Every orthodontist is familiar with Newton's Third Law of Motion: For every action, there is an equal an opposite reaction. When you push on one tooth, you have to be pushing on something else (tooth, appliance, bone, neck) in the opposite direction. We call this the problem of "anchorage" and it is a consideration in every treatment.
But there is one situation in the mouth that, I am guessing (based on my personal experience), very few orthodontists have thought about regarding equal and opposite reactions - that is the tongue thrust swallow. The tongue thrust (or reverse swallow) has the tongue pushing against the front teeth during swallowing instead of up on the palate where it belongs.
We all know that a thrusting tongue pushes the teeth enough for them to move, sometimes dramatically, causing them to flare forward or even creating a huge space between the upper and lower teeth. But what is the equal and opposite reaction to that?
The tongue and other structures used for swallowing are tethered to the lower jaw bone by some of its muscular fibers (genioglossus, mylohyoid, geniohyoid). So when the tongue pushes forward against the teeth, it also pushes back against the lower jaw. This pushes the head of the jaw joint back into its socket. This compresses the cushioning cartilage disk in the joint. Between 1-2,000 times a day. Microtrauma to a sensitive structure every time you swallow. A damaged disk is what creates the clicking, popping, locking and pain of TMJ problems.
And we wonder why people associate TMJ problems with malocclusion and orthodontic treatment? Tongue thrusters and mouth breathers have already predisposed their joints to damage for years before the braces go on...for years before all their teeth grow in.
This is yet another reason why early interception of soft tissue dysfunction is so critical.
That's not so hard to swallow, is it Issac?
When orthodontists talk about the influences of heredity and natural processes on the way a child grows, they refer to "Growth and Development". For instance, if we are unsure if a 6 year old is going to need braces, we might "wait for further growth and development". Or if a child's jaw structure seem to be getting worse as he grows older, we describe it as "poor growth and development". If we want to explain to a parent why a child's teeth are crooked, we say....you guessed it....G&D.
But this view of the way a person grows is limited because it is missing an extremely important element in the way a child grows and develops: Adaptation. Neither growth (a change in size or mass), nor development (the genetically pre-determined maturing of a structure) leaves room for the interaction of the person with the environment. The expression of genetic potential DEPENDS on how the individual and the environment interact.
Not all of the details of our face and position of our teeth are predetermined. The bones grow and the teeth erupt under the guidance of all the forces that surround them - from the muscles, airway, posture, swallowing, nutrition, habits, etc. They ADAPT to the surrounding forces (Functional Matrices in Moss' terms). And this element of change is every bit as important as growth and development.
It's not just G&D. It's G,D&A! And THAT is the missing link in our thinking.
We all know that a thrusting tongue pushes the teeth enough for them to move, sometimes dramatically, causing them to flare forward or even creating a huge space between the upper and lower teeth. But what is the equal and opposite reaction to that?
The tongue and other structures used for swallowing are tethered to the lower jaw bone by some of its muscular fibers (genioglossus, mylohyoid, geniohyoid). So when the tongue pushes forward against the teeth, it also pushes back against the lower jaw. This pushes the head of the jaw joint back into its socket. This compresses the cushioning cartilage disk in the joint. Between 1-2,000 times a day. Microtrauma to a sensitive structure every time you swallow. A damaged disk is what creates the clicking, popping, locking and pain of TMJ problems. 