Surface and mechanical properties of different coated orthodontic archwires

Objectives: The objective of this study was to evaluate the mechanical properties and surface characteristics of coated superelastic Ni-Ti archwires of three companies with different coatings before and after clinical use. Materials and Methods: Coated 0.016 inch mandibular archwires of three different companies with different coatings (G & H - epoxy coated on all sides, Rocky Mountain Orthodontics (RMO) - Teflon coated on labial surface, and American Orthodontics (AO) - Teflon coated on all sides) were used in this study. Twenty wires from each company, 10 as received and 10 retrieved from patients after 4 weeks of clinical use, were tested for load deflection and surface roughness. An independent sample t-test was done to compare surface roughness and load-deflection characteristics and one-way ANOVA analysis to compare between groups. Results: Both retrieved and as-received G & H wires showed less force levels during loading and unloading compared to RMO and AO wires (P < 0.05). In both test and control groups, G & H wires produced slightly higher surface roughness values compared to AO and RMO. In all the three company wires, roughness values increased significantly before and after clinical use. Conclusion: Retrieved coated archwires of all the three companies produced lower loading and unloading force values compared to as-received coated archwires. Surface roughness of coated archwires increased after use.