title: Force systems in the initial phase of orthodontic treatment -- a comparison of different leveling arch wires.
abstract: OBJECTIVE
  The determination of orthodontically-effective forces and moments places great demands on the technical equipment. Many patients report severe pain after fixed appliance insertion. Since it is assumed that pain from orthodontic appliances is associated with the force and moment levels applied to the teeth and since the occurrence of root resorption is a common therapeutic side effect, it would seem important to know the actual magnitudes of the components of the active orthodontic force systems. The aim of the present study was therefore to measure initial force systems produced by different leveling arch-wires in a complete multi-bracket appliance and to assess whether force and moment levels can be regarded as biologically acceptable or not.
  
  
  METHODS
  The actual bracket position in 42 patients was transferred onto a measurement model. Forces and moments produced by a super-elastic nickel-titanium (NiTi) archwire, a 6-strand stainless steel archwire, and a 7-strand super-elastic NiTi archwire were determined experimentally on different teeth.
  
  
  RESULTS
  Average forces and moments produced by the super-elastic NiTi arch wires were found to be the highest. In spite if their larger diameter, the stranded arch wires' average force and moment levels were lower, especially that of the stranded super-elastic archwire. Nevertheless, maximum force levels sometimes exceeded recommended values in the literature and must be considered as too high.
  
  
  CONCLUSIONS
  The measured arch wires' initial force systems differed significantly depending on the type of archwire and its material structure. Stranded arch wires produced lower force and moment levels, and we recommend their use in the initial phase of orthodontic treatment.
authors.affiliation: Poliklinik für Kieferorthopädie, Moorenstr. 5, Geb. 18.21, 40225 Düsseldorf, Germany. fuck@uni-duesseldorf.de
authors.forename: Lars-Michael
authors.initials: LM
authors.lastname: Fuck
authors.forename: Dieter
authors.initials: D
authors.lastname: Drescher
mesh_terms: D001732:Bite Force; D019544:Equipment Failure Analysis; D006801:Humans; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013314:Stress, Mechanical