Utilization of computer-aided design/computer-aided manufacturing (CAD/CAM) rapidly increases in dental medicine. Making of computer-engineered complete denture is based on scanning of patient data, designing of prosthesis and milling or rapid prototyping. This is digital denture, term that includes innovative devices, software programmes and corresponding materials. Industrially polymerized cross-linked polymethyl methacrylate (PMMA) is the material used for fabrication of digital denture. The aim of this study is to analyze the different cross-linked PMMA used for fabrication of CAD/CAM complete denture.

Fabrication of temporary restorations is an essential part in dentistry and especially in oral implantology. Polymethyl methacrylate is used for a long time as material for temporary restorations and many improvements has been done to increase its properties, especially fracture resistance. Crosslinking and computer-assisted design/computer-assisted machining permit fabrication of long-term temporary restorations with flexural strength high enough and good modulus of elasticity that do not fracture easily under functional loads.

We evaluated the biocompatibility of four types of commercial alloys (two CoCr alloys and two NiCr alloys) used to make dental bridges. For the cell biology tests, a human osteosarcome type culture cell line MG63 (American Type Culture Collection) was used. Taking into account the results obtained, it can be said that the best results in terms of cell proliferation were observed for the Ni-Cr / Solibond N alloy closely followed by Co-Cr / Heraenium CE, then Co-Cr / Solibond C and Ni-Cr / Kera N, while cell viability tests revealed that the Co-Cr / Heraenium CE alloy exhibits the best biocompatibility, followed by Ni-Cr / Kera N, Co-Cr / Solibond C and Ni-Cr / Solibond N.

FEM studies were made on a zirconia dental bridge of 4 elements with supports on 2.4 and 2.7, and edentation on 2.5 and 2.6. Appling a compressive force of 350N on Z direction, quite normal for mastication, was analyzed the behavior of the dental bridge. Zirconia, although having a high mechanical strength, is fragile when rotation or bending movements occur. The analysis reveals some bridge deficiencies, which may be due either to inaccuracies in the prosthetic abutment construction (especially in relation to their inclination), to the technique of realization or to insufficient dental support. In our study, the most vulnerable elements are the crowns on teeth 2.4 and 2.7. Finite element analysis, highlighting possible structural and design deficiencies, may be a solution to improve dental bridges. The only disadvantage of the finite element analysis that was performed before the actual restoration is related to the fact that performing the simulations involves a time-consuming phase.

In our study we compared in vitro the tensile strength of 4 types of adhesive systems used for brackets, two using bonding and two self-etching. The detachment test were made by the Instron� 8801 universal mechanical testing machine, from the Mechanical Testing Laboratory of the Materials Resistance Department, the Faculty of Engineering and Management of Technological Systems, the Polytechnic University of Bucharest. From the experimental results we find that the used adhesives offer good shear resistance. Vertise Flow adhesive used for sample 2, which has the highest shear stress at break (tmax ~ 25 MPa), is clearly highlighted. Vertise Flow is follow by the Orthocem adhesive used for sample 1 with tmax ~ 14 MPa, then the Neobond adhesive used in sample 4 with tmax ~ 13 MPa, and the weakest of the adhesives is Grandio Flow used for sample 3 (tmax ~ 12 MPa). We believe it is necessary to carry out further studies on larger batches of samples to obtain results that can be validated by statistical analysis.