Types of orthodontic retainers - 1) Removable (Essix, Hawley, Vivera®).   2) Permanent (fixed, bonded, lingual wire).

- Which makes the best choice? / Applications / Advantages & Disadvantages / Pictures

Orthodontic
Retainers

Once your dentist has finished straightening your teeth, the retention phase of your treatment will begin.

During this phase (which, at least in theory, can last the remainder of your life), you will be required to wear some type of dental retainers. This is true no matter what kind of braces or orthodontic system was used.

Types of orthodontic retainers.

There are generally two kinds of dental retainers, Removable and Fixed.

And just as their names imply, they differ by way of the fact that one type is permanently attached (bonded) to your teeth whereas the other is just worn according to your dentist's instructions.

There's no single best type.

Make sure to quiz your dentist about which of these types of appliances they'll consider for use with your case because, as this page outlines, each kind has its own distinct advantages and disadvantages. Not in just how they accomplish their job, but what they're like to wear.

Also, don't overlook the fact that it's common that a different type of appliance is used on each arch. The most common configurations are: 1) Hawley upper, permanent lower. 2) Essix upper, permanent lower.


A) Permanent orthodontic retainers.

Other terms used to refer to "permanent" appliances are "bonded" or "fixed" retainers. That's because they're attached directly to your teeth. They cannot be removed.

A Permanent (lingual wire) orthodontic retainer.

A permanent orthodontic retainer.

Construction.
  • The simplest form of this type of retainer is one where it consists of a single strand of solid or braided wire.
  • The wire is bent so it fits passively up against the backside (tongue or palate side) of the straightened teeth.
  • It's then bonded in place using dental composite (standard dental bonding material).

Fixed retainers were first introduced in the 1970's. This was an era when many new applications for the science of dental bonding were introduced.

Examples.
  • The most common type of fixed dental retainer is a small wire that has been positioned on the backside of a patient's lower front teeth (it's sometimes referred to as a "lingual wire"). Valiathan (2008) states that this is the most frequently used retainer for lower teeth. [page references]
  • While less common, bonded retainers can also be utilized with upper teeth. Although, the patient's "bite" sometimes makes this configuration awkward or impossible.
How long is a fixed retainer left in place?

Unless there are reasons why it should be removed (see below), bonded retainers are typically left in place indefinitely. One study (Booth 2008) found that this type of appliance is capable of providing acceptable service in excess of 20 years.

Advantages and disadvantages of permanent retainers.

1) Fixed retainers make it harder to clean your teeth.

The biggest disadvantage of bonded retainers is that they make it more difficult for the patient to brush and especially floss.

Study - Cleaning difficulty. - Sawhney (2013) polled subjects who wore different types of orthodontic retainers. One question asked was how difficult it was to maintain oral hygiene.

  • In regard to upper retainers, bonded ones were considered the most difficult to clean (24%) vs. Hawley (8%) and Essix (4%).
  • Similar findings were found with lower appliances (the most frequent application for fixed retainers) at a rate of 33% vs. Essix (9%) and Hawley (6%).

Study - Gum inflammation. - In situations where proper maintenance isn't performed, dental plaque and tartar will tend to accumulate in the region of the retainer and this may place the person at greater risk for complications such as gum disease.

  • A study by Heier (1997) evaluated orthodontic patients that either wore removable or bonded retainers at 1, 3 and 6 month intervals.
  • It determined that while there was more plaque and tartar build up on the teeth of subjects having fixed retainers, the gum health of the groups did not vary significantly.

But don't interpret this study as suggesting that this issue is never a problem, it just shows that it isn't always. For people for whom it is, their appliance should be removed and another form of retention used.

Floss threaders. - Effective flossing around a bonded retainer typically requires the use of a floss "threader." This device allows the user to work the floss underneath their wire, so they can floss the portion of their teeth in that region.

2) With permanent appliances, compliance is never a concern.

The great advantage of bonded retainers is that the dentist does not have to rely on patient cooperation. Unlike removable retainers that may be misplaced or simply not worn, fixed appliances are always in place to perform their duty.

3) The retainer can't be seen.

Another nice advantage of permanent retainers is that due to their location on the backside of the teeth it's very difficult for others to detect them.


B) Removable orthodontic retainers.

There are two basic categories of removable dental retainers. They are the Essix and Hawley appliances. As discussed below, each type offers its own specific advantages and disadvantages.

1) Essix retainers.

Essix style orthodontic appliances are also sometimes referred to as "invisible" retainers because they're made using clear plastic. They may also be referred to as "overlay" retainers because they fully cover over the teeth. They were first introduced in the early 1970's.

Construction.

These are vacuum-formed appliances that are relatively simple to make. Many dentists fabricate them right in their own office.

An Essix orthodontic retainer.

A vacuum-formed orthodontic retainer.

  • An impression of the patient's teeth is taken and transformed into a plaster cast.
  • A thin sheet of plastic (around 0.030 inch) is then heated and using a vacuum unit is sucked down over the cast (thus creating the needed shape for the retainer).
  • The excess plastic is trimmed away. The finished appliance may cover all of the patient's teeth on the arch (upper or lower jaw) or else just some grouping of them.
Appearance.

These retainers look very similar to Invisalign® aligners. But instead of being changed every few weeks, they are worn indefinitely (per your dentist's instructions).

For Invisalign® patients, the use of Essix retainers may seem the logical choice since they are already familiar with wearing this type of appliance. And in fact, Align Technology, Inc. (the maker of the Invisalign® system), manufactures its own version of the Essix appliance called Vivera® retainers.

Advantages and disadvantages unique to Essix retainers.

Advantages.
  • When they're worn, they are fairly unnoticeable. However, similar to Invisalign® aligners there can be tip-offs that you're wearing them. And, in fact, Sawhney (2013) found that only 77% of patients who wore upper Essix retainers considered their appearance "good."
  • Our Sawhney (2013) study mentioned above found that this type of retainer interfered with maintaining oral hygiene the least.
Disadvantages.
  • While usually less so than with Hawley retainers, Essix appliances can interfere with speech. (In the same way as Invisalign® aligners.)
  • Essix retainers are non-adjustable. Your dentist can't use them to make further alignment corrections or refinements. (They can with a Hawley.)
  • An Essix retainer should be inspected regularly and examined by your dentist if a problem (tear, crack, hole or breakage) has been detected. The nature of their plastic is one where it may distort if exposed to heat (wet or dry).

    Despite their relatively flimsy appearance, some recent studies (Keenan 2012, Sun 2011) have suggested that they have a similar survival rate as Hawley appliances. Sawhney (2013) found that upper Hawley and Essix retainers has similar rates of breakage (25% vs. 23%).


2) Hawley orthodontic retainers.

Hawley appliances are the granddaddy of retainers. They were first introduced in the 1920's. And even today they are the most used type of retainer for upper teeth. (Valiathan 2010)

A Hawley orthodontic retainer.

A Hawley orthodontic retainer.

Construction.

Hawley retainers have a design that involves wires and clasps anchored in a relatively thick plastic body. The plastic aspect covers over the roof of the patient's mouth or else lies along the tongue side of their lower teeth.

The clasps grasp around selected teeth so the retainer is anchored securely. The retaining "bow" wire runs across the front side of the teeth and maintains their alignment.

Appearance.

The most noticeable feature of a Hawley retainer is the bow wire that runs across the front side the the patient's teeth. The plastic body remains well hidden. Sometimes it's constructed using plastic that has bold colors or a personalized design.

Advantages and disadvantages unique to Hawley retainers.

Advantages.
  • A Hawley retainer is adjustable. That means it can be used to further refine the alignment of your teeth. Or, if you've failed to wear your retainer faithfully, it can be adjusted so to guide your teeth back into place.
  • Hawley's appear to have a more rugged construction than Essix-style retainers. But as we mention above, recent studies have suggested that patient's experience similar survival rates for both types of appliances.
  • Where as an Essix must be replaced if damaged, a Hawley can be repaired (either it's wire or plastic components).
The bow wire on a Hawley orthodontic retainer.

The bow wires of Hawley appliances are quite obvious.

Disadvantages.
  • One of the biggest disadvantages of wearing a Hawley is its appearance. It has a bow wire that runs across the front side of the wearers teeth and it's quite obvious to others when the retainer is worn.

    However, Sawhney (2013) found only about half of Hawley wearers found its appearance objectionable (59% for upper appliances, 53% for lowers).

  • The thickness of the retainer's plastic body (especially in the area behind your upper front teeth) can interfere with speech. If you have this difficulty, however, your dentist should be able to at least minimize this problem by trimming the plastic so it's as thin as possible.

    When polling patients who wore upper retainers, Sawhney (2013) found that 82% of Hawley wearers felt that their appliance affected their speech (as opposed to 62% with Essix and 8% fixed).

    With lower retainers, these numbers were: 60% Essix and Hawley, 6% fixed.


General advantages and disadvantages of removable retainers.

Besides the specific factors outlined above for each individual type of appliance, there are some general issues associated with removable retainers that should be considered.

a) Their biggest advantage is also a disadvantage.

Just as their name implies, removable retainers can be taken out. You can remove them when you eat, brush and floss, or during those times when wearing them is not required.

The problem is, this also means that they can be lost or simply not worn (dentists call this "poor patient compliance"). And no retainer can perform its intended function if it's not in place.

b) Removable appliances may cause excessive salivation.

Wearing anything in your mouth may trick it into producing extra saliva.

That's because, to our bodies, having something in our mouth is usually a sign that a meal is coming. So in response to wearing your retainer, it will start to produce the extra saliva it thinks it will need for the upcoming "meal."

This isn't much of a problem for most people. And over time, your body should return to normal as it realizes that the extra saliva isn't required.

 

 
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