title: Mechanical environment change in root, periodontal ligament, and alveolar bone in response to two canine retraction treatment strategies.
abstract: OBJECTIVE
  To investigate the initial mechanical environment (ME) changes in root surface, periodontal ligament (PDL), and alveolar bone due to two treatment strategies, low or high moment-to-force ratio (M/F).
  
  
  METHODS
  Indiana University-Purdue University Indianapolis. Eighteen patients who underwent maxillary bilateral canine retraction.
  
  
  METHODS
  Finite element models of the maxillary canines from the patients were built based on their cone beam computed tomography scans. For each patient, the canine on one side had a specially designed T-loop spring with the M/F higher than the other side. Four stress invariants (1st principal/dilatational/3rd principal/von Mises stress) in the tissues were calculated. The stresses were compared with the bone mineral density (BMD) changes reported previously for linking the ME change to bone modeling/remodeling activities. The correlation was tested by the mixed-model anova.
  
  
  RESULTS
  The alveolar bone in the direction of tooth movement is primarily in tension, while the PDL is in compression; the stresses in the opposite direction have a reversed pattern. The M/F primarily affects the stress in root. Three stress invariants (1st principal/3rd principal/dilatational stress) in the tooth movement direction have moderate correlations with BMD loss.
  
  
  CONCLUSIONS
  The stress invariants may be used to characterize what the osteocytes sense when ME changes. Their distributions in the tissues are significantly different, meaning the cells experience different stimuli. The higher bone activities along the direction of tooth movement may be related to the initial volumetric increase and decrease in the alveolar bone.
authors: Department of Mechanical Engineering, Indiana University-Purdue University, Indianapolis, IN, USA.
authors: F
authors: F
authors: Jiang
authors: Z
authors: Z
authors: Xia
authors: S
authors: S
authors: Li
authors: G
authors: G
authors: Eckert
authors: J
authors: J
authors: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D000539:Alveolar Process / Q000502:physiology*; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology; D016723:Bone Remodeling / Q000502:physiology; D002648:Child; D054893:Cone-Beam Computed Tomography / Q000379:methods; D003481:Cuspid / Q000473:pathology*; D005260:Female; D020342:Finite Element Analysis; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008437:Maxilla / Q000502:physiology; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D010513:Periodontal Ligament / Q000502:physiology*; D013314:Stress, Mechanical; D014087:Tooth Movement Techniques / Q000295:instrumentation / Q000379:methods*; D014092:Tooth Root / Q000502:physiology*; D055815:Young Adult
keywords: canine retraction; finite element analysis; mechanotransduction