Rethinking Bicuspid Extraction Patterns

 From: Morton Speck [mailto:mortspeck@gmail.com]
Sent: Monday, January 31, 2011 10:04 AM
To: escostudyclub@yahoo.com
Subject: Rethinking Bicuspid Extraction Patterns

Before I launch into one of my favorite topics, it’s great to see a refurbished ESCO as well as many of the usual suspects.  Thanks Huibi!

Now to cut to the chase!

Most of us consider extracting the four 1st bicuspids in a Cl. 1 crowded case a no-brainer because that tooth is closest to the crowding.  However, that is not always the best strategy in the maxillary arch for the following reasons: since the 1st bicuspid is generally larger than the 2nd, the presence of the 1st bicuspid makes the reopening of the extraction site less likely; furthermore, should the space reopen, it is less obvious because of its more distal position; equally important, the difference in the gingival heights of the cuspid and 2nd bicuspid can compromise smile esthetics.  The natural juxtaposition of the cuspid and 1st bicuspid results in a much more pleasing appearance.

Maxillary 1st bicuspids are also traditionally removed in single arch extraction cases, most notably in Cl. ll div. 1 cases.  For the reasons stated above, I would argue again that the maxillary 2nd bicuspid should be the tooth of choice in most cases.  The extraction of the maxillary first molar in single arch extraction cases is also a valid option, but that is the topic for another discussion.
With these considerations, I would ask ESCO readers why they would argue against the removal of maxillary 2nd bicuspids in the majority of cases, and in all cases where this size disparity exists, barring any periodontal considerations.
My guess is that most practitioners avoid removing maxillary 2nd bicuspids, either because they never gave it serious thought, or they were wary of the additional mechanics required and/or the anchorage-taxing problems this protocol entails.  But to trade a superior result for treatment expedience, in my view, does a disservice to your patient.  I respectfully suggest that if you have consistently favored 1st bicuspid extractions in the situations I have described, that you reconsider your options.

Attached are a couple of slides (click here ESCO) that illustrate the size and gingival height difference in a particular case.

Mort Speck
Lexington, MA

5 responses to “Rethinking Bicuspid Extraction Patterns

  1. Totally agree, Mort. I find very few cases where anchorage is so critical that 1st premolars are the required extractions.
    I think the major reason for the “default extraction” of 1st premolars would be poor biomechanics.
    I’m with you, reconsider those extraction patterns, and look at the better aesthetics (intra- and extra-orally) after 2nd premolar extractions. If necessary, change your mechanics. Especially consider Tip-Edge!
    Cheers,
    Brett Kerr,
    Brisbane,
    Australia

  2. You are looking for controversy. Not a fluffy topic that we are all likely to agree upon. I respect your opinion; I will bite in the interest of discussion. Firstly, one of the arguments that I have read for extracting upper first bis instead of upper second bis is due to the cervical anatomy due to the bifid buccal and lingual roots on the maxillary fist bi. If I remember, the argument was that this area is harder to maintain periodontally so the second bicuspid is easier to maintain in good health. Secondly, I am unaware of any research that shows that a larger extraction space (not significantly larger but somewhat larger as in this case) is more likely to re-open. Orthodontic history is replete with common sense things that we commonly accepted as gospel but later were proven false. The old theory that third molars cause anterior crowding comes up as an example. It made sense. However, things just don’t work that way. (Thanks Dr. Bo Shanley) 3rd, Is the difference in gingival height due to a difference in the actual height of the crown or in the height of the clinically evident crown. Ginvivoplasty can correct the latter situation. If the concern is cosmetics, then the anteriors should be of first concern. If you have adjusted the height to width radios on all of your upper canines, laterals, and centrals, (ala David Sarver) and I applaud you greatly if you have, then you are already using a laser and additional gingivoplasty on the bicuspids will be little more work. 4th In my hands and in my practice, maintaining anchorage is occasionally something that I need the patient to cooperate with. My patients are not all perfect and the amount of cooperation needed can be a factor in the quality of the outcome. I am looking for something that gives a good outcome the greatest percentage of the time, not something that gives a spectacular outcome with great cooperators but gives a less than should have been achievable outcome with the less cooperative. I owe them my best also. A great example of this is some of the case studies that we all read in the journals. Too many of them are treatment plans that took a great risk in order to achieve a spectacular outcome. The patient cooperated excellently, had great growth, or the sun moon and stars all lined up for them. They get printed as a result. The failures never make it to print. We would all say that, that treatment should have never been attempted on that patient. We are here to help all of our patients. So choosing teeth to extract based upon ease of mechanics and needed cooperation is not necessarily a lazy thing for the orthodontist, it can be the best for your patients over all. If you are getting great results with your technique, then I applaud you, and I thank you for your perspective, it was interesting. Baring additional evidence, I am still not convinced that first bi extractions should be eliminated. Very respectfully,
    Rob Kazmierski

  3. Mort,
    Nice to see you back in the fray, you always have some good insights.
    For me, the choice of which tooth to extract depends on the needs of the case. I use the VTO module in dolphin to help me integrate space needs, anchorage, molar correction, incisor tipping etc. and get a good picture of what tooth movement is needed. If my analysis says that to get good occlusion, the molar needs to come forward 4mm and the canine back 3mm, then a 2nd bi is the obvious choice. My feeling is that resolution of a tooth size arch length descrepancy is really just a math problem with the only part open to “art vs science” is where you plan to put the incisors. Everything else can pretty much be quantified with a number and it just depends if the mechanics and anchorage can be provided go get the desired movement.
    Two specific types of cases come to mind when I think 2nd bi’s should be considered and are often overlooked.
    1) Cases with upper crowding, no lower crowding and minimial overjet. These are usually maxillary deficient class 3′s, often with a higher FMA, that makes them look class 2. Taking out 2nd bis protects the lip support and the mechanics work out to get the molar forward and create space for the often blocked out high cuspid.
    2) Crowding with midlines off 2mm or more. Moving the midline “creates” space in the side you are moving away from and “adds” crowding to the side you are moving to. Usually the crowding is worse to the side that the midline is off to and it is counterintuitive to take out a 2nd bi on that side but if you do the math, it is the clear choice.
    When I take out 2nd bi’s, I close the space on a 17x25ss sectional first (with out bonding the anterior teeth) then move to traditional first bi mechanics. Often the canine drifts back with the first bi and helps unravel the anteriors.
    I agree with you that 2nd bi mechanics should be in every orthodontists tool kit. They create multiple options when first bi’s create to much space or space in the wrong place.

    John McDonald
    Salem, OR
    PS. Nice photos, what is your flash set up? I see shadows but the lighting is even. Is it a dual point system?

    Sincerely,
    John McDonald
    Salem, OR

  4. Jayaram Mailankody

    Hello,
    Congrats Speck, for your objective evaluation of tooth size of upper 5s(usually smaller than 4s) and the height of gingival contour(mostly smaller than 4s). These are definitely factors to be considered while planning therapeutic extractions, not just maths alone!
    The readers may well recall the earlier discussion in ESCO digest on the premolar(5s) bracket slot height, and opne bite tendencies. Gingivectomy and lasers are invasive ways of addressing the anatomical normalcy(variation?)or mecahnical insufficiency.
    I would also like to add that the aprehension to extract upper second bicuspids may be due to the prevalent class II patterns, which may worsen by further mesial shift of upper 6s. In a place like mine, with class III predominance, this has a special beneficial role.
    While in the lower arch, the morphology is different, i.e: 5s are larger than 4s. So also the broad/flat distal contact of 5 cannot be substituted by rounded, smaller distal of 4s; lower 5s also have a large well defined occlusal table compared to the 4s with a canine like sloped buccal cusp with practically absent lingual cusp. My message is, in the lower arch tooth morphology favours extraction of 4s rather than 5s. I do understand that morphology is only one of the(important) factors to be considered while choosing extractions.
    Ultimately, astute clinician in the orthodontist should decide and recommend the best option to the patient(case) in the chair rather than formulas, prescriptions or comapanies(manufacturer/trader).
    Thanks for reminding the orthodontic community about this message!
    Jayaram Mailankody
    Kerala, India.

  5. Hi Mort:
    No debate here. I agree. I tell my dental colleagues that insist that the smile narrows when extractions are performed, that it does not. Rather, they are seeing a patient that had first bicuspids extracted and they now have a large canine in proximal contact with a shorter 2nd premolar. If this is the case, a laser most often will resolve the issue and the smile no longer has the narrowed look. But, a 2nd premolar extraction plan would also have resolved this issue. Would they place veneers on short posterior teeth or lengthen them first. It really is no different. Big smiles come from long posterior teeth, not wider smiles. Just my two cents worth. Mark

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