Mechanical and Surface Properties of Initial and Working Aesthetic Orthodontic Archwires

The study aimed to compare mechanical properties and surface characteristics of initial and working aesthetic archwires with their conventional counterparts. High Aesthetic Sentalloy (full rhodium coating nickel-titanium; Dentsply GAC) represented the initial aesthetic archwires; and FLI TRU-CHROME (labial PTFE-coated stainless steel; RMO) as the working aesthetic archwires; together with their conventional counterparts were analysed. A three point bending test was conducted using a universal testing machine (AGS-X SERIES, Shimadzu, Japan) to determine the load-deflection characteristics of archwires. Surface hardness was evaluated by Vickers microhardness test (HMV-FA, Shimadzu, Japan). A 3D Optical Surface Texture Analyzer (ALICONA, InfiniteFocus Real3D, Belgium) and a Field Emission Scanning Electron Microscope (FESEM, FEI Quanta 250, USA) were used for surface evaluation. Results showed that loaddeflection characteristics of High Aesthetic Sentalloy archwires did not differ from its control, whereas FLI TRU-CHROME archwires exhibited higher loading and unloading forces than its counterpart. No statistically significant difference in surface hardness was found between FLI TRU-CHROME and its control archwires. The coating surfaces of both aesthetic archwires were rougher than the non-coated conventional archwires, with similar roughness between non-coated surface of FLI TRU-CHROME archwires and its counterpart. FLI TRU-CHROME archwires showed a distinct coating thickness but coating layer is undefined in High Aesthetic Sentalloy archwires. In conclusion, the aesthetic rhodium coated nickel titanium archwire has similar mechanical properties as control nickel titanium archwire without being adversely affected by the addition of the coating layer. The aesthetic coated PTFE stainless steel archwire has higher load response which could be an advantage as rigid wire in working stage of orthodontic treatment. Based on their performance, their use could be recommended in cases where aesthetic aspect is crucial and where the friction aspect is not critical as their surface roughness values increased.