Retainers and Retention

Dr. Mah on retainers

In the broadest sense, my recommended protocol for retention is the method which best suits the patient.

First, it is important to have a discussion with the patient about retention before treatment is accepted and initiated. I can't tell you how many times I've heard from patients that have had aligner therapy that they were not told that retention was necessary. These patients had relapse and were seeking retreatment.

Secondly, I consider the patient's malocclusion and look specifically for factors that are associated with significant relapse tendency. Such factors include: generalized spacing, severe rotations, tongue thrusting, anterior open bite, deep bites and retreatments.

Next, I have a frank discussion with the patient regarding fixed vs. removable retention and learn from them which type they will most likely comply with. I ask questions about their occupation and whether it involves doing a lot of public speaking and ask whether they have recently lost items such as keys or a cell phone. In this discussion, I also explain the pros and cons of fixed vs. removable retention.

I've found a diversity of patient responses. Some patients request Hawley–type retainers as they have had previous experience with them and like their durability. Other patients have become accustomed to the aligners, like the comfort and esthetics and simply want to continue with thermoformed retainers. Yet others wish to be "done with" appliances and don't want to give the effort to continue to remember to insert and remove appliances. In these situations, fixed retention is the best option. I inform these patients that they will need to use floss threaders and take a little more time cleaning around the fixed retainer but this is rarely a significant set back for them. I also recommend fixed retention for patients with the aforementioned significant relapse factors. In the most severe situations, I consider using both fixed retention AND a thermoformed retainer or a Hawley on top.

In summary, if the patient has a mild or moderate malocclusion without significant relapse factors, a variety of retention options are available, in part depending on their preference. If there are significant relapse factors, I recommend fixed retention and occasionally both for severe situations. Most commonly, the fixed retention I use is a braided wire bonded to each tooth, extending from canine to canine.

As far as how long to wear them, this is not an easy question to address. A variety of retention options and wear schedules are available. One common recommendation is full–time wear for about 12 months and night–time wear in the following years. Every patient is different, however, and the clinician must recognize the risk factors for significant relapse, as mentioned above. Clinicians must use their judgement to treat and retain as appropriate.

Most patients (and in fact, many dentists) don't know that humans lose approximately 1mm of dental arch length per decade of life with the longest arch lengths occurring in the late teenage years. While 1mm of arch length loss may not be significant in the twenties and thirties, by the time one reaches the age of 50, 3–4mm of arch length has been lost and dental misalignment has now appeared or worsened. For this reason, ideal tooth alignment is almost never seen in individuals over the age of 60. Anatomists theorize that the lack of a coarse diet and lack of interproximal tooth wear is to blame, but this is only a theory. Not surprisingly, arch length loss follows the general pattern of bone loss of all bones in the human body. Peak bone mass is achieved in the late teenage years or early twenties. Sadly, it's all downhill from then.

Understanding that the normal process of aging is working against good dental alignment, I recommend long–term retention. When patients ask how long they need to wear retainers, I explain this phenomenon to patients and most understand. I use an analogy that relapse is like wrinkles. Wrinkles will happen, one just doesn't know exactly when and where. Further, there are three things that are certain in life—death, taxes and orthodontic relapse. Fortunately, one can ward off the latter by wearing retainers long–term. The removable types often do not need to be worn all the time but only at night or even less to maintain dental alignment while we enter our golden years.