Tooth positioning appliances: An orthodontist’s experience

I keep my mind open to new ideas but am always skeptical of the “quick-fix” solutions to age-old problems. However, though I think research is the key to establishing a real understanding of issues, evidence-based dentistry or evidence-based orthodontics just cannot keep up with clinical innovations and, thus, our experience and judgment is tested on a daily basis.

For years, I wondered about the claims being made about tooth-guidance appliances and whether there was really a place for this type of appliance in my practice.

I started to see things differently after seeking a solution to one of the many vexing problems I encounter with fixed appliance therapy every single day: namely, closing open bites. It all started when I had a run of lateral open bites with tongue thrusts that resisted vertical elastics, spurs and everything else I could throw at them. You know the ones when you’re just about to finish up, and the bite just won’t settle down. And getting these cases referred out for the oral myology they need doesn’t always happen. I now have a certified oral myologist in my practice.

What caught my eye about tooth-guidance appliances when I first read about them was the fact that they were not solely aimed at influencing the teeth, but that they were focusing on the musculature.

Case 1

This patient presented in my practice at the age of 10 with severe crowding. Treatment involved the use of an upper Farrell Bent Wire System (BWS) combined with MRC’s Soft Pre-Orthodontic (T4K) appliance (Figs. 1a, 1b).

The patient also took part in Trainer Activities to improve oral habits. After a period of 11 months, the BWS was removed and the hard T4K was used. Treatment continues and will use the Myobrace to finish the case (Figs. 2a, 2b).

Case 2

This patient entered my clinic at nine years of age with a Class II Division 1, bimaxillary retrusion. She had a narrow maxillary arch, lip entrapment under the excess over jet, deep anterior overbite and crowding of the lower anterior teeth. She had a forward head posture with habitual open mouth posture. Facial muscles were overactive on swallowing. She also has a low maxillary frenum and a midline diastema (Figs. 3a,3b).

After one year of treatment with an upper and lower BWS (six and four months, respectively), i2n trainer (for three months) and an i2 trainer (for six months), the malocclusion and the soft tissue dysfunctions were corrected. The bi-maxillary retrusive skeletal pattern and profile remains at this point, though much growth remains (Figs. 4a,4b).

Case 3

This patient presented in my clinic at age 7 with an adequate arch form but a deep overbite. This is a perfect case to show how a little interceptive treatment can go a long way to solving problems that would be harder to correct later on (Figs. 5a,5b).

The Soft T4K was used for four months, followed by the Hard T4K for three months longer, at which point the overbite was resolved. The Hard T4K was used for seven more months, at which point less intensive use of the Hard T4K was prescribed. The T4K was used to assist 10 minutes of daily trainer activities to improve poor oral habits during a period of 18 months, after which the use of the T4K was discontinued. The patient still performs posture exercises for the long term (Figs. 6a,6b).

Correcting deep overbites with fixed appliances can be difficult, requiring bite planes or turbos along with full strap ups. This case was essentially solved in the first four months and continued to improve thereafter. No other treatment is anticipated

Every orthodontist knows the musculature is influential on growth and development. For this, the evidence is clear. Angle[1] knew it. Alfred Rogers[2] knew it. Graber[3] knew it and raised holy hell about it. Straub[4] helped create a subspecialty around it. Harvold[5] showed us how critical airway is. The same Proffit[6] signed off on Tulloch’s[7] work taught us about postural tongue position. Moss[8] and Enlow[9] showed us how it worked. Estuki Kondo’s “Muscle Wins”[10] shows soft tissues and local factors to be critical in the development of mal-position and malocclusion of the teeth.

The question that all these icons of our specialty raised is whether the soft tissues and skeletal structures of the mouth and face are indeed genetically determined, or if perhaps they are subject to the same environmental influences as all other bones and muscles of our body (Boyd 2012)[11]. Indeed, you can change the muscle mass of your biceps in two weeks just by stressing it with weights. Likewise, two weeks prone in a hospital bed can render them weak. Why can’t the same apply to the muscles of the mouth?

We also know that bone responds to the forces that surround it, in both the functional and capsular matrices.[8] The action of the muscles certainly influences hard tissues.

The capsular matrices of the mouth are constantly active: if we are not talking, eating, swallowing, laughing or drinking, we are certainly breathing. There is never a moment of non-activity of the oro-naso-pharynx, and the way it is being used is reflected in how the structures that surround it grow. Again, muscle rules.

Isn’t it likely that all relapse we deal with, both orthodontic and orthognathic, has less to do with the teeth than it does with the muscles that created the malformations in the first place? It seems so simple a concept, why is it still considered so radical a thought?

We can’t say that muscles can’t be trained. We teach the tongue and the masticatory muscles to speak a language, don’t we? Why can’t we teach muscles to swallow and posture properly, too? The tongue doesn’t need to be pushing against the teeth, ruining all my good orthodontic work. I want to teach it to go up on the palate where it belongs during rest and swallowing.

Tooth positioning and myofunctional orthodontic appliances have provided me with a treatment modality that I can use in my office to train the musculature. Yes, these appliances do have the disadvantage of requiring cooperation. So do elastics. So do piano lessons and dance lessons and schoolwork for that matter. And sometimes we suffer the children. But when they comply, I am finding that controlling the musculature — getting the tongue away from the teeth and calming the lips and cheeks during swallowing and rest - has been a godsend for my orthodontics.

When it comes to early treatment, the same thinking applies. The muscles of the functional matrix are certainly active way before we ever get to see these kids. Tongue thrusts develop early. Mouth breathing — and all the allergies, asthma and URT infections that go with it — are present even in the very young. Can we say that it is having no effect on the growing osseous structures? Could the way the bones of the face form be free from their influence? With all that the evidence shows, it becomes impossible, even irresponsible, to overlook the potential that muscle has to influence the teeth and face.

However, the question of how much of facial growth is genotype and how much is phenotype is indeed a legitimate one and is certainly open to debate. Personally, with my reading of the literature (Mew, 2004)[12] and what I’ve come to learn about musculature, I am leaning more toward the “phenotype” side than ever before. I think we are missing the point when we talk about the “growth and development” that we give so much lip service to. Instead, we should be talking about “growth, development and adaptation” with an emphasis on the latter element.

In my view, and in Tom Graber’s view[3], the musculature is doing “early treatment” to the face whether we are there or not. And what we see by the time kids are “ready for braces” is the by-product of that muscular treatment.

So, to me, the debate over genotype or phenotype and the credibility of early treatment and the influence of the muscles begs the question: Am I going to stand by with benign neglect while the muscles are literally distorting this child’s teeth, alveolus, maxilla and, yes, even face? Isn’t that like saying, “We can’t change people’s behavior (diet and exercise), so let’s just wait for them to have a heart attack and then argue about whether a bypass or stent is best” (like we argue about one-phase and two-phase therapies)?

It’s a fallacious argument. The crooked teeth aren’t the disease. Like a heart attack, they are merely symptomatic of a problem that has been festering for years. And just as physicians have a responsibility to teach their patients about the benefits of good diet and exercise (whether we listen or not), I believe we have a responsibility to teach our patients and parents about good and bad muscular habits and their affect on their precious children’s faces. We are the physicians of the face, not just tooth mechanics. The periodontists know this. I think it is time we orthodontists learn this as well.

And once you learn this lesson, well, the teeth will guide themselves into place.

Note: This article appeared in Ortho Tribune U.S. Edition, Vol. 7 No. 6, Winter 2012 issue. A complete list of references is available from the publisher.