4 Premolar extractions: worried about face/TMJ, have had multiple opinions, 3 say extractions, 1 says no extractions (photos)

Premolar Extractions Controversy



There is probably no facet of
orthodontic treatment that has caused as much controversy as the decision to
extract, or not to extract, permanent teeth: and more specifically, whether to
extract four premolars or to “develop” room for non-extraction treatment.



Besides the obvious reasons of avoiding the trauma and
expense of surgery, and the desire to preserve permanent teeth; other alleged
negative sequela, such as TMD problems, flattened facial profiles, and “dark
buccal corridors” have contributed to the premolar extraction controversy. Like
a pendulum, the popularity of premolar extractions has swung back and forth,
between the extremes of non-extraction at any cost and “routine” extractions to
achieve arbitrary cephalometric norms.



Some of the factors we consider
are:




When dealing with a fairly “normal” orthodontic
problem (no gross asymmetries) the decision to extract four
premolars is straightforward although often not easy. It is impossible to
extract less than a whole tooth, and usually the extraction of a tooth on
the left requires an extraction on the right to balance the midline.
Likewise, lower extractions usually require upper extractions (and visa
versa) to prevent excessive overjet or underbite. These parameters
normally lead to extraction of four first premolars or to treat as a
non-extraction case. There are times when upper premolars only, a single
lower incisor extraction, molar extraction, or interproximal enamel
reduction (IPR) are appropriate but, in general, the decision for
extractions is often framed around “4-bi’s”.





Given the usual all or nothing nature of the
premolar extraction decision, it is no surprise that different
orthodontists often appear to have conflicting treatment plans for
the same patient. The reason is not that they see very
different problems or have radically different philosophies of treatment,
but rather that each doctor has a different line in the gray area between
extractions and nonextraction. Two treatment plans that appear very
different can both be based on a similar analysis of the patient’s
problem, but end up with very different treatments due to the black and
white nature of the decision making process.





It is important to understand that in borderline
cases there are no correct or right answers. Both treatments
performed by competent orthodontists would produce a good result, but
neither is perfect. Each option would have pros and cons, and
orthodontists and dentists could (and do!) spend endless amounts of time debating
which option is “right”.





We try to avoid extractions as much as possible, but extractions should be considered when
esthetics and stability call for it.
Truthfully, almost any patient can be treated without
extractions and, often, this is technically the easier way. This is the reason that the weekend
orthodontic courses aimed at general dentists almost always stress
nonextraction treatment.





Where there is a conflict between
facial esthetics and dental stability, it is our judgment to favor esthetics.
This is not to say that patients with flat facial profiles and
extreme crowding should be treated without extractions, nor that patients
with full profiles and large tongues should have teeth extracted, but
rather that esthetics should be the primary determinant of treatment in
any borderline situation. In these
cases it is very important that the patient understands the necessity of
long-term retention





Contrary to the beliefs of many nonextraction
proponents, good scientific studies (evidenced based) done on TMD and
orthodontic treatment fail to show any correlation between the
development of TMD type problems and the extraction (or
nonextraction) of teeth. All
dentists can remember patients who develop TMD problems after extraction
treatment and, if you feel there is a correlation, you will fixate on
these patients. Statistically, you
are just as likely to find TMD problems in patients treated nonextraction
or, for that matter, patients who never received orthodontic treatment at
all.





Scientific studies have also shown that well
treated extraction cases do not adversely affect facial profiles. Again, it
is easy to visualize patients with flat profiles who have had premolar
extractions. Assuming a good
treatment decision, these patients would have had a flat profile even if
they never had treatment (and an extremely unstable dental alignment if
they had been treated without extractions). The truth is: tight facial
structures (flat faces) lead to crowding, which leads to extraction rather
than extractions cause flat faces. As a matter of fact, the most dished in
and flattened faces often belong to those patients whom we have treated without
any extractions. Like the TMD controversy, negative esthetic effects
attributed to extractions fall into our favorite logical fallacy “post
hoc ergo propter hoc” (after this therefore because of this). Other studies have also shown that dark
buccal corridors and a narrow smile are not “caused” by premolar
extractions.





A good selling point for premolar extractions can
be a patient with moderate crowding and well-formed and positioned third
molars. Treated without premolar extractions
this patient usually needs third molars removed. Extract premolars, close
some of the space by mesial movement of the posterior teeth, and hopefully
the thirds can erupt and be kept—an exchange of four small, easily removed
teeth for four molars that would be difficult to extract. Unfortunately no
guarantee can be made that the thirds will always come in with enough
room.





There seems to be a great deal of confusion about
early expansion treatment (AKA arch development or growth
modification). There is a important
difference between expanding a constricted upper arch to match a normal
lower arch (OK) and significantly expanding both arches in a patient whose
arches may be narrow, but are in a normal transverse occlusal relationship
to each other (not OK). Although it
is possible to upright lingually verted lower posterior arches (which may have
collapsed in, to compensate for a narrow maxillary arch), it is not
possible to expand the mandibular basal bone, as there is no suture to
distract as in the maxilla. Of
all the inviolate “facts” of orthodontics, one of the most established is
the stability of the lower inter-canine width. Expansion beyond the original width is
almost a guarantee of collapse and recrowding.





Every decade or so a new “magic bullet” comes
along promising the ability to create space and avoid extractions or
unstable expansion. The latest
iteration of this is the Damon™ orthodontic bracket with its
manufacturer’s promise of extremely light forces that “grow” more room
than regular braces. As usual, no
good science backs up these claims!




In an attempt to avoid first
premolar extractions, various alternatives can be considered:



oExpanding the arch, especially in a flat-faced
individual, is often preferable to extractions, with the understanding this is
an unstable correction and perpetual detention will be needed.



oFor
patients with a good posterior occlusion, a good upper arch with relatively
small upper incisors, moderately severe lower crowding, and minimal overbite,
the extraction of a lower incisor can be considered. Extraction
of an incisor should be evaluated very carefully, for it can result in an untreatable
problem with excessive overjet/overbite in the wrong individual.



oInterproximal
enamel reduction (IPR)
can provide a moderate amount of room but should be reserved for older
patients. Excessive IPR as an initial treatment complicates the orthodontist’s
ability to correct minor relapses in the future.



oConsider
extraction of second premolars rather than first premolars.
Theoretically, this reduces the amount of anterior retraction when only some
space is needed for crowding and the facial profile is acceptable. This works best when the second premolars
resemble the first, but large, molar-like second premolars may provide too much
room and small, canine-like first premolars may not work against first molars.



oDistilization
of full arches is very difficult so extraction of third molars or even second
molars to provide anterior room has never been shown to provide significant
space. With the advent of temporary
anchorage devises (TAD’s) this may become a “new” way to treat
nonextraction…. we’re already trying it!



Bottom line: Extractions are just a tool, not good or bad
in themselves. Used right, they improve
the quality of treatment, used wrong they may create a poor result.