Abstract Objective  This study investigated biomechanical behavior of custom post core made of six different materials on the tooth with and without the ferrule under different occlusal load. Materials and Methods  Three-dimensional models of mandibular first premolar, with and without ferrule, reconstructed from micro-computed tomography image are restored with different custom post core and zirconia crowns. By using the finite element analysis, von Mises stress shown in MPa was measured under simulated axial and oblique load of 200 [N]. To compare the stress distribution, six different custom post core materials were chosen: zirconia, Ni-Cr alloy, gold alloy, glass fiber-polyether ether ketone, polyether ether ketone, and carbon fiber-polyether ether ketone. Results  Custom post cores with a higher modulus of elasticity showed higher measured stress in the posts, but less stress in dentin. Measured stress in custom post core under oblique loading was approximately three times higher compared with axial loading. Stress in custom post core and in dentin under both types of loads was slightly higher in teeth without ferrule effect. Conclusion  The use of custom cast post cores made of different alloys is recommended in restoration of endodontically treated teeth, with extensive loss of tooth structure especially in teeth without ferrule effect.

Analysing of material flows within the boundaries of the production system it is possible to conclude that the sources and sinks of those material flows are storages. In those storages in the function of the kind and the type numerous processes are implemented. These storage processes along with the material handling processes are responsible for quantitative and dynamic balancing of material flows and as such have a significant impact on the total cost and productivity of the production system. Due to the above reasons, the design of storage is an important task which needs to be adequately accessed. Regardless of the kind and the type and the associated processes within storage one of the main activities in the design phase of storage is to define its location, with special emphasis on interaction with other elements of the production system (production and processing equipment, material handling equipment and devices, etc.). Namely, selection of the right location, among other things ensuring the necessary conditions which will make the process of storage to meet the technical and technological, economic, organizational, IT and other requirements upon it.

Today’s business of manufacturing systems is entirely dictated by the dynamics of the market and every day there is a need for adjustment of the structure and parameters of associated manufacturing systems. Those adjustments should ensure the operation of manufacturing systems in more favourable manufacturing and economic conditions, and often this process is directly linked with the starting of investment process. On the other hand, every day practice proves that evaluation of investment program during selection of structure of manufacturing system with the aim to accomplish production plans and reduction of production costs is often based on insufficient sets of information. Lack of information may result in inappropriate insight into overall techno-economic effects that can be achieved by investment program. Within this paper are presented researches which resulted in development of a new systematic approach in the analysis of potential structures and parameters of manufacturing systems with the aim to plan, project or reengineer manufacturing systems on the basis of minimal production costs.

Introduction: An abfraction lesion is a type of a non-carious cervical lesion (NCCL) that represents a sharp defect on the cervical part of tooth, caused by occlusal biomechanical forces. The largest prevalence of the NCCL is found on the mandibular first premolar. The goal of the study is, by means of a numerical method – the finite element method (FEM), in an appropriate computer program, conduct a stress analysis of the mandibular premolar under various static loads, with a special reference to the biomechanics of cervical tooth region. Material and methods: A three-dimensional model of the mandibular premolar is gained from a µCT x-ray image. By using the FEM, straining of the enamel, dentin, peridontal ligament and alveolar bone under axial and paraxial forces of 200 [N] is analyzed. The following software were used in the analysis: CT images processing–CTAn program and FEM analysis–AnsysWorkbench 14.0. Results: According to results obtained through the FEM method, the calculated stress is higher with eccentric forces within all tested tooth tissue. The occlusal load leads to a significant stress in the cervical tooth area, especially in the sub-superficial layer of the enamel (over 50 MPa). The measured stress in the peridontal ligament is approximately three times higher under paraxial load with regard to the axial load, while stress calculated in the alveolar bone under paraxial load is almost ten times higher with regard to the axial load. The highest stress values were calculated in the cervical part of the alveoli, where bone resorption is most commonly seen. Conclusion: Action of occlusal forces, especially paraxial ones, leads to significant stress in the cervical part of tooth. The stress values in the cervical sub-superficial enamel layer are almost 5 times higher in relation to the superficial enamel, which additionally confirms complexity of biomechanical processes in the creation of abfraction lesions.