- Clear aligners cannot do everything. If someone tells you they can fix any case, it is worth asking a second question.
- Each aligner moves a tooth about 0.2 mm. That is why you need many aligners and a fair amount of time.
- At our clinic in Busan, about 40% of patients need at least one new set of aligners made during treatment.
- The key factor is not the brand. It is how many hours a day you actually wear the aligners.
Clear aligners are hard to see, you can take them out to brush, and eating is easier. Those advantages are real. But they also feed a common misunderstanding in the consultation room: the idea that clear aligners can simply fix everything.
This column explains which tooth movements work well, which ones are difficult, and what to check before you start. If you live in Korea or are just visiting, it may help you ask better questions.
At our English-speaking dental clinic in Seomyeon, you get 1:1 English interpretation from your first consultation through the end of treatment. So you can ask every question below in your own language.
How do clear aligners move your teeth?
Clear aligners are thin, transparent trays. Each tray is shaped very slightly differently from the way your teeth sit right now. Your teeth slowly move to close that small difference.
One aligner moves a tooth about 0.2 mm. That is a tiny distance. So you switch to the next aligner in the series, and the teeth move step by step.
Put simply, the treatment repeats the same loop many times.
- The dentist works out which movements your teeth need.
- A series of aligners is made, each one slightly different from the last.
- You wear one aligner, and your teeth move toward its shape.
- You switch to the next aligner and repeat the cycle.
This is why aligner treatment needs many trays and a fair amount of time. A tiny step per tray adds up to real movement over the whole series.
Many patients also ask what it feels like. Try pressing one of your teeth firmly with a finger for three seconds. You will feel a dull ache.
Expect that same feeling for a few days each time you switch to a new aligner. For most people it is more of a pressure than a sharp pain.
Can clear aligners handle every kind of tooth movement?
This is the heart of the matter. Clear aligners do not produce every type of movement equally well. Some movements are routine, and others are hard to achieve with aligners alone.
| Type of movement | With aligners |
|---|---|
| Tipping a tooth sideways | Works well |
| Tilting protruding front teeth back | Usually works well |
| Closing small gaps between teeth | Works well |
| Moving a whole tooth, root included, in a straight line | Difficult |
| Rotating a round tooth | Difficult |
| Pulling a tooth further out of the gum | Difficult |
| Moving back teeth a long way backward | Difficult |
| Closing large spaces left by extracted teeth | Very difficult |
Why is there such a gap between the two groups? A clear aligner wraps around the tooth and pushes it. A push is good at tipping a tooth over.
Standing a root upright is a different job. So is pulling a tooth further out of the gum. A simple push is not well suited to either one.
Round, smooth teeth are a special problem. Canines, for example, give the aligner nothing to grip. The plastic tends to slip around the tooth instead of turning it.
So the first question is not which aligner to choose. It is which movements your teeth actually need.
Why are attachments and IPR often part of the plan?
To handle the harder movements, dentists usually add one or both of two tools. You should hear about both before you agree to a plan.
Attachments
Attachments are small bumps bonded to the surface of your teeth. They give the aligner something to hold, so it can push in the right direction.
Rotation and root movement become possible because of them. They are close to your tooth color, so they are not obvious from a distance.
However, saying that nothing gets attached to your teeth is not accurate. Most difficult movements need attachments. If several sit on your front teeth, people can see them up close.
Your speech may sound slightly different for the first few days. Most people adjust within a week.
Interproximal reduction (IPR)
IPR means very lightly polishing the sides of neighboring teeth to create a little space. It is a way to make room without taking teeth out.
Sometimes it is needed. But you should hear in advance how much will be removed and why.
This point comes up often in real patient disputes in Korea. Reported cases involved excessive IPR and poor explanation.
Both tools are common parts of aligner treatment. The point is not to avoid them at all costs. It is to hear about them clearly before treatment starts.
| Item | Attachments | IPR |
|---|---|---|
| What it is | Small tooth-colored bumps bonded to the teeth | Very light polishing between teeth |
| Why it is used | Gives the aligner a grip for rotation and root movement | Creates space without extracting teeth |
| Can others see it? | Hard to notice, but visible up close on front teeth | Not an add-on you can see |
| What to ask | How many, and on which teeth? | Is it needed, how much, and why? |
Why does clear aligner treatment sometimes take longer?
We want to be honest about this. Among our own patients, about 40% need at least one new set of aligners made partway through treatment.
A plan may start at around 30 weeks and end up at 60 or even 100 weeks. This is not a failure. It is a common part of the process, but one you should know about before you begin.
| Number | What it means |
|---|---|
| About 0.2 mm | How far one aligner moves a tooth |
| About 40% | Share of our patients who need at least one new set of aligners |
| Around 30 weeks | An example of an initial treatment plan |
| 60 to 100 weeks | How long some of those plans end up running |
| 20 to 22 hours | The usual daily wear target |
| Within a week | When most people get used to speaking with aligners |
The usual reasons treatment runs longer are listed below.
- Not enough wear time. This is the reason we see most often.
- Teeth not following the plan. This depends on the shape of the roots and the condition of the bone.
- Lost or broken aligners along the way.
- A change of goals in the middle of treatment.
So in your consultation, ask what happens if treatment takes longer. That is a more useful question than how many weeks it will take.
Also ask when a new set of aligners is made and how much extra time it may add. Knowing this early makes a longer timeline less of a surprise.
How many hours a day should you wear clear aligners?
It is not the aligner, and it is not the brand. What matters most is how many hours a day you wear it.
Being removable brings real benefits in daily life.
- You can take the aligners out to eat.
- You can brush your teeth as usual.
- They are hard for other people to notice.
But removability is also their big weakness. While clear aligners sit in a drawer, nothing happens.
Fixed braces keep working while you sleep. Aligners stop working the moment they leave your mouth.
The usual target is 20 to 22 hours a day. That is roughly what remains after meals and brushing. If this is not kept, the plan loses its meaning.
That is why we ask about your daily routine in the consultation. Typical questions look like this.
- How many meals do you eat a day?
- Do you snack often?
- How often do you drink coffee?
If your routine means taking the aligners out many times, we look at other options with you from the start.
Taking them out briefly for a photo is fine. But if that happens several times a day, the hours run short. Add up your total time without them, and the picture becomes clear.
What should you ask before starting clear aligners in Busan?
Whichever clinic you choose, these five questions tell you a lot about the plan.
- "Can the movements my teeth need be done with clear aligners?" First find out which movements your case requires.
- "How many attachments will I have?" Check the number and where they will go.
- "Will you do IPR, and how much?" The answer should come with numbers.
- "What happens if things don't go to plan?" Ask when new aligners are made and how much extra time that may add.
- "How would it be different with fixed braces?" You need a comparison to make a real decision.
If a clinic has a staff counselor run the first consultation, we suggest asking to talk with the dentist first. Deciding which movements you need is part of the diagnosis.
Age on its own does not rule out aligner treatment. But we check the gums first. If the bone around the teeth has shrunk, the range of possible movement changes.
Also plan for the end of treatment. You will need to wear a retainer, because teeth tend to drift back after orthodontic treatment. We will cover retainers and gum health in separate columns.
Finally, keep the order in mind. Choosing the method first and then fitting the diagnosis to it is the wrong way around. The diagnosis comes first, and the appliance follows.
Frequently asked questions
Do clear aligners hurt less than fixed braces?
The feeling is different. Each aligner moves the teeth just a small amount, so the ache tends to be milder. But it returns each time you switch aligners, so think of it as discomfort spread out in smaller pieces.
Can I switch to fixed braces partway through?
Yes. If the planned movements are not happening, we sometimes change methods midway or add fixed braces to part of the mouth. It helps to talk about this possibility before you start.
Is it safe to keep plastic aligners in my mouth all day?
Studies have reported that clear aligners can release microplastics. Dental experts currently say more research is needed, and no conclusion has been reached yet. We do recommend basic care: do not clean aligners in hot water, and do not keep using a damaged aligner.
Can I get clear aligner treatment in English in Busan?
Yes. We provide 1:1 English interpretation from the first consultation through the end of treatment. To book, call 010-8555-2854, or +82-10-8555-2854 if you are calling from abroad.
Clear aligners are a good option. But they cannot do everything.
First comes the question of which movements you need.
The appliance comes after that.
Hearing "this works, and this is difficult"
is more trustworthy than hearing
that everything can be done.
At our clinic in Seomyeon, we start with the movements your teeth need.
If you are considering clear aligners, Reset Dental Clinic is near Seomyeon Station Exit 2 (5-min walk), opposite Lotte Hotel Busan. A 1:1 English interpreter stays with you from your first consultation through the end of treatment. Call 010-8555-2854 to book a consultation.
References
- KDCA National Health Information Portal, "Orthognathic surgery and orthodontic treatment" (in Korean) — what orthodontic treatment can and cannot solve
- Dental News (Korean Dental Association), "Clear aligner treatment: caution needed with attachments and IPR" (in Korean) — problems with attachment use and IPR raised by the national consumer agency
- Dental News (Korean Dental Association), "Clear aligners: IPR and treatment limits must be explained and recorded" (in Korean) — why treatment limits should be explained and documented in advance
- Dental News (Korean Dental Association), "More research needed on microplastics from clear aligners" (in Korean) — the current expert position on microplastics from aligners
- Dental News (Korean Dental Association), "Strategies for retreating side effects of adult orthodontics" (in Korean) — side effects seen in adult orthodontics and how retreatment is approached
Written by Reset Dental Clinic Support Team
Medical review Dr. Kim Hyun-joo, Head Dentist · Esthetic prosthodontics
Last updated September 19, 2026
This article is general information and does not replace diagnosis or treatment for individual patients. If you have symptoms, please see a dentist.
