@article{LiashenkoHrynevichDalton2020, author = {Liashenko, Ievgenii and Hrynevich, Andrei and Dalton, Paul D.}, title = {Designing Outside the Box: Unlocking the Geometric Freedom of Melt Electrowriting using Microscale Layer Shifting}, series = {Advanced Materials}, volume = {32}, journal = {Advanced Materials}, number = {28}, doi = {10.1002/adma.202001874}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-217974}, year = {2020}, abstract = {Melt electrowriting, a high-resolution additive manufacturing technology, has so far been developed with vertical stacking of fiber layers, with a printing trajectory that is constant for each layer. In this work, microscale layer shifting is introduced through deliberately offsetting the printing trajectory for each printed layer. Inaccuracies during the printing of sinusoidal walls are corrected via layer shifting, resulting in accurate control of their geometry and mechanical properties. Furthermore, more substantial layer shifting allows stacking of fiber layers in a horizontal manner, overcoming the electrostatic autofocusing effect that favors vertical layer stacking. Novel nonlinear geometries, such as overhangs, wall texturing and branching, and smooth and abrupt changes in printing trajectory are presented, demonstrating the flexibility of the layer shifting approach beyond the state-of-the-art. The practice of microscale layer shifting for melt electrowriting enables more complex geometries that promise to have a profound impact on the development of products in a broad range of applications.}, language = {en} } @article{HoehneSchwarzbauerSchmitter2020, author = {H{\"o}hne, Christian and Schwarzbauer, Raphael and Schmitter, Marc}, title = {Introduction of a new teaching concept for crown preparation with 3D printed teeth}, series = {European Journal of Dental Education}, volume = {24}, journal = {European Journal of Dental Education}, number = {3}, doi = {10.1111/eje.12532}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218133}, pages = {526 -- 534}, year = {2020}, abstract = {Introduction For both students and teachers, it is challenging to learn and teach a correct crown preparation. The purpose of this study was the design, feasibility and evaluation of a 3D printed tooth model with internal preparation for dental education in crown preparation and to analyse the quality of the prepared printed teeth in comparison with prepared standard model teeth. Materials and methods A printable tooth was designed and printed by a stereolithographic printer. 38 fourth-year dental students in the first clinical course in prosthodontics were trained in a voluntary course using printed teeth. Different aspects of the printed tooth were evaluated by a questionnaire using German school grades (1 best to 5 worst). The quality of the preparation with the printed teeth and standard training teeth was also rated in an evaluation form done by an expert group consisting of five experienced dentists. Results The workflow was feasible and cost-effective for the production of the teeth. The overall rating of the printed tooth was {\O} 2.0 ± 0.34 in the questionnaire completed by the students. The students rated the printed tooth model ({\O} 2.1 ± 0.85) as significantly better than the standard model tooth ({\O} 3.3 ± 0.77; P = .000). The students reported great benefits in the use of this model tooth, for example valuable replacement of a standard model and real teeth, direct control of material loss. The quality of the preparation was evaluated by the expert group as significantly better with an overall mean grade of {\O} 2.6 ± 0.37 for the printed teeth compared to {\O} 2.9 ± 0.42 for the standard model teeth (P = .000). Conclusions The feasibility of this teaching concept was confirmed. The students favoured to work on the innovative 3D-teeth with internal preparation, emphasising the usefulness of this technique in dental education. The expert group confirmed also the significant training effect of this tooth model in contrast to a standard model tooth.}, language = {en} } @article{HoehneDickhautSchmitter2020, author = {H{\"o}hne, Christian and Dickhaut, Nora and Schmitter, Marc}, title = {Introduction of a new teaching concept for dentin post preparation with 3D printed teeth}, series = {European Journal of Dental Education}, volume = {24}, journal = {European Journal of Dental Education}, number = {3}, doi = {10.1111/eje.12528}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-215586}, pages = {499 -- 506}, year = {2020}, abstract = {Introduction The preparation for dentin posts is difficult and hard to learn. There are currently no reproducible simulation models to train this clinical procedure. The purpose of this study was the design, feasibility and evaluation of a three-dimensional (3D) printed tooth model for the pre-clinical teaching of students. Materials and methods A printable tooth was designed and printed by a stereolithographic printer. A total of 48 fourth-year dental students in the first clinical course in prosthodontics were trained in a voluntary hands-on course on 4 similar printed teeth. The students used standard model teeth and real-teeth models during their education. They had experience in caries removement and root canal treatment on real patients. Root perforations were counted for every attempt. The different benefits of the 3D printed tooth were evaluated by a questionnaire using German school grades from 1 (best) to 6 (worst). Results The overall rating of the printed tooth was {\O}1.9 ± 0.3. The item "suitable exercise option" was rated {\O}2.0 ± 0.8, and the teeth were "easy to use" {\O}1.9 ± 0.9. The item "realistic approach to dentin post preparation" was rated {\O}2.1 ± 0.8, and the teeth showed the "shortcomings at a root perforation" {\O}1.5 ± 0.6. The students reported to have much more motivation and enthusiasm to improve their skills with the printed teeth {\O}2.1 ± 0.9. They had a strong desire to include these teeth in their pre-clinical education before the first patient treatment {\O}1.6 ± 0.8. The success rate of the dentin post preparation was significantly better for the second 25\% (P = .047) and fourth 48\% (P = .04) attempt. Conclusions The feasibility of this teaching concept was confirmed. The students had the possibility to learn a correct dentin post preparation on a printed tooth model. The learning effect with this tooth model was rated as good to very good by the questionnaire.}, language = {en} }