title: Maximum principal strain as a criterion for prediction of orthodontic mini-implants failure in subject-specific finite element models.
abstract: OBJECTIVE
  To investigate the most reliable stress or strain parameters in subject-specific finite element (FE) models to predict success or failure of orthodontic mini-implants (OMIs).
  
  
  METHODS
  Subject-specific FE analysis was applied to 28 OMIs used for anchorage. Each model was developed using two computed tomography data sets, the first taken before OMI placement and the second taken immediately after placement. Of the 28 OMIs, 6 failed during the first 5 months, and 22 were successful. The bone compartment was divided into four zones in the FE models, and peak stress and strain parameters were calculated for each. Logistic regression of the failure (vs success) of OMIs on the stress and strain parameters in the models was conducted to verify the ability of these parameters to predict OMI failure.
  
  
  RESULTS
  Failure was significantly dependent on principal strain parameters rather than stress parameters. Peak maximum principal strain in the bone 0.5 to 1 mm from the OMI surface was the best predictor of failure (R(2) = 0.8151).
  
  
  CONCLUSIONS
  We propose the use of the maximum principal strain as a criterion for predicting OMI failure in FE models.
authors.affiliation: a  PhD candidate, Section of Orthodontics and Dentofacial Orthopedics, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
authors.forename: Mhd Hassan
authors.initials: MH
authors.lastname: Albogha
authors.affiliation: b  Associate Professor, Section of Orthodontics and Dentofacial Orthopedics, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Kitahara
authors.affiliation: c  Associate Professor, Research Institute of Applied Mechanics, Kyushu University, Kasuga, Japan.
authors.forename: Mitsugu
authors.initials: M
authors.lastname: Todo
authors.affiliation: d  Professor and Chairman, Department of Mathematics, National Defense Academy of Japan, Yokosuka, Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Hyakutake
authors.affiliation: e  Professor and Chairman, Section of Orthodontics and Dentofacial Orthopedics, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Takahashi
mesh_terms: D001842:Bone and Bones; D015921:Dental Implants; D019232:Dental Restoration Failure; D019544:Equipment Failure Analysis; D020342:Finite Element Analysis; D006801:Humans; D011475:Prosthesis Failure; D013314:Stress, Mechanical
chemical_list: D015921:Dental Implants
keywords: Finite element analysis; Maximum principal strain; Orthodontic mini-implant
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