5199 research outputs found

    Comparative Analysis of the Visual, Refractive and Aberrometric Outcome with the Use of 2 Intraocular Refractive Segment Multifocal Lenses

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    To demonstrate the results of ray tracing higher- and lower-order aberrations in pseudophakic eyes with rotationally asymmetrical segment multifocal lenses, total high- and low-order aberrations, measured by root mean square value (RMS), refraction, uncorrected distance and uncorrected near visual acuity (UCDVA and UCNVA), and tear break-up time, were measured at scotopic size in 42 eyes of patients implanted with bifocal refractive Mplus15/Mplus30 IOL with +1.5 dpt near addition (42 eyes of patients implanted with Mplus15)/+3.0 dpt near addition (91 eyes of patients implanted with Mplus30), and 107 eyes of control group. No significant differences were noticed between the examined groups concerning UCDVA, UCNVA, and tear break-up time (p < 0.001). Coma and total high-order aberrations were significantly higher for the Mplus30 lens in comparison to the Mplus15 lens and the control group (Coma, Trefoil p < 0.001, Secondary Astigmatism p = 0.002). The spherical aberrations were significantly higher in the lower-addition lens (p = 0.016) in comparison to the control group and to the higher-addition lens group (p < 0.001). Both intraocular lens models were successful at reaching refractive aim, good distance, and near function with the lower higher-order aberrations for the low-addition lens

    Projektbericht: Summa Cum Fraude – Wissenschaftliches Fehlverhalten und der Versuch einer Gegenoffensive. Öffentlicher Teil

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    Das Projekt befasste sich mit der zentralen Fragestellung, inwieweit die bestehenden Mechanismen zur Selbstkontrolle in der Wissenschaft in der Lage sind, wissenschaftlichem Fehlverhalten effektiv entgegenzuwirken. Es wurden 207 Fälle von wissenschaftlichem Fehlverhalten ausführlich dokumentiert und an die betroffenen Verlage gemeldet. Dabei kamen nur solche Fälle zur Meldung, bei denen die Indikatoren für wissenschaftliches Fehlverhalten eindeutig waren (z.B. war die Manipulation von Daten mit bloßem Auge erkennbar). Leider hat sich schnell herausgestellt, dass selbst in diesen eindeutigen Fällen das tatsächliche Handeln durch die Journale von den in den ethischen Grundsätzen der Verlage formulierten Richtlinien zum Umgang mit wissenschaftlichem Fehlverhalten in der Mehrzahl der Fälle nahezu diametral abweicht. In vielen Fällen kann von einem Handeln nicht einmal die Rede sein, da Journale selbst auf wiederholte Meldungen desselben Falles von wissenschaftlichem Fehlverhalten nicht reagieren. In dieser Hinsicht kann die eigentliche Frage, inwieweit die Mechanismen zur Selbstkontrolle in der Wissenschaft tragfähig sind, prinzipiell nicht oder nur zu einem Teil beantwortet werden, da diese Mechanismen durch die Verweigerungshaltung vieler Journale gar nicht erst zum Einsatz kommen. So gesehen scheint es auch fraglich, ob zusätzliche Maßnahmen, die auf Grundlage der aus diesem Projekt hervorgegangenen Erfahrungen formuliert werden sollten, die Situation merklich verbessern könnten, da sie den Maßnahmenkatalog, der von Journalen nach wie vor ignoriert werden wird, allenfalls aufblähen. Neben diesen ernüchternden Befunden aufseiten der Journale war auch auf Seiten der sich fehlverhaltenden Autoren wenig Erfreuliches zu festzustellen. In nicht seltenen Fällen ist bei einigen Autorengruppen wissenschaftliches Fehlverhalten tägliche Praxis. Bei der Recherche von Fachartikeln mit manipuliertem Datenmaterial hat es sich fast schon zum Regelfall entwickelt, dass die Durchsicht der Publikationslisten einer einmal auffällig gewordenen Autorengruppe weiteres unlauteres Datenmaterial zutage bringt. Wenn zu den o.a. 207 Fällen alleine ein Autor mit mehr als 30 Fällen beiträgt, so kann man sagen, dass wissenschaftliches Fehl-verhalten stellenweise das Fundament einzelner Karrieren bildet. Flankierend gaben zehn Expert*innen in Interviews Vorschläge zur Verbesserung des Umgangs mit fragwürdigen Publikationen ab. Genannt wurden Beratung, Transparenz, Workshops zur Wissenschaftsethik und zur Identifikation fragwürdiger Inhalte, Open Science-Praktiken (z.B. Prä-Registrierung, Open Access zu Daten, Open Review), verbindliche Richtlinien und Monitoring von Retractions. Bibliotheken wurden besonders als Vermittler von Publikationskompetenz erwähnt. Allerdings wurde von den Expert*innen das gravierende Problem der Nicht-Reaktion der Journale kaum mit Verbesserungsvorschlägen bedacht.The project addressed the central issue of the extent to which existing mechanisms for self-regulation in science are effective in countering scientific misconduct. A total of 207 cases of scientific misconduct were thoroughly documented and reported to the relevant publishers. Only cases with clear indicators of scientific misconduct, such as visibly manipulated data, were reported. Unfortunately, it quickly became apparent that even in these clear cases, the actions taken by journals deviated significantly from the ethical guidelines outlined in their principles regarding scientific misconduct. In many instances, the journals did not even respond to repeated reports of the same case of scientific misconduct. This raises the fundamental question of the viability of self-regulation mechanisms in science, as these mechanisms are often not even utilized due to the resistant attitude of many journals. Thus, it remains questionable whether additional measures formulated based on the findings of this project could significantly improve the situation, as they might merely expand the catalogue of actions that journals continue to disregard. Aside from these disheartening findings regarding journals, there were also discouraging observations concerning authors engaged in misconduct. In some author groups, scientific misconduct has become a routine practice. When researching articles with manipulated data, it has almost become routine to uncover further instances of dubious data in the publication lists of author groups that have previously attracted attention. If a single author contributes to more than 30 out of the aforementioned 207 cases, it is evident that scientific misconduct forms the foundation of certain career trajectories. In parallel, ten experts provided suggestions for improving the handling of questionable publications through interviews. Recommendations included consultation, transparency, work-shops on scientific ethics and content identification, Open Science practices (such as pre-registration, open data access, and open review), binding guidelines, and retraction monitoring. Libraries were particularly highlighted as educators in publication competence. However, the experts scarcely addressed the significant issue of journals' non-responsiveness with proposals for improvement.Deutsche Forschungsgemeinschaft (DFG

    Expression of 3q Oncogene SEC62 Predicts Survival in Head and Neck Squamous Cell Carcinoma Patients Treated with Primary Chemoradiation

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    Primary chemoradiotherapy (CRT) is an established treatment option for locally advanced head and neck squamous cell carcinomas (HNSCC) usually combining intensity modified radiotherapy with concurrent platinum-based chemotherapy. Though the majority of patients can be cured with this regimen, treatment response is highly heterogeneous and can hardly be predicted. SEC62 represents a metastasis stimulating oncogene that is frequently overexpressed in various cancer entities and is associated with poor outcome. Its role in HNSCC patients undergoing CRT has not been investigated so far. A total of 127 HNSCC patients treated with primary CRT were included in this study. The median follow-up was 5.4 years. Pretherapeutic tissue samples of the primary tumors were used for immunohistochemistry targeting SEC62. SEC62 expression, clinical and histopathological parameters, as well as patient outcome, were correlated in univariate and multivariate survival analyses. High SEC62 expression correlated with a significantly shorter overall survival (p = 0.015) and advanced lymph node metastases (p = 0.024). Further significant predictors of poor overall and progression-free survival included response to therapy (RECIST1.1), nodal status, distant metastases, tobacco consumption, recurrence of disease, and UICC stage. In a multivariate Cox hazard proportional regression analysis, only SEC62 expression (p = 0.046) and response to therapy (p < 0.0001) maintained statistical significance as independent predictors of the patients’ overall survival. This study identified SEC62 as an independent prognostic biomarker in HNSCC patients treated with primary CRT. The role of SEC62 as a potential therapeutic target and its interaction with radiation-induced molecular alterations in head and neck cancer cells should further be investigated

    A Case Study of the Use of Smart EV Charging for Peak Shaving in Local Area Grids

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    Electricity storage systems, whether electric vehicles or stationary battery storage systems, stabilize the electricity supply grid with their flexibility and thus drive the energy transition forward. Grid peak power demand has a high impact on the energy bill for commercial electricity consumers. Using battery storage capacities (EVs or stationary battery systems) can help to reduce these peaks, applying peak shaving. This study aims to address the potential of peak shaving using a PV plant and smart unidirectional and bidirectional charging technology for two fleets of electric vehicles and two comparable configurations of stationary battery storage systems on the university campus of Saarland University in Saarbrücken as a case study. Based on an annual measurement of the grid demand power of all consumers on the campus, a simulation study was carried out to compare the peak shaving potential of seven scenarios. For the sake of simplicity, it was assumed that the vehicles are connected to the charging station during working hours and can be charged and discharged within a user-defined range of state of charge. Furthermore, only the electricity costs were included in the profitability analysis; investment and operating costs were not taken into account. Compared to a reference system without battery storage capacities and a PV plant, the overall result is that the peak-shaving potential and the associated reduction in total electricity costs increases with the exclusive use of a PV system (3.2%) via the inclusion of the EV fleet (up to 3.0% for unidirectional smart charging and 8.1% for bidirectional charging) up to a stationary battery storage system (13.3%)

    Pharmakokinetisches Modell für Propofol-Sufentanil während Allgemeinanästhesie

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    Hintergrund: Eine große Herausforderung bei der Durchführung von Allgemeinanästhesien ist der sichere und effektive Umgang mit Medikamenten. Ein Grund hierfür stellt die große interindividuelle Variabilität der Pharmakokinetik von Arzneimitteln dar. Im Rahmen von total intravenöser Anästhesie dosieren Anästhesisten Medikamente u.a. unter Berücksichtigung deren pharmakologischer Eigenschaften, aufgrund von eigener Erfahrung und anhand klinischer Zeichen der Patienten. Eine Echtzeit-Konzentrations-Messung wie bei der balancierten Anästhesie mit Inhalationsanästhetika existiert aktuell nicht oder ist nur durch hohen Aufwand im Labor möglich. Mittels Target-Controlled-Infusion (TCI) ist es allerdings möglich Plasmakonzentrationen von Medikamenten anzusteuern, die auf Grundlage pharmakokinetischer Modelle berechnet wurden. Es gibt bereits eine Vielzahl von pharmakokinetischen Modellen für Propofol und für Sufentanil. Eine populationspharmakokinetische Untersuchung, die Wechselwirkungen zwischen beiden Medikamenten herausstellen konnte, existiert bisher nicht. Ziel dieser Arbeit sollte die Berechnung eines populationsbasierten pharmakokinetischen Models von Propofol und Sufentanil sein. Der Einfluss von Covariaten sollte beschrieben und mögliche Interaktionen zwischen den beiden Medikamenten eruiert werden, um daraus adäquate Dosierungsempfehlungen ableiten zu können. Methoden: In dieser prospektiven Studie führten wir eine Allgemeinanästhesie mit Propofol und Sufentanil bei 35 Patienten im Alter von 35 - 88 Jahren durch. Die Propofolgabe erfolgte als TCI mit dem Parametersatz des Marsh-Modells. Sufentanil wurde bolusweise nach Bedarf des Patienten dosiert. Während der Narkose wurden arterielle Blutproben entnommen und die Plasmakonzentrationen von Propofol und Sufentanil mittels Hochleistungsflüssigkeitschromatographie (HPLC) ermittelt. In die Analyse wurden 341 Blutproben eingeschlossen. Die Berechnung des pharmakokinetischen Modells wurde anschließend mit dem Software-Programm NONMEM durchgeführt. Ergebnisse: Die erhobenen Daten konnten sowohl für Propofol, als auch für Sufentanil an ein 3-Kompartiment-Modell angepasst werden. Als relevante Covariaten im Propofol-Modell wurden Alter > 60 Jahren, Körpergröße und Quotient aus Herzfrequenz und diastolischem Blutdruck auf die Eliminationsclearance Clelim(Propofol) sowie Körpergröße auf das zentrale Kompartiment V1 identifiziert. In das Sufentanil-Modell konnte die Covariate Alter > 60 Jahren mit Einfluss auf die Eliminationsclearance Clelim(Sufentanil) integriert werden. Ebenso zeigte sich eine Interaktion von Propofol und Sufentanil auf pharmakokinetischer Ebene. So ließ sich eine Reduktion der Eliminationsclearance Clelim(Sufentanil) von Sufentanil mit Zunahme der Propofolkonzentration im zentralen Kompartiment V1 des Propofol-Modells feststellen. Die Modellbewertung erfolgte anhand der Objektivierungsfunktion und Goodness-of-fit Plots. Es zeigte sich eine gute Korrelation der gemessenen und der durch das Modell vorhergesagten Plasmakonzentrationen mit einer Präzision von 15,9% für das Propofol-Modell und 18,9% für das Sufentanil-Modell. Zusammenfassung: Bei der Komedikation mit Propofol und Sufentanil müssen pharmakokinetische Wechselwirkungen berücksichtigt werden, die zu einer Dosisanpassung während der Narkose führen. Bei älteren Patienten ist eine Dosisreduktion von Propofol und Sufentanil sinnvoll, um Nebenwirkungen zu vermeiden.Background: A major challenge in the performance of general anesthesia is the safe and effective handling of medication. One reason for this is the large inter-individual variability of the pharmacokinetics of drugs. In the context of total intravenous anesthesia, anesthesiologists dose medications on the one hand taking into account pharmacological properties and on the other hand on the basis of their own experience and of clinical signs of the patients. A realtime concentration measurement as with balanced anesthesia with inhalation anesthetics does not currently exist or is only possible through high effort in the laboratory. By means of targetcontrolled infusion (TCI), however, it is possible to control plasma concentrations of drugs that have been calculated on the basis of pharmacokinetic models. There are already a variety of pharmacokinetic models for propofol and for sufentanil. A population pharmacokinetic study that is able to identify interactions between the two drugs does not yet exist. The aim of this work should be the calculation of a population-based pharmacokinetic model of propofol and sufentanil. The influence of covariates should be described and possible interactions between the two drugs should be determined in order to be able to derive adequate dosage recommendations. Methods: In this prospective study, we performed general anesthesia with propofol and sufentanil in 35 patients aged 35 - 88 years. Propofol administration was carried out as TCI with the parameter set of the Marsh model. Sufentanil was dosed bolus-wise as required by the patient. During anesthesia, arterial blood samples were taken and plasma concentrations of propofol and sufentanil were determined using High-performance-liquid-chromatographie (HPLC). 341 blood samples were included in the analysis. The calculation of the pharmacokinetic model was then carried out with the software program NONMEM. Results: The collected data could be adapted to a 3-compartment model for both propofol and sufentanil. Relevant covariates in the propofol model were identified as age > 60 years, height and quotient of heart rate and diastolic blood pressure to the elimination clearance Clelim(Propofol) and height to the central compartment V1. In the sufentanil model, the covariate age > 60 years with influence on the elimination clearance Clelim(Sufentanil) could be integrated. There was also an interaction of propofol and sufentanil at the pharmacokinetic level. Thus, a reduction in the elimination clearance Clelim(Sufentanil) of sufentanil with an increase in the propofol concentration in the central compartment V1 of the propofol model could be observed. The model evaluation was based on the objective function and goodness-of-fit plots. There is a good correlation of the plasma concentrations measured and the plasma concentrations predicted by the model with a precision of 15.9% for the propofol model and 18.9% for the sufentanil model. Summary: In comedication with propofol and sufentanil, pharmacokinetic interactions must be taken into account, that leading to dose adjustment during anesthesia. In elderly patients, a dose reduction of propofol and sufentanil is useful to avoid side effects

    Frozen Stored Teeth : Autogenous Dentin as an Alternative Augmentation Material in Dentistry

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    Tooth Shell Technique (TST) with the use of autologous dentin has proven to be a suitable method of grafting in the context of lateral ridge augmentation. This present feasibility study aimed to retrospectively evaluate the preservation by lyophilization of processed dentin. Thus, the frozen stored processed dentin matrix (FST: 19 patients with 26 implants) was re-examined with that of processed teeth used immediately after extraction (IUT: 23 patients with 32 implants). Parameters of biological complications, horizontal hard tissue loss, osseointegration, and buccal lamella integrity were used for evaluation. For complications, the observation period was 5 months. Only one graft was lost (IUT group). In the area of minor complications, without the loss of an implant or augmentation, there were two cases of wound dehiscence and one case with inflammation and suppuration (IUT: n = 3, FST: n = 0). Osseointegration and integrity of the buccal lamella were present in all implants without exception. Statistically, there was no difference between the groups studied for the mean resorption of the crestal width and the buccal lamella. Results of this study show that prepared autologous dentin preserved with a conventional freezer had no disadvantage compared to immediately use autologous dentin in terms of complications and graft resorption in the context of TST

    Urokinase versus Alteplase in Patients with Intermediate–High-Risk Pulmonary Embolism Treated with Ultrasound-Accelerated Endovascular Thrombolysis

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    Background. Ultrasound-accelerated thrombolysis (USAT) is a safe and effective treatment for patients with intermediate–high-risk pulmonary embolism (PE). In all studies investigating USAT in the setting of PE, the recombinant tissue-plasminogen activator (rt-PA) alteplase or actilyse was used. Currently, there is a shortage of alteplase (Alteplase, Boehringer Ingelheim) in Europe. It is unknown whether the efficacy of urokinase (UK) is comparable with alteplase for USAT in patients with PE. Methods. Patients with intermediate–high-risk PE undergoing USAT with urokinase and alteplase were included in this study. One-to-one nearest neighbour matching was performed to account for baseline differences. We identified one patient treated with USAT and UK (n = 9) for each patient treated with USAT and alteplase (n = 9). Results. A total of 56 patients underwent USAT. The treatment was successful in all patients. The propensity score matched the identified nine pairs of patients. There were no statistically significant differences in the change in right ventricle-to-left ventricle (RV/LV) ratio (0.4 ± 0.3 versus 0.5 ± 0.4, p = 0.54), systolic pulmonary artery pressure (17.3 ± 8.0 versus 18.1 ± 8.1, p = 0.17), or improvement of RV function (5.8 ± 3.8 versus 5.1 ± 2.6, p = 1.0). The complication rates were comparable (11% in both groups, p = 0.55). There were no deaths in hospital or during 90 days in either group. Conclusions. In this case-matched comparison, the short-term clinical and echocardiographic outcomes showed comparable results between USAT–UK and USAT–rt-PA

    Parametric analysis of the coating thickness development of electrophoretically deposited carbon nanotube coatings

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    In this study, the coating thickness evolution of pristine and oxidized carbon nanotubes (CNT) on stainless steel substrates is investigated. Potentiostatic electrophoretic deposition (EPD) is used as a coating technique with two different additives, triethylamine (TEA) and magnesium nitrate hexahydrate (Mg-Nit). Moreover, the depositions are conducted at different voltages (50, 100 and 150 V). Confocal laser scanning microscopy is used to determine the thickness of the CNT depositions after 1, 2, 5, 10, 20 and 30 min. Furthermore, the ability of Hamaker’s law to accurately predict coating thickness development is investigated for the thickness evolution on stainless steel. Independent of the additive, the results show that higher voltages lead to increased deposition rates. Comparing the two additives, Mg-Nit generally allows for a higher CNT deposition rate than TEA and forms thicker layers. Coating thickness development can be approximated as linear during the initial 5 min with Mg-Nit and during the initial 20 min with TEA. Finally, Hamaker’s law allows for a fairly accurate approximation for the thickness development of CNT coatings with TEA on stainless steel

    The Functional Self : The Minimal Self-Concept Is Protected Against Negative Content

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    Current research describes a particular component of the self-concept that influences a wide variety of cognitive processes while it depicts a rather basic component of the self-concept. However, this minimal self seems to be anything but simple; in fact, it seems to be highly functional. Based on previous findings on newly formed self-associations, we put the postulated functionality of this minimal self to another test by retesting its protection mechanisms against negative content. In a pilot experiment, we did not find an overall reduction of negative selfassignments against neutral self-assignments. However, the results indicated an initial difference (as hypothesized) between negative and neutral self-assignments, which decreases over the course of the experiment. We put this interactive effect of valence and block to test in our main experiment, which replicated the data pattern of the pilot experiment. In sum, the results indicate a mandatory integration of stimuli into the self-concept and also a reduction of the integration due to negative valence, thereby supporting a robust protection mechanism

    Knochenschädigung im Rahmen der Implantatinsertion : eine biomechanische und histologische Pilotstudie

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    Aim: Achieving primary implant stability during implant placement is an important factor in attaining osseointegration, which determines the long-term clinical success of dental implants. Primary stability is largely dependent on the quality of the alveolar bone as well as the implant design with its specific drilling protocol. Due to the creation of a drill hole as well as cortical bone compression during implant placement, traumatization of the bone appears unavoidable. To reduce the extent of marginal bone resorption, implant manufacturers as well as implantologists try to minimize the traumatic bone damage during the implantation procedure. The aim of this in vitro study was to measure the forces acting on the alveolar bone during the insertion of two different implant systems, to evaluate the extent of bone damage by means of a subsequent histological analysis and to establish possible correlations. Material and Methods: Implants of two bone-level systems (Astra; Straumann; n = 5) were inserted into fresh bovine bone. The insertion torque was recorded with the surgical contra-angle handpiece. Strain gauges were used to monitor the resulting bone strain on the buccal wall. Subsequently, primary stability of the implant was determined by means of Osstell measurement. Histological analysis determined bone to implant contact and bone density as well as signs of bone damage such as microcracks, macrocracks and the extent of bone deformation. In addition to comparing the implant systems (Welch t-Tests), all measurement parameters were tested for possible correlations (Pearson product moment correlation coefficient), with the level of significance set at α = 0.05. Results: Straumann implants produced slightly increased readings for insertion torque (p = 0.772), strain development (p = 0.893) and primary implant stability (p = 0.642). Histologic assessment revealed significantly increased bone to implant contact in the Straumann group compared to the Astra group (cortical p = 0.014; trabecular p = 0.016), with only slight differences in bone density (cortical p = 0.466; trabecular p = 0.360). A significantly increased number of microcracks in the cortical bone was observed in the Astra group (p = 0.020). A correlation of insertion torque with bone to implant contact in cortical bone (p = 0.029) was found in the Straumann group. In trabecular bone, the number of macrocracks correlated with bone to implant contact (p = 0.029). Astra implants showed a correlation of insertion torque with bone to implant contact in the trabecular region (p = 0.007). There was also a correlation between implant stability and the number of macrocracks in the trabecular bone (p = 0.016), furthermore between the number of macrocracks in the cortical region and the bone to implant contact (p = 0.019). Conclusion: The present study demonstrated that bone damage of varying degrees is inevitable during implant placement. Clinically, they mainly manifest in the peri-implant cortical bone. When developing a new implant macrodesign, attempts should be made to achieve implant stability by compression in the trabecular bone so as to relieve the peri-implant cortical area.Ziel: Das Erreichen von Primärstabilität bei der Implantation ist ein wichtiger Faktor zur Erzielung von Osseointegration, was den langfristigen klinischen Erfolg dentaler Implantate bedingt. Die Primärstabilität hängt maßgeblich von der Qualität des Alveolarknochens sowie der Implantatform mit seinem spezifischen Bohrprotokoll ab. Durch das Anlegen eines Bohrstollens sowie durch die kortikale Knochenkompression bei der Implantatinsertion erscheint eine Traumatisierung des Knochens unvermeidbar. Um das Ausmaß einer marginalen Knochenresorption zu verringern, versuchen Implantathersteller sowie Implantologen die traumatische Knochenschädigung während des Implantationsvorganges zu minimieren. Ziel dieser in vitro Studie war es, die während der Insertion zweier verschiedener Implantatsysteme am Alveolarknochen einwirkenden Kräfte messtechnisch zu erfassen, anhand einer anschließenden histologischen Analyse das Ausmaß der Knochenschädigung zu evaluieren und mögliche Zusammenhänge zu erkennen. Material und Methoden: Die Implantate zweier Bone-Level Systeme (Astra; Straumann; n = 5) wurden in frische Rinderknochen inseriert. Das Eindrehmoment wurde mit dem chirurgischen Winkelstück festgehalten. Mit Hilfe von Dehnungsmessstreifen zeichnete man die dabei an der bukkalen Wand entstehende Knochendehnung auf. Anschließend erfolgte die Bestimmung der Primärstabilität des Implantates mittels Osstell-Messung. In der histologischen Analyse ermittelte man den Knochen-Implantat-Kontakt und die Knochendichte sowie Anzeichen von Knochenschäden wie Mikrorisse, Makrorisse und das Ausmaß der Knochendeformation. Neben dem Vergleich der Implantatsysteme (Welch t-Test) wurden alle Messparameter auf mögliche Korrelationen untersucht (Pearson Produkt-Moment-Korrelationskoeffizient), wobei das Signifikanzniveau auf α = 0.05 festgelegt wurde. Ergebnisse: Straumann-Implantate wiesen leicht erhöhte Messwerte für das Eindrehmoment (p = 0.772), die Knochendehnung (p = 0.893) und die Primärstabilität (p = 0.642) auf. Die histologische Beurteilung erbrachte einen signifikant größeren Knochen-Implantat-Kontakt der Straumann Gruppe im Vergleich zur Astra Gruppe (kortikal p = 0.014; trabekulär p = 0.016), wobei sich die Knochendichte nur gering unterschied (kortikal p = 0.466; trabekulär p = 0.360). Eine signifikant erhöhte Zahl an Mikrorissen im kortikalen Knochen fand sich bei den Astra-Implantaten (p = 0.020). Eine Korrelation des Eindrehmomentes mit dem Knochen-Implantat-Kontakt im kortikalen Knochen (p = 0.029) ergab sich in der Straumann Gruppe. Im trabekulären Knochen korrelierte die Anzahl der Makrorisse mit dem Knochen-Implantat-Kontakt (p = 0.029). Bei Astra-Implantaten fand sich eine Korrelation des Eindrehmomentes mit dem Knochen-Implantat-Kontakt im trabekulären Bereich (p = 0.007). Auch zwischen der Implantatstabilität und der Anzahl der Makrorisse im trabekulären Knochen bestand eine Korrelation (p = 0.016), weiterhin zwischen der Anzahl der Makrorisse im kortikalen Bereich und dem Knochen-Implantat-Kontakt (p = 0.019). Schlussfolgerung: In der vorliegenden Untersuchung konnte gezeigt werden, dass bei der Implantatinsertion Knochenschäden unterschiedlichen Ausmaßes unvermeidlich sind. Klinisch treten sie vornehmlich im peri-implantären kortikalen Knochen in Erscheinung. Bei der Entwicklung eines neuen Implantat-Makrodesigns sollte man daher versuchen, Implantatstabilität durch Kompression im trabekulären Knochen zu erzielen, um den kortikalen Bereich zu entlasten

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