title: Quantification of the force systems delivered by transpalatal arches activated in the six Burstone geometries.
abstract: OBJECTIVE
  To evaluate the force systems produced by transpalatal arches (TPAs) activated according to the six classes of geometries described by Burstone and Koenig.
  
  
  METHODS
  Sixty appliances were tested for first-order activations using a mechanical force testing system. The TPAs were first checked for passivity in sagittal, transverse, and vertical planes at the measuring machine. Then 10 appliances per group were activated using a millimeter template to obtain the six classes of geometries, and the activated appliances were inserted into lingual tubes of the Force System Identification machine that recorded the deactivation forces and moments delivered by both terminal ends of the TPAs.
  
  
  RESULTS
  The overall force system with the actual values of forces and moments recorded by each type of activation was illustrated and compared with the mathematical model reported by Burstone and Koenig. Although a great consistency of the direction of forces and moments were observed, the theoretically feasible force systems could not be fully accomplished by the TPA activated for the six classes of geometries.
  
  
  CONCLUSIONS
  The first-order activations of the TPA can deliver predictable force systems in respect to the direction of forces and moments attainable, but some unexpected forces and moments are also produced. Careful clinical monitoring is, therefore, strongly recommended when using this statically indeterminate system.
authors.forename: Maurício Tatsuei
authors.initials: MT
authors.lastname: Sakima
authors.forename: Michel
authors.initials: M
authors.lastname: Dalstra
authors.forename: Angelo Vicentini
authors.initials: AV
authors.lastname: Loiola
authors.forename: Gustavo Hauber
authors.initials: GH
authors.lastname: Gameiro
mesh_terms: D000202:Activator Appliances; D003799:Dental Stress Analysis; D006801:Humans; D016382:Orthodontic Appliance Design; D009969:Orthodontic Wires; D013193:Stainless Steel; D014087:Tooth Movement Techniques / Q000295:instrumentation*
chemical_list: D013193:Stainless Steel
keywords: Orthodontic appliances; Transpalatal bar