Orthodontic retention

Q. What is the biggest misconception about orthodontic treatment?

A. If I could just tell people one thing about orthodontics it would be this:

      Teeth are NOT like fence post that are set in concrete.  With a fence post, you place it where you want it, pour concrete around the base, hold it in place (retain) and, when the concrete sets up, the fence post is stable and should never move. 

Now this is NOT what happens with teeth!  Teeth are never fixed to the jaw bones. 

They always have the capability to move.  So why don’t they; why do crooked teeth stay crooked until the orthodontist moves them; why do straight teeth stay straight if a patient is blessed with straight teeth and never needed orthodontic treatment?  The answer is that, in both cases, the teeth still can move…they just don’t “want” to move, at least not right then.  

        In both cases, the teeth are stable (crooked and straight) in their respective positions because the forces on them from the bite, tongue, lips and cheeks balance out.  Change the forces with braces, or with just normal aging, and the teeth will move. This is why we never tell a patient to stop wearing their retainers.  Even if the teeth might stay straight for years, forces change over time, and the teeth will move. Retainers will hold teeth in position because they can overcome any unbalanced forces that might affect the teeth.

         Now all of this is not to say that it makes NO difference where the orthodontist puts the teeth.  Ideally, we try and find the most stable position possible for each patient.  If we do this, then the teeth will tend to stay straight, with or without retainers (not that we recommend not wearing retainers). 

         This is where diagnosis comes in.  Let’s say a patient has extremely crowded teeth due to very large teeth and a small mouth. The teeth are stable in their crooked position, but if we just expand the arches to make room for all the teeth, are we not moving them out to an unstable position?  But if we extract some teeth (so we can leave the remaining teeth in the arch, but straight), then the final result should be much more stable.

           
           My wife had orthodontic treatment 50 years ago and, like many people, she stopped wearing her retainers after a few years.  Yet, because she had teeth taken out for crowding, her final result was stable and, even 50 years later, her teeth look great.  Now this doesn’t happen for everybody, but this is what we try to achieve, and this is the reason why we try so hard to get everything perfect and why we reluctantly are forced to extract teeth in some patients.

Why Teeth are not like fence posts

 (And bone is not like concrete)

Over the years one of our favorite sayings has been “teeth are not like fence posts stuck in concrete”.  What we mean is, unlike concrete, the bone around the teeth never hardens to the point that it becomes solid and prevents all tooth movement.  No matter how long a tooth is retained in place, the bone support will always allow movement if there is unbalanced pressure on the tooth.  This pressure can come from the bite, lips, tongue, or orthodontic appliances.  Only when all of these forces are balanced, or when retainers are used, will the tooth not move.  This is like a fence post stuck in a bucket of sand.  It will stay in place only if nobody pushes it.

Each individual’s dental, neuromuscular, and skeletal situation determines the forces on the teeth.  After the initial stabilization with retainers (a few months) your teeth may or may not try to move. Even in those cases where the teeth are stable (people who never needed braces) the balance may change years latter and the teeth will move.  It makes no difference how long the teeth are straight (either naturally or with retainers)…. if the balance of forces changes the teeth will move.

Bottom line: Yes, some people get away with not wearing their retainers  Unfortunately we don’t always know who needs retainers and who doesn’t!  And so, after all you’ve been through to get this point, doesn’t it make sense to hold what you have by wearing your retainers!