Comparison of microleakage under orthodontic brackets bonded with five different adhesive systems: in vitro study

BACKGROUND

Orthodontic treatment is associated with numerous adverse side effects, such as enamel discoloration, demineralization or even caries. The presence of microleakage between the enamel and the adhesive and between the adhesive and the base of the orthodontic bracket allows penetration of the bacteria, molecules, and liquids into the enamel and can lead to unpleasant "white spot lesions" or secondary caries beneath and around the brackets. The aim of this in vitro study was to evaluate microleakage in five adhesive systems commonly used in orthodontic practice for bonding brackets.

METHODS

One hundred extracted premolars were divided into five groups of twenty teeth. Stainless steel Legend medium metal brackets were bonded to teeth using five adhesive systems: resin-reinforced glass ionomer cement GC Fuji Ortho LC (GCF) and composite materials Light Bond (LB), Transbond XT (TB), Trulock™ Light Activated Adhesive (TL), and GC Ortho Connect (GCO). The specimens were subjected to thermal cycling, stained with 2% methylene blue, sectioned with low-speed diamond saw Isomet and evaluated under a digital microscope. Microleakage was detected at the enamel-adhesive and adhesive-bracket interfaces from occlusal and gingival margins. Statistical analysis was performed using generalized linear mixed models with beta error distribution.

RESULTS

Microleakage was observed in all materials, with GCF showing the highest amount of microleakage. Composite materials GCO, TB, and LB exhibited the lowest amount of microleakage with no statistical difference between them, while TL showed a statistically significantly higher amount of microleakage (p < 0.001). The enamel-adhesive interface had more microleakage in all composite materials (GCO, LB, TB, and TL) than the adhesive bracket-interface (p < 0.001). The highest amount of microleakage occurred in the gingival region in all materials.

CONCLUSION

Composite materials showed better adhesive properties than a resin-reinforced glass ionomer cement. The presence of microleakage at the enamel-adhesive interface facilitates the penetration of various substances into enamel surfaces, causing enamel demineralization and the development of dental caries.

Landscape epidemiology of neglected tick-borne pathogens in central Europe

Studies of tick-borne diseases (TBDs) in Europe focus on pathogens with principal medical importance (e.g. Lyme disease and tick-borne encephalitis), but we have limited epidemiological information on the neglected pathogens, such as the members of the genera Anaplasma, Rickettsia, Babesia and Candidatus Neoehrlichia mikurensis. Here, we integrated an extensive field sampling, laboratory analysis and GIS models to provide first publicly available information on pathogen diversity, prevalence and infection risk for four overlooked zoonotic TBDs in the Czech Republic. In addition, we assessed the effect of landscape variables on the abundance of questing ticks at different spatial scales and examined whether pathogen prevalence increased with tick density. Our data from 13,340 ticks collected in 142 municipalities showed that A. phagocytophilum (MIR = 3.5%) and Ca. Neoehrlichia mikurensis (MIR = 4.0%) pose geographically uneven risks with localized hotspots, while Rickettsia (MIR = 4.9%) and Babesia (MIR = 1.1%) had relatively homogeneous spatial distribution. Landscape variables had significant effect on tick abundance up to the scale of 1 km around the sampling sites. Questing ticks responded positively to landscape diversity and configuration, especially to forest patch density that strongly correlates with the amount of woodland-grassland ecotones. For all four pathogens, we found higher prevalence in places with higher densities of ticks, confirming the hypothesis that tick abundance amplifies the risk of TB infection. Our findings highlight the importance of landscape parameters for tick vectors, likely due to their effect on small vertebrates as reservoir hosts. Future studies should explicitly investigate the combined effect of landscape parameters and the composition and population dynamics of hosts on the host-vector-pathogen system.

Rodent Host Abundance and Climate Variability as Predictors of Tickborne Disease Risk 1 Year in Advance

Using long-term data on incidences of Lyme disease and tickborne encephalitis, we showed that the dynamics of both diseases in central Europe are predictable from rodent host densities and climate indices. Our approach offers a simple and effective tool to predict a tickborne disease risk 1 year in advance.

Does EmbryoGlue transfer medium affect embryo transfer success rate?

OBJECTIVE

Verification of the effect of EmbryoGlue (EG) transfer medium enriched with hyaluronan on the embryo transfer success rate.

DESIGN

A prospective study.

SETTING

Fertimed, Fertility Treatment Centre, Olomouc.

METHODS

484 patients undergoing IVF + ET were engaged who were divided according to the medium used during transfer: Sage or Vitrolife culture medium (n = 135) and EG transfer medium (n = 349). The influence of other factors was also evaluated: age, number of received oocytes, percentage of fertilised oocytes, endometrium height on the day of transfer, number of preserved embryos, number of transferred embryos and the length of cultivation (48, 72, 96, 120 h). These factors were considered quantitative variables while the method of hormone stimulation, the type of culture medium and the application of EG were considered qualitative (categorical) variables.

RESULTS

With the use of EG the chances of conception increased by approximately 9%. The negative effect of higher age on implantation proportion and the positive effect of cultivation prolongation were proven. The effect of EG on miscarriages was not proven. The probability of miscarriage diminished with higher oocyte fertilisation. The culture medium used (Sage or Vitrolife) before the application of EG does not affect the gravidity result.

CONCLUSION

Using the transfer medium of EmbryoGlue before embryo transfer affects the pregnancy rate (PR) in a positive manner. The influence on pregnancy loss with the application of EG was not proven.

HCG level after embryo transfer as a prognostic indicator of pregnancy finished with delivery

OBJECTIVE

To examine patients after embryo transfer for predictive influence of the human chorionic gonadotropin (hCG) level on the probability of finishing pregnancy with delivery.

DESIGN

Retrospective study.

SETTING

Fertimed, Fertility Treatment Centre, Olomouc.

METHODS

490 patients pregnant after IVF + ET treat-ment placed in the study. The influence of other factors: age (patients 20-50), number of transferred embryos (one, two and more) and the length of cultivation on the probability of finishing pregnancy with delivery or loss and the possibility to predict multiple pregnancy was also related to the known hCG value. The transferred embryos were divided into two groups - early (cultivation 48 and 72 hrs) and prolonged cultivation (PC 96 and 120 hrs). The answer here, therefore, is a multinomial variable with four levels. For that reason the data was analysed through a multinomial logistic model vs. multinomial distribution of a mistake and generalised logistic link function.

RESULTS

The hCG level grows exponentially in the course of the 9th to 17th day after an embryo transfer (ET). The probability of one child delivery after the transfer of one embryo overdue after prolonged cultivation (96 or 120 hrs) grows with the average and above-average hCG values on the day of the draw. The hCG value was 678 (564-815) IU/l1 on the 14th day after ET in pregnancy ended in delivery, 321 (216-477) IU/l on average in abortion, 82 (51-132) IU/l in biochemical pregnancy and 1070 (737-1554) IU/l in multiple pregnancy. The probability of multiple pregnancy increased with hCG values greatly above the average and on the other hand, below-average values indicated abortion or biochemical pregnancy. The patients age was not proven to be of significant influence, the hCG level slightly decreased with higher age. On the contrary, an increasing frequency of abortions depending on the increasing age of the mother was once again confirmed.

CONCLUSION

The measured hCG values are considerably different depending on the pregnancy result, which is why this value is considered a quality predictive factor of the pregnancy result.

Dissecting geographic variation in population synchrony using the common vole in central Europe as a test bed

Spatial synchrony of population fluctuations is ubiquitous in nature. Theoretical models suggest that correlated environmental stochasticity, dispersal, and trophic interactions are important promoters of synchrony in nature to leave characteristic signatures of distance‐dependent decays in synchrony. Recent refinements of this theory have clarified how distance‐decay curves may steepen if local dynamics are governed by different density‐dependent feedbacks and how synchrony should vary regionally if the importance and correlation of environmental stochasticity is location‐specific. We analysed spatiotemporal data for the common vole, Microtus arvalis from 49 districts in the Czech Republic to examine the pattern of population synchrony between 2000 and 2014. By extending the nonparametric covariation function, we develop a quantitative method that allows a dissection of the effects of distance and additional variables such as altitude on synchrony. To examine the pattern of local synchrony, we apply the noncentered local‐indicators of spatial association (ncLISA) which highlights areas with different degrees of synchrony than expected by the region‐wide average. Additionally, in order to understand the obtained pattern of local spatial correlations, we have regressed LISA results against the proportion of forest in each district. The common vole abundances fluctuated strongly and exhibited synchronous dynamics with the typical tendency for a decline of synchrony with increasing distance but, not with altitude. The correlation between the neighbor districts decreases as the proportion of forest increases. Forested areas are suboptimum habitats and are strongly avoided by common voles. The investigation of spatiotemporal dynamics in animal populations is a key issue in ecology. Although the majority of studies are focused on testing hypotheses about which mechanisms are involved in shaping this dynamics it is crucial to understand the sources of variation involved in order to understand the underlying processes.

Density-dependent life histories in female bank voles from fluctuating populations

Using long-term data sets from two lowland floodplain forest bank vole populations in central Europe, we tested two predictions that with increasing densities: (i) proportions of nonparous females in winter populations would increase; and (ii) age of both nonparous and parous females would increase. These two predictions follow from the assumption that changes in age structure are driven by density-dependent shifts in age at first reproduction. Both populations were sampled by snap trapping between 1956 and 1976. For each year, we examined samples of animals collected between November and April for proportions of females with and without breeding experience and analysed their variation in age relative to the population density. The presence or absence of placental scars was used to discriminate between the parous and nonparous animals. Age was determined by measuring the length of the first mandibular molar (M1 ) roots. Both populations exhibited multi-annual fluctuations in numbers closely resembling those in northern Fennoscandia. The proportion of nonparous females in our total sample was 0.73, suggesting that it is uncommon for parous female bank voles to breed in two successive years and that their life histories are largely designed for breeding in one season only as a major reproductive strategy. Using a logistic-binomial regression model, we found that the probability of females being nonparous or parous at capture varied significantly with time, space and population density. The final model producing the best fit to data predicted that the proportion of nonparous females would be slightly larger over winter and substantially larger after high-density breeding seasons, which is consistent with the tested prediction. With increasing densities during the breeding seasons, both the nonparous and parous females became older at the onset of winter. Again, the field evidence was consistent with the predicted pattern. The age of parous females in the autumn at high densities was older, mainly because of an increased proportion of females entering their second winter. We propose a new intrinsic mechanism by which a delayed density dependence in age-specific fitness components can arise in microtines. This mechanism, based on an increased bimodality in age at first reproduction towards northern latitudes, has a potential to explain the south-north gradient in cyclicity observed in microtine populations in Fennoscandia.

Europe-wide dampening of population cycles in keystone herbivores

Suggestions of collapse in small herbivore cycles since the 1980s have raised concerns about the loss of essential ecosystem functions. Whether such phenomena are general and result from extrinsic environmental changes or from intrinsic process stochasticity is currently unknown. Using a large compilation of time series of vole abundances, we demonstrate consistent cycle amplitude dampening associated with a reduction in winter population growth, although regulatory processes responsible for cyclicity have not been lost. The underlying syndrome of change throughout Europe and grass-eating vole species suggests a common climatic driver. Increasing intervals of low-amplitude small herbivore population fluctuations are expected in the future, and these may have cascading impacts on trophic webs across ecosystems.

The distribution and spreading pattern of Dermacentor reticulatus over its threshold area in the Czech Republic--how much is range of this vector expanding?

Host-seeking Dermacentor reticulatus ticks were detected by flagging method at 46 localities at south-east part of the Czech Republic, in the basins of rivers Morava and Dyje. Exact north-west distribution limits of D. reticulatus were defined in this area for the first time. Detailed prediction map of probabilities of D. reticulatus occurrence was obtained using GIS analysis. Spatial model delimited a south-north gradient in probability across the studied area, with highest probabilities above 0.8 in its southernmost part. Abundance of D. reticulatus varied markedly between localities in interval 0.33-222 of ticks per flag per hour. The highest abundances were in flooded areas at lower streams, towards upper streams abundance and density of these ticks decreased. Females prevailed in samples with population sex ratio of 0.413, significantly deviating from parity. Larvae and nymphs of this species were not detected by flagging. Although D. reticulatus range expansion probably did not reach such a degree as reported in other countries, these ticks became very abundant in some parts of studied area. Since spreading of vector-borne diseases became a problem in Europe, the knowledge of their exact recent geographic ranges is important for future modelling of their shift predictability.

Tula virus in populations of small terrestrial mammals in a rural landscape

Over 5 years (2000-2004), populations of small mammals from a rural landscape in southern Moravia (Czech Republic) were investigated for the presence of Tula virus (TULV) antigen using the ELISA set Hantagnost. In total, 1566 individuals from 10 species were examined. The prevalence in the common vole (Microtus arvalis Pallas 1778), the main reservoir of TULV, was 10% (n = 871). The prevalence of TULV antigen increases with its population numbers. The highest number of TULV antigen-positive common voles was found in set-aside plots and winter crops, such as rape and winter wheat. All these habitats are important for common vole overwintering. Older and heavier individuals were more often hantavirus antigen positive. From the other small mammal species, 186 pygmy field mice (Apodemus uralensis Pallas, 1811) were examined, of which 3 were positive, which represents the first hantavirus antigen positive record for this species, and of 195 wood mice (Apodemus sylvaticus Linnaeus, 1758) only 1 was positive. The remaining five rodent species (Apodemus flavicollis Melchior, 1834, Mus musculus Linnaeus, 1758, Micromys minutus Pallas, 1771, Myodes glareolus Schreber, 1780, Microtus subterraneus de Sélys-Longchamps, 1836) and two Soricomorpha (Sorex araneus Linnaeus, 1758, Sorex minutus Linnaeus, 1766) were hantavirus antigen negative.

Is there a declining trend in ovarian function among infertility clinic patients?

BACKGROUND

There is a growing body of evidence that testicular function has decreased rapidly over the last 50 years. However, much less is known about corresponding trends in ovarian function. Herein, we examine the temporal changes in ovarian function in a large sample of infertile patients from the Czech Republic over a period of 14 years.

METHODS

In a retrospective study, we analysed a large body of data from women, 20-40 years of age, undergoing IVF/ICSI treatment between 1995 and 2008. We defined ovarian function using five variables: basal FSH level, estradiol (E2) level on the day of HCG administration, dose of gonadotrophins used for ovarian stimulation, number of retrieved oocytes and dose of gonadotrophins per oocyte. Controlling simultaneously for temporal changes in patient age and stimulation protocol, we applied generalized additive models to describe the temporal trends.

RESULTS

During the study period the mean age of the study population increased by 2.7 years. Whereas the basal FSH and gonadotrophin dose did not change over time, the E2 level and oocyte retrieval declined, and the dose of FSH per oocyte increased during the study period.

CONCLUSIONS

The results are indicative of a small, but detectable decrease in ovarian function over a period of 14 years, which is not causally related to the ageing population.

[The age of women treated for infertility increases]

OBJECTIVE

The age of women at first child in the Czech Republic increases. We investigated whether this trend translates into the group of patients treated for infertility by IVF.

SETTING

Fertimed, infertility centre, Olomouc.

METHODS

We summoned data from 4689 women treated for infertility in our centre. We investigated the age of the patient, FSH levels, E2 levels, number of FSH units needed for ovarian stimulation, number of oocytes and embryos. We analysed the results by the method of regression analysis.

RESULTS

We found that the mean age increased from 28.7 to 32 years in a period of 10 years. We also demonstrated that the increasing age was accompanied by a decrease in ovarian function.

CONCLUSION

Women older than 32 years should be informed about the decreased ability to conceive. The treatment of women for infertility can be complicated by the growing age of patients in coming decades.

Common vole (Microtus arvalis) population sex ratio: biases and process variation

Vole population sex ratio varies seasonally. However, population sex ratios have usually been estimated using naïve estimators that do not allow for biases owing to the sex difference in capture probabilities and movement distances (i.e., effective areas sampled). Here we aimed to advance the methodological approach, recognizing that there are two different classes of contributing mechanisms to the pattern which are best addressed separately: (1) those mechan isms imposing a systematic error (bias) in population estimates and (2) those generating the true process variation. Analyzing 7-year capture–recapture data in the common vole (Microtus arvalis (Pallas, 1778)), we quantified both types of biases and revealed that the bias owing to differential capture rates was often severe and less predictable, whereas that owing to differential effective areas was smaller and overestimated male numbers for most of the year. We demonstrated unambiguously that the unbiased population sex ratio indeed varies seasonally, with the males usually being more numerous over winter and spring. By testing predictions from two mechanistic hypotheses to explain the process variability, we found evidence for both the differential recruitment hypothesis and the differential survival hypothesis. From April–May to August, it was the females that were recruited more to the population and that had higher survival rates than males. We suggest that the seasonal variation in the population sex ratio is not merely a result of biasing mechanisms but an important population property driven by the joint effect of differential recruitment and differential survival between sexes.

Age variation in a fluctuating population of the common vole

We analysed variation in age in a fluctuating population of the common vole ( Microtus arvalis) in southern Moravia, Czech Republic, to test the assumption of the senescence hypothesis that the age of voles increases with increasing population density. Between 1996 and 1998, we monitored the demographic changes by snap-trapping and live-trapping in a field population passing through the increase, peak and decline phase of the population cycle. We used the eye lens mass method to determine the age of snap-trapped animals and those that died in live-traps. The average age of winter males was clearly higher after the peak phase breeding season than before it. No such phase-dependent shift in age, however, was observed in the female component. Male age continued to increase from autumn to spring over the pre-peak winter, and the highest age was in spring of the peak phase year. However, after the peak phase breeding season the highest age was achieved in winter, with the decline phase males during the next spring tending to be younger. The average age of females in spring populations was always lower than in winter populations. The average age of voles from live-traps was always higher than voles from snap-traps, particularly in winter and spring populations, suggesting the presence of senescent animals. Although the density-dependent changes in age are consistent with those observed for other voles, they provide only weak evidence that population cycles in the common vole are accompanied by pronounced shifts in individual age, particularly in female voles.

A new geographical gradient in vole population dynamics

A new geographical gradient in the dynamics of small rodents is demonstrated by analysing 29 time series of density indices of the common vole (Microtus arvalis) from Poland, the Czech Republic and the Slovak Republic. This gradient extends from more stable northerly populations in coastal Poland to more variable and cyclic populations in the southernmost parts of the Slovak Republic, and is hence a reversal of the Fennoscandian gradient. All studied variables (such as mean density, cycle amplitude, density variability and the coefficients in a second-order autoregressive model) exhibit consistent latitudinal variation. Possible underlying factors are discussed. In particular, we suggest that seasonality may be a key element in explaining the observed new gradient.