Moving teeth with braces is a simple matter of physics. Following Newton’s third law of motion that each action must be countered by an equal and opposite reaction, moving teeth becomes a simple matter of putting enough force on a tooth to move it through the bone and gums to the right place. So essentially braces just push or pull on teeth, using a variety of devices and methods, to move them through the bone. Unfortunately, in moving teeth, a couple of difficulties can arise.
One problem is trying to move one tooth without moving the tooth or teeth you are pushing or pulling against. Just like if you were trying to push yourself off of an object, the larger and more stable the object you are pushing against, the greater the force you can push with. If the object has rollers or can move, then it is hard to move yourself without moving the object in the opposite direction. In regards to teeth, this is why it is relatively easy to move smaller front teeth by using larger back teeth to push or pull against. The problem comes when you need to move larger teeth and all you have to push against is smaller teeth. Often, instead of moving the tooth you intended to, you end up moving the tooth you were trying to push against.
The second problem arises when there is not a tooth or anchor point to push or pull against. The most effective line of force is a straight line. Think about pulling a sled with a rope. It is hard to get a sled to go straight when you pull the rope at an angle. The same goes for teeth. In addition, if there is just not a tooth to push against then you have a problem. The classic case is if you want to move the very back tooth backwards. There is nothing behind it to use to pull against so that movement becomes very difficult.
With the advent and advancement of dental implants in modern dentistry we have seen additional uses for them in orthodontic treatment. Most people have heard of dental implants used to replace teeth or hold a denture in place.
But, now we are seeing what are referred to as temporary anchorage devices (TADs), which are essentially small temporary implants that are placed in the bone and used as anchoring points to pull or push against. An analogy is placing a bolt in a wall or the ground and attaching a cable for anchorage.
TADs can be placed with minimal trauma and in just about any part of the mouth. Since they are placed directly into the bone, they offer a strong fixed point to use as an anchor that will not move like teeth will when pressure is applied. Since they can be placed just about anywhere, they can be located in a straight line to the tooth you are trying to move, so the force can be much more efficient and the movement can usually be done quicker. Once the tooth or teeth have moved into position the TAD is easily removed.
TADs work especially well in adults. As we reach adulthood the bone in our jaws becomes harder and moving teeth through that bone becomes more difficult. In addition, often in adults we are attempting to move back teeth into better positions due to bite or shifting issues. Moving large back teeth in adults can be extremely difficult at best. With TADs we now have the option to place a solid anchor point against which we can pull or push large back teeth.
TADs, and other advancements in dentistry, continue to push the realm of what treatment is possible. They have made treatment of adults and teens more predictable and usually faster. If you or your family member is interested in orthodontic treatment, discuss the modern advancements in orthodontic with your dentist or orthodontist. Often they can make your life and theirs much easier.
Kevin Martin, D.D.S., is a family and cosmetic dentist in Kingsport. He practices at Martin Dentistry with his father, Dr. Tim Martin. E-mail questions or topics of interest to firstname.lastname@example.org, visit www.martindentistry.net or call 247-8172.