The first aim of this study was to assess displacements and micro-strain induced on different grades of atrophic cortical and trabecular mandibular bone by axially loaded dental implants using finite element analysis (FEA). The second aim was to assess the micro-strain induced by different implant geometries and the levels of bone-to-implant contact (BIC) on the surrounding bone. Six mandibular bone segments demonstrating different grades of mandibular bone atrophy and various bone volume fractions (from 0.149 to 0.471) were imaged using a micro-CT device. The acquired bone STL models and implant (Brånemark, Straumann, Ankylos) were merged into a three-dimensional finite elements structure. The mean displacement value for all implants was 3.1 ±1.2 µm. Displacements were lower in the group with a strong BIC. The results indicated that the maximum strain values of cortical and cancellous bone increased with lower bone density. Strain distribution is the first and foremost dependent on the shape of bone and architecture of cancellous bone. The geometry of the implant, thread patterns, grade of bone atrophy and BIC all affect the displacement and micro-strain on the mandible bone. Preoperative finite element analysis could offer improved predictability in the long-term outlook of dental implant restorations.

10 ray Micro CT and Nano CT Research Group CEITEC BUT Brno University of Technology Technická 2896 2 616 69 Brno Czech Republic

Department of Oral and Maxillofacial Surgery Oral Pathology VU University Medical Center Amsterdam The Netherlands

Institute of Solid Mechanics Mechatronics and Biomechanics Faculty of Mechanical Engineering Brno University of Technology Technická 2896 2 616 69 Brno Czech Republic

Oral and Maxillofacial Unit Department of Otorhinolaryngology Tampere University Hospital FI 33521 Tampere Finland

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