One academic year under COVID-19 conditions: two multicenter cross-sectional evaluation studies among medical students in Bavarian medical schools, Germany students' needs, difficulties, and concerns about digital teaching and learning.

BACKGROUND: Since March 2020, COVID-19 has created a need for adaptation in many areas of life. This study explores medical students' perspectives on digital teaching under conditions of the COVID-19 pandemic. It focuses on expectations and concerns about digital teaching, the evaluation of specific aspects of teaching, and requests for future teaching. METHODS: Six German faculties have joined forces within the Bavarian network for medical education to develop and deploy a common core questionnaire. Cross-sectional surveys were conducted at the end of the summer semester 2020 and winter semester 2020/21. Medical students from different semesters participated in the online survey. Data was analyzed descriptively and/or inferentially. Item differences across semesters were examined using contingency tables and Chi2 tests. Mean values were compared using the independent samples t-test; answer frequencies in retrospective and prospective concerns were compared using contingency tables and Chi2 tests with Yates' correction. RESULTS: In the summer semester 2020, 1565 students and in winter semester 2020/21, 1727 students took part in the survey. Students' main prospective concern was lack of social exchange between fellow students (70%), but also with teachers. Second and third most often concerns were a lack of practical training (68%) and lack of integration of on-site digital teaching (50%). Approximately 7% of the students lacked sufficient access to technical equipment.. Approximately 39% of the students lacked a sufficient internet connection for synchronous digital teaching, 17% for asynchronous digital teaching. On-site teaching was the preferred form of teaching (60%), and there was a preference for asynchronous (24%) over synchronous (15%) digital teaching. Teaching recordings (79%) were particularly popular to complement future on-site teaching. CONCLUSIONS: The following areas of education under COVID-19 conditions are highly important to medical students: adequacy of information sharing, integration of opportunities for exchange with fellow students and teachers, possibility to perform practical trainings. After the normalization of the pandemic situation, on-site teaching should be supplemented with blended learning concepts such as the inverted classroom model. Percentages of results are rounded averages from summer and winter semesters.

Morphology of the enamel-dentine junction in sections of anthropoid primate maxillary molars.

The shape of the enamel-dentine junction (EDJ) in primate molars is regarded as a potential indicator of phylogenetic relatedness because it may be morphologically more conservative than the outer enamel surface (OES), and it may preserve vestigial features (e.g., cuspules, accessory ridges, and remnants of cingula) that are not manifest at the OES. Qualitative accounts of dentine-horn morphology occasionally appear in character analyses, but little has been done to quantify EDJ shape in a broad taxonomic sample. In this study, we examine homologous planar sections of maxillary molars to investigate whether measurements describing EDJ morphology reliably group extant anthropoid taxa, and we extend this technique to a small sample of fossil catarrhine molars to assess the utility of these measurements in the classification of fossil teeth. Although certain aspects of the EDJ are variable within a taxon, a taxon-specific cross-sectional EDJ configuration predominates. A discriminant function analysis classified extant taxa successfully, suggesting that EDJ shape may a reliable indicator of phyletic affinity. When considered in conjunction with aspects of molar morphology, such as developmental features and enamel thickness, EDJ shape may be a useful tool for the taxonomic assessment of fossil molars.

Quantification of dentine shape in anthropoid primates.

The external shape and thickness of the enamel component of primate molars have been employed extensively in phylogenetic studies of primate relationships. The dentine component of the molar crown also has been suggested to be indicative of phylogenetic relationships, but few studies have quantified dentine morphology in order to evaluate this possibility. To explore the utility of dentine shape as an indicator of phylogenetic affinity, a two-dimensional geometric morphometric analysis (EDMA-II) was performed using nine homologous landmarks on a sample of sectioned maxillary molars of extant ceboid, cercopithecoid, and hominoid primates. Results indicate that dentine shape (the configuration of the enamel-dentine junction, or EDJ) can distinguish taxa at every taxonomic level examined, including superfamilies, subfamilies, and closely related genera and species. This supports the idea that dentine morphology may be useful for phylogenetic studies. It is further suggested that the morphology of the EDJ may be more conservative than enamel morphology, and perhaps better-suited to phylogenetic studies. Among the samples studied, cercopithecoid primates have a unique dentine shape, and it is suggested that the development of bilophodont molars may be related to the distinctive EDJ configuration in cercopithecoids.

A new 3-d approach to determine functional morphology of cercopithecoid molars.

Functional relationships between diet and tooth morphology form an integral part of primatological and paleontological research. Previously, mostly two-dimensional parameters have been used to compare and interpret the complex crown morphology of cercopithecine and colobine molars. However, as teeth are three-dimensional objects, any dimensional reduction in describing their morphology must result in loss of information. In the current study we use a high resolution optical topometric system to record crown morphology in different wear stages in order to extract three-dimensional (3-d) parameters from virtual 3-d models. Structural parameters such as relief index, occlusal surface area, enamel area and strike and dip of cusp slopes as well as wear facets can be calculated, reflecting the changing occlusal topography of molars due to attrition and abrasion. By comparing mostly fruit-eating cercopithecines and leaf-eating colobines, functional implications of tooth wear, occlusal jaw movement and resulting relief can be inferred. Our analyses show that the main differences in occlusal relief between these genera do not change with wear. Colobines maintain higher occlusal relief, whereas in cercopithecines all cusps wear flat quite rapidly. Detailed models of wear for cercopithecoid molars will be used to reconstruct diet and will enhance our knowledge of the paleoecology of Cercopithecoidea.