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PD Dr. Alexander Welk

Germany, Greifswald
1988-1993: Studium der Zahnmedizin an der Ernst-Moritz-Arndt-Universität Greifswald. 1993: Approbation als Zahnarzt. 1993-2001: Wissenschaftlicher Mitarbeiter an der Poliklinik für Zahnerhaltung, Parodontologie und Endodontologie am Zentrum für Zahn-, Mund- und Kieferheilkunde der Universität Greifswald. Seit 1995: 1995 nationale und internationale Referententätigkeit in der postgradualen zahnmedizinischen Weiterbildung. 1997: Promotion. Seit 2001: Oberarzt an der Poliklinik für Zahnerhaltung, Parodontologie und Endodontologie am Zentrum für Zahn-, Mund- und Kieferheilkunde der Universität Greifswald. 2003-2005: zweijähriger Forschungs- und Lehraufenthalt an der University of Tennessee - Health Science Center - College of Dentistry / Restorative Dentistry Department, Memphis, USA. 2007: vierwöchiger Forschungs- und Lehraufenthalt an der University of Minnesota, School of Dentistry, Minneapolis, USA. 2012: Habilitation und Venia legendi für das Fach Zahn-, Mund- und Kieferheilkunde an der Ernst-Moritz-Arndt-Universität Greifswald.

Events

  
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Deutscher Zahnärztetag 2018

MISSERFOLGE - erkennen, beherrschen, vermeiden9. Nov 2018 — 10. Nov 2018Congress Center Messe Frankfurt
Speakers: Karl-Ludwig Ackermann, Sarah Al-Maawi, Bilal Al-Nawas, Kurt Werner Alt, Anna Greta Barbe, Tobias Bauer, Daniel Bäumer, Marco Baz Bartels, Grietje Beck, Katrin Bekes, Christoph Benz, Dirk Bleiel, Johannes Boesch, Martin Boost, Wolfgang Buchalla, Oskar Bunz, Fabian Cieplik, Monika Daubländer, Sybille David-Hebgen, Andreas Dehler, Renate Deinzer, Sonja H. M. Derman, Konstanze Diekmeyer, Ingmar Dobberstein, Heike Dyrna, Thomas Eger, Guido Elsäßer, Anne Sophie Engel, Peter Engel, Norbert Enkling, Susanne Fath, Stefan Fickl, Michael Frank, Roland Frankenberger, Rene Franzen, Kerstin Galler, Carolina Ganß, Roland Garve, Christian Ralf Gernhardt, Werner Geurtsen, Shahram Ghanaati, Petra Gierthmühlen, Christiane Gleissner, Steffani Görl, Werner Götz, Susanne Grässel, Dominik Groß, Stefan Grümer, Claus Grundmann, Martin Guffart, Heinz-Michael Günther, Norbert Gutknecht, Peter Hahner, Elmar Hellwig, Christian Henrici, Katrin Hertrampf, Fabian Huettig, Michael Hülsmann, Bruno Imhoff, Holger Jentsch, A. Rainer Jordan, Ana Elisa Kauling, Moritz Kebschull, Christian Kirschneck, Joachim Klimek, Andrea Klink, Thomas Klinke, Birte Koch, Thomas Kocher, Eva Köllensperger, Heike Maria Korbmacher-Steiner, Bernd Kordaß, Hannah Kottmann, Pablo Krämer-Fernandez, Gabriel Krastl, Birgit Krause, Till Kreutzer, Conrad Kühnöl, Stefanie Kurzschenkel, Thorsten Kuypers, Günter Lauer, Hans-Christoph Lauer, Elfi Laurisch, Tina Lawall, Karl Martin Lehmann, Silke Lehmann-Binder M.Sc., Dirk Leisenberg, Ulrike Lübbert, Michael Lüpke, Thomas Malik, Jutta Margraf-Stiksrud, Lorenz Meinel, Gudrun Mentel, Wibke Merten, Louisa Mewes, Johanna Isabel Moosmüller, Martin U. Müller, Wolfgang Müller, Nicole Nicklisch, Ina Nitschke, Michael J. Noack, Marina Nörr-Müller, Karina Obreja, Dietmar Oesterreich, Puria Parvini, Ingrid Peroz, Waldemar Petker, Oksana Petruchin, Andree Piwowarczyk, Peter Pospiech, Peter Proff, Sven Reich, Katharina Reichenmiller, Katharina Reinecke, Bernd Reiss, Svenja Rink, Christiane Rinnen, Jerome Rotgans, Didem Sahin, Sonja Sälzer, Petra Santander, Heidrun Schaaf, Jürgen Schäffer, Elisabeth Schiffner, Ulrich Schiffner, Markus Schlee, Maximiliane Amelie Schlenz, Peter Schmidt, Andrea-Maria Schmidt-Westhausen, Claas Ole Schmitt, Sigmar Schnutenhaus, Jörg Schröder, Gerd Schröter, Andreas Schulte, Philipp Schwaab, Frank Schwarz, Falk Schwendicke, Clemens Schwerin, Sinan Sen, Önder Solakoglu, Hansmartin Spatzier, Christian H. Splieth, Norbert Staab, Bernd Stadlinger, Sabine Steding, Marcus Stoetzer, Giorgio Tabanella, Gisela Tascher, Hendrik Terheyden, Valentina A. Tesky, Jan Tetsch, Juliane von Hoyningen-Huene, Maximilian Voß, Michael Walter, Alexander Welk, Dietmar Weng, Hans-Jürgen Wenz, Jens Westemeier, Lotta Westphal, Annette Wiegand, Karl Frederick Wilms, Michael M. Wolf, Diana Wolff, Anne Wolowski, Johann-Dietrich Wörner, Sylvia Wuttig, Mohamed Younis, Stefan Zimmer, Lisa Zumpe
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This author's journal articles

  
Journal of Craniomandibular Function, 1/2010
Pages 11-26, Language: English, GermanBernhardt, Olaf / Wenzler, Christine / Welk, Alexander / Meyer, Georg

A study on the influence of a centric splint on changes in posture in the region of the (cervical) spine with the sonoSens® Monitor in patients with craniomandibular dysfunction

Several studies on the association carried out on changes in posture and craniomandibular dysfunction (CMD) have demonstrated different results. The aim of this study was to test the effects of stabilization splints in centric relation on the posture of walking CMD patients and controls. The posture of 20 CMD patients and 19 healthy subjects was evaluated with the sonoSens® Monitor before (U1), immediately after (U2), and 1 week after (U3) the insertion of a stabilization splint with centric relation. The sonoSens® Monitor is a diagnostic system for the dynamic monitoring of posture. The technology consists of a device measuring the delay of ultrasound impulses, using four pairs of small sensors that are placed at specific sites on the neck and the back. During each measurement the sensors continuously record changes in distance between each pair of sensors, while the subjects are walking straight ahead for 7 minutes. The range of flexion and torsion of the body while walking was recorded for the cervical, thoracic and lumbar spine. At each appointment a clinical functional examination was performed. All measured parameters were tested for group differences with a non-parametric test. There were no significant differences between the groups at U1, U2 and U3 for the regularity indices or for the sagittal and frontal range of motion and of torsion. There were also no statistically significant differences of these parameters within the groups between U1, U2 and U3. Pain and the impairment in quality of life were reduced significantly for the test group between U1 and U3 (P 0.03), whereas no changes were recorded for the control group. The results of this study indicate that oral appliance therapy has no significant influence on the posture of CMD patients and controls measured while they walked. However, further studies are necessary to verify these results. Keywords: centric splint, craniomandibular dysfunction, gait analysis, posture
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Quintessence International, 4/2009
PubMed ID (PMID): 19417872Pages 279-285, Language: EnglishSplieth, Christian H. / Alkilzy, Mohammad / Schmitt, Jan / Berndt, Christine / Welk, Alexander

Effect of xylitol and sorbitol on plaque acidogenesis

Objective: To evaluate the in vivo potential of xylitol to reduce plaque acidogenicity in comparison to sorbitol. Method and Materials: After completing a questionnaire on general health, smoking, diet, and oral hygiene habits, 61 dentate adults refrained from oral hygiene for 3 days before the clinical baseline examination, which included decayed, missing, and filled teeth (DMFT) index, mutans streptococci and lactobacilli counts, and plaque acidogenicity (cH) index after a sucrose rinse. Then the participants were randomly allocated to consume either sorbitol or xylitol lozenges (5 pieces/day, 2 g each) for 4 weeks and were asked to refrain from oral hygiene for the 3 days prior to the final examination (cH, area pH 7, bacterial counts). Results: The variation of acidogenicity in different individuals was considerable at baseline (range: 0.2 to 446.6 min*µmol/L) with a mean value of 37.9 ± 58.9 min*µmol/L for the sorbitol group and 60.6 ± 87.6 min*µmol/L for the xylitol group. At the end of the study, the reduction in the xylitol group (42.9 ± 80.6 min*µmol/L) was statistically significantly higher than in the sorbitol group (6.0 ± 69.4 min*µmol/L, P = .034), which was also confirmed in an additional analysis excluding 2 participants with extreme values (reduction for xylitol: 29.5 ± 36.9 min*µmol/L; sorbitol: 1.7 ± 57.0 min*µmol/L; P = .019). Statistically significant differences were also found for the area below pH 7 (reduction for xylitol: 10.8 min pH; sorbitol, 0.2 min pH; P = .0025). Conclusion: The regular consumption of xylitol lozenges modifies dental plaque, resulting in a marked reduction in the plaque acidogenicity, which could not be detected using sorbitol lozenges. Therefore, xylitol could have an additional benefit in caries prevention. Keywords: acidogenicity, caries, cH index, plaque, prevention, sorbitol, xylitol
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Quintessence International, 7/2007
PubMed ID (PMID): 17694212Pages 565-569, Language: EnglishMeller, Christian / Welk, Alexander / Zeligowski, Thomas / Splieth, Christian

Comparison of dentin caries excavation with polymer and conventional tungsten carbide burs

Objective: To compare the effectiveness of polymer burs (SmartPrep, SS White) and conventional carbide burs in removing dentin caries. Method and Materials: Thirty extracted permanent teeth were assigned to 2 groups according to the caries removal technique. One experienced clinician performed all excavation procedures, monitoring the caries removal by checking the hardness of the dentin with a dental explorer. The excavation working time was documented and stopped in each group when a leather-hard texture was reached. After the teeth were embedded and sectioned (400 µm), the caries in the remaining dentin was assessed using a caries detector. On microscope images of the samples, the mean stain depth of the remaining carious tissue per tooth was measured by AnalySIS computer software. Results: Mean carious surface areas differed minimally but not statistically significantly after use of polymer burs (31.5 mm2 ± 0.18) and carbide burs (38.1 mm2 ± 0.15). Mean carious surface staining depth was slightly smaller with carbide burs (0.26 mm ± 1.38) than with polymer burs (0.40 mm ± 1.15). The mean-quartile test for the total carious surface (P = .363) and the carious margin (P = .681) showed no statistically significant differences. Of the carbide bur-treated samples, 84.5% were caries free as opposed to 93.0% in the polymer bur group. The results also showed no significant difference between the mean working time of the polymer burs (5.11 minutes) and the carbide burs (4.99 minutes). Conclusion: Under these experimental conditions, polymer burs and tungsten carbide burs were similarly effective for caries removal. Keywords: carbide bur, caries removal, dentin caries excavation, dentin hardness, polymer bur
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Quintessence International, 6/2007
PubMed ID (PMID): 17625632Pages 489-497, Language: EnglishWelk, Alexander / Immenroth, Marc / Sakic, Petar / Bernhardt, Olaf / Eberspächer, Hans / Meyer, Georg

Mental training in dentistry

Objective: Since fine-motor movements and complex procedures, which are often necessary in dental practice, can be compared to those used by professional athletes, the purpose of this study was to determine the impact of the mental training technique, established in sport science, on dentistry. Method and Materials: In a randomized, controlled study, 2 groups of 20 and 21 dental students in their second semester (experimental group with mental training, and control group with conventional training, respectively), were evaluated at 2 time points (pre- and posttest) by measuring the effect of training by the criteria "knowledge," "process," and "quality" of a crown preparation on the computer-assisted Dental-Simulator (DenX). Results: The improvements of the experimental group and of the control group from pre- to posttest could be distinguished for all criteria in favor of the experimental group, in which improvements of knowledge (F1,39 = 72.674, P .001) and process (F1,39 = 6.63, P = .01) were statistically significantly better. Conclusion: The significantly greater improvements of the experimental group regarding knowledge and process compared to the control group indicate that the improvement in learning and performance caused by mental training is detectable in dental education, especially with regard to cognitive aspects of dental procedures. Keywords: crown preparation, dental education, learning method, mental training, randomized controlled trial, tooth preparation
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International Journal of Computerized Dentistry, 3/2006
PubMed ID (PMID): 17194051Pages 253-265, Language: English, GermanWelk, Alexander / Splieth, Christian / Wierinck, E. / Gilpatrick, R. O. / Meyer, G.

Computer-assisted Learning and Simulation Systems in Dentistry - A Challenge to Society

Introduction: Computer technology is increasingly used in practical training at universities. However, in spite of their potential, computer-assisted learning (CAL) and computer-assisted simulation (CAS) systems still appear to be underutilized in dental education. Materials and Methods: Advantages, challenges, problems, and solutions of computer-assisted learning and simulation in dentistry are discussed by means of MEDLINE, open Internet platform searches, and key results of a study among German dental schools. Results: The advantages of computerassisted learning are seen for example in self-paced and self-directed learning and increased motivation. It is useful for both objective theoretical and practical tests and for training students to handle complex cases. CAL can lead to more structured learning and can support training in evidence-based decision-making. The reasons for the still relatively rare implementation of CAL/CAS systems in dental education include an inability to finance, lack of studies of CAL/CAS, and too much effort required to integrate CAL/CAS systems into the curriculum. Conclusion: To overcome the reasons for the relative low degree of computer technology use, we should strive for multicenter research and development projects monitored by the appropriate national and international scientific societies, so that the potential of computer technology can be fully realized in graduate, postgraduate, and continuing dental education. Keywords: computer-assisted learning, computer-assisted simulation, problem-based learning, evidencebased medical/dental education, dental simulator, virtual reality dental simulation
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Quintessence International, 10/2006
PubMed ID (PMID): 17078280Pages 811-817, Language: EnglishSteffen, Heike / Löw, Angela / Rosin, Michael / Welk, Alexander

Comparison of K hand files and ProFiles 0.06/0.04 in simulated curved root canals prepared by students

Objectives: The objective of this study was to compare the step-down technique in simulated curved root canals using K hand files (VDW) and ProFiles 0.06/0.04 (Dentsply Maillefer). Method and Materials: A total of 72 canals were blindly prepared by instructed students: 1 block with K files and a second one with ProFiles 0.06/0.04 in connection with the EndoStepper (SET). Postoperative images of the canals were taken, and an independent dentist assessed preparations for amount and position of material removed during preparation. Efficacy of the instruments is described in terms of canal shape, instrument failure, canal blockages, and preparation time. Results: ProFile instrumentation provided well-centered and tapered preparations while maintaining the apical foramen; in contrast, the use of K files resulted in frequent alterations of the root canal. In the apical portion, both techniques showed unprepared areas. The coronal diameter in hand-instrumented canals was more irregular and wider than in those mechanically prepared. There was no separation of a ProFile instrument. Hand instrumentation was faster than mechanical, but the difference was not statistically significant. Conclusion: Under the conditions of the study, the ProFile rotary system was simple and safe to use and created better preparations than hand instrumentation. Keywords: hand instrumentation, mechanical preparation, nickel-titanium, rotary, simulated root canals
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International Journal of Computerized Dentistry, 2/2004
Pages 123-130, Language: English, GermanWelk, Alexander/Splieth, Christian/Rosin, M./Kordaß, Bernd/Meyer, G.

DentSim - A Future Teaching Option for Dentists

Apart from a requirement to acquire more and more academic knowledge, during their training, dental students need to acquire a full range of highly precise manual and technical skills, including excellent hand/eye coordination, to enable them to visualize and understand how to prepare cavities, prior to placing restorations. Furthermore, unlike medical students, dental students are in the position of administering treatment to patients very early in their training. The increasing academic workload means that these skills have to be mastered in a short space of time. This you will gain in the future only through the use of effective methods of the educations - for example by the use of the computer-assisted dental simulators (DentSim/DenX), which serves the visual-, audio- and practical learning channel simultaneously. Unlike the conventional phantom heads, the DentSim-unit has the following advantages - the acquisition of knowledge takes place in a multimedia learning environment with a high audio-visual content and degree of interaction and complexity, - problem-oriented learning takes place through clinically relevant work, - individual students can work to personalized programs through the digital tutor function, - two-dimensional knowledge is transferred into three-dimensional spatial work, - three-dimensional preparations can be easily analysed by two-dimensional error analysis. - all preparation exercises are recorded for error and effectiveness analysis. Apart from student training, the computer- assisted simulators can also be used for the evaluation of the effectiveness or the quality control of various teaching methods in the context of Evidence Based Dental Education. Keywords: computer-assisted dental simulator, dental simulation, computer- assisted preparation exercises, digital tutor function, problem-oriented learning, evidence based dental education
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Quintessence International, 2/2001
Pages 119-130, Language: EnglishRosin, Michael / Fleissner, Peter / Welk, Alexander / Steffen, Heike / Heine, Burkhard

The influence of surface configuration on the retention of posts designed for use with a cast-on technique

Objectives: The combination of an individually cast core and a prefabricated metal post is one of the many techniques to restore endodontically treated teeth. The surface characteristics of commercially available posts vary considerably and likely influence retention. In this study, the surface configuration of 11 castable prefabricated post systems and their retention at the post-cement interface were investigated. Method and materials: Scanning electron microscopic photos were made to assess surfaces of the posts. Etchant residues or applied surface layers were also analyzed with an electron beam microprobe. For the retention measurements, 6 posts from each system were cemented in artificial root canals with a zinc phosphate cement. Retention was measured on a universal testing machine. Results: Analysis of variance and the Ryan-Einot-Gabriel-Welsch F test revealed significant differences in retention between posts; these differences were related to the microstructure of the surfaces of the posts. In general, the coarser the surfaces, the better the retention. Gold plating of the etched surface for one manufacturer resulted in less retention compared to posts of the same type and size that were not plated. Conclusion: The surface configuration of a post could be an important factor when selecting a prefabricated post system.
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