Hygiene with aligners: the tray holds everything in the mouth against the tooth

Because aligners are removable, hygiene is assumed to be simpler than with fixed appliances. In one respect it genuinely is; in another it introduces a risk fixed appliances do not have.

The advantage is real: brush, floss and interdental brush all work on completely free surfaces, with no brackets and no wires to work around.

The problem arises while the tray is in place. By covering the crowns completely, it reduces contact between saliva and the tooth surfaces, and saliva is what buffers acids, clears sugars and supplies the minerals for remineralisation.

If the patient reinserts the aligner after eating without brushing, they seal food residue against the enamel for the following hours, in an environment where salivary clearance cannot reach.

Worse still is the habit of drinking sugary or acidic beverages with the tray in the mouth: the liquid seeps between plastic and tooth and pools exactly where saliva cannot dilute it.

The practical rule to hand over is a single one, and it should be phrased this way: with the aligner in the mouth, only water. Everything else means taking it out.

The lesions that follow are white spots at the cervical margin and on smooth surfaces, the same areas as in fixed orthodontics but reached through a different mechanism: not obstruction to cleaning, but absent salivary clearance.

Where risk is high, a high-fluoride toothpaste is indicated, and the best moment to apply it is immediately before reinserting the tray, which prolongs its contact with the surfaces.

On cleaning the tray, the first point is the water: it must be cold. Hot water deforms the thermoplastic material, and the deformation is irreversible. It is a frequent mistake and it costs a tray.

The second point is toothpaste, which should be avoided: abrasives dull the plastic, and the micro-scratches they leave retain biofilm better than a smooth surface does. A dedicated soft brush with water alone is enough for daily work.

For periodic cleaning there are dedicated effervescent tablets; coloured mouthwashes should be avoided, as they stain the plastic permanently.

Attachments deserve separate attention. They are composite bonded onto the tooth surface, with margins that retain plaque exactly as restoration margins do. A single-tuft brush run around each attachment is more effective than brushing with a conventional brush alone.

In summary: the tray reduces contact between saliva and teeth, residue trapped under a reinserted aligner sits against enamel for hours, with the tray in place only water should be drunk, cleaning is done with cold water and no toothpaste, and attachments need a single-tuft brush.