title: Effects of different types of tooth movement and force magnitudes on the amount of tooth movement and root resorption in rats.
abstract: OBJECTIVE
  To investigate differences in the amount of tooth movement and root resorption that occurred after tipping and bodily movement of the maxillary first molar in rats.
  
  
  METHODS
  Ten-week-old female Wistar rats were divided into two groups according to type of tooth movement and subdivided into four subgroups according to the magnitude of applied force. Nickel-titanium closed-coil springs exerting forces of 10, 25, 50, or 100 g were applied to the maxillary left first molars to induce mesial tooth movement. We designed a novel orthodontic appliance for bodily tooth movement. Tooth movement distance and root resorption were measured using microcomputed tomography and scanning electron and scanning laser microscopy.
  
  
  RESULTS
  The amount of tooth movement in the bodily tooth movement group was less than half that in the tipping tooth movement group. The greatest amount of tooth movement occurred in the 10-g tipping and 50-g bodily tooth movement subgroups, and the amount of tooth movement decreased with the application of an excessive magnitude of force. Conversely, root resorption increased when the heavier orthodontic force was applied in both groups. Root resorption in the tipping tooth movement group was approximately twice that in the bodily tooth movement group.
  
  
  CONCLUSIONS
  Root resorption in the tipping tooth movement group was more pronounced than that in the bodily tooth movement group. Although the amount of tooth movement decreased when extremely heavy forces were applied, root resorption increased in both the tipping and bodily tooth movement groups in rats.
authors.affiliation: a  Postgraduate Student, Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Takako
authors.initials: T
authors.lastname: Nakano
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Hotokezaka
authors.forename: Megumi
authors.initials: M
authors.lastname: Hashimoto
authors.forename: Irin
authors.initials: I
authors.lastname: Sirisoontorn
authors.forename: Kotaro
authors.initials: K
authors.lastname: Arita
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kurohama
authors.forename: M Ali
authors.initials: MA
authors.lastname: Darendeliler
authors.forename: Noriaki
authors.initials: N
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D003722:Dental Alloys / Q000737:chemistry; D005260:Female; D021621:Imaging, Three-Dimensional / Q000379:methods; D008437:Maxilla; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D008963:Molar / Q000473:pathology*; D009532:Nickel / Q000737:chemistry; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation; D016382:Orthodontic Appliance Design; D009969:Orthodontic Wires; D051381:Rats; D017208:Rats, Wistar; D012391:Root Resorption / Q000209:etiology*; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry; D019228:Tooth Crown / Q000473:pathology; D014087:Tooth Movement Techniques / Q000009:adverse effects / Q000145:classification*; D014092:Tooth Root / Q000473:pathology; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: Root resorption; Tooth movement; Type of tooth movement
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