When an uprighting spring coil is used to upright a mesially tipped mandibular second molar (#18), what is the typical biomechanical result?

An uprighting spring applies a tipping force to upright a mesially tilted molar. Because the force is applied at the crown level without controlling the root apex separately, the result is a simple tipping movement: the crown tips distally (toward the desired upright position) while the root tends to move mesially. Additionally, since the point of force application (the bracket/band) is occlusal to the center of resistance of the tooth, the moment created tends to extrude the tooth. To achieve true bodily uprighting or controlled root movement with minimal extrusion, additional mechanics (intrusive forces, tip-back bends, or skeletal anchorage) are required.