So now that you've spent a significant amount of time, effort, energy, and resources to create a beautiful smile, you want to keep it that way! A retainer allows you to do just that - to protect and maintain the beautiful smile that we've collaborated to perfect! We have plenty of orthodontic research and literature that shows that teeth tend to have a "memory" of their previously crooked state - that is to say we need to resist their urge to return to their prior position. The fancy phrase used to describe that tendency of a tooth to move back to where it came from is Orthodontic Relapse and it's something we work very hard to prevent.
Many different types of retention (retainers) exist but the basic principles are all the same. Retainers are designed to hold the teeth in place after an orthodontist has finished moving them to their ideal position. Webster's dictionary lists these following excerpts among the definitions of "retain". (1)
Hawley retainers are the classic style of retainer you may think of when someone mentions the word "retainer".
These retainers rest on the roof (or floor) of the mouth and hug your molars and your front teeth - supporting all of the teeth with a healthy amount of acrylic resin that prevents teeth from shifting back to where they came from. The acrylic on the roof of the mouth can take a little while to get used to (temporarily creating certain speech articulation difficulties) but they're often well tolerated and can last decades with careful care and maintenance. Occasionally we'll modify this type of retainer to push teeth with springs or to pull teeth closer together if any residual space exists.
Clear retainers come in different thicknesses and materials but almost all wrap completely around a tooth to encompass whatever portion of the tooth extends above the gum-tissues. These are more beneficial in certain clinical scenarios - especially when patients will tend to be aware of "grinding" or "clenching" issues as well as when patients start out with an "open-bite" (teeth don't meet properly in the front of the mouth).
This type of retainer tend to be our "go to" or most commonly prescribed retainer (unless some scenario would indicate that another type of retainer is a superior choice). This type of retainer generally wears out a bit quicker (depending on the type of material selected). We tend to recommend replacing these every 3-5 years as they start to "wear out" past this time period. Good technique for insertion/removal as well as care and maintenance is vital to extending the lifespan of this workhorse of a retainer.
Fixed or "Permanent" retainers are bonded on to the lingual (or tongue side) of the teeth. These retainers hold the teeth steady by giving them a firm material to rest upon while resisting the forces applied from the oral musculature (tongue, lips, cheeks, etc). They are often used in concert with another removable retainer (typically a clear retainer) to maintain our permanent alignment. The inside of the teeth are generally "roughened" to facilitate a reliable "bond" and the wire or chain is thereafter "glued" to the teeth using orthodontic resins and bonding materials. As you might imagine, flossing can be a bit more challenging and thus we teach proper oral hygiene techniques when we place these retainers. For the very small proportion of patients who receive these retainers and discover they cannot keep up with the demands of oral hygiene, we will be happy to remove the fixed retainer after an arbitrary period (typically 6 months) which allows for the bone, periodontal fibers, and gingiva to stabilize around the new tooth position.
This type of retainer is highly recommended in scenarios where teeth begin in an overly crowded position or where a "gap" exists between the front teeth (referred to as a diastema).
Wait - how often and how long will I have to wear these things?
There are many different philosophies about retention however a number of orthodontic papers and research have served to clarify the situation. We now know that humans as a rule will tend to grow (or change) up into their 70s and 80s. This means that bones and tooth position are not stable but under the constant influence of changing muscle tension as well as their underlying bony support. With this in mind, I always remind patients that they only have to wear retainers "as long as they want their teeth to be straight". While this statement is a bit silly, it does allow for the truth of the constant potential for teeth to shift throughout our lives. If the rest of our bodies are constantly changing, why should our teeth be any different? Orthodontic clinicans find that teeth have the highest potential for relapse (or teeth shifting back to where they came from) soon after orthodontic treatment stops. This means that someone who stops wearing retainers 3 months after treatment is completed will have more potential for relapse then someone who stops wearing retainers 6 months after treatment is completed. That person who stops wearing retainers 6 months after treatment is completed will have more relapse-potential from someone who stops wearing retainers one year after completion and so on. The question of how much more relapse potential is a much more difficult question to answer.
The next topic of discussion is usually how long during the day should I wear my retainers? Do I have to wear them all day long? A classic orthodontic study addresses this issue and it compares relapse (or teeth shifting back to where they came from) for two groups of people. One group wore their retainers all day and all night and the second group wore their retainers just at night. From a scientific standpoint there wasn't any real (clinical) difference between the two groups lending support to the theory that night-time wear of retainers is sufficient. The truth is more complex, however, as certain tooth movements will lend themselves to a higher probability of relapse. I always advise my patients that if they can tell a tooth is trying to shift on them to please consider wearing their retainers full-time at least until we can stabilize the tooth or come up with a different game-plan for that tooth.