PSI - Issue 33

Dario Milone et al. / Procedia Structural Integrity 33 (2021) 734–747 D. Milone et al./ Structural Integrity Procedia 00 (2019) 000–000

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Once the markers had been calibrated, a standard polygon polygonization was carried out. Once obtained the model with the surfaces that approximate the assembly, Space Claim (software that uses rapid modelling tools to draw precise parts on mesh data) was used for geometry modelling. To create the implants and orient them in space, the axes that best approximated the position and orientation of the prosthesis were identified. Finally, the geometry was exported and the assembly cad was made. 2.3. FEM analysis Once the 3d model was obtained, the authors focused on functionality, and on the type of connection between the components. For this reason, the dimensions of the cortical bone and the cancellous bone were schematized as in (Cervino et al., 2018; Cicciù et al., 2019, 2018). The bone was schematized as a cylindrical volume as in (Shelat et al., 2011). A number of 29 components were tested as described below in Fig. 2 (for each part of the assembly, markers were attributed). The identification numbers are as follow: abutment (1-4), screw (5-8), bridge (9), cortical bone (10-13), fixture (14-17), cancellous bone (18-21), seeger ring (22-25), equator (26-29).

Fig. 2. a) Frontal view of assembly; b) top view of assembly; c) frontal view of prothesis; d) Section view of bone e) frontal view of Seegers.

2.4. System setup

Four different OT Bridge prosthesis system approaches for the rehabilitation of complete edentulism were analysed and compared. All systems used 4 implants and two of them (posterior prosthesis) are inclined as mentioned in Fig. 3b. A fixed connection with the prosthetic bar was modelled. The Seeger ring was connected inside the abutment (Fig. 3a), as specified by the manufacturer. The difference between the four-prosthesis system configuration consisted in the number of connection screws applied, respectively 4, 3, 2 and none.