Dental trays and mouthguards: which type for which purpose?

One word, at least six different devices

A dental tray is a removable shell that covers all or part of a dental arch. Yet the term covers devices with different roles, thicknesses and materials: the occlusal splint (night guard) protects against grinding, the aligner moves teeth, the retainer holds them, the whitening tray carries a gel, the sports mouthguard absorbs impacts and the mandibular advancement device treats some forms of snoring.

This muddle of vocabulary has real consequences. A patient who says “I already have a guard” may be describing a device that is entirely wrong for the problem. And using one in place of another can, depending on the case, achieve nothing, damage the device or even move the teeth.

This article is a guide to telling them apart. It does not replace an examination, which remains essential to know which device suits you.

Recognising each tray and what it does

• The occlusal splint (night guard): made of rigid resin, thicker, worn mainly at night. Its surface is adjusted to the way you close your mouth, to spread forces and protect the enamel. Our article on teeth grinding explains its benefits and limits.
• The aligner: a thin, transparent, very close-fitting shell worn almost all day and swapped for the next one on a schedule. Each aligner differs slightly from the last, and that difference is what moves the teeth in clear aligner treatment.
• The retainer: similar to an aligner but passive. It holds the teeth after orthodontics, usually at night. Our article on retainers covers how to use it.
• The whitening tray: thin and flexible, sometimes with small reservoirs in front of the teeth, it keeps a peroxide-based gel against the enamel during supervised teeth whitening.
• The sports mouthguard: thick, soft, often multi-layered, it absorbs impacts in contact sports.
• The mandibular advancement device: two linked trays that hold the lower jaw slightly forward during sleep. It is considered after a medical sleep assessment, particularly if sleep apnoea is suspected.

There are also medication trays, for example to apply a fluoride gel in people at very high risk of decay, on prescription.

Over the counter or custom-made: what really changes

Pharmacies and online shops sell so-called boil-and-bite trays: you soften them in hot water, then bite into them so they take the shape of your teeth. They have real value in some situations, such as an occasional mouthguard for sport when nothing better is available. Their limits come from how they are designed:

• the fit is approximate, the thickness uneven, and the tray may not stay in place well;
• the bite is not adjusted: worn every night for months, an unbalanced tray can change how the teeth meet or strain the jaw joint;
• for grinding, a soft tray is not designed for the job, and in some people it even seems to encourage chewing movements;
• for whitening, a tray that overlaps the gums leaves gel in contact with them, with a risk of irritation, and the strength of products sold freely is not always clear. In Europe, regulations reserve the more concentrated products for use under a dentist's supervision.

A custom-made tray starts from an impression of your teeth. It is made in the material and thickness suited to its role, then adjusted in the mouth and checked over time. It is this tailoring, more than the plastic itself, that makes the difference.

Common mistakes: using one tray for another

Some situations come up again and again in the surgery:

• wearing an old aligner as a night guard for grinding: it is too thin and soon cracks under clenching, and if it no longer matches the current position of the teeth, it can apply unwanted force;
• putting whitening gel in an aligner during treatment without advice: some dentists allow it with a precise protocol, but it is not something to improvise;
• using a sports mouthguard at night: its thickness and softness are not meant for prolonged wear;
• buying an anti-snoring device without an assessment: snoring can mask sleep apnoea, which needs a medical diagnosis, and a poorly adjusted device can cause jaw pain or, over time, alter the bite;
• forcing in a retainer that no longer fits: if it is very tight, the teeth have moved; forcing it hurts and solves nothing;
• wearing a tray that covers only some of the teeth for a long time: the uncovered teeth can shift.

The common thread is simple: a tray acts on the teeth constantly, even when you cannot see it. It must therefore serve a precise purpose, agreed with the dentist.

How a custom tray is made

The process varies with the type of device but generally follows the same steps:

• examination: the dentist checks the teeth, gums and jaw joint and confirms the indication;
• impression: increasingly digital, with an intraoral scanner and no impression paste; for some trays, the closing position of the jaws also has to be recorded;
• fabrication: depending on the device, the tray is thermoformed over a model of your teeth or made in rigid resin by a laboratory;
• fitting and adjustment: the dentist checks that it goes in without forcing, does not hurt the gums and, for an occlusal splint, that the contacts are well balanced;
• follow-up: a review visit corrects any pressure points, and wear is monitored at later check-ups.

When the impression is digital, the file can be kept. It may make a replacement easier if the tray is lost, provided the teeth have not moved and no treatment has changed their shape in the meantime.

Wear and replacement: signs to watch for

No tray lasts for ever. How long it remains usable depends on its type, its material and how hard you clench. Signs that call for a check:

• a crack, a hole or a thinned area, common on night guards and retainers;
• a tray that floats and no longer clicks into place, or one that is unusually tight;
• distortion after contact with hot water or being left in the sun;
• a persistent smell or cloudy look despite cleaning;
• new pain in the teeth, jaw or temples on waking.

Bring your tray to every check-up, even if it looks fine: the wear facets on it give the dentist valuable clues, such as how intensely you clench at night. Suitable daily cleaning also extends its life: gentle brushing in cold or lukewarm water, no abrasive toothpaste, and always storing it in its case.

Which tray is right for you? Advice in Agdal

The right approach is to start from the problem, not the device: worn teeth or pain on waking, teeth to straighten or hold in place, a shade to lighten, a risky sport, snoring. At German Dental Clinic in Agdal, the dentist examines your teeth, gums and jaw joint, takes a digital impression if a tray is indicated, and explains which device fits your situation.

When a tray falls within another specialist's field, for example a mandibular advancement device that first requires a sleep assessment, you will be told so clearly. If you live in Rabat and are unsure which tray you need, or yours no longer fits, you are welcome to book an appointment.