title: Ideal orthodontic alignment load relationships based on periodontal ligament stress.
abstract: OBJECTIVE
  To test the hypothesis that periodontal ligament (PDL) stress relationships that yield resistance numbers representing load proportions between different teeth depend on alignment load type.
  
  
  METHODS
  Finite element models of all teeth, except the third molars, were produced. Four different types of loads were applied, and the third principal stresses of different teeth in standardized areas of most compression were calculated. Based on these results, resistance numbers, representing the load proportions for each tooth derived from PDL stress, were determined.
  
  
  RESULTS
  The third principal stress values for typical alignment loads in the areas of most stress were very different for different load types for each tooth. Differences in resistance numbers between teeth also varied with different loads.
  
  
  CONCLUSIONS
  Resistance numbers, that is, load proportion numbers between teeth to achieve similar stress at the compressive PDL zone, depend on the type of applied load.
authors: Loma Linda University School of Dentistry, Loma Linda, CA, USA.
authors: R F
authors: RF
authors: Viecilli
authors: C J
authors: CJ
authors: Burstone
mesh_terms: D001641:Bicuspid / Q000502:physiology; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D003481:Cuspid / Q000502:physiology; D020342:Finite Element Analysis; D006801:Humans; D007180:Incisor / Q000502:physiology; D008954:Models, Biological; D008963:Molar / Q000502:physiology; D009969:Orthodontic Wires; D010513:Periodontal Ligament / Q000502:physiology*; D013314:Stress, Mechanical; D014087:Tooth Movement Techniques / Q000295:instrumentation / Q000379:methods*; D014092:Tooth Root / Q000502:physiology
keywords: anchorage; finite element analysis; orthodontics; periodontal ligament; stress