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Presurgicalortho1

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robbypowell's version from 2018-09-17 14:56

Notes

compensation vs decompensation:
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-the worst screw-ups you'll ever see are surgical screw-ups

 

-harrell not a fan of surgery first (before compensation)
-compromises range of tx capabilities
-compromises orthodontic outcome

 

-unless patient has a perfect storm of surgery first, requiring no compensation... patients should be decompensated

 

 

Poor setup for orthognathic success:
-in orthognathic cases...
-often people say.
"we'll do everything we can orthodontically, but your child may end up needing surgery"

 

-after tx isn't able to accomplish outcomes... then patient is even MORE compensated to exisitng skeletal discrep
-creates much more difficult case
-doomed to fail
-if you leave lower incisors then as soon as retention stops relapse will happen and be devastation
-because incisors will want to be upright over that bone
-oral surgeons don't often understand these concepts

 

-Surgical goals
-get teeth up over boney base
-teeth need to be as close to class 1 over bone base
-operate with NO regard as to what the posterior occlusion looks like
-archwires should be bent to simulated position of teeth on simulated cast

 

-when can you not make that work?
-transverse discrepency
-class 2 with real deep curve of spee
-when curve of spee leveld post-surgically?
-downside is change in incisor position
-patients will become edge to edge

 

Mild transverse discrepency can be corrected surgically first when you're already going to be doing maxillart osteotomy

 

post-surgical orthodontics can usually be done in a 6 month time frame and set up is successfully executed

 

-
when might it take longer than usual?
-if ectopic or impacted canine
=you're still going to have to guide that thing down and fix everything else

 

- - - -
so, what is the NORMAL positioning of teeth in class 1 ... so that we can set-up for this post-surgically

 

M1 to SN 103
m1 to PP 110
L1 to MP 90

 

mild skeletal discrep and we will camoflauge... ortho only
-when surgery... we DECOMPENSATE

 

-for surgery... we operate around the constraints of Max incisor in head position
-setup around that
-for ortho only... we operate around the constraints of Mandibular arch (especially anterior)
-setup around that

 

----
Class 2 mechanics all have the effect of uprighting the maxillary incisors and proclination of mandibular incisors

 

what are the potential downsides of camoflauge compensation for Class 2-
-diminuition of profile ---> compromised esthetics
-run out of bone in mandibular arch --> create periodontal problems

 

Class 3 mechanics all have the effect of proclining the maxillary incisors and uprighting of mandibular incisors

 

what are the potential downsides of camoflauge compensation for Class 3-
-max incisors "stretched" to limit --> mobility, forces too close to right angles to long axis of tooth
-watch out for fremitus
-minimize anterior guidance

 

--
mandibular symphisis thickenss is more limiting in dolicho-facial patients (thin symphisis) and more forgiving in brachy-facial patients (thick symphisis)

 

Brachy-facial alveolar processes allow for greater compensation (and decompensation)

 

-
5 degrees of proclination = 1 mm of crowding
-space gain by incisor proclination can carry a high price in
-periodontal concerns
-relapse potential

 

----
"the orthodontist is given a limited amount of basal bone... he/she should NOT seek to enlarge that area... efforts to do so will be rewarded ONLY with FAILURE"

 

flared mandibular incisors tend to rebound post-treatment (relapse)
-following tenets of stability led to Boley having stability of patients at 25 years out

 

-----
more than 3 mm of curve of spee... problematic
-for each mm curve of spee... --> 0.5 mm on each side needed to avoid blowing the incisors forward

 

(assuming that on a narrow arch it creates a need for more space per degree and on a broad arch it creates a need for less)

 

----
when you compensate or decompensate an arch... you also need to think about midlines and how correction affects the space demands on each side of the arch

 

---
-class 3 elastics can help prevent flaring of man incisors during (class 2 deep bite) COS leveling... tieing off in posterior can too
-judicious IPR
-extraction of appropriate teeth (by extracting lower 1st bicuspids less proclining force aka more retrusive force)
-can use high negative torque value in man anterior
-

 

a negative torque value places root apex more facial (with big fat rectangular archwire)