bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of different engine‐driven, sound ultrasound systems and the Canal Master on root canal preparation: an in vitro study
Authors: MARROQUÍN B. BRISEÑO , SOBARZ0‐NAVARRO V. , DEVENS S. 
Published: September 2010

SummaryDifferent methods and automated devices have been developed to accomplish the enlarging and debriding of root canals. The occurrence of undesired effects on the root canal walls was compared in vitro between a theoretically ideally shaped canal and the Canal Leader, Canal Finder, 3000 Endo Sonic Air, Cavi Endo 25, Enac System, Piezon Master 400 and the Canal Master. Clear casting resin models were used for this purpose. A photographic double exposure was used to superimpose the images of the original canals on the enlarged canals, thus enabling measurement of the material removed. Measurements were made at six different points. Significance was defined at the 5% level (P= 0.05).Ail instruments and/or devices, with the exception of the Cavi Endo 25. enlarged the convex side of the canals significantly greater at level 1 in comparison to the ideal. On the concave side, significantly smaller differences were found between the ideal and the results of all the enlarging devices, with the exception of the Canal Master. On the convex side at level 2, the Canal Leader, Canal Finder, Cavi Endo, Enac System and Endo Sonic Air showed no statistical differences between ideal and effective material removal. The Piezon Master showed significantly lower material removal in comparison to the ideal. The Canal Master demonstrated statistically higher differences when compared with the ideal. On the concave side, all devices showed a statistically higher difference between the ideal and actual material removed, with the exception of the Canal Master and Cavi Endo. On the convex side at level 3, the Canal Finder, Canal Leader, Endo Sonic Air and Cavi Endo removed significantly less material than desired. At this level on the concave side, the Canal Master removed insignificantly more material than ideal. All other devices exhibited statistically higher differences.
Simulation models for teaching endodonticsurgical procedures
Authors: JACKSON A.P. , TIDMARSH B.G. 
Published: September 2010

SummaryModels which simulate oral conditions pertaining to endodontic surgical procedures are most suitable if they contain natural teeth and have hard and soft tissues which handle realistically. In addition, the model should possess radiological characteristics similar to bone. A simple custom‐b&t model which fulfils these requirements is described.
Efficacy of various concentrations of NaOCl and instrumentation techniques in reducing Enterococcus faecalis within root canals and dentinal tubules
Authors: Berber V. B. , Gomes B. P. F. A. , Sena N. T. , Vianna M. E. , Ferraz C. C. R. , Zaia A. A. , Souza‐Filho F. J. 
Published: September 2010

AbstractAim  To evaluate the efficacy of 0.5%, 2.5% and 5.25% sodium hypochlorite (NaOCl) as intracanal irrigants associated with hand and rotary instrumentation techniques against Enterococcus faecalis within root canals and dentinal tubules.Methodology  A total of 180 extracted human premolar teeth were infected for 21 days with E. faecalis. The specimens were divided into 12 groups, as follows: group 1: 5.25% NaOCl + Hybrid technique (Valdrighi et al. 1998); group 2: 5.25% NaOCl + nickel–titanium (NiTi) rotary technique 4 mm shorter than the apex (by FOP‐UNICAMP); group 3: 5, 25% NaOCl + NiTi rotary technique (Hero 642); group 4: 2.5% NaOCl +Hybrid technique; group 5: 2.5% NaOCl + NiTi rotary technique 4 mm shorter than the apex; group 6: 2.5% NaOCl + NiTi rotary technique (Hero 642); group 7: 0.5% NaOCl + Hybrid technique; group 8: 0.5% NaOCl + NiTi rotary technique 4 mm shorter than the apex; group 9: 0.5% NaOCl + NiTi rotary technique (Hero 642); group 10: sterile saline solution + Hybrid technique; group 11: sterile saline solution + NiTi rotary technique 4 mm shorter than the apex; group 12: sterile saline solution + NiTi rotary technique (Hero 642). Canals were sampled before and after preparation. After serial dilution, samples were plated onto brain heart infusion (BHI) agar, and the colony forming units (CFU) that were grown were counted. The teeth were sectioned into three thirds and dentine chips were removed from the canals with conical burs. The samples obtained with each bur were immediately collected into test tubes containing BHI broth, and were incubated at 37 °C and plated onto BHI agar. The CFU were counted and analysed.Results  At all depths and thirds of the root canals and for all techniques used, 5.25% NaOCl was shown to be the most effective irrigant solution tested when dentinal tubules were analysed, followed by 2.5% NaOCl. No differences among concentrations in cleaning the canals were found.Conclusions  Especially at higher concentrations, NaOCl, was able to disinfect the dentinal tubules, independent of the canal preparation technique used.
The adhesion between fibre posts and composite resin cores: the evaluation of microtensile bond strength following various surface chemical treatments to posts
Authors: Vano M. , Goracci C. , Monticelli F. , Tognini F. , Gabriele M. , Tay F. R. , Ferrari M. 
Published: September 2010

AbstractAim  To evaluate the influence of various surface treatments to fibre posts on the microtensile bond strength with different composite resins.Methodology  A total of 110 fibre posts were randomly divided into five groups, according to the surface pre‐treatment performed. Group 1: immersion in 24% H2O2 for 10 min and silanization for 60 s; group 2: immersion in 10% H2O2 for 20 min and silanization for 60 s; group 3: immersion in 4% hydrofluoric acid gel for 60 s and silanization for 60 s; group 4: silanization of the post surface for 60 s and application of the bonding agent G‐Bond; group 5: silanization of the post surface for 60 s (control group). After treatment, two posts were randomly selected from each group to evaluate the morphological aspect of the post surface with scanning electron microscopy. The remaining posts in each group were divided into five subgroups of five posts each, which differed in the type of composite resin used for the core build‐up. Post‐core strength were calculated and the differences among experimental groups were analysed with two‐way anova and the Tukey test (α = 0.05).Results  The post‐core strengths achieved in groups 1 and 2 were significantly higher (P < 0.05), than those of groups 3, 4 and 5. The post‐core strength in the control group was significantly lower (P < 0.05) than all other groups.Conclusions  Hydrogen peroxide and hydrofluoric acid both modified the surface morphology of fibre posts and with silane, significantly enhanced the interfacial strength between them and core materials.
Ex vivo study of the efficacy of H‐files and rotary Ni–Ti instruments to remove gutta‐percha and four types of sealer
Authors: Kosti E. , Lambrianidis T. , Economides N. , Neofitou C. 
Published: September 2010

AbstractAim  To compare the efficacy of ProFile rotary Nickel–Titanium (Ni–Ti) instruments and Hedstroem‐files (H‐files) combined with Gates‐Glidden (GG) drills during removal of gutta‐percha root fillings used in combination with one of the four representative sealers.Methodology  Forty‐eight single‐rooted human teeth, with fully formed apices and straight root canals were used. The root canals were accessed and instrumented using a stepback technique with H‐files. They were randomly assigned to four groups and subsequently filled with a combination of lateral and vertical condensation of gutta‐percha and one of the following sealers: Roth 811, AH26, Endion and Roekoseal. The root fillings were removed 1 year later, using either H‐files in combination with GG drills or the ProFile Ni–Ti system. Teeth were then grooved longitudinally and split. The amount of gutta‐percha and sealer remaining on the root canal walls was traced and scored visually with the aid of a stereomicroscope. The scores were analysed and statistically compared with the Kruskal–Wallis test between the ProFile and H‐file groups, as well as among the four sealer subgroups. Two samples from each group were studied under the scanning electron microscope to enhance inspection of canal walls and remaining material.Results  Sealer remnants were observed with both techniques mainly in the middle and apical third of the root canal. The ProFile system and the H‐files were associated with similar amounts of remaining filling material (P > 0.05). In the cervical third of the root canal all sealer remnants were removed with both techniques. In the middle and apical third AH26 was associated with a statistically significant greater quantity of remnants on the root canal walls with both removal techniques (P < 0.05). Endion, Roth 811 and Roekoseal were associated with approximately the same amount of filling material in the middle third of the root canal (P > 0.05), whereas in the apical third Endion was associated with significantly more remnants of filling material than the other two sealers with either ProFile or H‐files (P < 0.05).Conclusions  None of the methods used for the removal of root fillings was totally effective, especially in the apical third of the root canal.
Removal efficacy of various calcium hydroxide/chlorhexidine medicaments from the root canal
Authors: Lambrianidis T. , Kosti E. , Boutsioukis C. , Mazinis M. 
Published: September 2010

AbstractAim  To compare the efficiency of removing calcium hydroxide [Ca(OH)2]/chlorhexidine (CHX) (gel), Ca(OH)2/CHX (solution) and Ca(OH)2/saline pastes with the use of instrumentation and irrigation with sodium hypochlorite and ethylene diamine tetraacetic acid (EDTA) solutions. Moreover the role of the patency file in the cleanliness of the apical third of the root canal was evaluated.Methodology  Sixty‐four human single‐rooted teeth with straight canals were used. Root canal preparation was performed with a stepback technique using Hedström (H) files. Teeth were randomly assigned to three groups and subsequently filled with one of the pastes: Ca(OH)2/CHX (gel), Ca(OH)2/CHX (solution) and Ca(OH)2/saline paste. The medicaments were removed 10 days later using instrumentation and irrigation with 1% sodium hypochlorite and 17% EDTA, with or without obtaining patency of the apical foramen with a size 10 H‐file. The crowns were removed at the cemento‐enamel junction and the roots were grooved longitudinally and split into halves. Images of all halves were acquired with the use of a flatbed scanner. A scoring system of 1 to 4 was used to assess the amount of residue on the cervical, middle and apical third of the canal. Data were subjected to statistical analysis using Kruskal–Wallis and Mann–Whitney tests, with Bonferroni correction, at 95% confidence level (P < 0.05).Results  Remnants of medicament were found in all experimental teeth regardless of the experimental material used and the use of the patency file. When examining the root canal as a whole, Ca(OH)2/CHX (gel) paste was associated with significantly larger amount of residue, whereas the Ca(OH)2/CHX (solution) paste was associated with less amount (P < 0.05) than the other two medicaments with or without the use of a patency file.Conclusions  None of the techniques used in this study removed the inter‐appointment root canal medicaments effectively; the use of the patency file facilitated removal of more of the medicament in the apical third of those straight canals.
A comparative study of root canal preparation with NiTi‐TEE and K3 rotary Ni‐Ti instruments
Authors: Jodway B. , Hülsmann M. 
Published: September 2010

AbstractAim  To evaluate and compare several parameters of curved root canal preparation using two different Ni‐Ti systems: NiTi‐TEE (Sjöding Sendoline, Kista, Sweden) and K3 (Sybron Endo, Orange County, CA, USA).Methodology  Fifty extracted mandibular molars with mesial root canal curvatures ranging from 20 to 40° were divided into two groups. In one group, 50 root canals were instrumented using NiTi‐TEE files to an apical size 30; 0.04 taper (the largest available size at the time of this study). In the other group, 50 root canals were prepared with K3 instruments to an apical size 45; 02 taper. Both systems were used in a crowndown manner, with copious NaOCl (3%) irrigation and a chelating agent (Calcinase Slide, lege artis, Dettenhausen, Germany), employing torque‐controlled motors. For assessment of shaping ability, pre‐ and postinstrumentation radiographs and cross‐sectional photographs of canals were taken and changes in canal curvature and root canal diameter documented. Cleaning ability was evaluated by investigating specimens of the apical, medial and coronal third of the root canal wall under a scanning electron microscope using 5‐score indices for debris and smear layer. Procedural errors (instrument separations, perforations, apical blockages, loss of working length) and working time were recorded. Nonparametric anova was used to compare straightening of canal curvatures, canal cross‐sections and canal wall cleanliness (P < 0.05), whereas working time was analysed using the parametric anova (P < 0.05).Results  Both Ni‐Ti systems maintained curvature well: the mean degree of straightening was 0.2° for NiTi‐TEE and 0.4° for K3 with no statistical significance between the groups. Post‐instrumentation cross‐sections of the root canals revealed an acceptable contour (round or oval) in 50.6% of cases for the NiTi‐TEE group and in 65.3% of cases for the K3 group. The difference was not significant. The SEM investigation of canal walls showed equally good debris removal for both systems: NiTi‐TEE prepared canal walls in 74.7% of cases with scores I and II; K3 achieved these scores in 78.7% of cases. For smear layer, NiTi‐TEE and K3 only received good scores (I and II) in 38.7% and 40% of canal wall specimens, respectively. For both parameters, no significant differences were found between groups. File fractures did not occur, but loss of working length was observed in one case following the preparation with NiTi‐TEE and in three cases during K3 instrumentation. Mean working time was significantly shorter for NiTi‐TEE (170 s) than for K3 (208 s).Conclusions  Both systems maintained original canal curvature well and were safe to use. Whilst debridement of canals was considered satisfactory, both systems failed to remove smear layer sufficiently.
The trade‐off between thermal tolerance and behavioural dominance in a subtropical South American ant community
Authors: Bestelmeyer Brandon T. 
Published: September 2010

Summary 1. The distribution, ecology, and behaviour of ants (Hymenoptera: Formicidae) is profoundly influenced by environmental stress and competition. As in plants, trade‐offs in adaptations to these factors are the basis for functional classifications of ant taxa and communities at a global scale. 2. Theory predicts a trade‐off between stress tolerance and competitive dominance in both plants and ants. In ants, low temperature is thought to be stressful, so I hypothesized that there would be a positive relationship between temperature and behavioural dominance. I evaluated this relationship in a South American, Chaco ant community. 3 The activity and behaviour of ground‐foraging, omnivorous ants were examined at baits in open and closed, forested habitats during different seasons and times of day to characterize the responses of ant taxa to variation in microclimate and competitors. 4. Behaviourally dominant ants were most active at moderately high temperatures, whereas subordinate species were active at extreme temperatures, when they had virtually exclusive access to resources. 5. The patterns presented here and those observed in other studies suggest that there is a general trade‐off between behavioural dominance and thermal tolerance in ants. This trade‐off creates a linear relationship between temperature use and dominance for ants up to ≈ 35 °C, but extremely high temperatures may also be stressful such that the full relationship is actually unimodal.
Breeding territory size affects fitness: an experimental study on competition at the individual level
Authors: Both Christiaan , Visser Marcel E. 
Published: September 2010

Summary1.Descriptive studies have shown that the annual mean fecundity and survival in bird populations decline as density increases. Experimental studies in which breeding density has been manipulated show that density causally affects reproduction in some but not other species.2.In a 3‐year study on great titsParus majorwe manipulated density by removing about one‐third of territorial great tit pairs from half the study area each year. The removal resulted in an increase in territory size of the remaining birds in the experimental sub‐area.3.Fecundity and survival did not differ between the experimental low‐density and the control sub‐areas. The experiment thus did not show a causal relationship between breeding density and fecundity and survival at the level of the population.4.The data were analysed further with respect to individual territory size, the level at which competition is assumed to operate. Pairs in the experimental sub‐area enlarged their territories. We argue that variation in territory enlargement is not caused by individual quality.5.Both pre‐manipulation territory size and territory enlargement positively affected the probability that a territorial pair nested, the growth rate of their chicks, the number of fledglings that recruited into the breeding population and the survival of the territorial adults. No effect of territory enlargement was observed on clutch size, nor on the probability that pairs started a second brood.6.The positive effect of the experimental territory enlargement argues for a causal effect of territory size on these reproductive parameters, independent of individual quality.7.An effect of the density reduction on fecundity may not be detectable at the population level, either due to the large variation in territory sizes within the experimental treatments or to the negative effect of the experimentper se, which counter balances the positive effect of territory enlargement.
Species‐specific utilization of food sources by sympatric woodlice (Isopoda: Oniscidea)
Authors: Zimmer Martin , Topp Werner 
Published: September 2010

Summary 1. In long‐term laboratory studies, the influence of different food materials on parameters of population dynamics was compared in the sympatric woodlice, Porcellio scaber and Oniscus asellus, as a measure of interspecific differences in the utilization of food. 2. Freshly fallen leaf litter of different tree species had been acidified and microbially inoculated prior to the experiments. By analysing the influence of pH level, density and activity of litter‐colonizing microbiota and several physico‐chemical characteristics of the leaf litter, we obtained information on those factors that determine food quality. 3. The studied species responded similarly to different leaf litter species in that both P. scaber and O. asellus performed better on litter with low C:N ratio. Overall, both isopod species reproduced more successfully on litter with higher pH levels, containing half the levels of tannins and other phenolics. 4. Interspecific differences were obvious with respect to the significance of litter‐colonizing microbiota, and the dependence of juveniles on particular food parameters. While the performance of adult P. scaber was influenced by both litter‐colonizing microbiota and physico‐chemical characteristics of the leaf litter, adult O. asellus were influenced by leaf litter characteristics, but not by litter‐colonizing microbiota. Juvenile mortality was affected by the tested food parameters in O. asellus, but not in P. scaber. Growth rates of juveniles of both species were influenced by physico‐chemical characteristics of the leaf litter. Additionally, leaf litter microbiota had a significant influence on growth rates in juvenile P. scaber, but not in juvenile O. asellus. 5 Reasons for, and consequences of, similarities and differences between the observed sympatric species, and intraspecific differences between ontogenetic stages, are important aspects of soil ecology and may help explain the sympatric coexistence of two species belonging to the same guild of saprophagous soil animals.
Population density of migratory and resident brown trout (Salmo trutta) in relation to altitude: evidence for a migration cost
Authors: Bohlin T. , Pettersson J. , Degerman E. 
Published: September 2010

AbstractFor anadromous salmonids, the positive relations found in previous studies between adult size/age and stream characteristics suggest that the migration cost increases with stream length, water discharge and the altitude of the spawning site. In this study we hypothesized that the altitude of the spawning site is positively related to the migration effort.Life‐history theory predicts (i) that the equlibrium egg density, which is a fitness measure, thereby will decline more rapidly with altitude in migratory than in stream‐resident populations, and therefore (ii) that residency will be selected for at large enough altitudes.As the density of juveniles is a function of egg density, we hypothesized that (a) altitude has stronger effect on juvenile density in migratory than in resident populations, and (b) juvenile density is larger in migratory than in resident populations.We tested (a) and (b) using multivariate methods for electrofishing data from 164 sea‐migratory and 167 stream‐resident populations of brown troutSalmotruttaL. in Sweden. Both predictions were supported; the juvenile density was larger and declined more rapidly with altitude in migratory than in resident populations.The results are further evidence that migration costs reduce fitness in anadromous salmonids.
Long‐term variability in secondary production of an intertidal bivalve population is primarily a matter of recruitment variability
Authors: Van Der Meer Jaap , Beukema Jan J. , Dekker Rob 
Published: September 2010

Abstract

The importance of recruitment processes in determining benthic population dynamics has received considerable interest among marine ecologists in the last two decades. Observational demographic studies, in which recruits were followed to and through the adult state, aimed to estimate whether the variation in the numbers of recruits is dampened by density‐dependent post‐recruitment processes. These studies revealed conflicting results on the importance of post‐recruitment density dependence, but were performed over at most a few years.
Based on a study of the demography and growth of the bivalve Macoma balthica (L.) on an intertidal flat in the Dutch Wadden Sea for a period of almost 30 years, we explored the extent to which the among‐cohort variability in recruitment was reflected in the secondary production (which results from the combined action of recruitment, mortality and growth) of the adult population.
Since growth in length was of the Von Bertalanffy type and post‐recruitment instantaneous mortality rate was approximately constant for each cohort, production could be explicitly written in terms of the following parameters: recruit density, condition (ratio of mass to cubic length), Von Bertalanffy growth coefficient, asymptotic cubic length, and expected life span.
Decomposing the among‐cohort variability in production in terms of the covariance matrix of these parameters revealed that most of the variance in production could be attributed to year‐to‐year variability in recruit density.
Small negative covariances between recruit density and asymptotic size and expected life span indicated weak density dependence after recruitment.
The major cause of temporal variation in abundance and production is inter‐annual variation in recruitment and competition for resources seems to play a small role in affecting post‐recruitment population density and production.