I often see patients that present with this dilemma and they want to know, what is the best option for them? There are many factors to consider before making a decision regarding extraction or removal of permanent teeth: stability, gingival health, oral hygiene, facial features, root resorption (shortening of the roots), length/time of treatment, and sometimes, the cost of treatment. When I make a decision to remove permanent teeth, I base that decision, as with all treatment decisions that I make, on the grounds of previous research studies that have been evaluated, often duplicated, and published in peer-reviewed orthodontic journals. Prior to making the decision to either remove or retain permanent teeth, we take a series of orthodontic records (panoramic and cephalometric x-rays, images of the face and teeth, and plaster models) which are then evaluated to determine the best course of action for that individual.
Over the course of the next week or two, I will attempt to shed some light on this subject by discussing each factor that I mentioned earlier in detail and give an overview of how that factor will affect the decision to extract or not extract. I will begin by looking at the stability factor and how stability plays a role in the decision to remove teeth or not.
In general, the position of the teeth on the jaws prior to treatment is determined by the muscles of the lips/face and tongue, particularly the anterior teeth. The teeth have erupted into this position, and this is where they are most stable. If the anterior teeth must be considerably moved outward or tipped forward away from their jaw-bones thus encroaching on the lips and their corresponding muscles, they are more likely to relapse following the removal of braces and retainer wear. If on the other hand, the patient is in their early teens, the upper jaw can be expanded predictably without the potential for relapse. As we age, past sixteen years old, the suture or junction in the middle of the roof of the mouth fully ossifies and can only be separated via jaw surgery. On the other hand, or jaw, the suture in the middle of the lower jaw fuses or ossifies at a very young age and can only be expanded via surgery.
The distance between the lower canines or I-teeth therefore is used as a gold-standard in orthodontics as a predictor of future stability. As we age, this distance becomes slightly reduced naturally with wear and use of the teeth, and any increase in this distance during treatment is doomed to be lost following the removal of braces and retainer wear. This is the one component of stability that has readily been duplicated in many post orthodontic stability studies and is accepted as a hallmark of orthodontic stability. Therefore, if we plan to expand the upper arch when there is no problem with the fit or occlusion of the upper arch with the lower arch (otherwise known as a posterior cross-bite), we must then expand the lower arch, increasing the inter-canine distance and thereby subsequently increasing the relapse potential. For this reason, it is not a good idea to arbitrarily expand the dental arches to gain space or make the smile wider, unless permanent-lifetime-retention is applied to the teeth.
And finally, any treatment that requires the significant forward movement or growth of the lower jaw will always tend to flare or procline the lower anterior teeth, thus placing them in an unstable position; therefore it is often necessary to remove lower teeth to prevent this from occurring. Often, upper teeth are removed to eliminate the need for the kind of treatment that would require forward movement or growth of the lower jaw in an effort to avoid proclining the lower anterior teeth into an unstable position.
I hope that this short explanation of stability and its role in determining whether or not to remove permanent teeth does not add to your confusion about braces. If so, keep reading my future blogs regarding this issue as I delve further into this topic to help clear the fog regarding this important decision.
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