Phase I Crozats are used primarily for the arch development phase of a comprehensive treatment plan -- a plan that includes straight wire fixed appliances for the final alignment of individual teeth. Shown here, the upper appliance has Class II hooks added, while the auxiliary springs on the lower appliance are soldered to the body wire (rather than the mesial extension). Some prefer this for ease of adjustment. Note: The lower lap springs only effect the incisors while individual push springs are placed on the cuspids. This ensures more individual tooth movement.