How aligners move teeth
Each tray is made to a shape a fraction different from where your teeth sit now. Seated, it flexes over the teeth and pushes them toward that shape. Steady light pressure remodels the bone around the root, which is how teeth move whether the force comes from a tray or a wire.
The sequence is planned in advance from a scan and the trays are made in order. You wear each for the interval you are given, usually a week or two, then move to the next. The movement per tray is small on purpose: heavier force does not move teeth faster, it damages the ligament and can shorten roots.
Attachments, IPR and the parts not in the advertising
Aligner treatment involves more than the trays. These come up in most cases, and they are easier to accept when nobody springs them on you halfway through.
- Attachments
- Small tooth-colored bumps bonded to certain teeth to give the tray something to grip. Without them a smooth tray slides over a rounded tooth instead of turning it. They come off at the end.
- Interproximal reduction
- Called IPR. A fraction of a millimeter of enamel is polished from between certain teeth to make room for crowded teeth to line up. It is how crowding is resolved without extracting anything.
- Buttons and elastics
- Some bite corrections need elastics hooked between the upper and lower arches, attached to small buttons. They are visible while worn, and you hear about them before you start.
- Refinements
- A second set of trays made partway through, once the teeth have moved and the plan needs updating against reality. Most cases have at least one round, and it is routine rather than a sign of failure.
What aligners handle, and what they struggle with
Aligners have improved and the limits have not disappeared. The honest split looks like this.
- Handled well: crowding and spacing. Mild to moderate crowding, gaps, and relapse after teenage braces. This is most adult treatment.
- Handled well: tipping teeth into line. Teeth that need tilting rather than moving bodily respond predictably.
- Handled well: alignment before restorative work. Small targeted movement so a crown, bridge or implant fits properly.
- Difficult: severe crowding. When teeth must travel a long way, or teeth have to come out for room, fixed appliances control the outcome better.
- Difficult: round teeth and large rotations. Canines and premolars are close to cylindrical, and a smooth tray has little to grip when it needs to spin one. Attachments help without solving it.
- Difficult: bite discrepancies and molar movement. Correcting a marked overbite, underbite or crossbite, or moving molars bodily through bone, is where aligners are least predictable and a referral beats an optimistic plan.
Which group you are in is a records question, not a photograph question. Orthodontics covers what gets referred.
Supervised treatment and mail-order aligners
Aligners bought online from a company that never examines you are a different product from aligners planned in a dental office.
| Consideration | Planned in a dental office | Mail-order aligner kits |
|---|---|---|
| Examination and x-rays | A full examination and x-rays before anything moves, so decay, infection and bone loss are found first. | A self-taken impression or a kiosk scan. No x-rays, and nobody looks in your mouth. |
| Gums and bone | Assessed and treated first, because moving teeth through diseased gum tissue loses bone. | Not assessed. Bone loss you cannot see does not stop the trays shipping. |
| Attachments and IPR | Available, which is what makes rotations and crowding correctable. | Generally not, so the plan is limited to what a plain tray can do. |
| When it goes wrong | The dentist who planned it is responsible, and you can walk in. | A support queue, and a bite you may end up paying a dentist to correct. |
Retainers are not optional
The day the last tray comes out, the teeth are held by fibers that have spent months being stretched, and those fibers pull. Without retention teeth relapse toward where they started. Most adults we treat for crowded lower front teeth had braces once and stopped wearing the retainer.
Plan on a removable retainer worn at night with no end date, a thin wire bonded behind the front teeth, or both. A bonded wire needs checking, because one that comes loose at one end can move a tooth by itself.
Invisalign questions
Will Invisalign work for my teeth?
It depends what has to move and how far. Some cases suit aligners, some need fixed braces, and some need a specialist. Records and an examination answer that, not a photograph.
Does it hurt?
The first two or three days on each new tray feel tight and teeth can be tender to bite on. It fades. Changing trays before bed helps, because you sleep through the worst.
Can I drink coffee with them in?
Water only. Hot drinks can distort the plastic, and anything sugary or acidic sits against enamel with nowhere to drain. That is how people finish with straight teeth and new decay.
How much does it cost, and does insurance help?
The fee depends on the number of trays and the complexity, so it is quoted after records, in writing. Some dental plans include an orthodontic benefit and many do not, and nobody here will tell you yours does before it is verified. See insurance and payment options.