Custom trays: What advantages do they offer over stock bleaching trays?

The superior fit of custom-made bleaching trays can help to enhance the whitening process and minimize user discomfort.

As an alternative, stock trays (like those that come in store-bought kits) can be worn. However, they do have some disadvantages. People who wear Invisalign® aligners or Essix retainers may wonder if they can be used as whitening trays.

What are "custom" bleaching trays?

Just in case you don't already know, the term "custom tray" refers to whitening trays that are fabricated in a dental laboratory, specifically for that person who will wear them.

When they're made, a dentist starts off by taking impressions of their patient's teeth and surrounding gum tissue. These impressions are then used to create plaster casts. The trays are then fabricated directly on the casts, thus ensuring an accurate and customized fit.

What features need to be customized?

1) The tray's outline.

One of the biggest advantages that a custom bleaching tray can offer (as compared to a stock tray) is the way that it has been trimmed to fit along the wearer's gum line.

A tray's edges should fully cover over the surface of each individual tooth, yet not significantly cover over any portion of the user's gum tissue. Here's why:

A) Properly trimmed tray edges help to minimize gum tissue irritation.

A design where the edges of the whitening tray lie just short of the gum line can help to minimize the amount of soft tissue irritation that is experienced by the user during the bleaching process.

1) A properly trimmed tray can help to minimize the contact of (potentially irritating) bleaching gel with the user's gum tissue. This can be especially important in those situations where a relatively higher concentration whitener is being used.

2) It's also possible that the edge of a poorly trimmed bleaching tray might rub against the wearer's gums and be a source of mechanical irritation.

B) A bleaching tray should cover over the entire surface of each tooth.

If a bleaching tray falls short of covering over the entire front surface of each tooth being treated, the results of the whitening process may be compromised.

An even and uniform whitening effect can only be predictably produced with the use of a properly designed tray.

2) The tray's fit.

When a bleaching tray is worn it needs to stay in place well, especially if a person expects to perform their whitening treatments when others are around. The fabrication process used to make custom trays can be counted upon to provide this type of fit.

3) The addition of "reservoirs."

An added advantage of custom trays is that they can be designed so they have bleach reservoirs.

These are small spaces that run along the front side of a tooth that hold an additional quantity of bleaching gel. Due to the presence of this extra amount of whitener, the tooth surface underneath receives exposure to a greater number of bleaching molecules.

The need for reservoirs is not universally agreed upon. For more information, use this link: Bleaching Tray Reservoirs.

Stock bleaching trays.

As compared to their custom counterparts, the stock bleaching trays that come with store-bought kits (including those trays that can be user modified) cannot predictably offer the same features and advantages. However, for many people, the results they can provide are perfectly satisfactory.

1) Stock trays don't usually have a proper fit over the teeth.

One common problem with stock bleaching trays is that they don't cover over the entire front side of the teeth being treated.

And when they don't, it may be impossible for a person to create an even whitening effect (the tray-covered parts of the teeth may lighten more than the uncovered portions do).

2) Stock trays usually cover over gum tissue.

Essentially all stock whitening trays will extend over the wearer's gum tissue to some extent.

1) It's possible that this contact may cause mechanical irritation. Of course, a simple solution for this problem is to trim back the offending portion of the tray.

2) Usually the bigger problem associated with overextended whitening trays is that they hold bleaching gel in direct contact with the wearer's gums and, as a result, cause tissue irritation.

This may not be much of a problem for most people but for some it can be. Especially in those situations where a relatively high concentration (and therefore potentially more-irritating) whitener is being used, or else the time frame associated with each individual bleaching treatment is comparatively long.

3) Stock trays may not stay in place well.

Custom trays usually have better retention than their stock counterparts. However, loose trays aren't always so much of concern.

This is because, when a tray is loaded, the whitening gel creates a cohesion effect that helps to keep even a loose-fitting one in place. (It does, however, take more whitener to adequately fill a poorly fitting tray.)

If you're performing your whitening treatments in public (like when doing errands) having snug-fitting trays may be important. If you're just at home alone, however, this issue may not be much of a concern.

Can Invisalign® aligners and dental retainers be used as bleaching trays?

People who are undergoing Invisalign® treatment or have Essix-style (clear plastic) orthodontic retainers may wonder if these appliances can be used as bleaching trays. As an answer, yes they can. However, they will tend to have those same limitations and deficiencies that we discuss above in regard to stock trays.

As disadvantages, you can probably expect that your appliance will:

• Not cover over 100% of the front side of your teeth.
• Will cover over your gum tissue more than is ideal.
• Will not have the design benefit of tray reservoirs.

As an advantage, however, Invisalign® aligners and Essix retainers usually stay in place well. And, despite the deficiencies listed above, the whitening results you get when using this type of substitute bleaching tray may be perfectly satisfactory to you.