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The role of P2X7 receptor in anxiety and depression: characterization of transgenic mouse models
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Evidenzbasierte, softwarebezogene Anforderungsanalyse für Patientenregister in der medizinischen Forschung
Get PDFUrsrpung und Grund der Freiheit in Fichtes Wissenschaftslehre Nova Methodo und Schellings Initia Philosophiae Universae
Get PDFGeschlechtsspezifische Auswirkungen von LC-HF-Diäten auf den Fett-, Glukose-, Leberstoffwechsel und auf die GH/IGF-I Achse von Ratten
Get PDFDigitaler kieferorthopädischer Workflow unter Berücksichtigung funktionstherapeutischer Aspekte
Get PDFZielstellung
Ziel der vorliegenden Studie ist, einen digitalen Workflow für die Erwachsenenkieferorthopädie unter Einbeziehung funktioneller Aspekte des Kiefergelenks zu erarbeiten und die aktuelle Evidenzlage von dafür notwendigen Teilschritten zusammenzutragen sowie zukünftige Entwicklungsbereiche aufzuzeigen. Als klinischer Anteil soll eine Methode entwickelt werden, um die individuelle Scharnierachse ohne extraoralen Registrierbehelf digital zu bestimmen.
Material und Methoden
Die Literaturübersicht wird als ausführliche Handsuche in PubMed/MEDLINE und aus referenzierten Quellen erstellt. Das neu erdachte, dreidimensionale Verfahren wird als Proof-of-concept an einem Probanden modifiziert und getestet. Mit dem CentricGuide wird die zentrische Kondylenpostion registriert und anschließend per DVT und MRT validiert und beurteilt. Die Berechnung der Scharnierachsen erfolgt in Matlab anhand von im zahntechnischen Laborscanner digitalisierten Endpositionen mehrerer rotatorischer Öffnungsbewegungen aus der registrierten Zentrikposition.
Ergebnisse
Ein vollständig digitaler, kieferorthopädischer Workflow unter Einbeziehung funktioneller Aspekte des Kiefergelenkes ist technisch möglich. Mit dem CentricGuide gelingt es bei diesem Probanden, reproduzierbar eine zentrale Position der Kondylen in den Fossae einzustellen. Der erdachte Ansatz ist bei diesem Probanden geeignet, die individuelle Scharnierachse auf 2 mm genau zu lokalisieren.
Schlussfolgerungen
Der digitale Workflow sollte zugunsten einer patientenindividuelleren Planung und Therapie stärkere Verbreitung finden. Dazu sind weitere klinische Studien zur Validierung der Teilschritte und das Zusammenführen all dieser in einer anwenderfreundlichen Software notwendig. Zur schnellen und einfachen, digitalen Bestimmung der individuellen Scharnierachse sollten entsprechende Algorithmen in die Software von Intraoralscannern aufgenommen und klinisch an größeren Kohorten überprüft werden.Objective
A fully digital workflow for orthodontics in adults incorporating functional aspects of the temporomandibular joint (TMJ) is proposed. The current scientific evidence of necessary substeps ranging from planning and simulation to execution is presented. Regarding the substep of patient specific hinge axis determination a novel method independent of any facebow is developed and tested.
Materials and Methods
To gather scientific evidence PubMed/MEDLINE is searched and the bibliography of relevant articles is considered. As a proof-of-concept the novel 3D-method is tested and refined based on one subject. The centric relation is determined using CentricGuide and evaluated through the means of cone-beam computed tomography (CBCT) and magnetic resonance imaging (MRI). To investigate rotatory jaw opening multiple bite registrations of intermediate positions starting from the same centric relation bite are taken and later digitized in a dental laboratory scanner. Calculation of hinge axes is carried out in Matlab.
Results
A fully digital workflow for orthodontics in adults incorporating functional aspects of the TMJ is technically feasible. Using CentricGuide a centric condyle-fossa-relation was achieved reproducibly in this subject. Furthermore, hinge axis location could be determined with an accuracy of 2 mm using the novel method.
Conclusion
To improve patient specific planning, simulation and treatment the digital workflow should be increasingly adopted. This can be accelerated by validating all substeps in clinical studies and finally uniting the whole workflow in a user-friendly software. Algorithms for hinge axis determination (possibly similar to the approach presented) should be implemented in the software of intraoral scanners and tested on validation cohorts. This may lead to an easy, digital and more patient specific, clinical procedure
Mathematisches Modell und klinische Simulation transmittierter Bestrahlungsstärke bei Lichtpolymerisation durch moderne CAD/CAM-Komposit-Restaurationen
Get PDFStatement of problem: Pre-estimating the irradiance passing through a CAD/CAM composite restoration for properly curing a luting composite is challenging due to irradi-ance loss by reflection and the influence of various exposure conditions.
Objective: To establish a mathematical model for predicting the true transmitted irra-diance through CAD/CAM resin-based composites (RBCs) and the clinically relevant trans-mitted irradiance that can be expected when luting a CAD/CAM restoration. The influence of irradiance, exposure distance, light curing unit (LCU) angulation and direction of polymeri-zation was analyzed when curing through specimens of different thicknesses.
Methods: Seven modern CAD/CAM RBCs and one CAD/CAM glass-ceramic (control group) were sectioned and polished to plane-parallel specimens of 0.5 to 5 mm thickness (in 0.5 mm steps, n = 6, resulting in 432 specimens in total). Three of the CAD/CAM RBCs were additionally used to produce 45 crown-shaped specimens with fissure thicknesses of 1.0, 1.5 and 2.0 mm (n = 5). Irradiance of a violet-blue LED light curing unit (LCU) (power modes: Standard, High and Plasma) was measured with a spectrometer after passing through each specimen. 180 exposure conditions per crown were investigated by variation in LCU curing mode, angulation, exposure distance and direction. Material specific parame-ters were calculated based on linear regression of the measured irradiances. Data was com-pared based on comparison of 95% confidence intervals and using univariate ANOVA fol-lowed by Tukey HSD (α = 0.05).
Results: The measured transmitted irradiance passing through the specimens de-creased exponentially for increasing specimen thickness. Significantly highest values of transmitted irradiance were measured for 0.5 mm thick specimens for all materials (p < 0.05). The decadic absorption coefficient for CAD/CAM-RBCs ranged from 0.292 mm-1 to 0.387 mm-1 while the control group (glass-ceramic) reached a significantly lower value of 0.283 mm-1. The reflection correcting factor for plane RBC specimens reached values from 0.117 to 0.177 (glass-ceramic: 0.178), resulting in a reflection ratio for plane-parallelly pol-ished surfaces from 12.6% to 18.4% (glass-ceramic: 18,5%). Significant difference between the RBCs and control group is noted, as the glass-ceramic offers a comparably high reflec-tion ratio and the significantly lowest absorption coefficient, overall resulting in the highest transmitted irradiances. The modified reflection correcting factor for the selected RBC crowns ranges from 0.305 to 0.337, which was significantly higher than the correction for plane specimens (0.136–0.177). The correction model enables the calculation of transmit-ted irradiances based on the obtained material parameters and for varying radiant emit-tance and restoration thickness. Exemplarily calculated for 2-mm increments, the model predicts a reduction of measurable transmitted irradiance compared to the incident irradi-ance by 80–89% for plane specimens and by 88–92% for crowns, thus the crowns offered an averaged 32% lower transmitted irradiance compared to plane specimens. For photo-polymerization, 8–12% of the LCU’s radiant emittance can be expected after passing through an RBC based crown of 2-mm fissure thickness. Transmitted irradiance decreases significantly with increasing exposure distance and decreasing incident irradiance. For tilt angles greater than 10°, transmitted irradiances are significantly reduced (–11% for 20°, –23% for 30°, p < 0.05). Significantly lowest transmitted irradiances were measured for ves-tibular curing direction (up to –15%, p < 0.02).
Conclusion: A correction model can predict the transmitted irradiance after passing through a dental restoration as function of radiant emittance, restoration thickness and material specific parameters. The practitioner can be supported by this model to adapt ma-terial choice of dental restoration and adhesive system to the individual situation. Variation in exposure conditions shows significant negative effect on the transmission of light and should be limited
