Invisalign uses a series of custom-made clear plastic trays to gradually shift your teeth into new positions. Each tray, called an aligner, applies gentle, controlled force to specific teeth, moving them in small increments over weeks and months. The result is straighter teeth and a corrected bite without the brackets and wires of traditional braces.
How the Aligners Move Your Teeth
Each set of aligners is slightly different from the last, designed to push certain teeth a fraction of a millimeter in a specific direction. When you snap an aligner over your teeth, it doesn’t fit perfectly on purpose. That small mismatch creates pressure, and your bone tissue responds by gradually remodeling around the tooth roots, allowing teeth to shift into the position the aligner is guiding them toward. You wear each set for one to two weeks before switching to the next one in the series.
The aligners are made from a material called SmartTrack, a medical-grade plastic engineered for orthodontic use. Compared to earlier aligner materials, SmartTrack adapts more closely to the shape of your dental arch and delivers more consistent force throughout each wear cycle. It’s also biocompatible, transparent, and resilient enough to hold up in your mouth for days at a time without losing its shape.
What Invisalign Can Correct
Invisalign treats most of the same alignment and bite problems that traditional braces address. The most common issues include:
- Crowding: teeth packed too tightly, causing them to overlap, rotate, or sit in front of or behind each other
- Gaps: spaces between teeth from missing teeth, jaw size, or natural spacing
- Overbite: upper front teeth overlapping the lower front teeth too much vertically
- Underbite: lower teeth sitting in front of the upper teeth
- Crossbite: some upper teeth closing inside the lower teeth instead of outside
- Open bite: upper and lower teeth not meeting when the mouth is closed
That said, some movements are harder for aligners than for braces. Pushing teeth up into the gum (intrusion), pulling back teeth downward (posterior extrusion), and rotating cylindrical teeth like canines and premolars are consistently the most challenging movements for clear aligners. Severe cases in these categories may still call for traditional braces or a combination approach.
Attachments: The Hidden Helpers
For anything beyond simple straightening, your dentist will likely bond small tooth-colored bumps to some of your teeth. These are called SmartForce attachments. They’re made of composite resin, the same material used for tooth-colored fillings, and they’re shaped and placed in precise locations custom to your treatment plan.
Attachments work like tiny handles. They give the aligner something to grip and push against, allowing it to apply force at specific angles that flat plastic alone can’t achieve. A tooth that needs to rotate, for example, might get an attachment on one side so the aligner can generate a twisting force. Without attachments, many tooth movements would be too imprecise or too slow. Your dentist removes them at the end of treatment by gently polishing them off.
The Treatment Process, Step by Step
Treatment starts with a digital scan of your teeth. Most providers use an iTero scanner, which captures 6,000 images per second to build a detailed 3D model of your mouth in just a few minutes. There’s no goopy impression tray involved.
Your dentist then uses software called ClinCheck to map out your entire treatment plan on screen. The software calculates how much force each tooth needs, which teeth should move first, and what sequence of aligners will get you from your current alignment to the final result. You can actually see a simulation of your teeth moving through each stage before treatment begins, so you’ll know what the projected outcome looks like.
Once you approve the plan, your aligners are manufactured and shipped to your dentist’s office, typically as a full set or in batches. You’ll switch to a new set every one to two weeks and visit your dentist every six to eight weeks so they can check progress, place or adjust attachments, and hand off your next round of trays.
How Long Treatment Takes
Most Invisalign treatments last between 12 and 18 months. Mild cases involving minor crowding or small gaps can wrap up in as little as 6 months, while more complex bite corrections may take closer to 24 months. The biggest variable you control is wear time: aligners need to stay in your mouth 20 to 22 hours per day. You take them out only to eat, drink anything other than water, and brush your teeth. Inconsistent wear is the most common reason treatment runs longer than planned.
A randomized controlled trial published in the Angle Orthodontist found that braces patients finished treatment roughly five months faster on average than aligner patients. However, the final quality of results, measured by a standardized scoring system, showed no significant difference between the two groups at the end of treatment or after six months of retention.
How Results Compare to Braces
For the majority of orthodontic cases, Invisalign produces results on par with traditional metal braces. The same randomized trial found that overall outcome quality scores were statistically equivalent between the two approaches. Where aligners fell slightly short was in long-term stability: alignment and overjet (how far forward the upper teeth sit relative to the lower teeth) worsened slightly more in the aligner group during the six months after treatment ended, compared to the braces group.
This doesn’t mean aligners are less effective overall. It does highlight that what you do after treatment matters just as much as the treatment itself.
What Happens After Your Last Aligner
Once your teeth reach their final positions, you’ll need a retainer to keep them there. Teeth have a natural tendency to drift back toward their original positions, especially in the first year after treatment. Without a retainer, you can lose a significant portion of the correction you spent months achieving.
Most Invisalign patients use clear removable retainers, which look similar to the aligners themselves. Vivera retainers, made by the same company, are about 30% stronger and twice as durable as other leading clear retainer brands. Initially, you’ll wear your retainer all day and night, removing it only for meals and brushing. Over time, your orthodontist will typically reduce that to nighttime-only wear. Each clear retainer lasts roughly 6 to 12 months with proper care, so you’ll replace them periodically.
Some patients opt for a bonded retainer instead: a thin wire cemented to the back of the front teeth that stays in place permanently and requires no daily compliance. Your orthodontist can help you decide which type fits your situation and how long you’ll need to wear it.