bluuebunny/crossref_metadata_2025 huggingface dataset:
TEMPORAL CHANGES IN VERTEBRATES DURING LANDSCAPE TRANSFORMATION: A LARGE‐SCALE “NATURAL EXPERIMENT”
Authors: Lindenmayer David B. , Cunningham Ross B. , MacGregor Christopher , Crane Mason , Michael Damian , Fischer Joern , Montague-Drake Rebecca , Felton Adam , Manning Adrian
Published: October 2008

Plantation development is a significant form of landscape change worldwide. We report findings from a large‐scale longitudinal natural experiment that quantified changes in Australian vertebrates as a former grazing landscape was transformed to one dominated by a radiata pine (Pinus radiata) plantation. The study included four main “treatments”: woodland remnants surrounded by emerging radiata pine (52 sites, termed “woodland treatments”), stands of radiata pine (10 sites, “pine controls”), woodland remnants where the surrounding landscape remained unchanged (56 sites, “woodland controls”), and paddocks with scattered woodland trees that surrounded the 56 woodland remnants (10 sites, “paddock controls”). In our study region, woodland is distinguished from forest by differences in tree height, tree spacing, bole length, and canopy development.

Between 1998 and 2006, occupancy rates of “woodland treatments” by most mammals and reptiles increased linearly. Similar trends occurred in the “woodland controls,” suggesting that species had increased landscape‐wide, rather than displaying year × treatment interaction effects. We cross‐classified birds according to the statistical significance and nature of time trajectories. Groups included those that: (1) declined in woodland treatments in comparison with woodland controls, (2) decreased within woodland treatments but increased in woodland controls, (3) declined across the entire study area, (4) increased within woodland treatments in comparison with woodland controls, (5) increased within woodland treatments but declined in woodland controls, and (6) increased across the entire study area.

Attributes of woodland treatments significantly associated with temporal changes in bird occupancy included: (1) age of surrounding pine stands; (2) number of boundaries with surrounding pines; (3) size of the woodland patches; (4) dominant vegetation type of woodland patches; and (5) temporal changes in vegetation structure in the woodland treatments.

Bird species associated with open country and woodland environments were disadvantaged by landscape transformation, whereas those that benefited were forest taxa and/or habitat generalists capable of inhabiting pine stands and adjacent woodland patches. Beyond this generalization, an unanticipated finding was a lack of association between life history attributes and landscape transformation. We suggest that several key processes are likely drivers of change at multiple spatial scales. Recognition of such processes is important for conservation in landscapes transformed by plantation expansion.
POLAR BEAR DIETS AND ARCTIC MARINE FOOD WEBS: INSIGHTS FROM FATTY ACID ANALYSIS
Authors: Thiemann Gregory W. , Iverson Sara J. , Stirling Ian
Published: October 2008

We used quantitative fatty acid signature analysis (QFASA) to examine the diets of 1738 individual polar bears (Ursus maritimus) sampled across the Canadian Arctic over a 30‐year span. Polar bear foraging varied over large and small spatial and temporal scales, and between demographic groups. Diets in every subpopulation were dominated by ringed seals (Phoca hispida) and, in the eastern Arctic, secondarily by harp seals (Pagophilus groenlandica). Beluga whales (Delphinapterus leucas) were an important food source for bears in the High Arctic, which is consistent with previous anecdotal reports. Foraging patterns were most similar among neighboring subpopulations with similar prey assemblages, but also differed geographically within Western Hudson Bay. The sexual size dimorphism of polar bears had an important effect on foraging, as large bearded seals (Erignathus barbatus) and walruses (Odobenus rosmarus) were consumed most often by older, male bears, whereas ringed seals and, where available, harbor seals (P. vitulina) were most important to younger age classes. Larger, older bears also had the greatest dietary diversity, apparently because of their ability to include larger‐bodied prey. During spring and summer, polar bears in some areas increased predation on migratory harp seals and beluga whales. In Western Hudson Bay, bearded seal consumption declined between 1995 and 2001 for both male and female bears and continued to decline among females up to the most recent sampling (2004). Ringed seal consumption in Western Hudson Bay increased between 1998 and 2001, perhaps in response to increased ringed seal productivity, but was not significantly affected by date of sea‐ice breakup. Overall, our data indicate that polar bears are capable of opportunistically altering their foraging to take advantage of locally abundant prey, or to some degree compensating for a decline in a dominant prey species. However, in other areas polar bears are dependent on the availability of ringed and bearded seals. Recent population data suggest that polar bears with the most specialized diets may be most vulnerable to climate‐related changes in ice conditions. The results of this large‐scale, ecosystem‐based study indicate a complex relationship between sea‐ice conditions, prey population dynamics, and polar bear foraging.
MEASURING BEE DIVERSITY IN DIFFERENT EUROPEAN HABITATS AND BIOGEOGRAPHICAL REGIONS
Authors: Westphal Catrin , Bommarco Riccardo , Carré Gabriel , Lamborn Ellen , Morison Nicolas , Petanidou Theodora , Potts Simon G. , Roberts Stuart P. M. , Szentgyörgyi Hajnalka , Tscheulin Thomas , Vaissière Bernard E. , Woyciechowski Michal , Biesmeijer Jacobus C. , Kunin William E. , Settele Josef , Steffan-Dewenter Ingolf
Published: October 2008

Bee pollinators are currently recorded with many different sampling methods. However, the relative performances of these methods have not been systematically evaluated and compared. In response to the strong need to record ongoing shifts in pollinator diversity and abundance, global and regional pollinator initiatives must adopt standardized sampling protocols when developing large‐scale and long‐term monitoring schemes.

We systematically evaluated the performance of six sampling methods (observation plots, pan traps, standardized and variable transect walks, trap nests with reed internodes or paper tubes) that are commonly used across a wide range of geographical regions in Europe and in two habitat types (agricultural and seminatural). We focused on bees since they represent the most important pollinator group worldwide. Several characteristics of the methods were considered in order to evaluate their performance in assessing bee diversity: sample coverage, observed species richness, species richness estimators, collector biases (identified by subunit‐based rarefaction curves), species composition of the samples, and the indication of overall bee species richness (estimated from combined total samples).

The most efficient method in all geographical regions, in both the agricultural and seminatural habitats, was the pan trap method. It had the highest sample coverage, collected the highest number of species, showed negligible collector bias, detected similar species as the transect methods, and was the best indicator of overall bee species richness. The transect methods were also relatively efficient, but they had a significant collector bias. The observation plots showed poor performance. As trap nests are restricted to cavity‐nesting bee species, they had a naturally low sample coverage. However, both trap nest types detected additional species that were not recorded by any of the other methods.

For large‐scale and long‐term monitoring schemes with surveyors with different experience levels, we recommend pan traps as the most efficient, unbiased, and cost‐effective method for sampling bee diversity. Trap nests with reed internodes could be used as a complementary sampling method to maximize the numbers of collected species. Transect walks are the principal method for detailed studies focusing on plant–pollinator associations. Moreover, they can be used in monitoring schemes after training the surveyors to standardize their collection skills.
GREENFALL LINKS GROUNDWATER TO ABOVEGROUND FOOD WEBS IN DESERT RIVER FLOODPLAINS
Authors: Sabo John L. , McCluney Kevin E. , Marusenko Yevgeniy , Keller Andrew , Soykan Candan U.
Published: October 2008

Groundwater makes up nearly 99% of unfrozen freshwater worldwide and sustains riparian trees rooted in shallow aquifers, especially in arid and semiarid climates. The goal of this paper is to root animals in the regional water cycle by quantifying the significance of groundwater to riparian animals. We focused our efforts on the cricket, Gryllus alogus: a common primary consumer found in floodplain forests along the San Pedro River, in southeast Arizona, USA. Cottonwood trees make groundwater available to G. alogus as dislodged, groundwater‐laden leaves (greenfall). We hypothesized that groundwater fluxes mediated by greenfall sustain G. allogus through the prolonged dry season and link these aboveground consumers to belowground aquifers.

To test this hypothesis, we first characterized gradients in absolute humidity (air) and water stress in field‐collected G. alogus. Absolute humidity declined with distance from river across wide stands of floodplain cottonwood forest during the dry season, but not during the rainy season. Similarly, G. alogus body water content declined along this gradient. Second, we measured evaporative water loss (EWL) by field‐captured G. alogus in the laboratory at temperatures bracketing field conditions. EWL ranged from 0.05 ± 0.009 g·individual−1·d−1 to 0.13 ± 0.03 g·individual−1·d−1 (mean ± SD, at 30° and 40°C, respectively). These daily losses are high, but still less than the water content of a single cottonwood leaf (0.296 ± 0.124 g H2O/leaf). Third, we designed field experiments to quantify the relative dependence of G. alogus on greenfall. G. alogus more frequently consumed greenfall than various controls consisting of dried leaves. This preference occurred in distal habitats and during the dry season, but not proximal to the river or in the rainy season. Finally, we compared estimated daily water fluxes via greenfall to (1) estimates of water demand of the entire G. alogus population at our field site, and (2) reports of cottonwood transpiration and San Pedro River base flow from other authors. By our estimates, groundwater fluxes via greenfall sustain G. alogus populations despite their trivial magnitude compared to stream discharge and cottonwood transpiration. Primary consumers in turn provide dietary water to higher trophic levels (e.g., abundant and speciose birds in the region) through trophic pathways, thereby fueling secondary production from the bottom up. Thus, riparian trees root animals in the regional water cycle.
SCALING FROM TREES TO FORESTS: TRACTABLE MACROSCOPIC EQUATIONS FOR FOREST DYNAMICS
Authors: Strigul Nikolay , Pristinski Denis , Purves Drew , Dushoff Jonathan , Pacala Stephen
Published: October 2008

Individual‐based forest simulators, such as TASS and SORTIE, are spatial stochastic processes that predict properties of populations and communities by simulating the fate of every plant throughout its life cycle. Although they are used for forest management and are able to predict dynamics of real forests, they are also analytically intractable, which limits their usefulness to basic scientists. We have developed a new spatial individual‐based forest model that includes a perfect plasticity formulation for crown shape. Its structure allows us to derive an accurate approximation for the individual‐based model that predicts mean densities and size structures using the same parameter values and functional forms, and also it is analytically tractable. The approximation is represented by a system of von Foerster partial differential equations coupled with an integral equation that we call the perfect plasticity approximation (PPA). We have derived a series of analytical results including equilibrium abundances for trees of different crown shapes, stability conditions, transient behaviors, such as the constant yield law and self‐thinning exponents, and two species coexistence conditions.
Acrylamide Monomer Leaching from Polyacrylamide‐Treated Irrigation Furrows
Authors: Lentz R. D. , Andrawes F. F. , Barvenik F. W. , Koehn A. C.
Published: October 2008

Water‐soluble anionic polyacrylamide (WSPAM), which is used to reduce erosion in furrow irrigated fields and other agriculture applications, contains less than 0.05% acrylamide monomer (AMD). Acrylamide monomer, a potent neurotoxicant and suspected carcinogen, is readily dissolved and transported in flowing water. The study quantified AMD leaching losses from a WSPAM‐treated corn (Zea mays L.) field using continuous extraction‐walled percolation samplers buried at 1.2 m depth. The samplers were placed 30 and 150 m from the inflow source along a 180‐m‐long corn field. The field was furrow irrigated using WSPAM at the rate of 10 mg L−1 during furrow advance. Percolation water and furrow inflows were monitored for AMD during and after three furrow irrigations. The samples were analyzed for AMD using a gas chromatograph equipped with an electron‐capture detector. Furrow inflows contained an average AMD concentration of 5.5 μg L−1 The AMD in percolation water samples never exceeded the minimum detection limit and the de facto potable water standard of 0.5 μg L−1 The risk that ground water beneath these WSPAM‐treated furrow irrigated soils will be contaminated with AMD appears minimal.
CFD Simulation of Hydrodynamics, Heat and Mass Transfer Simultaneously in Structured Packing
Authors: Khosravi Nikou M.R. , Ehsani M.R. , Davazdah Emami M.
Published: October 2008

This paper describes the results of computational fluid dynamic modeling of hydrodynamics, heat and mass transfer simultaneously in Flexipac 1Y operated under a counter-current gas-liquid flow condition. The simulation was performed for a binary mixture of methanol-isopropanol distillation. The pressure drop, the height of equivalent to theoretical plate (HETP) and temperature distribution across the column were calculated and compared with experimental data. The mean absolute relative error (MARE) between CFD predictions and experimental data for the pressure drop, HETP and temperature profile are 20.7%, 12.9% and 2.8%, respectively.
Hydrodynamic Characteristics of Mixing in a Non-Newtonian Liquid-Gas-Solid System
Authors: Jassim Thamer Mohammed , Sulaymon Abbas Hamid , Al-Wasiti Asawer Abdul Raswel
Published: October 2008

This work presents the study of mixing a three phase non-Newtonian system in a QVF gas sparged vessel. The three phase system consists of air-non Newtonian liquid (polyacrylamide solution)solid (alumina catalyst). The critical gas velocity for complete suspension of solid particles, mixing time, and bubble characteristics (bubble rise velocity, bubble diameter, bubble frequency, gas hold up, and number of bubbles) was studied with different polyacrylamid (PAA) concentrations (0.01, 0.03,0.05, 0.07) wt%, different particle diameters of alumina (63-500)µm, and different solid loading of alumina (0.5, 1.0, 1.5, 2.0)Kg. The critical gas velocity was found to increase with increasing apparent viscosity, solid loading, and particle diameter. Mixing time increases with increasing apparent viscosity, and decreases with increasing solid loading, and particle diameter. Bubble characteristics were measured axially and radially using a modified electroconductivity probe consisting of four tips, an interface, a visual basic program, and a personal computer. The results showed that increasing apparent viscosity and particle diameter caused an increase of bubble coalescence and hence, an increase in bubble diameter and bubble rise velocity and a decrease in gas hold up.
Development and Application of a Simulation Tool for Biomass Gasification Based Processes
Authors: Pröll Tobias , Hofbauer Hermann
Published: October 2008

A simulation tool for gasification based processes is presented for an equation-oriented, steady state modelling environment. The approach aims at an adequate description of phenomena linked to gasification. Background information is provided regarding the structure of the framework, thermodynamic data processing, and on the formulation of the model equations. The implemented substance streams are water/steam, ideal gases, inorganic solids, and organic mixtures. The models are based upon mass and energy balances and feature thermodynamic considerations. The addition of correlations for fluid dynamics or chemical kinetics is generally possible but not within the focus of this paper. The key-aspects of the typical unit-models, like pumps, turbines, heat exchangers, separators and chemical reactors are highlighted. The model of a dual-fluidized bed biomass gasifier is presented in detail. In a final case study, the suitability of the simulation tool is demonstrated for the description of the gasification-based biomass combined heat and power plant in Güssing/Austria.
Slip Effects on Flow and Heat Transfer of a Non-Newtonian Fluid on a Stretching Surface with Thermal Radiation
Authors: Mahmoud Mostafa Abd El-Hameed
Published: October 2008

An analysis is carried out to study the flow and heat transfer characteristics of a non-Newtonian power-law fluid over a stretching surface in the presence of radiation and slip condition at the surface. The local similarity solution is used to transform the system of partial differential equations, describing the problem, into a system of highly coupled non-linear ordinary differential equations. The transformed system of equations is solved numerically using the fourth order Runge-Kutta method coupled with the shooting technique. The effects of the radiation parameter and the slip parameter on both the flow and the heat transfer are investigated and discussed. Also, it is found that the local skin-friction coefficient decreases as the slip parameter increases. However, it is found that increasing the slip parameter or the radiation parameter has the effect of decreasing the local Nusselt number.
Fluidization, Mixing and Segregation of a Biomass-Sand Mixture in a Fluidized Bed
Authors: Zhang Yong , Jin Baosheng , Zhong Wenqi
Published: October 2008

Fluidization, mixing and segregation of a biomass-sand mixture in a 3D gas-fluidized bed have been investigated by means of visual observation, pressure fluctuation analysis and the bed-frozen method. Three types of mixtures are considered, in which biomass is a thin long stalk, and sand belongs to the Geldart B category. Experiments are carried out in a segmented fluidized bed equipped with multiple pressure transducers. Three initial packing conditions and two experiment procedures are used. The fluidization velocity varies to cover a wide range. Results show that in the local fluidization region, the mixing and segregation patterns are sensitive to the initial packing condition. In the case of a fully segregated state with biomass at the bottom, the bed inversion can be significantly observed due to the great segregation tendency of biomass. Further analyses indicate that the mixing ratio exerts a subtle influence on the competition between mixing and segregation by disturbing the coalescence and break-up of the bubble. In addition, the pressure fluctuation signal proves to be helpful in understanding the dynamic features of the phenomenology.
A Discovery-Learning Classroom Case on Accounting Data Transmission Systems
Authors: Fordham David R.
Published: October 2008

ABSTRACT: This paper describes a classroom exercise utilizing a technique known as “discovery learning.” The activity involves a hands-on lab composed of basic building blocks of a simple wireless network. Students engage in a physical activity that demonstrates the operation of individual layers of the seven-layer Open Systems Interconnect model. In the process, they uncover conceptual knowledge normally delivered via means that are more traditional such as lecture or reading. During one such lab session, students stumbled upon a real-world control breach. This discovery, completely unplanned by the instructor, vividly illustrated the critical importance of the topical material. The experience greatly increased student interest and motivation. Assessment data confirms that student comprehension and application is significantly enhanced.
Compensatory Damage Awards for Nonphysical Personal Injuries: The Murphy Pendulum
Authors: Gaffney Dennis J. , Smith-Gaffney Maureen H. , Weber Richard P. , Davis Richard O.
Published: October 2008

The Murphy case involves the question of whether compensatory damage awards received for nonphysical personal injury are subject to the federal income tax. Such awards had been excluded from a taxpayer's gross income since 1918, but in 1996, Congress amended I.R.C. Sec. 104(a)(2) with the intention of taxing these awards. The taxpayer (Murphy) received an award for nonphysical personal injuries after the 1996 amendment and has argued in three judicial proceedings that, despite the amendment, her award is not taxable. This paper traces the path of the Murphy case through the IRS and the courts, discusses the income tax issues raised in the various forums, and makes recommendations to clarify and improve the federal income tax treatment of compensatory damages for nonphysical personal injury.
Passive Rental Activity Issues Challenged in the Tax Court and on Appeal 2000–2006
Authors: Riordan Diane A. , Riordan Michael P.
Published: October 2008

Section 469 of the Internal Revenue Code limiting the current deduction of passive losses was introduced by the Tax Reform Act of 1986 in response to concerns that rental properties and other investments were acting as tax shelters for the rich. Application of the provision has resulted in a dynamic regulatory environment which often has been challenging to administer. The regulations have been amended and reissued so frequently that taxpayers have actually used the authoritative turmoil in the construction of their defensive arguments in the courts. In this paper we review a window of activity in the Tax Court and courts of appeal during the period just prior to the provision's twentieth anniversary to identify the issues that continue to challenge taxpayers and administrators. We find that, with few exceptions stemming from two of the six rental exceptions challenged in the Tax Court, the Commissioner has been successful in defending the Service's position on passive rental activity issues despite the dynamic environment.
Photocatalytic Antibacterial Effect of TiO2 Film of TiAg on Streptococcus mutans
Authors: Choi Jung-Yoon , Chung Chooryung Judi , Oh Keun-Taek , Choi Yoon-Jeong , Kim Kyung-Ho
Published: October 2008

Objective: To test through various oxidation procedures the differences in antibacterial activities against Streptococcus mutans (S mutans) of Titanium (Ti) and Titanium silver (TiAg) metals coated with TiO2.

Materials and Methods: This study examined the photocatalytic antibacterial effects on S mutans of Ti and TiAg ubstrates coated with two crystalline forms of TiO2 by thermal and anodic oxidation. A bacterial suspension of S mutans was pipetted onto TiO2-coated metal specimens and uncoated specimens with ultraviolet A (UVA) illumination for 20 to 100 minutes. The same specimen without UVA was used as the control. The level of colony-forming units of S mutans after UVA illumination was compared with that of the control.

Results: The level of colony-forming units of S mutans was significantly lower on TiO2-coated Ti and TiAg metal specimens after UVA illumination than on uncoated Ti and TiAg specimens. The level of colony-forming units of S mutans was significantly lower on the metals coated by anodic oxidation than on those coated by thermal oxidation. The TiO2 coating on TiAg had a significantly higher and more rapid antibacterial effect than did the TiO2 coating on Ti.

Conclusions: The antibacterial effect of a TiO2 film formed by anodic oxidation was superior to that formed by thermal oxidation. The addition of Ag to the Ti specimen indicated a synergistic effect on the photocatalytic antibacterial property against S mutans.
Electromyographic Activity of Masseter and Temporal Muscles with Different Facial Types
Authors: Vianna-Lara Michelle Santos , Caria Paulo Henrique Ferreira , Tosello Darcyde Oliveira , Lara Flávio , Amorim Maise Mendonça
Published: October 2008

Objectives: To compare the electromyographic (EMG) activity of the masseter and anterior portion of temporal muscles in different vertical facial types.

Materials and Methods: Clinical examination, cephalometric analysis, and electromyographic examination were performed in 44 volunteers ranging from 18 to 35 years old. The volunteers were classified on the basis of their vertical facial characteristics into three groups—brachyfacial, mesofacial, and dolicofacial—by the grouping analysis. The EMG records were obtained with three repetitions during mandibular rest, maximum voluntary contraction in intercuspidation, and simultaneous bilateral isotonic contraction. The Kolmogorov-Smirnov and Levene tests were applied to verify the normality and homogeneity of variance. Analysis of variance and the Kruskal-Wallis test identified statistical differences among groups that did not present normality and homogeneity of distribution, respectively. Significance for all statistical tests was set at P < .05.

Results: At rest, only the right temporal and masseter muscles presented statistically significant differences among the groups. The differences were observed between groups 1 and 2 (P = .02) and 1 and 3 (P = .038) for the right temporal muscle, and between groups 1 and 2 (P = .029) for the right masseter muscle. Generally, group 1 presented the lowest EMG values for the four muscles evaluated during rest. For isotonic evaluation, none of the groups of muscles presented statistically significant differences.

Conclusion: Different vertical facial types do not determine distinct patterns of EMG activity for the masseter and anterior portion of temporal muscles during rest and bilateral mastication.
Facial Soft Tissue Values in Persian Adults with Normal Occlusion and Well-Balanced Faces
Authors: Taki Amjad Al , Oguz Fatma , Abuhijleh Eyas
Published: October 2008

Objective: To determine the mean soft tissue facial profile for Persian adults as determined by the Holdaway analysis.

Materials and Methods: Lateral cephalometric radiographs for 62 Persian adults with normal occlusion were used.

Results: Persian adults have the same values of Holdaway soft tissue norms except for the skeletal profile convexity, H angle, basic upper lip thickness, and soft tissue chin thickness, which were increased in Persians in relation to Holdaway norms. When comparing men with women, the nose prominence (P < .001), basic upper lip thickness (P < .001), upper lip thickness (P < .001), inferior sulcus to H line (P < .001), and soft tissue chin thickness (P < .01) were significantly increased in Persian men compared with Persian women.

Conclusions: Persian adults differ from Holdaway's soft tissue norms in an increased skeletal profile convexity, H angle, basic upper lip thickness, and soft tissue chin thickness. These are recommended for use when formulating a treatment plan for this ethnic group.
Early Headgear Effects on the Eruption Pattern of the Maxillary Canines
Authors: Silvola Anna-Sofia , Arvonen Päivi , Julku Johanna , Lähdesmäki Raija , Kantomaa Tuomo , Pirttiniemi Pertti
Published: October 2008

Objective: To test the null hypothesis that early headgear (HG) treatment has no effect on the eruption pattern of the maxillary canines in the early mixed dentition.

Materials and Methods: Sixty-eight children (40 boys and 28 girls) with a Class II tendency in occlusion and moderate crowding of the dental arches were randomized into two groups. HG treatment was initiated immediately in the first group. In the second group only minor interceptive procedures were performed during the first follow-up period of 2 years. Orthopantomograms were taken at the baseline, three times at 1-year intervals, and after growth at the age of 16. Eruption geometry was performed. The space from the maxillary first molar to the lateral incisor was measured on the dental casts.

Results: The inclination of the maxillary canine in relation to the midline appeared to be significantly more vertically oriented on the right side in the HG group 1 and 2 years after starting the HG therapy (P = .0098 and P = .0003, respectively). The inclination in relation to the lateral incisors was smaller in the HG group bilaterally after 1 year and 2 years of HG treatment, and on the right side after 3 years of treatment.

Conclusion: The hypothesis is rejected. Early HG treatment significantly affects the inclination of the maxillary canine during eruption. The strongest influence was seen after 2 years of HG use, more prominently in the right-side canine.
Increased Occurrence of Dental Anomalies Associated with Second-Premolar Agenesis
Authors: Garib Daniela G. , Peck Sheldon , Gomes Simone Carinhena
Published: October 2008

Objective: To evaluate the prevalence of dental anomalies in patients with agenesis of second premolars and compare the findings with the prevalence of these anomalies in the general population.

Materials and Methods: A Brazilian sample of 203 patients aged 8 to 22 years was selected. All patients presented agenesis of at least one second premolar. Panoramic and periapical radiographs and dental casts were used to analyze the presence of other associated dental anomalies, including agenesis of other permanent teeth, ectopia of unerupted permanent teeth, infraocclusion of deciduous molars, microdontia of maxillary lateral incisors, and supernumerary teeth. The occurrence of these anomalies was compared with occurrence data previously reported for the general population. Statistical testing was performed using the chi-square test (P < .05) and the odds ratio.

Results: The sample with agenesis of at least one second premolar presented a significantly increased prevalence rate of permanent tooth agenesis (21%), excluding third molars. Among the sample segment aged 14 years or greater (N = 77), occurrence of third-molar agenesis (48%) exceeded twice its normal frequency. Significant increases in occurrence of microdontia of maxillary lateral incisors (20.6%), infraocclusion of deciduous molars (24.6%), and distoangulation of mandibular second premolars (7.8%) were observed. Palatally displaced canine anomaly was also significantly elevated (8.1%).

Conclusion: The results provide evidence that agenesis of other permanent teeth, microdontia, deciduous molar infraocclusion, and certain dental ectopias are the products of the same genetic mechanisms that cause second-premolar agenesis.
Impaction and Retention of Second Molars: Diagnosis, Treatment and Outcome
Authors: Magnusson Cathrine , Kjellberg Heidrun
Published: October 2008

Objective: To evaluate treatment outcome in patients with second molar impaction and retention.

Materials and Methods: A total of 135 second molars, 65 in the maxilla and 70 in the mandible were collected from 87 patients (45 girls and 42 boys) with a mean age of 15 years (range: 11– 19 years). Available patient records, x-rays, study casts, and photos were studied. The mean follow-up period was 22 months (range: 4–106 months).

Results: A total of 166 second molars were diagnosed as impacted, 24 as primary and 5 as secondarily retained; 80% of the second molars were orthodontically or surgically treated. In more than half of the treated patients the second molars failed to erupt into a proper position. Surgical exposure of the retained or impacted second molar was the treatment found most successful (71%). The least successful treatment (11%) used the third molar to replace the second molar after the second molar was extracted. No clear difference in treatment outcome could be detected between the impacted and the primary or secondary retained teeth. However, a clear difference was found between the impacted and the primary retained second molars regarding treatment strategy: 9% of the impacted and 67% of the primary retained teeth were left untreated. Dental crowding was found in 70% of the patients.

Conclusion: In more than half of the treated patients the second molars failed to erupt into a proper position. The most common treatment given (extraction of the second molar) was the least successful.
Third-Order Torque and Self-Ligating Orthodontic Bracket–Type Effects on Sliding Friction
Authors: Chung Michael , Nikolai Robert J. , Kim Ki Beom , Oliver Donald R.
Published: October 2008

Objective: To examine the influence of third-order torque on kinetic friction in sliding mechanics involving active and passive self-ligating brackets.

Materials and Methods: Wire-slot frictional forces were quantified and compared across five sets of brackets and tubes within a simulated posterior dental segment with −15°, −10°, −5°, 0°, +5°, +10°, and +15° of torque placed in the second-premolar bracket; a working archwire was pulled through the slots.

Results: Increasing the torque from 0° to ±15° produced significant increases in frictional resistance with all five sets of brackets and tubes. At 0° and ±5° of torque, generally less friction was created within the passive than within the active self-ligating bracket sets, and the conventional bracket sets with elastomeric ligation generated the most friction. At ±10° of torque, apparently with wire-slot clearance eliminated, all bracket-and-tube sets displayed similar resistances, with one exception at +10°. At ±15° of torque, one passive set and one active set produced significantly larger frictional resistances than the other three sets.

Conclusions: Third-order torque in posterior dental segments can generate frictional resistance during anterior retraction with the archwire sliding through self-ligating bracket slots. With small torque angles, friction is less with passive than with active self-ligating brackets, but bracket design is a factor. Frictional forces are substantial, regardless of ligation if the wire-slot torque exceeds the third-order clearance.
Biomechanical and Histomorphometric Characterizations of Osseointegration during Mini-Screw Healing in Rabbit Tibiae*
Authors: Wu Jing , Bai Yu-Xing , Wang Bang-Kang
Published: October 2008

Objective: To evaluate effects of different healing times on integration of titanium mini-screws and bones under unloaded conditions.

Materials and Methods: Biomechanical stability measurements and histomorphometric observations were performed in a rabbit tibia model after different healing times: 0 (immediate) and 1, 2, 4, and 8 weeks.

Results: Biomechanical stability and both maximum torque and maximum pullout load increased with healing time but increased significantly only after 4 weeks. Maximum torque and maximum pullout load both significantly correlated with healing time and with each other. Similarly, histomorphometric analyses showed that new bone formation increased with healing time but increased dramatically only after 4 weeks. The data may provide guidance for determining optimal implant plans in clinical practice.

Conclusion: Mini-screw healing is a continuous process, and week 4 is a critical time point in this process.
Effects of Ovariectomy on Rat Genioglossal Muscle Contractile Properties and Fiber-Type Distribution
Authors: Liu Yue-hua , Jia Shan-shan , Hou Yu-xia
Published: October 2008

Objective: To test the hypothesis that ovariectomy has no effects on contractile, histochemical, or biochemical properties of the rat genioglossus (GG).

Materials and Methods: Eight-week-old female Sprague-Dawley rats were randomly assigned into three groups: normal group (Normal), sham-operated group (Sham), and ovariectomized group (OVX). Four weeks later, genioglossal electromyography activity (EMGgg) and contractile properties were measured, including relative integrated EMG (iEMG), maximal twitch tension, 70%-decay time, and fatigue index (FI). Then rats were sacrificed and paired GG were removed for further analysis. Adenosine-triphosphatase (ATPase) staining was performed to determine the percent fiber-type distribution and to identify cross-sectional area (CSA) of muscle fibers. Myosin heavy chain (MHC) phenotypes were determined by gel electrophoresis.

Results: Ovariectomy reduced EMG activity and contractile properties of the GG. Following ovariectomy, the CSA of type IIA and the proportion of MHCIIA decreased significantly. The MHC isoform composition of GG transferred from relative slow-twitch to fast-twitch isoform, following the order MHCIIB → MHCIIX → MHCIIA. Sham operation had no effect on any of the parameters.

Conclusions: The hypothesis is rejected. The contractile properties of the GG are sensitive to ovariectomy. These changes were, at least in part, associated with changes in the amount and type of contractile protein expressed.
Use of Palatal Miniscrew Anchorage and Lingual Multi-Bracket Appliances to Enhance Efficiency of Molar Scissors-Bite Correction
Authors: Tamamura Nagato , Kuroda Shingo , Sugawara Yasuyo , Takano-Yamamoto Teruko , Yamashiro Takashi
Published: October 2008

This article reports the successful treatment method of scissors-bite correction using miniscrew anchorage and a lingual multi-bracket appliance. A female patient, 17 years and 4 months old, had a chief complaint of crowding of anterior teeth. The patient was given the diagnosis of Angle Class I malocclusion with bimaxillary protrusion and incisor crowding. She also showed a scissors-bite of the second molar on the right side. Miniscrews were inserted into the palatal region of the upper second molar to reinforce the anchorage, and a lingual multi-bracket appliance was placed into the maxilla. Miniscrews inserted palatally were used to correct the scissors-bite in the first 3 months; afterward, they were used to retract the six anterior teeth. The total active treatment period was 26 months. Because of the bite-plane effect, the upper and lower molars were separated in occlusion, and the scissors-bite was corrected effectively within a short time. The combined use of palatal miniscrew anchorage and lingual multi-bracket appliances enhances efficiency of molar scissors-bite correction.
Acceptability of Dental Appearance in a Group of Finnish 16- to 25-Year-Olds
Authors: Svedström-Oristo Anna-Liisa , Pietilä Terttu , Pietilä Ilpo , Vahlberg Tero , Alanen Pentti , Varrela Juha
Published: October 2008

Objective: To define a grade in the Aesthetic Component (AC) of the Index of Orthodontic Treatment Need (IOTN) that would differentiate between esthetically acceptable and unacceptable occlusions and that would also be both subjectively and objectively meaningful.

Materials and Methods: Dental appearance and self-perceived orthodontic treatment need were analyzed in a group of Finnish young adults (171 males, 263 females, age range 16–25 years). Subjective data were gathered using a questionnaire, and the respondents were requested to score their dental appearance on a visual analog type 10-grade scale. Professional assessment of dental appearance was performed by two orthodontists using the AC of the IOTN. The cutoff value between esthetically acceptable and unacceptable occlusions was defined using receiver operating characteristic curves.

Results: Sixty-six percent of orthodontically treated and 74% of the untreated respondents were satisfied with their own dental appearance. Every third respondent reported one or more disturbing traits in their dentition. The most frequently expressed reason for dissatisfaction was crowding; girls expressed dissatisfaction more often than boys did (P = .005). A self-perceived treatment need was reported infrequently by 8% of orthodontically treated and 6% of untreated respondents. In the logistic regression analysis, self-perceived need for orthodontic treatment was the only significant factor explaining dissatisfaction with own dental esthetics. On the applied scales, grades 1 and 2 fulfilled the criteria for satisfactory dental esthetics.

Conclusion: The results suggest that the AC grade 3 could serve as a cutoff value between esthetically acceptable and unacceptable occlusions.
Disk Position and Temporomandibular Joint Structure Associated with Mandibular Setback in Mandibular Asymmetry Patients
Authors: Kawakami Masayoshi , Yamamoto Kazuhiko , Inoue Tomohiro , Kajihara Atsuhisa , Fujimoto Masaki , Kirita Tadaaki
Published: October 2008

Objective: To determine the changes in articular disk position and the temporomandibular joint (TMJ) structure in patients who had an asymmetric setback of the mandible performed by a bilateral sagittal split ramus osteotomy with manual positioning of the condyle.

Materials and Methods: Twenty-two patients with skeletal Class III malocclusion being treated at Nara Medical University Hospital were evaluated using clinical examination and pre- and postoperative magnetic resonance images of their TMJs.

Results: Changes in articular disk position after asymmetric setback surgery were not statistically significant, although a tendency of anterior displacement in the fossa was noted. The anterior and posterior joint spaces did not show significant changes, whereas the condyle head of the deviated or contralateral side tended to be positioned downward.

Conclusion: The asymmetric setback of the mandible with intraoperative manual positioning of the condyle does not significantly change the disk position in the fossa.
Overjet at the Anterior and Posterior Segments: Three-Dimensional Analysis of Arch Coordination
Authors: Kook Yoon-Ah , Bayome Mohamed , Park Soo-Byung , Cha Bong-Kuen , Lee Young-Wuk , Baek Seung-Hak
Published: October 2008

Objectives: To compare the amounts of anatomical overjet measured from facial axis (FA) points with the amounts of bracket overjet measured from bracket slot center (BSC) points.

Materials and Methods: The samples consisted of 27 subjects with normal occlusion whose models were fabricated with a three-dimensional (3D) scanner and the 3Txer program (Orapix Co Ltd, Seoul, Korea). 3D virtual brackets (0.022″ Slot, MBT setup, 3M Unitek, Monrovia, Calif) constructed with a 3D-CAD program were placed on an FA point with the 3Txer program. The arch dimension and the amounts of overjet from FA and BSC points were measured. Paired t-tests and analysis of variance (ANOVA) tests were used for statistical analysis.

Results: No significant difference in arch width and depth was observed between FA and BSC points. Although the amounts of overjet measured from FA points showed homogenous distribution, a tendency to decrease from the anterior segment (2.3 mm) to the posterior one (2.0 mm) was noted. However, the amounts of overjet measured from BSC points were variable, especially in the premolar and molar areas. Significant discrepancies in the amounts of overjet in most of the areas between FA and BSC points (more than P < .05), except the lower second premolar and second molar areas, were reported, even though insets and offsets are part of the prescription for the base of straight-wire appliance (SWA) brackets.

Conclusions: The hypotheses that the amount of overjet measured from BSC points was 3 mm through the whole segments and that distribution of the amounts of overjet from BSC points was the same as that from FA points were rejected.
Change of Incisor Inclination Effects on Points A and B
Authors: Al-Abdwani Rasha , Moles David R. , Noar Joseph Harold
Published: October 2008

Objective: To identify and evaluate changes in the cephalometric position of points A and B due to an incisal inclination change caused by orthodontic treatment.

Materials and Method: A total of 103 pairs of consecutive pretreatment and posttreatment lateral cephalographs that met the inclusion criteria were systematically collected from the departmental database and digitized using a customized software program (Gela). Repeatability analyses showed good reliability and no evidence of bias. A statistical model was generated using a Generalized Estimating Equation approach to analyze the data accounting for growth and bodily movement because both factors influence the position of points A and B (P < .001, P < .001). Changes in tooth length were also accounted for, as these changes may influence the calculated position of the centroid (P = .002).

Results: Each 10° change in the maxillary incisor inclination results in a statistically significant average change in point A of 0.4 mm in the horizontal plane (P = .028). Each 10° change in the mandibular incisor inclination results in a borderline statistically significant average change in point B of 0.3 mm in the horizontal plane (P = .058). There were no significant changes in the vertical position of points A and B.

Conclusion: The effects of incisal inclination changes, due to orthodontic treatment, are of no clinical relevance to the position of point A and B, even though they may be statistically significant. The validity of points A and B as skeletal landmarks generally holds true, and accounting for treatment changes is unnecessary.
The Impact of Malocclusion/Orthodontic Treatment Need on the Quality of Life
Authors: Liu Zhijian , McGrath Colman , Hägg Urban
Published: October 2008

Objective: To assess the current evidence of the relationship between malocclusion/orthodontic treatment need and quality of life (QoL).

Materials and Methods: Four electronic databases were searched for articles concerning the impact of malocclusion/orthodontic treatment need on QoL published between January 1960 and December 2007. Electronic searches were supplemented by manual searches and reference linkages. Eligible literature was reviewed and assessed by methodologic quality as well as by analytic results.

Results: From 143 reviewed articles, 23 met the inclusion criteria and used standardized health-related QoL (HRQoL) and orthodontic assessment measures. The majority of studies (18/23) were conducted among child/adolescent populations. Seventeen of the papers were categorized as level 1 or 2 evidence based on the criteria of the Oxford Centre for Evidence-Based Medicine. An observed association between HRQoL and malocclusion/orthodontic treatment need was generally detected irrespective of how they were assessed. However, the strength of the association could be described as modest at best. Key findings and future research considerations are described in the review.

Conclusions: Findings of this review suggest that there is an association (albeit modest) between malocclusion/orthodontic treatment need and QoL. There is a need for further studies of their relationship, particularly studies that employ standardized assessment methods so that outcomes are uniform and thus amenable to meta-analysis.