Mhd Hassan Albogha1, Toru Kitahara2, Mitsugu Todo3, Hiroto Hyakutake4, Ichiro Takahashi5. 1. a PhD candidate, Section of Orthodontics and Dentofacial Orthopedics, Faculty of Dental Science, Kyushu University, Fukuoka, Japan. 2. b Associate Professor, Section of Orthodontics and Dentofacial Orthopedics, Faculty of Dental Science, Kyushu University, Fukuoka, Japan. 3. c Associate Professor, Research Institute of Applied Mechanics, Kyushu University, Kasuga, Japan. 4. d Professor and Chairman, Department of Mathematics, National Defense Academy of Japan, Yokosuka, Japan. 5. e Professor and Chairman, Section of Orthodontics and Dentofacial Orthopedics, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
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). MATERIALS AND 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.
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). MATERIALS AND 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.
Entities:
Keywords:
Finite element analysis; Maximum principal strain; Orthodontic mini-implant