It is not unusual to see cuspids blocked out of the arch form. In order to properly select an appliance to treat this problem, it is imperative that the practitioner understand the underlying cause of malocclusion. In this example, arch length is deficient because the patient lost her primary molars early. The first molars and bicuspids erupted mesially, and the arch is also slightly underdeveloped laterally due to a finger habit. To make room for the cuspids, both arch length and width need to be regained. Specifically, arch length needs to be gained by distalizing the posterior segments using this Three Screw Sagittal and its third (midline) expansion screw. As a general rule, the midline screw is activated first. Engaging it will provide the additional arch width desired and create enough lateral force to set up the anchorage needed to move the posterior segments distally. Keep in mind that second molars are not present. Once second molars have erupted, distalization of the posterior segments becomes very difficult with this design. Note: Many practitioners prefer adding cuspid retraction springs to this design so they can guide the cuspids into position as the space for them is made available.