MECHANICAL PERFORMANCE OF DIFFERENT NICKEL-TITANIUM ARCHWIRES USED IN DENTISTRY

The mechanical properties of superelastic (SE) and heat activated (HA) .014 inch NiTi orthodontic wires were evaluated and compared. A total of 132 wires were divided in 22 groups (n=6) according to six commercial brands, two lots from each wire, and SE or HA properties. Three-point bending test were conducted up to 3.1 mm at 36 +/- 1oC. Stress-deflection diagrams were determined and different mechanical properties were compared by analysis of variance and Tukey test (P=.05). HA wires showed a lower load (LMS) unload (UMS) mean stress, total (TR) and potential (PR) resilience than SE wires. However, HA wires demonstrated a higher hysteresis resilience (HR) and mechanical hysteresis (MH) than SE wires. According to comparisons between different lots from the same manufacturer and wire types, four groups matched in LMS, UMS, TR and PR (P>.05). These conclusions could lead clinicians in choosing archwires which exhibit similar performance, however are commercial offered at different costs.