Intrusion, in orthodontic history, was initially defined as problematic in early 1900s and was known to cause periodontal effects such as root resorption and recession.
True intrusion can be done with methods such as Burstonian segmental arch mechanics or the use of TADs anteriorly.
[3] This type of intrusion consists of extrusion of posterior teeth to correct the deep bite.
Robert M. Ricketts developed the Utility arch in 1950s[6] and it is considered to be an integral part of the Bioprogressive Therapy in Orthodontics.
His utility arch is a continuous wire that is engaged in a posterior 1st permanent molar tooth and front four incisors.
Activation of the intrusion arch is done by placing occlusally pointed gable bend at the posterior portion of the vestibular segment.
The anterior segment has a vertical bend distal to the lateral incisors with a posterior extension to which the intrusion cantilever springs are engaged bilaterally.
The retraction can be performed by using either an elastomeric chain or Niti Coil Spring which connects the distal extension of the anterior segment and the hook on the posterior molar tube.
Activation of the cantilever is done by making a bend mesial to the molar tube which allows the intrusion arch to be in vestibule when it's passive.
[8] In these types of cases, a patient has reduced anterior lower facial height and they have a skeletal deep bite tendency.
It is essential in these type of patients, to increase the vertical height of the face and one of the most common ways this can be performed is through relative intrusion.
An adolescence has an inter-maxillary growth space which allows the posterior molar eruption without any relapse in the later age when relative intrusion is performed in their orthodontic treatment.
However, if relative intrusion is performed in adults who have a deep bite tendency with short anterior lower facial height, there is a higher chance of relapse of this movement.
Thus it is important to use a wire that has a low load-deflection rate which gives a constant force of intrusion on the teeth and prevents the side-effect.
Another way to control the side-effect is to do intrusion-retraction which simultaneously achieves space closure but also prevents the dumping of the incisors.