Invisible orthodontics: clear aligners

Wear time is what decides the result

That is the one thing to take away. An aligner left on the bedside table moves nothing, and the treatment falls behind tray after tray.

Twenty to twenty-two hours a day means: out for meals and brushing, back in straight afterwards. In practice that leaves about two hours of freedom a day, meals included.

What aligners do well, and less well

• Well: moderate crowding, gaps, realigning the front teeth, relapse after an old treatment
• Less well: large rotations of canines or premolars, extrusion, major root movement

Those limits are partly worked around with small composite attachments bonded to certain teeth, giving the tray something to push against. They are removed at the end of treatment.

How it runs

• Assessment: clinical examination, panoramic X-ray, photographs, 3D digital impression
• Simulation of the planned movement, discussed before approval
• Manufacture of the full series of trays
• Handover of the first ones, attachments placed, wear explained
• Reviews every six to eight weeks
• Retention once the trays come out — the stage people underestimate

The first days of each tray

Pressure and tenderness on chewing come with each change of tray. They last a day or two then fade: that is the sign the tooth is moving, not that something is wrong.

Changing tray in the evening means the most sensitive phase passes during sleep.