Intrusion Arches in Orthodontics

Not all patients with deep overbite should be treated with the same mechanics. Some patients require intrusion of the anterior teeth, while others require primarily extrusion. This article has discussed the principles of incisor and canine intrusion and has demonstrated the use of intrusion springs that are capable of intruding incisors with minimal side effects on the posterior teeth. Six principles must be considered in incisor or canine intrusion: the use of optimal magnitudes of force and the delivery of this force constantly with low-loaddeflection springs; the use of a single point contact in the anterior region; the careful selection of the point of force application with respect to the center of resistance of the teeth to be intruded; selective intrusion based on anterior tooth geometry; control over the reactive units by formation of a posterior anchorage unit; and inhibition of eruption of the posterior teeth and avoidance of undesirable eruptive mechanics.