Arch wires come in a variety of preformed sizes and arch forms. Selecting the appropriate type, size and arch form for each patient is a critical step for success when using fixed mechanics. Some of the factors that need to be considered when choosing an arch wire are listed here: 1. Materials: Stainless steel Standard and heat activated nickel titanium (NiTi) 2. Sizes: Range from .014mm to .022mm in round, braided, square and rectangular wire 3. Forms: (with separate wires for the upper and lower arches) Tapered, Square and Ovoid Space Maintainers stocks a complete range of arch wires for all the major techniques currently in use. They can be ordered on a per patient basis. Since new designs and improvements in performance are a common occurrence in these wires, it is usually not desirable to maintain a large inventory in the general practice.