The “W” arch or Porter arch uses a stainless steel wire for expansion. The wire is soldered to bands on the upper first molars. The appliance can be constructed as a fixed removable that slides into sheaths on the upper first molar bands. Unilateral expansion can be achieved with proper activation.
There are two ways to activate the W arch before placing it in the mouth. Ricketts et al. (1979) originally suggested that operators activate the appliance with three-pronged pliers to incorporate expansion and molar-rotating force. Another method proposed by Kholoki (1995) employs an arch form chosen from a pentamorphic chart that serves as a pattern for regulating the W Arch. This appliance should be cleaned every day with toothpaste and a soft toothbrush, morning and night. Encourage the patient to give sufficient time to clean thoroughly around the appliance, gums, teeth, and bands to maintain proper hygiene and prevent inflammation. 3 minutes is recommended.