bluuebunny/crossref_metadata_2025 huggingface dataset:
Habitat area and structure affect the impact of seed predators and the potential for coevolutionary arms races
Authors: Mezquida Eduardo T. , Benkman Craig W.
Published: April 2010

Both habitat patch size and structure affect the abundance and occurrence of species and thereby can affect the ecology and evolution of species interactions. Here we contrast the level of seed predation and selection exerted by Common Crossbills (Loxia curvirostra complex) and red squirrels (Sciurus vulgaris) in the extensive mountain pine (Pinus uncinata) forests in the Pyrenees with their level of seed predation in two small, isolated forests. Crossbills consumed 5.1 times more seeds in the Pyrenees than in the isolated forests, and six of seven cone traits under selection by crossbills were enhanced in the Pyrenees. In contrast, red squirrels tend to be uncommon in the open mountain pine forests, consuming relatively few seeds in both regions and having limited impact on both mountain pine and the interaction between crossbills and mountain pine. Resident crossbills in mountain pine forests in the Pyrenees have larger bills than in nearby forests, consistent with local adaptation by crossbills and a coevolutionary arms race between crossbills and mountain pine. The mechanisms leading to variation in the interaction between crossbills and mountain pine should be general to many systems because habitat patch size and structure often vary across the range of a species.
Habitat isolation moderates the strength of top‐down control in experimental pond food webs
Authors: Chase Jonathan M. , Burgett Amber A. , Biro Elizabeth G.
Published: April 2010

Habitat isolation is well known to alter patterns of species' abundance, richness, and the ratios of predators : prey. Less clear, however, is how isolation alters interactions within food webs. Here, we present the results from an experiment performed in artificial ponds (mesocosms) manipulating habitat isolation crossed with a predator reduction treatment to disentangle how isolation mediates the top‐down effect of predators. The strength of the trophic cascade, from predators, through herbivores, to producers, was considerably stronger in connected than in isolated habitats. We further found that the overall richness of both predator and herbivore species declined strongly with isolation. Experimental predator reductions suggest that the mechanism underlying the herbivore response was likely mediated by a keystone predator effect; when predators were reduced, herbivore richness was lower, and there was no discernable effect of isolation on herbivore richness. Finally, we found that the composition of predators in more isolated habitats consisted of species that were smaller and likely less effective predators than species that persisted in less isolated habitats. In all, our experiment showed that habitat isolation can alter the structure of communities by a combination of direct effects of the species in question, as well as effects mediated through their interactions in the food web.
Constructing confidence: rational skepticism and systematic enquiry in local ecological knowledge research
Authors: Davis Anthony , Ruddle Kenneth
Published: April 2010

Key attributes of the social research contributions on indigenous ecological knowledge (IEK), local ecological knowledge (LEK), and traditional ecological knowledge (TEK) are analyzed using the most frequently cited literature generated by the “ISI Web of Knowledge” and “Google Scholar” search engines. They are further exemplified by an examination of two contrasting approaches to the analysis of IEK/LEK/TEK. The results show that IEK/LEK/TEK is treated predominantly via definitions, and few articles examine concepts, research design, methods, or operational attributes. Consequently, there is no consensus on the content of IEK/LEK/TEK, the primary components of which await examination via focused research. These are fundamental issues, since IEK/LEK/TEK misrepresented by social research would probably deepen disempowerment of those it purports to champion. Research topics are suggested to address these issues.
Contributions of demography and dispersal parameters to the spatial spread of a stage‐structured insect invasion
Authors: Miller Tom E. X. , Tenhumberg Brigitte
Published: April 2010

Stage‐structured models that integrate demography and dispersal can be used to identify points in the life cycle with large effects on rates of population spatial spread, information that is vital in the development of containment strategies for invasive species. Current challenges in the application of these tools include: (1) accounting for large uncertainty in model parameters, which may violate assumptions of “local” perturbation metrics such as sensitivities and elasticities, and (2) forecasting not only asymptotic rates of spatial spread, as is usually done, but also transient spatial dynamics in the early stages of invasion. We developed an invasion model for the Diaprepes root weevil (DRW; Diaprepes abbreviatus [Coleoptera: Curculionidae]), a generalist herbivore that has invaded citrus‐growing regions of the United States. We synthesized data on DRW demography and dispersal and generated predictions for asymptotic and transient peak invasion speeds, accounting for parameter uncertainty. We quantified the contributions of each parameter toward invasion speed using a “global” perturbation analysis, and we contrasted parameter contributions during the transient and asymptotic phases. We found that the asymptotic invasion speed was 0.02–0.028 km/week, although the transient peak invasion speed (0.03–0.045 km/week) was significantly greater. Both asymptotic and transient invasions speeds were most responsive to weevil dispersal distances. However, demographic parameters that had large effects on asymptotic speed (e.g., survival of early‐instar larvae) had little effect on transient speed. Comparison of the global analysis with lower‐level elasticities indicated that local perturbation analysis would have generated unreliable predictions for the responsiveness of invasion speed to underlying parameters. Observed range expansion in southern Florida (1992–2006) was significantly lower than the invasion speed predicted by the model. Possible causes of this mismatch include overestimation of dispersal distances, demographic rates, and spatiotemporal variation in parameter values. This study demonstrates that, when parameter uncertainty is large, as is often the case, global perturbation analyses are needed to identify which points in the life cycle should be targets of management. Our results also suggest that effective strategies for reducing spread during the asymptotic phase may have little effect during the transient phase.
Parasites and pathogens lag behind their host during periods of host range advance
Authors: Phillips Ben L. , Kelehear Crystal , Pizzatto Lígia , Brown Gregory P. , Barton Di , Shine Richard
Published: April 2010

The process of rapid range expansion (as seen in many invasive species, and in taxa responding to climate change) may substantially disrupt host–parasite dynamics. Parasites and pathogens can have strong regulatory effects on their host population and, in doing so, exert selection pressure on host life history. We construct a simple individual‐based model of host–parasite dynamics during range expansion. This model shows that the parasites and pathogens of a range‐expanding host are likely to be absent from the host's invasion front, because stochastic events (serial founder events) in low‐density frontal populations result in local extinctions or transmission failure of the parasite/pathogen and, hence, a preponderance of uninfected hosts in the invasion vanguard. This pattern is true for both density‐dependent and density‐independent transmission rates, although it is exacerbated in the case of density‐dependent transmission because, in this case, transmission rates also decline on the front. Data from field surveys on the prevalence of lungworms (Rhabdias pseudosphaerocephala) in invasive cane toads (Bufo marinus) support these predictions, in showing that toads in newly invaded areas of tropical Australia lack the parasite, which only arrives 1–3 years after the toads themselves. The resultant “honeymoon phase” immediately post‐invasion, when individuals in the invasion‐front population are virtually pathogen‐free, may lead to altered host population dynamics on the invasion front, causing, for example, high densities in invasion‐front populations, followed by a decline in numbers as parasites and pathogens arrive and begin to reduce host viability. The honeymoon phase may ultimately impact the evolution of life‐history investment strategies in both host and parasite on the invasion vanguard, as hosts are released from immune challenges and parasites continuously expand into a favorable and unoccupied niche.
Experimental evidence for neutral community dynamics governing an insect assemblage
Authors: Siepielski Adam M. , Hung Keng-Lou , Bein Eben E. B. , McPeek Mark A.
Published: April 2010

The high levels of species diversity observed within many biological communities are captivating, yet the mechanisms that may maintain such diversity remain elusive. Many of the phenotypic differences observed among species cause interspecific trade‐offs that ultimately act to maintain diversity through niche‐based coexistence. In contrast, neutral community theory argues that phenotypic differences among species do not contribute to maintaining species diversity because species are ecologically equivalent. Here we provide experimental and observational field evidence that two phylogenetically very distantEnallagmaspecies appear to be ecologically equivalent to one another. Experimental abundance manipulations showed that each species gains no demographic advantage at low relative abundance, whereas manipulations of totalEnallagmaabundance resulted in large increases in per capita mortality and large decreases in growth for both species. Moreover, demographic rates and relative abundances of multipleEnallagmaspecies were uncorrelated with major environmental gradients in an observational study of 20 natural lakes. These are the expected patterns if species are ecologically equivalent. However, these results do not imply that all damselflies in these lakes are ecologically identical. Previous experimental results have demonstrated the operation of strong coexistence mechanisms maintainingEnallagmaand its sister‐genusIschnurain these littoral food webs. Combined with a simple theoretical model we present, these results taken together show how both neutral and niche dynamics can jointly structure communities.
Lakeshore zoning has heterogeneous ecological effects: an application of a coupled economic‐ecological model
Authors: Butsic Van , Lewis David J. , Radeloff Volker C.
Published: April 2010

Housing growth has been widely shown to be negatively correlated with wildlife populations, avian richness, anadromous fish, and exotic invasion. Zoning is the most frequently used public policy to manage housing development and is often motivated by a desire to protect the environment. Zoning is also pervasive, taking place in all 50 states. One relevant question that has received little research concerns the effectiveness of zoning to meet ecological goals. In this paper, we examined whether minimum frontage zoning policies have made a positive impact on the lakes they were aimed to protect in Vilas County, Wisconsin, USA. We used an economic model that estimated when a given lot will be subdivided and how many new lots will be created as a function of zoning. Using the economic model, we simulated the effects of multiple zoning scenarios on lakeshore development. The simulated development patterns were then input to ecological models that predicted the amount of coarse woody debris (CWD) and the growth rate of bluegills as a function of residential density. Comparison of the ecological outcomes under different simulated zoning scenarios quantified the effect of zoning policies on residential density, CWD, and bluegill growth rates. Our results showed that zoning significantly affected residential density, CWD counts, and bluegill growth rates across our study area, although the effect was less clear at the scale of individual lake. Our results suggest that homogeneous zoning (i.e., for a county) is likely to have mixed results when applied to a heterogeneous landscape. Further, our results suggest that zoning regimes with a higher minimum shoreline frontage are likely to have larger ecological effects when applied to lakes that are less developed.
Carbon and water fluxes from ponderosa pine forests disturbed by wildfire and thinning
Authors: Dore S. , Kolb T. E. , Montes-Helu M. , Eckert S. E. , Sullivan B. W. , Hungate B. A. , Kaye J. P. , Hart S. C. , Koch G. W. , Finkral A.
Published: April 2010

Disturbances alter ecosystem carbon dynamics, often by reducing carbon uptake and stocks. We compared the impact of two types of disturbances that represent the most likely future conditions of currently dense ponderosa pine forests of the southwestern United States: (1) high‐intensity fire and (2) thinning, designed to reduce fire intensity. High‐severity fire had a larger impact on ecosystem carbon uptake and storage than thinning. Total ecosystem carbon was 42% lower at the intensely burned site, 10 years after burning, than at the undisturbed site. Eddy covariance measurements over two years showed that the burned site was a net annual source of carbon to the atmosphere whereas the undisturbed site was a sink. Net primary production (NPP), evapotranspiration (ET), and water use efficiency were lower at the burned site than at the undisturbed site. In contrast, thinning decreased total ecosystem carbon by 18%, and changed the site from a carbon sink to a source in the first post‐treatment year. Thinning also decreased ET, reduced the limitation of drought on carbon uptake during summer, and did not change water use efficiency. Both disturbances reduced ecosystem carbon uptake by decreasing gross primary production (55% by burning, 30% by thinning) more than total ecosystem respiration (TER; 33–47% by burning, 18% by thinning), and increased the contribution of soil carbon dioxide efflux to TER. The relationship between TER and temperature was not affected by either disturbance. Efforts to accurately estimate regional carbon budgets should consider impacts on carbon dynamics of both large disturbances, such as high‐intensity fire, and the partial disturbance of thinning that is often used to prevent intense burning. Our results show that thinned forests of ponderosa pine in the southwestern United States are a desirable alternative to intensively burned forests to maintain carbon stocks and primary production.
Evolution of prey in ecological time reduces the effect size of predators in experimental microcosms
Authors: terHorst Casey P. , Miller Thomas E. , Levitan Don R.
Published: April 2010

Ecologists have long studied the effect of predators on prey population abundance while evolutionary biologists have measured prey trait evolution in response to predation. Ecological and evolutionary processes were generally thought to occur on different time scales, but recent evidence suggests that evolution may alter the ecological effects of predation over the course of ecological experiments. We used a protozoan and its mosquito‐larvae predator, naturally found in the water‐filled leaves of pitcher plants, to examine the effect of prey evolution on predator–prey interactions. In experiments conducted over 12 days (approximately 50 prey generations, but less than one predator generation), we measured a decrease in the effect of mosquito larvae predators on protozoa prey populations. In a separate set of experiments, we found that the presence of predators corresponded with evolution of smaller cell size and increased population growth rate. In ecological experiments, two situations commonly occur: strong selection pressure applied by the treatment itself and discrepancies in generation times of associate species. Our results suggest that in either situation, the resulting evolutionary patterns may lead to dramatic and important changes in ecological effect size.
Human behavior influences infectious disease emergence at the human–animal interface
Authors: Alexander Kathleen A , McNutt J Weldon
Published: April 2010

Although human behavior is frequently cited as a factor influencing the emergence of disease at the human–animal interface, few empirical studies have demonstrated this relationship. We compare humans and their domestic animals living in close proximity to populations of the endangered African wild dog (AWD, Lycaon pictus) in both Kenya and Botswana. We identify culturally based differences in domestic‐stock grazing practices among pastoralists that strongly influence frequency of contact between domestic dogs and AWDs, with parallel differences in disease‐related mortality in AWD populations. Using this study and other examples, we illustrate a conceptual model of the interaction between human behavior and emerging infectious diseases at the human–domestic‐animal–wildlife interface. Human cultural behavior has the potential to influence pathogen adaptation, host susceptibility, spatial distribution, and pathogen exposure and contact rates between susceptible hosts, reservoir hosts, and pathogen communities. This affects the pathogen's basic reproductive number (R0), ability to invade, and persistence potential. Human behavior may be the key that unlocks the proverbial Pandora's Box, allowing infectious diseases to emerge.
Ecological assessment of estuarine sediments by pyrosequencing eukaryotic ribosomal DNA
Authors: Chariton Anthony A , Court Leon N , Hartley Diana M , Colloff Matthew J , Hardy Christopher M
Published: April 2010

Biodiversity assessment underpins our understanding of ecosystems and determines environmental management decisions on resource use and conservation priorities. Recently, a new discipline – environmental or ecological genomics (ecogenomics) – has emerged from major advances in sequencing technologies, such as pyrosequencing (a technique based on the detection of pyrophosphate during nucleotide incorporation), and enabled extraordinary progress in the way biodiversity can be assessed. Since 2008, numerous high‐impact microbial metagenomic sequencing studies, which have relied on both classical and next‐generation sequencing, have been published. As a result, many previously unrecognized taxa and biota have been identified, but none of these studies explored eukaryote diversity. Here, we illustrate the power of applying next‐generation pyrosequencing to identify and enumerate eukaryote species assemblages in the context of assessing the impacts of human activity on ecosystems.
HIV Infection and Bone Loss Due to Periodontal Disease
Authors: Aichelmann‐Reidy Mary E. , Wrigley Dena L. , Gunsolley John C.
Published: April 2010

Background: The goal of this study is to determine whether HIV infection or high‐risk behaviors associated with HIV infection are related to alveolar bone loss in a sample of subjects screened at a dental school clinic.

Methods: Subjects were included in this study (N = 355) if they were HIV positive or had high‐risk behaviors associated with HIV infection as identified by health risk behavior screening questionnaire. Bone loss measurements were obtained from radiographs. Both bivariate relationships and multivariate relationships between alveolar bone loss and three sets of variables were evaluated: high‐risk behavior questions, demographic variables, and HIV infection.

Results: The following variables were found related to alveolar bone loss in bivariate relationships: age (P ≤0.0001); smoking (pack‐years) (P ≤0.0001); race (P ≤0.002); gender (P ≤0.032); male‐male sex (P <0.001); diabetes (P ≤0.015); sharing of needles (P ≤0.02); and hepatitis C positive (P ≤0.05). In the multiple regression model, age, smoking, race, gender, and male‐male sex remained significant. In both analyses, HIV‐positive individuals had similar bone loss compared to those who were HIV negative.

Conclusions: These results suggest that HIV infection is not related to alveolar bone loss in individuals with high‐risk behaviors for HIV infection. These results also suggest that previously reported relationships between HIV infection and increased alveolar bone loss may be explained by other factors, such as smoking. Individuals in this study population with risk behaviors associated with HIV infection smoked at a high rate and, because of the smoking behavior, have a high rate of periodontal disease.
Free Gingival Grafts: Graft Shrinkage and Donor‐Site Healing in Smokers and Non‐Smokers
Authors: Silva Cléverson O. , Ribeiro Érica Del Peloso , Sallum Antônio Wilson , Tatakis Dimitris N.
Published: April 2010

Background: This prospective clinical study aims to evaluate the influence of cigarette smoking on free gingival graft (FGG) healing, by assessing FGG dimensional changes and donor‐site wound healing.

Methods: Twelve non‐smokers and 10 smokers treatment planned for FGG to augment keratinized tissue dimensions in the mandibular incisor area completed the study. All subjects received standardized FGG of same dimensions. Probing depth, gingival margin position, clinical attachment level, keratinized tissue (KT) width, gingival thickness, and FGG dimensions (width, length, and area) were assessed and recorded before surgery, and 7, 15, 30, 60, and 90 days postoperatively. The palatal donor area was evaluated for immediate bleeding and complete wound epithelialization. Differences between the two groups (smokers and non‐smokers) were statistically analyzed.

Results: FGG dimensions changed significantly postoperatively. At 90 days postoperatively, FGG width, length, and area were respectively reduced by 31%, 22%, and 44% in non‐smokers and by 44%, 25%, and 58% in smokers (no significant differences between groups; P >0.05). Significant KT increases were observed in both non‐smokers and smokers (5.4 and 4.8 mm, respectively). Donor‐site immediate bleeding was significantly more prevalent in non‐smokers (75%) compared to smokers (30%) (P = 0.04). At 15 days postoperatively, donor‐site complete epithelialization was much more prevalent in non‐smokers (92%) than in smokers (20%) (P <0.002).

Conclusion: Smoking alters FGG donor‐site wound healing by reducing immediate bleeding incidence and by delaying epithelialization, although it does not have discernible effects on postoperative FGG dimensional changes.
Immunoexpression of Angiogenesis, Nitric Oxide Synthase, and Proliferation Markers in Gingival Samples of Patients With Aggressive and Chronic Periodontitis
Authors: Artese Luciano , Piattelli Adriano , de Gouveia Cardoso Luciana Aparecida , Ferrari Daniel S. , Onuma Tatiana , Piccirilli Marcelo , Faveri Marcelo , Perrotti Vittoria , Simon Maciej , Shibli Jamil Awad
Published: April 2010

Background:In periodontal tissues, angiogenesis seems to be important for the maintenance of healthy tissues and in periodontal diseases. Angiogenesis is regulated through a complex interplay of molecular signals mediated by growth factors involving extracellular matrix remodeling, endothelial cell migration and proliferation, capillary differentiation and anastomosis. However, the influence of angiogenesis in the development, progression, and healing of periodontal lesions is currently under investigation. This immunohistochemical study evaluates the expression of vascular endothelial growth factor (VEGF), microvessel density (MVD), nitric oxide synthase (NOS) 1 and 3, and Ki‐67 in gingival tissues of patients with aggressive and chronic periodontitis.

Methods:Twenty‐seven human gingival biopsies were taken from patients with chronic periodontitis (n = 14 patients), generalized aggressive periodontitis (n = 6 patients), and healthy periodontia (n = 7 patients). The specimens were immunohistochemically stained for VEGF, MVD, NOS 1 and 3, and Ki‐67.

Results:The levels of VEGF, MVD, NOS 1 and 3, and Ki‐67 were found to be significantly different among groups (P>0.001). Patients with aggressive periodontitis had higher levels of these markers compared to those in patients with chronic periodontitis and healthy patients.

Conclusions:The analysis demonstrates a higher expression of all immunologic markers particularly in subjects with aggressive periodontitis. In summary, the data from this pilot investigation suggests that VEGF is an important factor in the pathogenesis of the aggressive and chronic forms of periodontitis.
Classical Versus Contemporary Treatment Planning for Aggressive Periodontal Disease
Authors: Nevins Myron , Kim David M.
Published: April 2010

Background: This case report presents a patient with a history of generalized aggressive periodontitis who has been maintained with the same periodontal prostheses for the past 40 years.

Methods: A 39‐year‐old healthy woman extremely susceptible to inflammatory periodontal disease presented to our office in 1968. Non‐surgical therapies were completed to evaluate tissue response and the patient's compliance with oral debridement. A prosthetic consultation was completed and accepted before periodontal surgery was initiated. Several teeth were deemed untreatable and removed at the time of consultation and construction of the provisional maxillary and mandibular prostheses.

Results: Clinical decisions were based on this patient's existing periodontal status, the restorability and the strategic value of specific teeth, the occlusal jaw relationship, and the esthetic concerns of the patient. She has been compliant with periodontal maintenance performed every 3 months since the conclusion of active treatment in 1969.

Conclusions: A periodontally compromised dentition punctuated by teeth with limited clinical roots and significant edentulous span requiring splinting was treated successfully with traditional therapies. The result has endured for 40 years with no additional loss of teeth.
Inflammatory Infiltrate, Microvessel Density, Vascular Endothelial Growth Factor, Nitric Oxide Synthase, and Proliferative Activity in Soft Tissues Below Intraorally Welded Titanium Bars
Authors: Fanali Stefano , Perrotti Vittoria , Riccardi Luciano , Piattelli Adriano , Piccirilli Marcello , Ricci Laura , Artese Luciano
Published: April 2010

Background:The aim of the present study is a comparative evaluation of inflammatory infiltrate, microvessel density, vascular endothelial growth factor, nitric oxide synthase, and proliferative activity in soft tissues below intraorally welded titanium bars.

Methods:Twenty‐two patients participated in this study. All patients carried immediately loaded one‐stage titanium implants splinted with intraorally welded titanium bars. Each patient underwent two gingival biopsies, a control biopsy harvested from an area of mucosa 5 mm away from the titanium bar and a test biopsy from the mucosa below the titanium bar, which were histologically and immunohistochemically processed.

Results:No fractures or radiographically detectable alterations of the welded frameworks were present. In all the cases examined, the average of the modified plaque index was 1, no suppuration or bleeding on probing was present, and probing depth was ≤3 mm. However, the immunohistochemical analysis revealed some differences. The inflammatory infiltrate was mostly present in test sites and its extension was much larger than in control sites. Statistically significant differences were found in microvessel density and Ki‐67 expression among control and test groups (P<0.0001). The high intensity of vascular endothelial growth factor, nitric oxide synthase 1, and nitric oxide synthase 3 expression were mainly detected in the test group, whereas the low intensities were mostly expressed in controls, with statistically significant differences (P<0.0001).

Conclusions:In the present study, the immunohistochemical analysis shows that the tissues below the titanium bars underwent a higher rate of inflammatory and reparative processes. However, further long‐term studies, where clinical and immunohistochemical data are collected in parallel, should be conducted for a better understanding of the expression pattern of inflammation markers.
Evaluation of Parathyroid Hormone Bound to a Synthetic Matrix for Guided Bone Regeneration Around Dental Implants: A Histomorphometric Study in Dogs
Authors: Valderrama Pilar , Jung Ronald E. , Thoma Daniel S. , Jones Archie A. , Cochran David L.
Published: April 2010

Background:A polyethylene glycol (PEG)‐based hydrogel matrix covalently bound to a 35‐amino acid peptide of parathyroid hormone cystein‐PTH 1‐34 (cys‐PTH 1‐34) was shown to enhance bone regeneration around implants. The aim of this study is to test if the addition of an integrin‐receptor–binding arginine‐glycine‐aspartic acid (RGD)–containing peptide at early healing time points improves the performance of the PEG matrix supplemented with cys‐PTH 1‐34 (PTH) when applied in acute defects around implants at early healing time points (2 and 4 weeks).

Methods:Six dogs received 48 implants. Each side of the mandible was randomly assigned for implantation at day 0 or 2 weeks. A circumferential critical‐size defect was created at each site before implantation. Sites were randomly assigned to one of four groups: 1) PEG alone (PEG group), 2) PEG plus RGD (PEG/RGD group), 3) PEG plus PTH (PEG/PTH group), and 4) PEG plus RGD plus PTH (PEG/RGD/PTH group). Dogs were sacrificed 2 weeks after the second surgery, and specimens were obtained for histologic analysis. For the statistical analysis, mixed linear regression with repeated measurements was used, and a Dunnett‐Hsu adjustment was made for multiple comparisons.

Results:At 2 weeks, the percentages of new bone formation within the defect were 12.43% for the PEG group, 15.95% for the PEG/RGD group, 15.32% for the PEG/PTH group, and 16.60% for the PEG/RGD/PTH group. At 4 weeks, the percentages of new bone formation within the defect were 30.01% for the PEG group, 27.90% for the PEG/RGD group, 29.89% for the PEG/PTH group, and 27.58% for the PEG/RGD/PTH group. A marginally significant difference (PEG/RGD/PTH group versus PEG group;P= 0.055) was found at 2 weeks but not at 4 weeks. The highest percentage of bone‐to‐implant contact (BIC) in the defect site at 2 weeks was observed for the PEG/RGD group (8.57%). The BIC after 4 weeks of healing ranged from 11.54% (PEG/RGD/PTH group) to 16.61% (PEG group). No statistically significant differences were observed in BIC.

Conclusions: The effect of binding PTH covalently to a synthetic, RGD‐modified PEG hydrogel marginally significantly improved bone formation at 2 weeks of healing compared to the use of PEG alone. Bone regeneration within the defects increased in all groups at week 4 of healing without statistically significant differences.
Culture and Characterization of Mesenchymal Stem Cells From Human Gingival Tissue
Authors: Mitrano Tomas I. , Grob Melisa S. , Carrión Flavio , Nova‐Lamperti Estefania , Luz Patricia A. , Fierro Francisca S. , Quintero Antonio , Chaparro Alejandra , Sanz Antonio
Published: April 2010

Background: Tissue engineering using mesenchymal stem cells (MSCs) is a recent therapeutic modality that has several advantages. MSCs have high proliferation potential and may be manipulated to permit differentiation before being transplanted, suggesting they may be an ideal candidate for regenerative procedures. Precise identification of cells capable of regenerating the periodontium is valuable because no predictable regeneration procedure has yet been described. The purpose of this study is to determine the presence of MSCs in human gingival connective tissue and their morphologic and functional characteristics.

Methods: Gingival connective tissue samples were obtained from five healthy students. The samples were deepithelialized, leaving only connective tissue. The explants were minced and cultured on tissue culture dishes for 3 to 4 weeks, after which cells were characterized by flow cytometry. Differentiation into osteogenic, chondrogenic, and adipogenic lineages was induced and evaluated by culture staining. An immunoregulation assay was also performed.

Results: The results show that gingival tissue cells fulfill the minimal criteria proposed by the International Society for Cellular Therapy to be defined as MSCs. Cell characterization was consistently positive for CD90, CD105, CD73, CD44, and CD13 markers and negative for hematopoietic markers CD34, CD38, CD45, and CD54. We observed differentiation in positive staining of adipogenic, chondrogenic, and osteogenic lineages. Furthermore, gingival cells showed immunomodulative capacity.

Conclusion: Gingival connective tissue could be a reservoir of MSCs that could be used in regenerative procedures based on tissue engineering.
Superficial Topography and Porosity of an Absorbable Barrier Membrane Impacts Soft Tissue Response in Guided Bone Regeneration
Authors: de Santana Ronaldo Barcellos , de Mattos Carolina Miller Leite , Francischone Carlos Eduardo , Van Dyke Thomas
Published: April 2010

Background: Surface topography and porosity of barrier membranes is suggested to impact the soft and hard tissue response. In this study, the specific soft and hard tissue response characteristics of a synthetic polylactide membrane are evaluated including soft tissue inflammation, osteogenesis, and osteopromotion.

Methods: Analysis of porosity and surface topography of the test material was performed by scanning electron microscopy. Transosseous parietal defects were surgically created bilaterally in 32 BalbC/ByJ mice and treated either with the barrier (test) or sham‐operated (control). Healing was assessed histologically and histomorphometrically with quantification of bone bridging.

Results: Scanning electron microscopy analyses of the barrier revealed a microstructure resembling cancellous bone. Interconnecting pores and channels, measuring between 6 and 60 μm in diameter, formed by smooth internal walls were observed throughout the device. Two distinct patterns of porosity were observed. The external surface of the membrane was characterized by a highly porous structure, with minimal interporous nodes and average pore sizes ranging between 6 and 20 μm in diameter. The internal surface was characterized by a minimal porous structure, with significant interporous nodes and average pore sizes ranging between 18 and 60 μm in diameter. Histomorphometric analyses demonstrated increased bone bridging by 60% and 300% in membrane‐treated sites after 14 and 28 days of healing, respectively. The rough surface of the barrier contained significantly more giant cells, whereas the smooth surface contained significantly more inflammatory cells.

Conclusion: The surface topographies engineered on different sides of the barrier promote differential soft tissue responses leading, however, to similar amounts of enhanced bone formation.
Periosteum‐Derived Cells as an Alternative to Bone Marrow Cells for Bone Tissue Engineering Around Dental Implants. A Histomorphometric Study in Beagle Dogs
Authors: Ribeiro Fernanda V. , Suaid Fabricia F. , Ruiz Karina G.S. , Salmon Cristiane R. , Paparotto Telma , Nociti Francisco H. , Sallum Enilson A. , Casati Márcio Z.
Published: April 2010

Background: The aim of this study is to investigate the potential use of periosteum‐derived cells (PCs) for tissue engineering in peri‐implant defects.

Methods: Bone marrow cells (BMCs) and PCs were harvested from seven adult beagle dogs, cultured in vitro, and phenotypically characterized with regard to their osteogenic properties. The animals were then subjected to teeth extraction, and 3 months later, two implant sites were drilled, bone dehiscences created, and dental implants placed. Dehiscences were randomly assigned to one of two groups: PCs (PCs + carrier) and BMCs (BMCs + carrier). After 3 months, the animals were sacrificed and the implants with adjacent hard tissues were processed for undecalcified sections. Bone‐to‐implant contact, bone fill within the limits of implant threads, and new bone area in a zone lateral to the implant were histometrically obtained.

Results: In vitro, phenotypic characterization demonstrated that both cell populations presented osteogenic potential, as identified by the mineral nodule formation and the expression of bone markers. Histometrically, an intergroup analysis showed that both cell‐treated defects had similar bone fill within the limits of implant threads and bone‐to‐implant contact (P >0.05), and although a trend toward higher new bone area values was found for the PC group, there was no significant difference between the experimental groups (P >0.05).

Conclusions: Periosteal and bone marrow cells presented a similar potential for bone reconstruction. As such, periosteum may be considered as an alternative source of osteogenic cells in implant dentistry.
Association Between Periodontitis and Hemorrhagic Stroke Among Koreans: A Case‐Control Study
Authors: Kim Hyun‐Duck , Sim Seon‐Ju , Moon Ja‐Young , Hong Yoon‐Chul , Han Dong‐Hun
Published: April 2010

Background: Several studies suggested that periodontitis is a risk factor for stroke, but the relationship between periodontitis and hemorrhagic stroke has not been widely reported. This study aims to evaluate the association between periodontitis and hemorrhagic stroke and to identify the risk group for this association.

Methods: We recruited 165 patients who were diagnosed via computed tomography brain imaging as having had a hemorrhagic stroke and 214 non‐stroke control subjects for a case‐control study. All participants underwent a clinical periodontal examination using clinical attachment level (CAL) as a marker. Information about sociodemographic factors, behavioral factors, systemic health, and a familial history of systemic health was gathered through an interview using structured questionnaires. The association between periodontitis and hemorrhagic stroke was evaluated using multivariate logistic regression analyses with adjustment for age, gender, income, education, hypertension, diabetes, body mass index, cardiac disease, familial hypertension history, familial diabetes history, familial cardiac disease history, smoking, and alcohol consumption. Subgroup analyses were also performed to investigate potential risk groups.

Results: After controlling for potential confounders, periodontitis (CAL ≥6 mm) was found to be significantly associated with hemorrhagic stroke (odds ratio: 2.5; 95% confidence interval: 1.1 to 5.6), but this association did not exhibit a dose‐dependent response for periodontitis (percentile of sites of periodontal pockets with CAL ≥5 mm among total probed pockets). The association between periodontitis (CAL ≥6 mm) and hemorrhagic stroke was significant for males, patients who had a lower income than control subjects, obese patients, and patients without diabetes.

Conclusions: Periodontitis may be an independent risk factor for hemorrhagic stroke. Risk groups include males, patients without diabetes, and obese subjects.
Salivary‐Soluble CD44 Levels in Smokers and Non‐Smokers With Chronic Periodontitis: A Pilot Study
Authors: Ghallab Noha , Shaker Olfat
Published: April 2010

Background: Smoking is the most important environmental risk factor for periodontal disease. Elevated levels of serum‐soluble CD44 (sCD44) have been detected in smokers and also have been recognized as a diagnostic marker in some smoking‐induced diseases. The present study investigates the salivary sCD44 profiles of smokers and non‐smokers with and without chronic periodontitis in response to scaling and root planing (SRP).

Methods: The study included 44 subjects divided into two groups: 22 patients with chronic periodontitis and 22 periodontally healthy subjects. Both groups were equally subdivided into smokers (n = 11) and non‐smokers (n = 11). Plaque index, gingival index, probing depth, and clinical attachment level were recorded only for chronic periodontitis patients. Salivary samples were collected from all 44 patients at baseline and after 1 month of SRP from the 22 chronic periodontitis patients. Assay for salivary sCD44 was carried out by enzyme‐linked immunosorbent assay.

Results: Baseline salivary sCD44 profiles were significantly higher when smokers were compared to non‐smokers in both chronic periodontitis patients and the control subjects (P <0.001) with the highest levels recorded in smokers within the chronic periodontitis group. There was a significant decline in salivary sCD44 levels after treatment in the chronic periodontitis group for both smokers and non‐smokers (P <0.01); however, the difference between groups was insignificant.

Conclusions: Salivary sCD44 might be considered a biomarker of periodontal destruction in smokers and non‐smokers. The research opens the door to further research into a role for CD44 as a diagnostic marker for periodontitis.
Classification of Dental Surface Defects in Areas of Gingival Recession
Authors: Pini‐Prato Giovanpaolo , Franceschi Debora , Cairo Francesco , Nieri Michele , Rotundo Roberto
Published: April 2010

Background: A clinical classification of surface defects in gingival recession area is proposed.

Methods: Two factors were evaluated to set up a classification system: presence (A) or absence (B) of cemento‐enamel junction (CEJ) and presence (+) or absence (−) of dental surface discrepancy caused by abrasion (step). Four classes (A+, A−, B+, and B−) were identified on the basis of these variables. To validate the classification three different calibrated examiners applied the proposed classification system to 46 gingival recessions and κ statistics were performed. The classification was used on 1,010 gingival recessions from 353 patients to examine the distribution of the four classes.

Results: The κ statistics for intrarater agreement ranged from 0.74 to 0.95 (almost perfect agreement), whereas interrater agreement ranged from 0.26 to 0.59 (moderate agreement). Out of 1,010 exposed root surfaces associated with gingival recession, 144 showed an identifiable CEJ associated with a root surface defect (Class A+, 14%); 469 an identifiable CEJ without any associated step (Class A−, 46%); 244 an unidentifiable CEJ with a step (Class B+, 24%); and 153 an unidentifiable CEJ without any associated step (Class B−, 15%).

Conclusion: The proposed classification describes the dental surface defects that are of paramount importance in diagnosing gingival recession areas.
Ten‐Year Results After Connective Tissue Grafts and Guided Tissue Regeneration for Root Coverage
Authors: Nickles Katrin , Ratka‐Krüger Petra , Neukranz Eric , Raetzke Peter , Eickholz Peter
Published: April 2010

Background: This study clinically evaluates the 10‐year results of connective tissue graft (CTG) and guided tissue regeneration (GTR) therapies using bioabsorbable barriers for root coverage (i.e., the reduction of recession depth).

Methods: In 15 patients, 38 Miller Class I and II recessions were treated. Recession defects received a CTG or GTR by random assignment. At baseline (immediately prior to surgery) and 6 and 120 ± 12 months after surgery, clinical parameters were obtained.

Results: Nine patients, who contributed 24 recession defects, were available for re‐examination at 120 ± 12 months. Six and 120 ± 12 months after receiving a CTG, statistically significant (P <0.05) root coverage was observed compared to baseline root coverage (6 months: 3.07 ± 1.74 mm; 120 ± 12 months: 2.07 ± 1.89 mm). The GTR therapy resulted in statistically significant root coverage compared to baseline root coverage only after 6 months (2.28 ± 1.77 mm; P <0.05). Both groups experienced a statistically significant loss of coverage from 6 to 120 ± 12 months (CTG: −1.0 ± 0.78 mm; GTR: −2.03 ± 2.24 mm). At 120 ± 12 months after CTG surgery, the stability of root coverage was statistically significantly better than 120 ± 12 months after GTR surgery (P = 0.002). The CTG caused more post‐surgical discomfort (P <0.05), but it resulted in a better treatment outcome (P <0.05) than GTR as perceived by patients.

Conclusion: The long‐term stability of root coverage (i.e., the reduction of recession depth) and esthetic results perceived by patients were significantly better 10 years after CTG surgery, statistically, than after GTR surgery using bioabsorbable barriers.
Short Implants in Maxillae and Mandibles: A Retrospective Study With 1 to 8 Years of Follow‐Up
Authors: Anitua Eduardo , Orive Gorka
Published: April 2010

Background: The aims of this study are to evaluate the long‐term survival rates of short dental implants in posterior areas in both jaws and analyze the influence of different factors on implant survival.

Methods: A retrospective cohort study design was used. Six hundred and sixty‐one patients received 1,287 short implants (<8.5 mm) between 2001 to 2008 in Vitoria, Spain. All implant installations were performed by two experienced surgeons and rehabilitations were done by three prosthodontists. Each implant failure was carefully analyzed. The potential influence of demographic factors, clinical factors, surgery‐depending factors, and prosthetic variables on implant survival was studied. Implant survival was analyzed using a life table analysis (Wilcoxon [Gehan] test).

Results: The overall survival rates of short implants were 99.3% and 98.8% for the implant and subject‐based analysis, respectively. The mean follow‐up period for the implants was 47.9 ± 24.46 months. A total of 9 out of 1,287 implants were lost during the observation period. None of the variables studied resulted in statistical association with implant failure because of the low number of failures.

Conclusion: Results of the present retrospective study show that treatment with short implants can be considered safe and predictable if used under strict clinical protocols.
Management of a Perplexing Sinus Lift Complication
Authors: Greenstein Gary , Cavallaro John
Published: April 2010

Background: This case report describes a dilemma that occurred after a maxillary right lateral window sinus lift was performed. The patient developed a gnawing pain in the sinus region but manifested no signs of sinusitis, and the subjacent teeth were asymptomatic. Differentiating between a pain that could be originating in the maxillary sinus or adjacent premolars was problematic.

Methods: After several weeks, a CT scan revealed no signs of sinusitis, despite the patient's belief that her discomfort was caused by her sinus lift. By the process of elimination, the decision was made to extract subjacent, asymptomatic premolars that had 50% bone loss and were previously endodontically treated.

Results: Extraction of asymptomatic premolars resulted in total elimination of her pain.

Conclusions: A differential diagnosis with regard to the source of the patient's pain had to be arrived at by the process of elimination rather than by validation. Confirmation that there was no sinus infection facilitated making the decision to remove asymptomatic premolars.