Material and Methods: 34 NiTi archwires from five different manufacturers (Dentaurum, Forestadent, Ormco, Ortho Organizers, 3M/Unitek) were evaluated for their mechanical properties in a three point bending test according to ISO norms on an Instron 4444. 6 archwires each were tested at 37°C. Deactivation curves were evaluated for the characteristic force level at 1.5mm deflection and the force variance over the plateau region. DSC was evaluated for A_f temperatures.

Results: Overall mean forces ranged from 0.48N (Copper NiTi 40°C, .016x.022”) to 6.9N (Nitinol Classic, .018x.025”) with ratios of variance ranging from 0.4 (Copper NiTi 40°C, .016x.022”) to 6.7 (Titanol Superelastic, .016”) and A_f temperatures from 10.9°C to 60.1°C. Three point bending yielded reliable results with very low standard deviations. Out of a total of 560 comparisons 80 (xy%) were not significant. 24 of the non-significant comparisons were found in between archwires of the dimension .016” to large rectangular archwires (.017x.025” - .019x.025”). Conclusion: The proposed evaluation method for NiTi archwires turned out to be a useful routine. The forces of the NiTi archwires ranged from 0.5 to 7N and cross-sectional dimension had a minor influence on force levels than in stainless steel wires. DSC measurements roughly correlated with the force levels.