The human skull and the maxillary bones have a very complicated architecture, determined by the outer walls, by the internal bone structures and their joining. In this paper CAD parametric software has been used to define complex virtual models. First, the mandible and jaw were defined using CT images. These images were imported into a CAD software using specific techniques and methods. These models have been finalized in SolidWorks where the virtual model of the studied system has been generated. Then, the virtual models were exported to a software for FEA simulation and prepared for every dentistry simulations. The structure of the maxillary bones contains spongy bone tissue, cortical bone tissue along with dental tissues. Each of these tissues have certain properties (elasticity, plasticity, density) assessed by flexibility. The analysis of the mechanical tension of the dental structures has been a subject of interest in recent years in order to determine the state of tension in the dental structures and to improve the mechanical strength of these structures. Such numerical techniques can give a better understanding of reactions and interactions of individual tissues. This involves a series of computational procedures to calculate stress in each element. Field variables can be interpolated by using form functions for scientific verification and validation of clinical assumptions. Various loadings have been applied to a personalized skull obtained from CT images using CAD techniques and procedures. On this system, FEM simulations were made and maps of stress, displacements and deformations were obtained that show the mechanical behavior of the maxillary dental system. Finally, important conclusions were highlighted.

Dental wear has accompanied human evolution, being strictly related to its way of life. Dental wear is a lesion of dental hard tissue commonly found in dental practice. Starting from the virtual skull model, the virtual models of the two upper premolars on the left hemisphere were generated, then the finite element method evaluated the stresses, displacements and strains generated by the resistance forces from the dental tissues of the two premolars during mandibular movements with occlusal contact. It is found that the value of these results increases as dental wear increases. This phenomenon is more visible in the teeth where the value almost doubles. Two explanations could be given for this situation: mechanically, these stresses are inversely proportional to the volume of the dental structures and, as they reduce, through dental wear, increase the stress, also, the sharp edges resulting from dental wear are mechanical stress concentrators.

In order, to understand the problems, which occur during the dentistry simulations, it was highly important to be acquainted with the anatomy of the human skull skeleton, the way these bone components are working together to achieve a normal functionality. In this respect CAD parametric software has been used as it allows to define models with a high degree of difficulty. First, the main bone components were defined by using CT images. These images were then transferred to a CAD software using different methods and techniques. These models were completed in SolidWorks where, step by step, the virtual model of the studied bone system has been defined. Using the direct measurement method on some skull components the virtual bone base elements were generated. Then, the virtual models were exported to a software for FEA simulation and prepared for every dentistry simulations. These models were tested and was generated the finite elements structure. In the end of the paper, were extracted interesting conclusions.

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