title: Saturation of the biological response to orthodontic forces and its effect on the rate of tooth movement.
abstract: OBJECTIVE
  Investigate the expression and activity of inflammatory markers in response to different magnitudes of orthodontic forces and correlate this response with other molecular and cellular events during orthodontic tooth movement.
  
  
  METHODS
  CTOR Laboratory; 245 Sprague Dawley male rats.
  
  
  METHODS
  Control, sham, and 5 different experimental groups received different magnitudes of force on the right maxillary first molar using a coil spring. In the sham group, the spring was not activated. Control group did not receive any appliance. At days 1, 3, 7, 14, and 28, the maxillae were collected for RNA and protein analysis, immunohistochemistry, and micro-CT.
  
  
  RESULTS
  There was a linear relation between the force and the level of cytokine expression at lower magnitudes of force. Higher magnitudes of force did not increase the expression of cytokines. Activity of CCL2, CCL5, IL-1, TNF-α, RANKL, and number of osteoclasts reached a saturation point in response to higher magnitudes of force, with unchanged rate of tooth movement.
  
  
  CONCLUSIONS
  After a certain magnitude of force, there is a saturation in the biological response, and higher forces do not increase inflammatory markers, osteoclasts, nor the amount of tooth movement. Therefore, higher forces to accelerate the rate of tooth movement are not justified.
authors: Consortium for Translational Orthodontic Research, New York University College of Dentistry, New York, NY, USA; Department of Orthodontics, New York University College of Dentistry, New York, NY, USA; Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA.
authors: M
authors: M
authors: Alikhani
authors: B
authors: B
authors: Alyami
authors: I S
authors: IS
authors: Lee
authors: S
authors: S
authors: Almoammar
authors: T
authors: T
authors: Vongthongleur
authors: M
authors: M
authors: Alikhani
authors: S
authors: S
authors: Alansari
authors: C
authors: C
authors: Sangsuwon
authors: M Y
authors: MY
authors: Chou
authors: E
authors: E
authors: Khoo
authors: A
authors: A
authors: Boskey
authors: C C
authors: CC
authors: Teixeira
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D018932:Chemokine CCL2 / Q000032:analysis; D018946:Chemokine CCL5 / Q000032:analysis; D016207:Cytokines / Q000032:analysis*; D007150:Immunohistochemistry; D018836:Inflammation Mediators / Q000032:analysis; D007375:Interleukin-1 / Q000032:analysis; D008297:Male; D008437:Maxilla / Q000276:immunology / Q000473:pathology; D008963:Molar / Q000276:immunology / Q000473:pathology; D009969:Orthodontic Wires; D010010:Osteoclasts / Q000473:pathology; D011506:Proteins / Q000032:analysis; D053245:RANK Ligand / Q000032:analysis; D012313:RNA / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical; D014087:Tooth Movement Techniques / Q000295:instrumentation*; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: C491766:Ccl2 protein, rat; D018932:Chemokine CCL2; D018946:Chemokine CCL5; D016207:Cytokines; D018836:Inflammation Mediators; D007375:Interleukin-1; D011506:Proteins; D053245:RANK Ligand; D014409:Tumor Necrosis Factor-alpha; D012313:RNA
keywords: cytokines; force; gene expression; orthodontics; osteoclasts; tooth movement