Orthotown January/February 2018 - 26

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I assume this is the single vector. It looks like the power chain is rotating the UR2 unfavorably,
with no control by the archwire. I would expect mesial tipping of UR2 also. At some point an
archwire (NiTi?) would need to go into the bracket of the UR2 to correct the rotations and
tipping. At what stage do you do this, and would this still be a bit problematic for the root of the
UR2 if the UR3 is still impacted? ■
12/8/2017

Fenrisúlfr
Member Since: 02/25/09
Post: 12 of 24

Sorry. Should have been clearer. The goal was to move the UR2 facially and out of crossbite
with a single force (no couple) so the wire was not in the slot. Once it was out of crossbite and
the 3s had cleared the apex of the 2s, the wire can engage the slot to correct the first and second
order issues. ■

12/8/2017

str8nerinva
Member Since: 03/12/08
Posts: 13 and 14 of 24

I agree with UCLA and Fen that extraction of U5s is indicated; 10+mm of crowding is a
boatload. Extracting U5s and using reciprocal open coil between U4s and U2s would develop
space for U3s and improve the angulation of the upper incisors, but this would also increase
overjet. I can understand the thought of extracting L5s with the moderate crowding present.
My concern is while the molar relationships are not Class II (end-on right, Class I left), this
patient is a skeletal Class II pattern. Unless there were significant Class II elastics and/or Forsus
to manage AP dental relationships, this case would likely finish out Class II end-on at best, with
some overjet. With extraction of L5s, the lower incisors would be retracted some-not nearly as
much as with extracting L4s. The increased labial angulation of the upper incisors would add
to the excess overjet.
Treating lower arch non-extraction will be a stability issue with the arch development needed
to address the moderate crowding. This could be mitigated to a degree with IPR. I have blown out
lower arches more than this one as an accommodation to patients not agreeing to surgery. One
has to pick the problem one wants to live with. It is likely necessary to accept some compromises
somewhere in this case. Just pondering the pluses and minuses of the different options.
Fen, thanks for the clarification. You describe correcting a crossbite of UR2 with single-vector
traction that tips the crown of UR2 labially. The root must tip lingually. This would make a lot
of sense if the UR3 is labial over the root of UR2. But if UR3 is palatally impacted, as in my
case particularly on the right side, wouldn't this tend to move the root of UR2 into the crown of
UR3, causing potential damage to root of UR2?
But you have to start somewhere to get room for the U3s. Unless, as I mentioned previously,
the U3s are exposed early and teased posteriorly away from the roots of U2. Then the U2 could
be moved with little concern. Thoughts? ■
12/8/2017

Fenrisúlfr
Member Since: 02/25/09
Posts: 15 and 16 of 24

I really don't think that will be an issue due to the fact that there is a lot of growth remaining
and at least some of that will be differential growth, which will certainly help in resolution of the
excessive overjet. Non-extraction on the lower will present stability issues, but more importantly,
the prospect of running out of OJ. The ceph is not in NHP. Correcting it to NHP reveals a Class I
skeletal pattern with a well-positioned maxilla and mandible, and severely retroclined upper

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