title: Predisposing Factors for Orthodontic Mini-Implant Failure Defined by Bone Strains in Patient-Specific Finite Element Models.
abstract: Factors responsible for the success or failure of orthodontic mini-implants (OMIs) in clinical settings are unclear. Failure of OMIs was found to be associated with increased maximum principal strain (MaxPN) when assessed using the subject-specific finite element (FE) modeling technique. The purpose of the present study was to identify factors that increase MaxPN and thereby predispose the OMI to failure. Using the FE method, MaxPN was calculated around 28 OMIs placed in orthodontic patients, 6 of which failed during the first 5 months. Sixteen potential risk factors related to patients or to OMI position were measured on computerized tomographic images or calculated in FE models. The impact of these factors on MaxPN was verified using regression analysis. Three factors were found to have significant nonlinear relationships with MaxPN: cortical bone quality, vertical angulation of the OMI, and proximity of the OMI to the tooth in the direction of force. In conclusion, failure of an OMI is a multifactorial problem, and position and angulation of the implant are among the affecting factors. Slight apical inclination and positioning at least 1 mm off the root in the direction of force may significantly decrease failure probability.
authors.affiliation: Section of Orthodontics and Dentofacial Orthopedics, Faculty of Dental Science, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Mhd Hassan
authors.initials: MH
authors.lastname: Albogha
authors.affiliation: Section of Orthodontics and Dentofacial Orthopedics, Faculty of Dental Science, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Kitahara
authors.affiliation: Research Institute of Applied Mechanics, Kyushu University, Kasuga, 816-8580, Japan.
authors.forename: Mitsugu
authors.initials: M
authors.lastname: Todo
authors.affiliation: Department of Mathematics, National Defense Academy of Japan, Yokosuka, 239-0811, Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Hyakutake
authors.affiliation: Section of Orthodontics and Dentofacial Orthopedics, Faculty of Dental Science, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. takahashi@dent.kyushu-u.ac.jp.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Takahashi
mesh_terms: D000293:Adolescent; D000328:Adult; D000071538:Cortical Bone; D015921:Dental Implants; D019544:Equipment Failure Analysis / Q000379:methods*; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008297:Male; D008954:Models, Biological; D011475:Prosthesis Failure
chemical_list: D015921:Dental Implants
keywords: Bone screws; Finite element analysis; Orthodontic anchorage procedures; Retrospective study; Risk factors