Quantification of the force systems delivered by transpalatal arches activated in the six Burstone geometries.
OBJECTIVE
To evaluate the force systems produced by transpalatal arches (TPAs) activated according to the six classes of geometries described by Burstone and Koenig.


MATERIALS AND 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.


CONCLUSION
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.
['Sakima|Maurício Tatsuei|MT|', 'Dalstra|Michel|M|', 'Loiola|Angelo Vicentini|AV|', 'Gameiro|Gustavo Hauber|GH|']
D000202:Activator Appliances D003799:Dental Stress Analysis D006801:Humans D016382:Orthodontic Appliance Design D009969:Orthodontic Wires D013193:Stainless Steel D014087:Tooth Movement Techniques
Orthodontic appliances Transpalatal bar