bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of Joule Heating Effect in Various Stages of Electromigration in Flip-chip Solder Joints by Infrared Microscopy
Authors: Hsiao Hsiang Yao , Chen Chih , Yao D. J. 
Published: April 2010

AbstractThe Joule heating effect at various stages under electromigration of flip-chip Sn3.5Ag solder joints was investigated under a current of 0.5 A at 100°C. During various stages of electromigration, voids may form and propagate and Joule heating effect may vary at different void sizes. To verify the void nucleation and propagation on Joule heating effect during electromigration process, the solder bump was stressed for different lengths of time and then examined by Kelvin bump probes and infrared microscopy. We found that voids started to form at approximately 1.2 times of the initial bump resistance. Then the voids propagated when the bump resistance increased. In addition, the temperature of the solder joints increased with the bump resistance and the increase of current stressing time. It increased very slowly in initial stages. In the last stage, the temperature of the solder bump increased rapidly due to the increase of the bump resistance and the local Joule heating effect.
Transition from coherent to ohmic conductance explained by a statistical model for the effects of decoherence
Authors: Zilly Matías , Ujsághy Orsolya , Wolf Dietrich E. 
Published: April 2010

AbstractUsing a statistical model for the effects of decoherence [1], we show that in linear tight-binding samples ohmic conductance (resistance proportional to length) is reached for any finite density p of decoherence sites, if the chemical potential μ of the contacts is within a conducting band. If μ is outside a band, or if due to disorder, no bands form, for high decoherence densities p>p* still ohmic conductance is reached, where p* is a critical decoherence density. For p<p*, the sample resistance increases exponentially with the length.
Natural analogues of degraded ecosystems enhance conservation and reconstruction in extreme environments
Authors: Richardson Paul J. , Lundholm Jeremy T. , Larson Douglas W. 
Published: April 2010

Ecosystem rehabilitation strategies are grounded in the concept that coexisting species fit their environments as an outcome of natural selection operating over ecological and evolutionary timescales. From this perspective, re‐creation of historical environmental filters on community assembly is a necessary first step to recovering biodiversity within degraded ecosystems; however, this approach is often not feasible in severely damaged environments where extensive physiochemical changes cannot be reversed. Under such circumstances management goals may shift from restoring historical conditions to reconstructing entirely new ecosystems or replicating natural ecosystems that may be locally novel but of regional conservation importance. This latter goal may be achieved by introducing to damaged sites species already adapted to filters maintaining the degraded state, through targeting assemblages from natural ecosystems biophysically analogous to the degraded state, here termed “degraded‐state analogue” (DSA) ecosystems. This hypothesis predicts that, in high‐stress sites where recruitment of previous inhabitants is strongly microsite‐limited, DSA species will be primarily propagule‐limited; furthermore, communities invaded by DSA species should shift in structure to reflect properties associated with high‐value DSA target ecosystems.We tested these predictions by experimentally sowing long‐abandoned limestone quarry floors with 18 perennial grass and forb species characteristic of rare natural limestone pavements called “alvars.” Alvar species established successfully under a range of microsite conditions manipulated to alter suspected constraints on colonization, including nitrogen deficiency, excessive CaCO3, and competition with weeds. Alvar species performed equivalently to seeded weed species known to thrive on quarry floors. Resident communities doubled in species richness following alvar species addition, supporting 17–20 species/0.18 m2(95% confidence interval) and providing refuge to regionally restricted or threatened species includingIris lacustris,Solidago ptarmicoides, andLiatris cylindracea. In contrast, maximum‐diversity reference plots on a pristine alvar supported 20–23 species/0.18 m2. Strong propagule limitation but weak microsite constraints on quarry colonization by alvar species combined with establishment of species‐rich communities comparable to natural alvar biodiversity hot spots confirms that targeting DSA assemblages in ecosystem reconstruction can promote both efficient site colonization and ex situ biodiversity conservation within difficult‐to‐restore anthropogenic wastelands.
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.