Normally, the problem with upper incisors is a lack of torque at the end of treatment. This is due to the play between the archwire and slot. In some prescriptions, an extra-torque series of brackets are available. With the GET prescription, it is preferred to decrease the size of the slot and maintain normal torque values. This has two advantages:
Allows for more predictable expression of torque values
Reduces the need of extra inventory for the orthodontist
The play of a .019″x.025″ wire in a .022″x.028″ slot is 8,7°, which means in real life it is more, taking into consideration side-effects in the production process.
The play of the same .019″x.025″, wire in a .020″x.028″ slot is 2,8°.
We have chosen the original straight wire with 11 degrees mesial tip, to allow for an increased arch length in the upper arch and 0 degrees torque to avoid too steep of canine guidance, which can lead to an immediate increase of Bennett movement.
We have chosen to add very little extra lingual crown torque (-10 degrees). We do not want to have upper premolars with a marked lingual inclination as an “open” position is better from a gnathological standpoint. However, 3 degrees extra negative torque are needed to compensate for side-effects of levelling, which tends to flare out premolars.
We have reduced the value of the distal rotation to the original straight wire value (U6) and even less (U7) than that. This is to avoid that the disto-vestibular cusp of the upper second molar to project lingually, which is a major source of pre-contacts. We have also chosen to increase the lingual crown torque to reduce the tendency of pre-contacts due to hanging palatal cusps of upper molars (especially second molars).