Orthodontic Appointment Intervals

Doctor, why is my appointment so far away?

Well I can’t speak for what the other orthodontists are doing; however none of these reasons actually explains the reasoning behind the establishment of your appointment intervals. There is actually a scientific basis for these intervals and it has to do with the turn-over and formation of bone around the roots of teeth. You see, it takes between six to eight weeks to get movement of the roots through the bone. Roots move optimally through the bone when there are light forces placed on them over a long period of time, and they move rather poorly when intermittent or interrupted heavy forces are placed on them.
The roots of teeth are comprised of a dynamic outer coating known as cementum. Between this cementum coating and the bone is a small space known as the periodontal ligament that is filled with nerve fibers and blood vessels and this is where all the tooth movement action occurs.  When light orthodontic forces are applied to teeth, those forces are translated to the roots which then get moved into the periodontal ligament space which upon compression, momentarily stops blood flow to the ligament. This then starts the process of bone removal followed by movement of the root.

If the pressure is applied too often, before bone turnover can be accomplished, then the cementum begins to get resorbed away, not the bone, resulting in dentin exposure and loss of root length, better known as root resorption or shortening of the roots. Efforts to help prevent root resorption have led to the development of special orthodontic wires which no longer require orthodontists to see patients on a monthly interval. The wires that most orthodontists use today are capable of delivering lighter forces over a longer period of time without deformation of the wire or root resorption. Orthodontic wires in the past were comprised entirely of stainless steel which allowed only heavy forces and had to be activated often to prevent permanent deformation of the wire often resulting in excessive forces and corresponding root resorption.

These new wires are comprised of composite alloys and are extremely costly. There are still the older wires on the market available to orthodontists at a very low price. This may account for the reason why some orthodontists continue to see their patients monthly. It also accounts for the majority of root resorption cases!

When considering appointment intervals, one must also take into consideration the type of orthodontic treatment. Some patients have impacted teeth which require special consideration and take longer to move or there are those patients that require growth of either the upper or lower jaws. Growth of a jaw cannot be compressed into a month and requires generally two to three monthly intervals. Seeing a patient each month is not going to do anything to increase the rate of jaw growth!

So, getting back to the question posed above, I’d like to ask you a rhetorical question: would you rather have your child miss school monthly and you miss work monthly and loose part of your child’s roots upon completion of orthodontics?  Or, would you prefer to finish treatment in the same amount of time with fewer office visits and no root resorption? I’ll take the eight week appointment, please!From time to time the question arises regarding a patient’s appointment interval, usually in response to what seems like an awfully long time before your next scheduled orthodontic appointment. I have heard concerns on the part of some parents that this interval is ‘dragging’ the treatment out too long or the reason that we schedule the appointment out so far is that we are too busy to see you or your child. In addition, most parents who had braces on their teeth as a child remember when their visits were always one month apart and they want to know why their child’s visits are not the same. Or they have a friend who has a child that is receiving treatment from another orthodontist and they are seen every month.