bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three‐dimensional finite element analysis of the application of attachment for obturator framework in unilateral maxillary defect
Authors: SUN J. , JIAO T. , TIE Y. , WANG D. 
Published: October 2007

Summary  Aims:  The aim of this study was to evaluate the stress on the abutment teeth and framework in a unilateral maxillary defect which was restored by an obturator retained by resin‐bonded extracoronal attachment.Methods:  A three‐dimensional finite element model of the human unilateral maxillary defect was constructed. Traditional obturator framework with four casting circumferential clasp was established (model 1). A continuous lingual guide plane of 0·5 mm thickness on all of the remaining teeth, with Mini‐SG/F attachment on the mesial surface of the central incisor was also established (model 2). The modelling and analytical processes were performed using the ANSYS technologies.Results:  Stress was transmitted to the anterior part of the palate, with stress values being lower on the anterior teeth compared with the posteriors. The highest stress value of model 1 and model 2 was 13·1 Mpa, 19·9 Mpa respectively. Stress concentrations were found at the junction of the attachment to the lingual guide plane and the anterior part of the lingual plane.Conclusion:  The results of this study suggest that the application of a resin‐bonded extracoronal attachment for obturator retention is in accordance with the design principles for the restorative treatment of maxillary defects. The design of the attachment framework needs to be further investigated. Benefit can be gained by splinting the abutment teeth.
Six costs of immunity to gastrointestinal nematode infections
Authors: COLDITZ I. G 
Published: October 2007

SUMMARY The strength of the immune response and the outcome of the interaction of a host with a parasite are influenced by genetic and phenotypic characteristics of both parties, and by environmental variables. Allocation of host resources to immune defence reduces resources available for other life‐history traits. This review identifies six potential costs to the host from immune activation. The costs are likely to be broadly applicable to other immune responses in vertebrate species. Five phenotypic costs arise from: (i) increased metabolic activity; (ii) reduced nutrient availability due to anorexia; (iii) altered priorities for nutrient utilization; (iv) change in size and turnover of pools of immune cells and proteins; and (v) immunopathology from inappropriate or excessive immune activation. Subsumed by these costs is the cost of altered efficiency of nutrient use. A sixth cost is the genetic cost which arises from a change in the capacity of offspring to express production and life‐history traits following selection for parasite resistance. The sensitivity of immune responses to the phenotypic status of the host, and the role the immune system shares with the neuroendocrine system in controlling use of resources underpin the importance of immunocompetence to the life‐history of the host.
US regulatory system for genetically modified [genetically modified organism (GMO), rDNA or transgenic] crop cultivars
Authors: McHughen Alan , Smyth Stuart 
Published: October 2007

SummaryThis paper reviews the history of the federal regulatory oversight of plant agricultural biotechnology in the USA, focusing on the scientific and political forces moulding the continually evolving regulatory structure in place today. Unlike most other jurisdictions, the USA decided to adapt pre‐existing legislation to encompass products of biotechnology. In so doing, it established an overarching committee (Office of Science and Technology Policy) to study and distribute various regulatory responsibilities amongst relevant agencies: the Food and Drug Administration, Environmental Protection Agency and US Department of Agriculture. This paper reviews the history and procedures of each agency in the execution of its regulatory duties and investigates the advantages and disadvantages of the US regulatory strategy.
Corporate Raiders, Performance and Governance in Europe
Authors: Croci Ettore 
Published: October 2007

Abstract I analyse 136 block purchases made by corporate raiders in Europe between 1990 and 2001. Contrary to the hypothesis that these investors expropriate the target companies, there is a positive market reaction to the first public announcement of these purchases. In the long‐run, raiders earn an abnormal profit when they sell their stakes. When they still held their positions at the end of the sample period, abnormal returns were insignificant. Raiders' activities do not improve operating performance. The findings are consistent with superior stock picking ability among these investors, but do not support the hypothesis that raiders are governance champions.
Optimal Microstructures
Authors: O'Hara Maureen 
Published: October 2007

Abstract This paper considers the basic issue of the optimal microstructure for trading financial assets. I propose a framework for addressing optimality that draws on the functions that markets perform. These functions include liquidity, price discovery, and the reduction of uncertainty. Because the characteristics of financial assets and their investors differ, I show that their optimal microstructure may differ as well. I illustrate these points by analysing the evolution of corporate and municipal bond trading in the USA. The paper also discusses the particularly important role that microstructure plays for developing financial markets.
The Effect of Socially Responsible Investing on Portfolio Performance
Authors: Kempf Alexander , Osthoff Peer 
Published: October 2007

Abstract More and more investors apply socially responsible screens when building their stock portfolios. This raises the question whether these investors can increase their performance by incorporating such screens into their investment process. To answer this question we implement a simple trading strategy based on socially responsible ratings from the KLD Research & Analytics: Buy stocks with high socially responsible ratings and sell stocks with low socially responsible ratings. We find that this strategy leads to high abnormal returns of up to 8.7% per year. The maximum abnormal returns are reached when investors employ the best‐in‐class screening approach, use a combination of several socially responsible screens at the same time, and restrict themselves to stocks with extreme socially responsible ratings. The abnormal returns remain significant even after taking into account reasonable transaction costs.
Volatility‐Spillover Effects in European Bond Markets
Authors: Christiansen Charlotte 
Published: October 2007

Abstract Volatility spillover from the US and aggregate European bond markets into individual European bond markets using a GARCH volatility‐spillover model is analysed. Strong statistical evidence of volatility spillover from the US and aggregate European bond markets is found. For EMU countries, the US volatility‐spillover effects are rather weak (in economic terms) whereas the European volatility‐spillover effects are strong. The bond markets of EMU countries have become much more integrated after the introduction of the euro, and in recent years they have become close to being perfectly integrated. The main driver of the integration appears to be convergence in interest rates.
Citizen Participation in a Mediated Age: Neighbourhood Governance in The Netherlands
Authors: UITERMARK JUSTUS , DUYVENDAK JAN WILLEM 
Published: October 2007

AbstractTwo developments — the fragmentation of governance and the mediatization of politics — lead governmental organizations to engage in discursive and institutional competition. These new circumstances also drastically change the relationship of governmental organizations to clients, target groups and the citizenry as a whole. We empirically investigate these changes through a study of a privately funded community development organization in the Netherlands, the Neighbourhood Alliance. In this case, it is no longer the citizenry that articulates a public discourse, but a public discourse that, through the mediation of an institutional entrepreneur like the Neighbourhood Alliance, stipulates what type of participation is appropriate. This development raises the critical issue of the nature and mechanisms of democratic engagement in a fragmented, mediatized polity.Résumé Deux évolutions — la fragmentation de la gouvernance et la médiatisation de la politique — poussent les organismes gouvernementaux à une concurrence symbolique. Ces contexte nouveau change aussi radicalement la relation de ces organismes avec les usagers, les groupes ciblés et les citoyens dans leur ensemble. Nous examinons ces transformations à travers une étude empirique d'une structure néerlandaise à fonds privés de développement de quartiers, Wijkalliantie (alliance de quartier). En l'occurrence, ce ne sont plus les habitants qui déclinent un discours public, mais un discours public qui, par le biais d'une entreprise institutionnelle comme l'alliance de quartier, spécifie le type de participation approprié. Cette évolution soulève la question cruciale de la nature et des mécanismes de l'engagement démocratique dans un fonctionnement politique fragmenté et médiatisé.
Systemic therapy of disseminated malignant melanoma: an evidence‐based overview of the state‐of‐the‐art in daily routine
Authors: Nashan D , Müller ML , Grabbe S , Wustlich S , Enk A 
Published: October 2007

AbstractAims  In the metastatic stage, malignant melanoma is resistant to systemic treatment and carries a poor prognosis. A critical, evidence‐based analysis of standard approaches based on an extended search of published literature and from different Internet sources is presented.Material and methods  A critical, evidence‐based analysis of standard approaches and their variations to systemic therapy based on an extended search of published literature and from different Internet sources is presented. Few meta‐analyses are available. Therefore, assessment of therapies is mainly based on randomized multicentre studies or clinical studies achieving an evidence level grade 1 or 2.Results  Monotherapy with DTIC (dacarbazine) is the standard. Based on overall survival data, polychemotherapies cannot be recommended. Combination of polychemotherapy with the cytokines interferon‐α and interleukin‐2 substantially augments chemotherapy induced response rates, but a meta‐analysis for survival does not support its therapeutic superiority. Biological therapies such as vaccinations have not yet delivered results on a higher evidence level. Thus, immunotherapies as well as chemo‐immunotherapies will have to be evaluated in further studies.Conclusions  Although the therapeutic efficacy is very limited, dacarbazine cannot be rejected as standard therapy for disseminated melanoma, because no other therapeutic regimen exhibits a survival benefit over DTIC in an evidence‐based analysis. This lack of therapeutic progress over the past 40 years clearly calls for further clinical studies, and patients should be enrolled into clinical trials whenever possible.
Ridge augmentation by applying bioresorbable membranes and deproteinized bovine bone mineral: a report of twelve consecutive cases
Authors: Hämmerle Christoph H. F. , Jung Ronald E. , Yaman Duygu , Lang Niklaus P. 
Published: October 2007

AbstractObjective: Lateral ridge augmentations are traditionally performed using autogenous bone grafts to support membranes for guided bone regeneration (GBR). The bone‐harvesting procedure, however, is accompanied by considerable patient morbidity.Aim: The aim of the present study was to test whether or not resorbable membranes and bone substitutes will lead to successful horizontal ridge augmentation allowing implant installation under standard conditions.Material and methods: Twelve patients in need of implant therapy participated in this study. They revealed bone deficits in the areas intended for implant placement. Soft tissue flaps were carefully raised and blocks or particles of deproteinized bovine bone mineral (DBBM) (Bio‐Oss®) were placed in the defect area. A collagenous membrane (Bio‐Gide®) was applied to cover the DBBM and was fixed to the surrounding bone using poly‐lactic acid pins. The flaps were sutured to allow for healing by primary intention.Results: All sites in the 12 patients healed uneventfully. No flap dehiscences and no exposures of membranes were observed. Nine to 10 months following augmentation surgery, flaps were raised in order to visualize the outcomes of the augmentation. An integration of the DBBM particles into the newly formed bone was consistently observed. Merely on the surface of the new bone, some pieces of the grafting material were only partly integrated into bone. However, these were not encapsulated by connective tissue but rather anchored into the newly regenerated bone. In all of the cases, but one, the bone volume following regeneration was adequate to place implants in a prosthetically ideal position and according to the standard protocol with complete bone coverage of the surface intended for osseointegration. Before the regenerative procedure, the average crestal bone width was 3.2 mm and to 6.9 mm at the time of implant placement. This difference was statistically significant (P<0.05, Wilcoxon's matched pairs signed‐rank test).Conclusion: After a healing period of 9–10 months, the combination of DBBM and a collagen membrane is an effective treatment option for horizontal bone augmentation before implant placement.
Esthetic outcomes of immediate implant placements
Authors: Evans Christopher D. J. , Chen Stephen T. 
Published: October 2007

AbstractBackground: Single‐rooted teeth deemed not restorable via conventional means may be candidates for implant placement at the time of tooth extraction. Immediate implant placements are believed to preserve soft and hard tissue form and contours, reduce the need for augmentation procedures, minimize surgical exposure of the patient, reduce treatment time and improve esthetic outcomes.Method: This retrospective review analyzed the esthetic outcomes of 42 non‐adjacent single‐unit implant restorations completed using an immediate implant surgical placement protocol.Results: The mean time in function was 18.9 months (range 6–50 months) and the majority of implants placed had a restorative platform diameter of 4.1 and 4.8 mm. A highly significant change in crown height due to marginal tissue recession of 0.9 ± 0.78 mm (P=0.000) was recorded for all sites, with no difference seen between implant systems (P=0.837). Thin tissue biotype showed slightly greater recession than thick tissue biotype (1 ± 0.9 vs. 0.7 ± 0.57 mm, respectively); however, this difference was not statistically significant (P=0.187). Implants with a buccal shoulder position showed three times more recession than implants with a lingual shoulder position (1.8 ± 0.83 vs. 0.6 ± 0.55 mm, respectively) with the difference being highly statistically significant (P=0.000).Conclusions: Immediate implant placement requires very careful case selection and high surgical skill levels if esthetic outcomes are to be achieved. Long‐term prospective studies on tissue stability and esthetic outcomes are needed.
Root contact during insertion of miniscrews for orthodontic anchorage increases the failure rate: an animal study
Authors: Chen Yuan‐Hou , Chang Hao‐Hueng , Chen Yi‐Jane , Lee David , Chiang Hsien‐Hsiung , Jane Yao Chung‐Chen 
Published: October 2007

Abstract:Objectives: Miniscrews and miniplates are increasingly being used for absolute anchorage during orthodontic treatment. However, potential problems of damaging adjacent roots and their consequences during mini‐implant placement in the alveolar process have not been clearly described.Materials and methods: Animal experiments were used to evaluate the stability of miniscrews placed with intentional root contact. The root repair was evaluated after screw removal. Seventy‐two miniscrews were surgically placed in the mandibular alveolar bone of six adult mongrel dogs with metabolic bone labeling at 3‐week intervals. Miniscrews of the experimental group were placed so that they contacted the root of the adjacent teeth, were retained for different time durations, and were then removed. The insertion torque, clinical measurements, removal torque, and histological findings were analyzed.Results: (1) miniscrews contacting the roots showed a significantly higher insertion torque than those without contact; (2) there was a significant difference in the removal torque measurements based on the mobility of miniscrews and the state of root contact; and (3) miniscrews contacting the root were at greater risk of failure.Conclusions: During placement of miniscrews in the aveolar process, increased failure rates were noticed among those contacting adjacent roots. Failed miniscrews appeared to be surrounded with a greater volume of soft tissue. When more inflammation was present, the adjacent roots seemed to experience more resorption. Nevertheless, the created lesion was repaired with a narrow zone of mineralized tissue deposited on the root surface, which was likely cellular cementum, and was mainly filled with alveolar bone, with the periodontal ligament space being maintained.
In vitro osteogenesis induced by cells derived from sites submitted to sinus grafting with anorganic bovine bone
Authors: Beloti Marcio Mateus , Martins Walter , Xavier Samuel Porfirio , Rosa Adalberto Luiz 
Published: October 2007

Abstract:Objectives: This study evaluated key parameters of the in vitro osteogenesis induced by osteoblastic cells obtained from sites submitted to sinus grafting with anorganic bovine bone (ABB) in comparison with cells derived from bone sites of the same patients.Materials and methods: In three patients, the augmentation of maxillary sinus was carried out using ABB (Bio‐Oss®). After at least 6 months, during the surgical intervention for titanium implants placement, biopsies were taken from these areas using trephine burs (grafted group). Bone fragments, of the same patients, from sites that had not received graft were also obtained with trephine burs and used as a control group. Osteoblastic cells were obtained from grafted and control groups by enzymatic digestion and cultured under standard osteogenic condition until subconfluence. First passaged cells were cultured in 24‐well culture plates. Cell adhesion was evaluated at 24 h. For proliferation and viability assay, cells were cultured for 1, 3, 7, and 10 days. Total protein content and alkaline phosphatase (ALP) activity were measured at 3, 7, 10, 14, 17, and 21 days. Cultures were stained with Alizarin red S at 21 days, for detection of mineralized matrix. Data were compared by Student's t‐test.Results: Cell adhesion and viability were not affected by cell source (P>0.05). Total protein content was greater (P<0.05) for grafted group. Cell proliferation, ALP activity, and bone‐like nodule formation were all greater (P<0.05) for the control group.Conclusion: Taken together, these results indicate that the in vivo long‐term contact of cells with ABB downregulates the expression of osteoblast phenotype and consequently the in vitro osteogenesis.
Immediate loading of single SLA implants: drilling vs. osteotomes for the preparation of the implant site
Authors: Stavropoulos Andreas , Nyengaard Jens R. , Lang Niklaus P. , Karring Thorkild 
Published: October 2007

AbstractObjectives: To evaluate whether or not preparation of the implant site with osteotomes instead of drilling may improve peri‐implant bone density and/or osseointegration, and whether or not this further improves the predictability of immediate loading of SLA implants.Material and methods: The second, third, and fourth premolars were extracted in both sides of the mandible in six dogs, and after at least 3 months four SLA implants were inserted into each side of the jaw. In three animals, the implant sites were prepared by means of osteotomes, while standard stepwise drilling was used in the remaining animals. In each side of the jaw, two non‐adjacent implants were restored with single crowns 4 days after installation, while the remaining two implants were left without crowns to serve as non‐loaded controls. After 2, 4, or 12 weeks of loading, specimens including the implants and surrounding tissues were obtained and processed for histologic analysis of undecalcified sections.Results: All implants placed with osteotomes were lost (five before delivery of the crowns and the rest during the first week after loading). None of the conventionally inserted implants, however, was lost, and histomorphometrical analysis revealed similar soft‐ and hard peri‐implant tissue characteristics at immediately loaded and non‐loaded implants at all observation times. Average bone‐to‐implant contact was 59–72% at immediately loaded implants vs. 60–63% at non‐loaded ones.Conclusion: Preparation of the implant site by means of osteotomes had a deleterious effect on osseointegration, while immediate loading of single, free‐standing, SLA implants following a conventional surgical protocol did not jeopardize their osseointegration.
A model study on flapless implant placement by clinicians with a different experience level in implant surgery
Authors: Van de Velde Tommie , Glor Fadi , De Bruyn Hugo 
Published: October 2007

Abstract:Introduction: Some implant companies advocate that flapless surgery is easy to perform and beneficial for aesthetics and patients morbidity. However, studies objectively analyzing the position in the bone of implants installed with this approach are lacking. This in vitro model study was performed to analyse deviations in position and inclination of implants placed with flapless surgery compared with the ideally planned position and to examine whether the outcome is affected by experience level.Methods: Identical radio‐opaque resin models were developed with a silicon lining mimicking the soft tissues and six edentulous single tooth spaces. Eighteen clinicians (six periodontists, six general dentists and six students) drilled four implant sites each (Straumann AG, Basel, Switzerland) with a flapless approach. Corresponding CT‐scan images of the models were available. A virtual implant program (Simplant, Materialise NV, Leuven, Belgium) was used to plan the ideal position and to compare this with the implant angulation and position of the test implants.Results: There were no significant differences between the experience groups for all parameters except for global deviations between dentist and students, angle deviations between dentists and students and horizontal deviations between specialists and students.In incisor sites, specialists and students deviated significantly more in global deviation and depth than dentists. In premolar and molar sites, there were no significant differences except for horizontal deviations between specialists and dentists in molar sites. As a consequence of the malpositioning, perforations were seen in 59.7% (43/72) of the implant occasions when the artificial mucosa was removed from the model.Conclusion: The three‐dimensional location of implants installed with flapless approach differs significantly from the ideal, although neighbouring teeth were present and maximal radiographical information was available. Within the limitations of this in vitro model study it seems necessary to point out that these deviations would in a clinical situation lead to complications such as loss of implant stability, aesthetical and phonetical consequences. The outcome is not influenced by the level of experience with implant surgery. This points out that more precise measurements of soft tissue in situ or additional use of guiding systems are recommendable.