Development of a device to simulate tooth mobility

Objectives: The testing of new materials under simulation of oral conditions is essential in medicine. For simulation of fracture strength different simulation devices are used for test set-up. The results of these in vitro tests differ because there is no standardization of tooth mobility in simulation devices. The aim of this study is to develop a simulation device that depicts the tooth mobility curve as accurately as possible and creates reproducible and scalable mobility curves. Materials and methods: With the aid of published literature and with the help of dentists, average forms of tooth classes were generated. Based on these tooth data, different abutment tooth shapes and different simulation devices were designed with a CAD system and were generated with a Rapid Prototyping system. Then, for all simulation devices the displacement curves were created with a universal testing machine and compared with the tooth mobility curve. With this new information, an improved adapted simulation device was constructed. Results: A simulations device that is able to simulate the mobility curve of natural teeth with high accuracy and where mobility is reproducible and scalable was developed

Generation and specification of unique neuronal sub-types: lessons from Drosophila neuropeptide neurons

The central nervous system (CNS) contains a daunting diversity of neuronal cell types. One of the major challenges of developmental neurobiology is to understand the regulatory mechanisms underlying this vast complexity. Studies in the Drosophila melanogaster (Drosophila) model system has contributed greatly to our understanding of neuronal cell sub-type specification, and the majority of mechanisms and genes identified in this system has proved to be of great value, and often more or less directly transferable to studies of mammalian neuro-development. In Drosophila, studies of the developmental generation of numerous different neuropeptide neurons have been highly informative, since these neurons are generated in a highly restricted and reproducible manner. In addition, neuropeptides are expressed at high levels and their regulatory regions have proven comparatively condensed, facilitating the generation of a multitude of antibodies and transgenic markers. Here, we first provide a general background to Drosophila CNS development. Then, we focus in more detail on various well studied neuropeptide neurons identified in this system, and describe what has been learned regarding the generation and differentiation of these highly unique neuronal sub-types. We intend this review to provide an overview of the variety of mechanisms that operate throughout the developmental period to generate highly unique neuronal sub-types. Finally, we conclude with some general remarks and perspectives regarding neuronal sub-type specification in general