Orthodontic mini-implant failure risk based on bone quality, metal type and how to represent its interface with the bone: finite element analysis

• Grant number: 19/15830-5
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): December 01, 2019
• Effective date (End): November 30, 2020
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal researcher: Josete Barbosa Cruz Meira
• Grantee: Gisele Lie Fukuoka
• Home Institution: Faculdade de Odontologia (FO). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Orthodontic mini-implants (OMIs) have been widely used in Orthodontics in recent years. Many scientific studies have used finite element analysis (FEA) to assess the risk of biomechanical failures associated with OMIs. However, a common mistake in many of the studies is to consider a perfect union between OMI and bone. Osseointegration is neither necessary nor desirable in OMIs. When it occurs, the risk of implant fracture increases at the time of removal. The objective of this study will be to evaluate the risk of loss of stability and fracture risk of OMI through FEA as a function of three variables: bone quality, whether osseointegrated or not, and the material of the mini-implant. Four clinical conditions regarding bone quality will be simulated, differentiated by increasing cortical bone thickness and the elastic modulus of the trabecular bone: dense maxilla, control maxilla, control mandible and dense mandible. For each bone will be simulated two conditions of OMI-bone interface (perfectly united, assuming osseointegration, and not joined, assuming absence of osseointegration) and two mini-implant materials (titanium and steel). The risk of loss of stability will be determined by deformation of the peri-implant bone and fracture risk of the mini-implant, by von Mises tensions in the OMI. (AU)