Contemporary esthetic nickel-titanium wires: do they deliver the same forces?

To test for differences in loading and unloading forces delivered by six coated nickel-titanium wires and their noncoated equivalents.

From six commercial companies, 0.016-inch diameter round and 0.016 × 0.022-inch rectangular cross-section nickel-titanium wires were procured "as is": Rocky Mountain Orthodontics (Denver, Colo), TP Orthodontics (La Porte, Ind), American Orthodontics (AO; Sheboygan, Wis), G&H (Franklin, Ind), Opal Orthodontics (South Jordan, Utah), and Forestadent USA (St Louis, Mo) (round only). The wires were evaluated using a three-point bending test based on the method in ISO Standard 15841.

No statistically significant differences (P > .05) in force values were found between coated and noncoated wires, listed by deflection in three-point bending, for these specific groups: 1 mm, TP round; 2 mm, TP round and G&H rectangular; 3 mm, G&H round and G&H rectangular; 2.5 mm,TP round and G&H rectangular; 1.5 mm, TP round, G&H round, G&H rectangular, and AO rectangular; and 0.5 mm, AO rectangular and G&H round.

Some manufacturers market esthetic wires delivering forces similar to the equivalent noncoated wires, when tested according to a standard three-point bend method.