans streptococci present in saliva or plaque at baseline and assessment of caries presence after a minimum of 6 months of follow-up. Participants' details, test methods, methodological characteristics and findings were extracted by one reviewer and cross-checked by another. Homogeneity was tested using chi2 tests. Results of plaque and saliva testing were pooled separately using a fixed effects model. Methodological quality of reports was low. Out of 9 studies included, data from 3 reports on plaque test assessment alone (n = 300) and from 4 reports on saliva test assessment alone (n = 451) were available for pooled analysis. The pooled risk ratio (95% CI) was 3.85 (2.48-5.96) in studies using plaque tests and 2.11 (1.47-3.02) in those using saliva testing. Presence of mutans streptococci, both in plaque or saliva of young caries-free children, appears to be associated with a considerable increase in caries risk. Lack of adjustment for potential confounders in the original studies, however, limits the extent to which interpretations for practice can be made.

In-vivo-Untersuchungen und „Desensibilisierung“

Bei korrekter Durchführung sind Prickund Patch-Haut-Testungen für den Patienten ungefährlich und benötigen keinen großen apparativen Aufwand. Intradermale Testungen können dagegen selten mit generalisierten Reaktionen einhergehen. Bei einer Anamnese mit schwerer Reaktion empfiehlt sich deshalb ein serielles Vorgehen mit erst Prick- und/oder Patch-Testungen; die intradermale Testung kann und soll nur im Falle einer ausbleibenden Reaktion zur weiteren Abklärung eingesetzt werden. Neuere Daten zeigen, dass Hauttestungen selbst bei der Abklärung schwerer oder gefährlicher Hypersensitivitätsreaktionen mit kleinem und gut vertretbarem Risiko durchgeführt werden können. In nicht irritativen Konzentrationen ist die Spezifität von Hauttesten bei vielen Medikamenten recht gut (> 85%). Die Testsensitivität variiert je nach Medikament, Art der Reaktion, zeitlichem Abstand zur Reaktion und Art des Testes. In der Regel ist sie zu klein, um einen starken klinischen Allergieverdacht entkräften zu können. Für die Diagnose einer Medikamentenallergie gibt es keinen verlässlichen goldenen Standard. Eine Reaktion bei einer doppelblinden Provokationstestung spricht für eine reproduzierbare substanzspezifische Unverträglichkeit, besagt aber nichts über den Pathomechanismus und belegt insbesondere nicht eine Allergie. Provokationstestungen können bei Soforttypreaktionen hilfreich sein, um einen unnötigen Verzicht auf wichtige Therapie-Optionen zu vermeiden. Bei Spättyp-Reaktionen sind aussagekräftige Provokationstestungen in der Regel schwierig, oder gar nicht durchführbar. Eine Provokationstestung mit dem mutmaßlich auslösenden Medikament sollte nur dann durchgeführt werden, wenn die Diagnose nicht mit anderen Methoden gestellt werden kann und es sich um ein für den betroffenen Patienten sehr wichtiges Medikament handelt.

Diffusion of HTO, Br-, I-, Cs+, Sr-85(2+) and Co-60(2+) in a clay formation: Results and modelling from an in situ experiment in Opalinus Clay

The migration of radioactive and chemical contaminants in clay materials and argillaceous host rocks is characterised by diffusion and retention processes. Valuable information on such processes can be gained by combining diffusion studies at laboratory scale with field migration tests. In this work, the outcome of a multi-tracer in situ migration test performed in the Opalinus Clay formation in the Mont Terri underground rock laboratory (Switzerland) is presented. Thus, 1.16 x 10(5) Bq/L of HTO, 3.96 x 10(3) Bq/L of Sr-85, 6.29 x 10(2) Bq/L of Co-60, 2.01 x 10(-3) mol/L Cs, 9.10 x 10(-4) mol/L I and 1.04 x 10(-3) mol/L Br were injected into the borehole. The decrease of the radioisotope concentrations in the borehole was monitored using in situ gamma-spectrometry. The other tracers were analyzed with state-of-the-art laboratory procedures after sampling of small water aliquots from the reservoir. The diffusion experiment was carried out over a period of one year after which the interval section was overcored and analyzed. Based on the experimental data from the tracer evolution in the borehole and the tracer profiles in the rock, the diffusion of tracers was modelled with the numerical code CRUNCH. The results obtained for HTO (H-3), I- and Br- confirm previous lab and in situ diffusion data. Anionic fluxes into the formation were smaller compared to HTO because of anion exclusion effects. The migration of the cations Sr-85(2+), Cs+ and Co-60(2+) was found to be governed by both diffusion and sorption processes. For Sr-85(2+), the slightly higher diffusivity relative to HTO and the low sorption value are consistent with laboratory diffusion measurements on small-scale samples. In the case of Cs+, the numerically deduced high diffusivity and the Freundlich-type sorption behaviour is also supported by ongoing laboratory data. For Co, no laboratory diffusion data were yet available for comparison; however, the modelled data suggests that Co-60(2+) sorption was weaker than would be expected from available batch sorption data. Overall, the results demonstrate the feasibility of the experimental setup for obtaining high-quality diffusion data for conservative and sorbing tracers. (C) 2007 Elsevier Ltd. All rights reserved.