The surface defects and roughness of orthodontic Ni–Ti archwires are related to the manufacturing andsurface finishing processes employed. On grouping archwires according to their surface characteristicsinstead the commercial brand, comparisons can be made of the influence of different surface finishings uponthe corrosion resistance of Ni–Ti archwires. This novel approach shows that orthodontic Ni–Ti archwires canbe grouped into 5 surface patterns according to a dominant surface defect. Each pattern is derived from agiven manufacturing process and shows a different response to corrosion in several media.