Biomechanical analysis of implant-supported prostheses varying connection system, retention system, restorative material, type and quality of bone tissue. Study by three-dimensional finite element method.

Author(s)

Cleidiel Aparecido Araujo Lemos

• Document type: Doctoral Thesis
• Press: Araçatuba. 2019-05-16.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araçatuba
• Defense date: 2019-03-07
• Advisor: Eduardo Piza Pellizzer; Fellippo Ramos Verri

Abstract

The aim of this thesis was to perform the analysis on the stress distribution for implant-supported fixed prostheses varying the implant-abutment connection system, the fixation system, restorative material, bone type, and the level of bone tissue around the dental implant using the finite element method. Furthermore, the aim was to perform a systematic review and meta-analysis about the effect of osteoporosis in terms of implants survival rate and marginal bone loss. In relation to the experimental methodology, 24 three-dimensional models were simulated with the aid of the Rhinoceros 3D 4.0 (NURBS Modeling for Windows, USA), SolidWorks 2011, and InVesalius (CTI, São Paulo, Brazil) softwares. Each model represented a bone section of the maxillary posterior area (bone type IV) (normal and osteoporotic), varying the level of bone resorption (at the level of the implant, loss of bone tissue in 1.5 mm, loss of bone tissue in 3.0 mm and loss of bone tissue in 4.5 mm). All models containing the presence of a dental implant with 4.0 mm in diameter and 10 mm in length with two different abutment-implant connection (external hexagon and Morse taper), restored with crowns (metaloceramic and/or monolithic) with different fixation system (cemented and/or screwed). The designs were exported to FEMAP v.11.2 pre-and postprocessing software (Siemens Product Lifecycle Management Software Inc. USA) for mesh generation and loading application of 200N axial and 100N oblique (45° in the long axis of implant, suppressing lingual cusps) in the slopes each cusp of the crown. The analysis was performed in the NEiNastran 11 (Noran Engineering, Inc., USA) and the results will be imported to FEMAP 11.2 through von Mises stress maps (implants and components) and maximum principal stress and microdeformation (bone tissue). The results of chapter 1 showed that the progressive loss of the bone tissue showed an influence on the stress distribution in the bone tissue, implants and components. The quality of the bone tissue (osteoporosis) affected only the microdeformation, mainly in the trabecular bone tissue. Morse taper implants showed lower stress concentrations in the bone tissue compared to external hexagon implants, only for models without bone loss. The external hexagon implants presented worse biomechanical behavior in the implants and screw fixation, especially in oblique loading. Regarding to chapter 2, it was possible to verify that Morse taper implants showed better biomechanical behavior area of cortical bone tissue and screw fixation compared to external hexagon implants for screwed prostheses. The cemented prostheses showed a slight reduction of stress in the cortical bone tissue; however, with greater stress in the fixation screw for the external hexagon implants. The type of restorative materials (metalceramic and/or monolithic) did not affect the biomechanical behavior of the structures. In chapter 3 after systematic review, a total of five studies were included for tabulation of the data. After performing the metaanalysis it was observed that dental implants should be considered as a viable treatment alternative for the rehabilitation of patients with osteoporosis; however, clinical care is necessary to guarantee the maintenance of peri-implant bone stability, due to high marginal bone loss was observed for patients with osteoporosis. (AU)

• FAPESP's process: 15/24442-8 - Biomechanical analysis of implant-supported prosthesis varying the type connection, the retention system, restorative material, type and level of bone tissue. Study by three-dimensional finite element method.
• Grantee: Cleidiel Aparecido Araujo Lemos
• Support Opportunities: Scholarships in Brazil - Doctorate