An appliance used in orthodontic treatment includes a retaining groove that is located directly adjacent a base of the appliance. The retaining groove is useful for keeping a wire segment or other item in place and in contact with a body of the appliance so that the item does not detach from the appliance during the course of treatment. The retaining groove is particularly useful for keeping tieback loops and other items having a thread-like configuration in a captive, compact and snug relationship with the appliance.