Concept and development of a measuring system for in vivo recording of orthodontically applied forces and torques in the multiband technique. Part I.

The cause of tooth movement with a multiband or multibracket appliance is the force system in the bracket, which is generated by an archwire and transmitted by a bracket to the respective tooth. Continuous arch wires are, from the biomechanical point of view, a statically multiply undetermined system. Quantitative determination of the forces and torques acting at the individual teeth, and thus observance of a non-critical level of applied forces, is therefore extremely problematic in practice, the force is applied by the orthodontist more or less "intuitively" on the basis of recommendations evolved in theory and in vitro. The measuring technique presented in this paper is designed to permit these force systems to be recorded in vivo for the first time, allowing account to be taken of the individual situation "tooth-periodontium-bone". Evolvement of an appropriate measuring principle was followed by development of the individual components of the measuring system. The results of the subsequent initial in vitro test series offer the prospect of successful clinical application.