title: Bone stress and strain after use of a miniplate for molar protraction and uprighting: a 3-dimensional finite element analysis.
abstract: BACKGROUND
  The aim of this study was to use the finite element method to evaluate the distribution of stresses and strains on the local bone tissue adjacent to the miniplate used for anchorage of orthodontic forces.
  
  
  METHODS
  A 3-dimensional model composed of a hemimandible and teeth was constructed using dental computed tomographic images, in which we assembled a miniplate with fixation screws. The uprighting and mesial movements of the mandibular second molar that was anchored with the miniplate were simulated. The miniplate was loaded with horizontal forces of 2, 5, and 15 N. A moment of 11.77 N·mm was also applied. The stress and strain distributions were analyzed, and their correlations with the bone remodeling criteria and miniplate stability were assessed.
  
  
  RESULTS
  When orthodontic loads were applied, peak bone strain remained within the range of bone homeostasis (100-1500 μ strain) with a balance between bone formation and resorption. The maximum deformation was found to be 1035 μ strain with a force of 5 N. At a force of 15 N, bone resorption was observed in the region of the screws.
  
  
  CONCLUSIONS
  We observed more stress concentration around the screws than in the cancellous bone. The levels of stress and strain increased when the force was increased but remained within physiologic levels. The anchorage system of miniplate and screws could withstand the orthodontic forces, which did not affect the stability of the miniplate.
authors.affiliation: Postgraduate student, Graduate Program in Orthodontics, School of Health and Biosience, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil.
authors.forename: Lucila Zimmermann
authors.initials: LZ
authors.lastname: Largura
authors.affiliation: Adjunct professor, Graduate Program in Numerical Methods, Department of Civil Engineering, Federal University of Paraná, Curitiba, Paraná, Brazil.
authors.forename: Marco André
authors.initials: MA
authors.lastname: Argenta
authors.affiliation: Professor, Department of Orthodontics, School of Dentistry, University of São Paulo, Araraquara, São Paulo, Brazil.
authors.forename: Maurício Tatsuei
authors.initials: MT
authors.lastname: Sakima
authors.affiliation: Full professor, Graduate Program in Orthodontics, School of Health and Biosience, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil.
authors.forename: Elisa Souza
authors.initials: ES
authors.lastname: Camargo
authors.affiliation: Full professor, Graduate Program in Orthodontics, School of Health and Biosience, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil.
authors.forename: Odilon
authors.initials: O
authors.lastname: Guariza-Filho
authors.affiliation: Professor, Graduate Program in Orthodontics, School of Health and Biosience, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil, postdoctoral fellow, Center for Advanced Dental Education, Saint Louis University, St Louis, Mo. Electronic address: tanakaom@gmail.com.
authors.forename: Orlando Motohiro
authors.initials: OM
authors.lastname: Tanaka
mesh_terms: D001696:Biomechanical Phenomena; D001860:Bone Plates; D016723:Bone Remodeling / Q000502:physiology; D001862:Bone Resorption / Q000503:physiopathology; D003198:Computer Simulation; D020342:Finite Element Analysis; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008334:Mandible / Q000502:physiology*; D008904:Miniaturization; D008954:Models, Biological; D008963:Molar / Q000473:pathology; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D013314:Stress, Mechanical; D013499:Surface Properties; D014057:Tomography, X-Ray Computed / Q000379:methods; D014087:Tooth Movement Techniques / Q000295:instrumentation*