Testing a computer-assisted bending machine for the fabrication of loops

The use of suitable orthodontic devices producing desired defined force sys tems is of importance for successful orthodontic treatment. Bending loops c an be difficult and time-consuming. Computerised fabrication would enable v ery precise reproduction of individual loops. A bending machine has now bee n developed within the framework of a computer-assisted treatment concept. In this study, a prototype machine was used to fabricate U-, T- and delta l oops made of stainless steel, cobalt chromium and titanium molybdenum wire. The various geometric parameters of each loop were measured to determine h ow precisely they had been produced. Furthermore, the force system of each loop were experimentally investigated during simulated activation in an ort hodontic measurement and simulation system. The results indicate that the g eometric parameters had an average error of 2.8 degrees for angles and 0.9 mm for lengths. Owing to the fabrication errors, loops of the same type pro duced different force systems. Overall, the new bending machine can fabrica te different types of loop, but the requirements of very precise fabricatio n are currently not met. This fact, together with further limitations in te rms of configuration, means that the machine cannot be used routinely at pr esent. However, the machine can nevertheless be considered a good basis for further development.