The lower posterior segments frequently erupt with lingual inclination of the crowns and the upper posterior segments erupt with buccal inclination of the crowns.  This will result in over-erupted “hanging” palatal cusps and occlusal interferences during lateral movements.  One of the requirements of the American Board is to level the Curve of Wilson to eliminate these interferences.  The Avex appliance is designed with progressive buccal crown torque (uprighting torque) in the lower posterior segment and progressive buccal root torque in the upper posterior segment to allow for leveling the Curve …