As orthodontist we are sometimes challenged by a quite difficult clinical situation: a mild to severe CLII and no overjet to solve it.
A classic, evergreen, old-school approach could be extraction of upper 4s and lower 5s and a careful management of anchorage. If one does not want to consider extraction, then he should find a way to gain overjet before to start CLII correction.
Would abundant IPR between lower incisors be enough?
And what about coupling the -6° torque on lower incisors and the +17° on upper centrals of MBT prescription? Would the -11° of the Low Torque Damon prescription for lower incisors together with the +22° on upper incisors be enough?
Combining IPR and torque selection seems to be a reasonable approach to gain some overjet. But there may be an even better way, and it’s the one provided by customized brackets (Insignia) + torque compensation for CLII treatment.
When I approached the Insignia system I was told about this feature, but it was really unclear to me how this was implemented into the brackets. As I have an insatiable curiosity I started to write email after email until I got a straight forward answer from the technical department of Ormco.
The answer was pretty exhaustive and I was really satisfied. I was positively impressed as the wire/slot torque play was considered as a factor for adding extra torque, to make it an effective system.
Practically this means that not only the torque is personalized according to the effective needs of that specific case (bracket customization), but also an extra torque is added to compensate the upper incisors retroclination & lower incisors proclination that represent the unavoidable side effects of any CLII mechanics.
How this apply into the mouth? Let’s see it with an interesting clinical case.
This young patient presented to me with a CLII head to head relation on the right side, and tendency to full CLII on the left side (intraoral pictures do not make it that clear, while the setup picture that is coming in a few lines is pretty evident). She hadn’t any other alignment problem, making of her that sort of case where all should be perfect in the end as she doesn’t have any other problem rather than a CLII.
The big problem was the 2mm of overjet that did not allow any true CLII correction!
My clinical goal is not only dental, I wish I could also improve her facial balance through enhancing chin projection as she’s still growing.
I thus decided to treat her with customized braces + torque compensation and a Forsus (my favorite CLII corrector together with the Motion appliance). The stiffer customized archwire that I selected was a couple of .019x.025SS. Thus the torque added to the upper incisors was +11.4° (and -11.4° were subtracted to the lower) with respect to the final approved position of my setup.
I spent the first 7 months into leveling and alignement to get at a standard pace to the .019x.025SS wires.
While on the .019x.025SS since one month I installed the Forsus-on-the-wire configuration with a 22 pushrod (I reinforced upper 6th and lower 4th with an extra layer of flowable composite to prevent debonding through the forsus phase).
After one month I switched from the 22 to the 25 pushrod, even if the correction seemed already enough, as I always like to achieve an overcorrection of the CLII into a super CLI with head to head incisors.
After 3 and a half months of Forsus treatment I removed the appliance spring and pushrod and left the two arches completely free to find again a sound CLI. I was helped in the task by having customized torque, tips and bracket heights pre-set by the beginning (the start with the end in mind philosophy). So upper and lower arches just need to match together again.
Using the Forsus in this way gives pretty predictable outcomes. I then dedicated my clinical time to solve minor problems as spacing and other minor but important details.
I was able to debond the lower and upper arch at a differential timing, since the settling of the lateral side of the mouth was preset, and I trusted it. Thus I debonded the lower arch after 14 months and the upper two months later.
The result was dentally nice, and very close to the pre-planned settling. The CLI seem sound.
I was happy of having controlled properly the torque issues through the Insignia system itself and no IPR (but arch transversal expansion), in this case.
But I was really astonished when I took her the final lateral ceph.
In fact her ANB got reduced by 2° / her mandible advanced by having the same amount of overjet in the beginning and in the end (thank you Forsus&growth), meanwhile the inclination of the lower incisor on the mandibular plane highly reduced from 106° to 98°! (thank you Insignia&torque compensation)
I never saw such an effect during a CLII correction with the lower incisors literally going backward, even if applying powerful proclining forces (the average proclination of the Forsus treatment is +6° on lower incisors on similar archwires, and I know it very well as I authored a couple of papers on the Forsus treatment).*,**
Superimposition on SN on point Sella (red pre-treatment, green post-treatment) clearly shows mandibular advancement favored by a powerful retroclination of lower incisors, that could be only due to the specially customized brackets that were used in this case.
This case was a real discover of the power of torque compensation applied to the Insignia brackets.
I honestly didn’t expect such an effect on lower incisors. I guess I would carefully setup torque compensation for any of future CLII treatment, aware of the possibilities of this smart and effective tool.
* Cacciatore G, Alvetro L, Defraia E, Huanca Ghislanzoni LT, Franchi L
Korean J Orthod 2014,44(3):136-142
** Cacciatore G, Huanca Ghislanzoni LT, Alvetro L, Giuntini V, Franchi L
Angle Orthod 2014,84(6):1010-1017
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