In the May 2010 issue of The American Journal of Orthodontics appears a study by Smithpeter and Covell which analyzes the relationship between orthodontic patients who tongue thrust and open bite of the front teeth. In this context , “ open bite “ means the front teeth are apart when the back teeth bite. Vertical overlap of the front teeth is termed “ overbite “ whereas “ open bite “ ( also termed “ reverse overbite “ ) can be related to a growth discrepancy of the jaws and/ or tongue thrusting. When swallowing or at rest, the tongue should NOT be positioned between the front teeth.
We have seen open bites in the front and / or on one or both sides. Relapse or recurrence after orthodontic treatment does happen even when jaw surgery has been undertaken in conjunction with braces. There seems to be a correlation among tongue thrusting, mouth breathing, nasal airway obstruction, narrow upper jaws with crossbite tendencies and open bites though this study speaks only to thrusting and open bites.
In this study, 76 orthodontic patients with open bites 27 of whom ( experimental group) received myofunctional therapy (tongue placement therapy) before, during or after their braces and 49 of whom did not (control group ) were compared with respect to how well their cases stabilized after treatment. The differences were highly statistically significant and as we would predict, those who underwent therapy were more stable.
What does this mean for patients?
1. Tongue placement issues can effect dental development and even the shape of the arches.
2. Early intervention is warranted in an effort to prevent serious bite issues later on.
3. Intervention with a myofunctional therapist or MFT ( in our experience a speech therapist with specialized training) and/ or the orthodontist ( appliance based therapy or APT) may be indicated. MFT is subjective by nature. Younger patients seem to do better with APT though it provides only for negative reinforcement while MFT holds open the possibility of retraining tongue position . Unfortunately, relapse of the thrusting can unpredictably occur with either approach and should be continually monitored after treatment for years. In our practice, we sometimes design special removable retainers fitted with prongs to “remind” the tongue to stay away from the teeth. They are generally effective if worn as prescribed. Additionally, while we avoid removable retainer wear during the day in favor of bonded retainers ( check out our website for examples and details), in thrusting patients we sometimes design a removable palatal stent to maintain the width of the upper jaw.
When allergy or nasal airway obstruction ( enlarged tonsils, adenoids, turbinates or deviated septums for example) may be contributing factors to thrusting or mouth breathing, referral to an allergist or ENT physician may be indicated. Such interdisciplinary management can be challenging to maintain as not all healthcare providers are familiar with the interrelationships that exist with dental development and may require additional explanation from the orthodontist. Interestingly, some orthodontists also do not recognize these factors and fail to account for them in treatment planning their cases. This study should reorient their thinking.
At Ziman Orthodontics we are always asking ourselves why a patients case looks the way it does and tongue thrusting is always in the backs of our minds when we see open bites. We have routinely referred to myofunctional therapists when indicated for over 20 years along with specialty referral as needed.