title: Effects of retraction force and anchorage reinforcement on occlusal force: a model study.
abstract: OBJECTIVE
  The aim of this study was to investigate the effects of retraction force and anchorage reinforcement with orthodontic mini implants on occlusal force.
  
  
  METHODS
  A strain gauge was attached to the palatal surface of the maxillary right first molar on an en masse retraction model.
  
  
  RESULTS
  Occlusal forces were measured from this model, according to different retraction forces that were generated by elastic chain, under varied compressive forces (simulating masticatory forces). This retraction experiment was then performed again, after using anchorage reinforcement with an orthodontic mini implant. Occlusal force decreased as retraction force increased. The decrease showed a significant difference above 150g of retraction force (P < 0.05) and was more definite under compressive force higher than 150 N (P < 0.001). After anchorage reinforcement with the orthodontic mini implant, however, occlusal force did not significantly decrease with increasing retraction force. Significant differences in occlusal force were noted between the conditions with and without anchorage reinforcement when the applied retraction force was greater than 200g.
  
  
  CONCLUSIONS
  Occlusal force tends to decrease during retraction, and this decrease can be prevented by anchorage reinforcement with orthodontic mini implants.
  
  
  CONCLUSIONS
  Further investigation on the actual masticatory process in humans is required for more clear clinical implication.
authors.affiliation: *Division of Orthodontics, Department of Dentistry, Ewha Womans University Medical Center and Divisions of.
authors.forename: MoonHee
authors.initials: M
authors.lastname: Kim
authors.affiliation: **Orthodontics and.
authors.forename: Kyung-sim
authors.initials: KS
authors.lastname: Seol
authors.affiliation: **Orthodontics and.
authors.forename: Yoonjung
authors.initials: Y
authors.lastname: Lee
authors.affiliation: ***Prosthodontics, Department of Dentistry, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: Jiman
authors.initials: J
authors.lastname: Park
authors.affiliation: **Orthodontics and.
authors.forename: Minji
authors.initials: M
authors.lastname: Kim
authors.affiliation: **Orthodontics and yschun@ewha.ac.kr.
authors.forename: Youn-Sic
authors.initials: YS
authors.lastname: Chun
mesh_terms: D001732:Bite Force; D015921:Dental Implants; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D008437:Maxilla / Q000473:pathology; D008904:Miniaturization; D003765:Models, Dental; D008963:Molar / Q000473:pathology; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation / Q000379:methods*; D016382:Orthodontic Appliance Design; D019516:Orthodontic Space Closure / Q000295:instrumentation / Q000379:methods*
chemical_list: D015921:Dental Implants