title: Biomechanics of a Distal Jet appliance. Theoretical considerations and in vitro analysis of force systems.
abstract: OBJECTIVE
  To analyze the forces and moments acting in the first molar region, induced by the Distal Jet appliance for maxillary molar distalization.
  
  
  METHODS
  Over a working section of 3 mm with reactivation of the loaded spring systems, the force systems of three laboratory-fabricated appliances of identical design were analyzed with a 3D metering device.
  
  
  RESULTS
  The force systems registered in vitro exhibited complex biomechanics. Regular reactivation of the loaded coils resulted in consistent distalizing forces and uprighting moments, in forces and moments toward buccal as well as slightly intrusive forces, and mesial-inwardly rotating moments. In the sagittal dimension, the Distal Jet appliance allows almost translatory molar distalization. Accordingly, applying uprighting activation is not necessary for treatment. Because of the application of the force palatal to the center of resistance of the molars, the teeth experience undesired mesial-palatal and distal-facial rotation.
  
  
  CONCLUSIONS
  The Distal Jet appliance allows almost translatory distal molar movement, and uprighting activation is not necessary for treatment. The force applied palatal to the center of resistance of the molars produces an undesired mesial-palatal and distal-facial rotation. Regular intraoral coil spring reactivation is needed.
authors.affiliation: Department of Orthodontics, University of Aachen RWTH, Aachen, Germany. gkinzinger@ukaachen.de
authors.forename: Gero S M
authors.initials: GS
authors.lastname: Kinzinger
authors.forename: Peter R
authors.initials: PR
authors.lastname: Diedrich
mesh_terms: D001696:Biomechanical Phenomena; D003799:Dental Stress Analysis; D006801:Humans; D008644:Mesial Movement of Teeth / Q000209:etiology; D008963:Molar / Q000502:physiology*; D009967:Orthodontic Appliances / Q000009:adverse effects*; D014087:Tooth Movement Techniques / Q000295:instrumentation*