title: Local osteoprotegerin gene transfer inhibits relapse of orthodontic tooth movement.
abstract: BACKGROUND
  In orthodontic treatment, teeth can relapse after tooth movement without retention. The aim of this study was to evaluate the inhibition effects of local osteoprotegerin (OPG) gene transfer on orthodontic relapse.
  
  
  METHODS
  Eighteen male Wistar rats were divided into 3 groups. The maxillary right first molars of all animals were subjected to orthodontic force and moved mesially. Three weeks later, the force was removed, and the teeth relapsed. During the 2-week relapse period, the 3 groups of rats received local OPG gene transfer (experimental group), mock vector transfer (mock group), and no injections (control group). Tooth movement and relapse were measured by using palatal superimpositions of 3-dimensional digital models. Histomorphometric analysis was used to quantify osteoclasts, and microcomputed tomography analysis was done to quantify the alveolar bone and the tibia.
  
  
  RESULTS
  Relapse was significantly inhibited and the number of osteoclasts was reduced in the experimental group. On the other hand, bone mineral density and bone volume fraction of alveolar bone were significantly increased. Bone mineral density and bone volume fraction of the tibia showed no significant difference between the groups.
  
  
  CONCLUSIONS
  Local OPG gene transfer to periodontal tissues could inhibit relapse after orthodontic tooth movement, through the inhibition of osteoclastogenesis.
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: Ningning
authors.initials: N
authors.lastname: Zhao
authors.forename: Jiuxiang
authors.initials: J
authors.lastname: Lin
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kanzaki
authors.forename: Juhua
authors.initials: J
authors.lastname: Ni
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Chen
authors.forename: Wei
authors.initials: W
authors.lastname: Liang
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000818:Animals; D015519:Bone Density / Q000235:genetics; D016723:Bone Remodeling / Q000235:genetics*; D003799:Dental Stress Analysis; D021621:Imaging, Three-Dimensional; D008297:Male; D008437:Maxilla; D010010:Osteoclasts / Q000502:physiology; D053244:Osteoprotegerin / Q000235:genetics* / Q000502:physiology*; D053245:RANK Ligand / Q000037:antagonists & inhibitors; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000037:antagonists & inhibitors; D055502:Secondary Prevention; D014087:Tooth Movement Techniques; D014162:Transfection / Q000379:methods; D055114:X-Ray Microtomography
chemical_list: D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B