robbypowell's version from 2018-09-17 20:17


Big picture:


Orthodontic Problem
-treat with ortho
-surgical correction
-with or without extraction
-not to treat with ortho
-everything is good but there's space between anteriors
(best to have prosth correction)


Extraction vs nonextraction...
-when to extract?
-which teeth to extract?


Lower Incisor crowding management:
-2mm +- 1 mm and normal leeway -----> Observe
-4 mm wait for point where E's are about to exfoliate ----> passive appliance tx
->4mm discrepency ----> active tx indicated
-phase 1 arch expansion (dolicho)
-serial extraction protocol (brachy)
->10 mm discrepency ----> EXTRACTIONS (almost always indicated)


limit of stability:
-proclining man incisors forward no more than 2mm
-tip out 3 0.5 mm
-tip out 4 2mm
-tip out 5 2.5 mm
-tip out 6 3 mm


-posterior tipping really only appropriate with lingually tipped posteriors


Why do extractions in conjunction with treatment?
-have been source of controversy in ortho since the beginning
-Wolff's Law- Bone will adapt to the stress loads it is placed under...
-Doesn't work this way


-Angle thought if you fit the teeth together then there couldnt be anything else wrong...
-"if you put all the teeth in then that is the way god intended it and those are good esthetics"
-he didn't have the capability to understand periodontal compromise created


current thought process: determine ideal facial esthetics ---> make teeth fit within these confines
-mandibular arch form limiting step for ortho only
-everything built around this


-will skeletal components underlying teeth... will this allow us to establish ideal occlusion?


Angle's conundrum
-Old Glory
-aboriginal skull from australia
-angle wanted to set aboriginal teeth into an anglo-saxon skull.... well... those dont fit
reasons to do extractions
-bimaxillary protrusion
-establish lip competency
-skeletal camoflauge
-midline correction
-deepen an overbite
-eliminate a dental problem


-picture teeth as cars in a parking lot
-if the lot is croweded then we only have a few choices about where to put them
-what options are there?
-reduce # of cars (extraction)
-make parking lot bigger (expansion)
-make the cars smaller (ipr)
-have to stay in the lot or we develop bigger dental problems
-pulpal death to teeth
-root resorption
-gingival resorption
-traumatic tooth mobility


the mandibular suture isn't there...
-never has been
-never will be
-closes and ossifies before birth or just after


extraction case 1


patient is dolicho
-red flag... worry about Anterior Open Bite
palatal expander done first
then extractions


-Bonded expander (posterior bite plate)
-nance placed
-patient referred to perio for cleaning
-follow-up for 3 months
-exts done
-LLHA placed
-Sectional mechanics
-U2-2 bonded
-L2-2 bonded


"if you want to get in trouble... strap an elastomeric chain onto NiTi to try to do space closure while you're leveling and aligning" - Harrell
-takeaway: don't do wholesale space closure on NiTi during the leveling and aligning phase... if you need to bring teeth in before leveling aligning then do it
-my assumption here is that you're going to get some very undesirable movement in terms of arch because NiTi doesn't have stiffness of archform capapble of resisting dental arch deformation
-i'll ask about it once we resume afternoon lecture
-Not only will you NOT accomplish leveling and aligning... you will close the spaces unfavorable and make the teeth less leveled and less aligned


-Open Bites & Extractions
=another big reason for extractions, esp in Class 1 skeletal, is reduction or elimination of ant open bites
-often patients will present class 2 appearing skeletal pattern and class 2 dental
-excess post maxillary height and "premature" contact of molars


-teeth need to be upright in order to achieve any overbite
-take out 4's --> can recline anteriors


Extraction is a BITE CLOSING process, accommodation of crowding is a BITE OPENING process


class 2 - can make extractions work for you by taking out 5's on man and 4's on max


Class 2 extraction pattenrs:
-in class 2 mal... three options generally possible:
=maxillary first bicuspids only
=max and man first bicuspids
=upper 4's lower 5's
=asymmetrical extractions when malocclusion not symmetrical


-always think twice about taking out lower teeth on Class 2
-always think twice about taking out upper teeth on Class 3


case 1 class 2 (end on) (half step)
-u4-u4 was done
-not alot of crowding
-so mechanically demanding because only bodily movement necessary
-although she has some serious curve of spee (deep bite) on mandible
-upper incisors proclines
-lower arch proclination appropriate



class 3 extraction patterns:
-upper and lower 4's
-upper 5's and lower 4's
-lower 4's or 5's only
-a single mandibular incisor
(often used in anterior crowding esp adults)


we'll look at an u5's/L4's case and a L5's case
120/80 is the camoflauge that we tend to shoot for
class 3 minimal crowding with edge to edge 0 mm overbite
reasons for extractions here
-lack of depth of bite
-incisor proclination (man)
-to establish overjet


--- because she was closer to Class 1 canine on left... that side extracted U5's and lower 5's (maintain anterior position)
-on L.. more class 3. so we pulled U5's and L4's... allowing greater distalization of anteriors on lower L


why is he not on second molars with bands?
-doesnt want to extrude molars because there is limited depth to the bite


when you protract an lower first molar and an upper first molar
-smoothest flattest water is just behind the boat
-second molars will draft... it's easier for them to shift mesially to close the space opened


Asymmetrical extractions:
-Type 1's (mandible is at fault) is much harder to treat
-remember that we must build around the mandible in ortho-only tx
-Type 2's (maxilla is at fault) is much easier to treat
class 2 div sub L Type 2 (maxilla at fault)


--- can use stops on wire to better guide tooth movement around wire...
-to stop distalization of canine to split difference and end up too lingual...
-can put stops on wire on molar while moving canine...
-then take stop out to bring back incisor segment


maxillary only bicuspid pattern yields better occlusal result and a faster result
(for the side that is a full step)


the most stable result for a class2 correction is a bicuspid in the maxillar arch only


don't work for the extraction pattern=== make the extraction pattern work for you===