Clear Aligner Problems: Not Fitting, Cutting, Broken, Lost

What are common clear aligner problems, and how are they solved?

Most problems that come up during clear aligner treatment are minor and can be solved at home: the aligner not fitting fully, its edge bothering the tongue or gums, breaking, getting lost, yellowing, odor, temporary changes in speech and the pressure felt when switching to a new aligner. On this page we cover each problem separately: what causes it, what you can do at home and when you need to call the clinic. The general rule is: do not go without an aligner, do not force it in despite pain, and call the clinic when you are unsure. It helps to first look at the how to use clear aligners page for the basic rules of wearing aligners.

The aligner doesn't fit fully; there is a gap between the teeth and the aligner

When you switch to a new aligner, seeing a small gap over the front teeth or over one or two teeth is common; the aligner has not yet moved the tooth to its new position. However, if the gap does not close within a few days, the teeth are falling behind the plan. The usual causes are insufficient wear (less than 20 hours a day), switching to the next aligner too early, not using chewies, or that tooth moving more slowly than expected.

What to do:

1. Bite on a chewie (a silicone roll that seats the aligner) over the area with the gap for 3–5 minutes several times a day.
2. Wear the aligner close to 22 hours a day; make up for any missed wear.
3. If it does not improve within two or three days, go back to the previous aligner and wear it for a few more days.
4. If the gap lasts more than a week or appears on more than one tooth, call the clinic. The orthodontist may extend the aligner interval or take a new scan and plan a refinement series.

Continuing to force in an aligner that does not fit steers the teeth in the wrong direction; reporting the problem early protects your treatment timeline.

The aligner cuts my tongue or gums

Aligner edges are trimmed along the gum line; sometimes an area is left a few millimeters too long or the trimmed edge is sharp. This can cause small sores and tenderness on the tongue, inside the lip or on the gums. Attachments bothering the tongue, on the other hand, are part of an adjustment period that usually passes within a week.

What to do:

• Very gently smooth the irritating edge with a clean nail file or fine sandpaper; do not shorten it too much, or the fit of the aligner will suffer.
• An oral protective gel from the pharmacy or orthodontic wax can be applied to the sore area.
• Rinsing with warm salt water speeds up healing.
• If the edge cuts the same spot on more than one aligner, show it to the clinic; the orthodontist can adjust the aligner or update the trim line with the manufacturer for the following aligners.

Gum bleeding or swelling may be a sign of inflammation rather than a cut; this should be reported to the clinic.

The aligner broke or cracked

Breakage usually comes from removing the aligner by pulling on the front teeth, biting while wearing it, clenching, or putting the aligner in a pocket. Small cracks may not affect the fit; large breaks disrupt the force the aligner applies.

What to do:

• If there is a small crack and the aligner fits fully, keep wearing it and let the clinic know.
• If the aligner has split in two or a piece has broken off, do not use it. Put in the previous aligner and call the clinic. Depending on how the plan is progressing, the orthodontist may let you move to the next aligner or order a new one.
• Do not try to repair the aligner with glue; adhesives are not safe for the mouth and distort the aligner's shape.

To prevent breakage, always remove the aligner starting from the back teeth and carry it in its case.

The aligner is lost

A lost aligner usually starts as an aligner wrapped in a napkin and left at a restaurant. The habit of putting the aligner in its case prevents most of this problem.

What to do:

1. Put in the previous aligner. This keeps the teeth from shifting back.
2. Call the clinic right away. Depending on the condition of the teeth, the orthodontist may let you move to the next aligner early or order a replacement for the lost one.
3. Do not go without an aligner: a few days without one causes the teeth to shift back and the next aligner not to fit.
4. If you do not have a spare aligner and are traveling, contact the clinic as soon as possible; with some systems an extra aligner may involve an additional charge, so it is useful to find out in advance.

The aligner turned yellow or cloudy

Yellowing comes from colored drinks, smoking and insufficient cleaning; cloudiness is usually micro-scratches from using toothpaste or a hard brush. Neither interrupts treatment; since aligners are changed every 7–14 days, each new aligner starts out clean. The solution is to drink only water while wearing the aligner, brush it morning and evening with liquid soap, and use a cleaning tablet two or three times a week. The detailed routine is on the how to clean clear aligners page.

The aligner smells

Odor is a sign of a bacterial film building up on the aligner surface. Putting the aligner in without brushing your teeth after eating, wrapping it in a napkin and neglecting to clean your tongue all make the odor worse. Brushing the aligner with liquid soap, soaking it in a cleaning tablet and brushing your teeth and tongue after every meal eliminate the odor. If the odor comes with gum bleeding or tooth sensitivity, it may be gum inflammation; in that case, see your dentist.

My speech has changed; I'm lisping

Because the aligner reduces the space between the tongue and teeth, sounds such as s, sh and z may change in the first days and saliva may increase. This is a temporary adjustment period; most people get used to it within 3–7 days. Reading aloud, talking on the phone and continuing to speak without taking the aligner out speed up adjustment. Removing the aligner often delays it. If a noticeable speech problem lasts more than two weeks, the clinic can check whether the aligner edges are too long.

My teeth hurt

A feeling of pressure and tenderness lasting 2–3 days when a new aligner is put in is normal; it shows that force is being transmitted to the teeth. This feeling is especially noticeable when biting and lessens with later aligners. Switching to a new aligner at night makes the first hours more comfortable. A pain reliever approved by your doctor can be used when needed; ask your dentist or pharmacist about which medication to take.

Pain symptoms that mean you should call the clinic:

• Throbbing pain in a single tooth that worsens with hot and cold (this may be a cavity or nerve problem)
• Noticeable looseness in a tooth
• Swelling, bleeding or pus in the gums
• Pain in the jaw joint, jaw locking or difficulty opening the mouth
• Pain that lasts more than a week and does not ease

An attachment came off

An attachment (a tooth-colored composite bump bonded to the tooth surface) coming off does not stop treatment, but it can disrupt the planned movement of that tooth. Keep wearing the aligner and inform the clinic; the attachment is rebonded as soon as possible or at the next appointment. If more than one attachment has come off, it is appropriate to ask for an earlier appointment.

Gum recession and sensitivity

Clear aligner treatment does not directly cause gum recession; however, in patients with thin gum tissue, tooth movement can make existing recession more noticeable. Gum redness and bleeding usually come from bacterial plaque building up under the aligner. Do not skip brushing and flossing; if bleeding continues, see your dentist for a tartar cleaning. Gum health is one of the things that should be evaluated before starting treatment; details are on the who are clear aligners suitable for page.

When should you call the clinic?

• If the aligner has not fit for more than two or three days
• If the aligner is broken or lost
• If a cutting edge has not improved with home care
• If a tooth feels loose, or there is gum swelling or pus
• If there is severe pain or pain lasting more than a week
• If an attachment has come off
• If your dentist has planned a procedure that changes the shape of a tooth, such as a filling, crown or extraction

Most problems are solved with a small adjustment when reported early; when reported late, they may require a refinement series and extra time. For the general course of treatment, see the how clear aligner treatment works page, and for the typical experience week by week, the living with clear aligners page. Your orthodontist decides at the examination what each symptom means and what should be done.