Mechanical Properties of Coated Aesthetic Superelastic Archwires

Methods: Four types of orthodontic archwires were investigated. Two superelastic NiTi and two coated Ultraaesthetic^® archwires, (.016 inch and .018X.025 inch) for both types, manufactured by G&H^® Wire Company (G&H^®, Greenwood, IN, USA). Conventional Orthos^® and Damon 2^® self-ligating brackets (Ormco,Orange,CA,USA) were used for each wire. All specimens were tested in a Zwick/Roell Z020 in a three point bending test at a speed of 1mm/min and deflected to 2 and 4 mm distances. The loading and unloading forces generated were recorded and load deflection curves plotted.

Results: The aesthetic wires produced statistically significantly lower forces in loading and unloading for all combinations when compared with the superelastic NiTi wires (p<0.05). For NiTi wires loading values were ranging from 252 g to 1202 g whilst the respective values for aesthetic wires were 192 g to 772 g. For all wires an increase in size resulted in an increase in force. .016 inch aesthetic wires showed permanent deflection when loaded for 4 mm using conventional brackets ligated with elastomeric modules but not with self-ligating brackets. Conclusions: Aesthetic archwires produced lower force values in loading and unloading compared with uncoated wires of same nominal size. A self-ligating bracket system improved the efficiency of aesthetic wires especially when deflected for large distances, as in cases of severe crowding.