Quantification of three-dimensional orthodontic force systems of T-loop archwires

Abstract

Objective: To demonstrate the three-dimensional (3D) orthodontic force systems of three commercial closing T-loop archwires using a new method and to quantify the force systems of the T-loop archwires. Materials and Methods: An orthodontic force tester (OFT) and a custom-made dentoform were developed to measure force systems. The system simulated the clinical environment for an orthodontic patient requiring space closure, which included measurement of three force components along, and three moment components about, three clinically defined axes on two target teeth. The archwires were attached to the dentoform and were activated following a standard clinical procedure. The resulting force system was measured using the OFT. Results: The force systems of the T-loops on the teeth were 3D. Activation in one direction resulted in force and moment components in other directions (side effects). The six force and moment components as well as the moment-to-force ratios in the clinically defined coordinate system were quantified. Conclusions: The commercial archwires do not provide force systems for pure translation. Quantification of the force system is critical for the selection and design of optimal orthodontic appliances.