Mechanical Analysis of Orthodontic Wires

Orthodontic tooth movement is a physiologic response to externally applied forces; the motive forces are primarily mechanical. The optimal application of orthodontic force enables maximum movement of teeth with minimal irreversible damage of the periodontal ligament (PDL), alveolar bone, and teeth. Since arch wires are the main force system in orthodontics, it is important in clinical practice that they deliver appropriate, predictable and repeatable forces during treatment. These specialized wires even promise shape memory properties and the possibility of super elastic behavior, which significantly impacts clinical practices. Since, standard stainless steel and titanium arch wires are still the materials of choice in many stages of treatment. They provide an attractive combination of stiffness, resilience and formability. However, clinical practitioners have commented on the variability of arch wire behavior for years. Inconsistent arch wire properties can contribute to unpredictable treatment duration and results. This paper examines the mechanical and physical characteristics of stainless steel and titanium wires to quantify their variability in engineering terms. From the results for both types of wires, the testing method provides the information required by designers wishing to improve the arch wire properties and provide valuable information to clinicians for their practice.