Clear aligners are removable, nearly invisible plastic trays that gradually straighten your teeth. Each tray is custom-shaped to apply gentle pressure, shifting teeth a fraction of a millimeter at a time until they reach their target positions. You swap in a new tray every one to two weeks, and a full course of treatment typically takes 12 to 18 months, though simpler cases can wrap up in as little as six months.
How Clear Aligners Move Teeth
Each aligner tray is slightly different from the one before it. When you snap a new tray over your teeth, it doesn’t quite fit, and that intentional mismatch creates a low, steady force against specific teeth. Your body responds to that pressure through a natural process: bone on the pressure side gradually breaks down, while new bone forms behind the tooth as it shifts. This remodeling cycle is the same biological mechanism that traditional braces rely on.
The force has to land in a sweet spot. Too little and nothing moves. Too much and you risk damaging the root or surrounding tissue. Research on the fluid pressure inside the ligament that anchors each tooth suggests the ideal range is quite narrow, which is why treatment planning involves detailed 3D scans and software simulations before a single tray is manufactured.
What They’re Made Of
Most aligners are made from one of two medical-grade thermoplastics. The most common is a modified form of polyethylene terephthalate (known as PETG), which is the same family of plastic used in food-safe containers. It’s stiff enough to push teeth, transparent, and scores high on biocompatibility testing. The second most common is a high-hardness thermoplastic polyurethane (TPU), which has a slightly higher stiffness and heat tolerance. Some newer systems use multilayered materials that sandwich different plastics together for a combination of flexibility and strength.
Regardless of the specific plastic, the trays are thin (usually under a millimeter), BPA-free, and designed to handle the warm, wet environment of your mouth without breaking down during the one to two weeks you wear each set.
What Aligners Can and Can’t Fix
Clear aligners work well for mild to moderate crowding, gaps between teeth, and certain bite adjustments like expanding the back teeth or tipping molars into better position. They’re also effective for minor intrusion, where a tooth needs to be pushed slightly deeper into the jawbone.
Some movements are harder to pull off with plastic trays alone. Pulling a tooth downward (extrusion), correcting severe rotations, uprighting a tilted molar, and closing large gaps left by extractions all present challenges. These movements aren’t impossible, but they often require small tooth-colored bumps called attachments bonded to your teeth to give the aligner something to grip. Without attachments, the smooth, rounded shape of certain teeth lets the tray slide rather than transmit force, a problem orthodontists sometimes call the “traffic cone effect.” Attachments create flat surfaces and leverage points so the aligner can rotate, pull, or torque a tooth more predictably.
Severe skeletal jaw discrepancies, meaning problems rooted in the size or position of the jawbone itself, generally fall outside what aligners can address.
How They Compare to Traditional Braces
In a comparative study of adult patients, those wearing clear aligners reported significantly less discomfort than those with conventional metal braces. On a 10-point pain scale, aligner wearers averaged 2.3 compared to 5.6 for braces wearers. That gap was widest at the start of treatment (3.1 versus 6.8) and narrowed over time, but aligner patients consistently reported less pain at every stage.
Aesthetic satisfaction told a similar story: aligner patients rated their appearance at 9.2 out of 10, versus 6.5 for braces patients. For adults who work in client-facing jobs or simply prefer discretion, that near-invisibility is often the deciding factor.
The removability of aligners also changes the hygiene equation. With braces, food gets trapped around brackets and wires, making brushing and flossing more difficult. With aligners, you pop them out before eating, brush your teeth normally, and put the trays back in. There are no dietary restrictions on hard or sticky foods.
The tradeoff is discipline. Braces work 24 hours a day whether you think about them or not. Aligners only work if you actually wear them.
Daily Wear Requirements
Clear aligners need to stay in your mouth for about 22 hours a day. That leaves roughly two hours total for eating, drinking anything other than water, brushing, and flossing. Falling significantly short of that 22-hour target slows tooth movement and can throw off the entire treatment plan, potentially requiring additional trays or extended timelines.
Each set of trays is worn for one to two weeks before you move to the next set in the sequence. Your orthodontist or dentist will specify the schedule based on how your teeth are responding. Skipping ahead to a later tray is a bad idea, since the teeth won’t have had time to settle into position, and forcing a tray that doesn’t fit can damage roots or gum tissue.
In-Office Treatment vs. Mail-Order Kits
Clear aligners are available through two broad channels: in-person treatment supervised by an orthodontist or dentist, and direct-to-consumer mail-order services. The clinical difference between these two paths is substantial.
In-office treatment starts with a full diagnostic workup: X-rays, bite analysis, gum health assessment, and evaluation of the bone supporting your teeth. Regular checkups (typically every six to eight weeks) let the provider catch problems early and adjust the plan. If a tooth isn’t tracking as expected, the orthodontist can order refinement trays, add attachments, or change the movement strategy.
Mail-order services generally rely on at-home impression kits or brief in-store scans, with monitoring done remotely through photos. Comprehensive diagnostics like X-rays are often skipped. Moving teeth without evaluating underlying bone or gum health can lead to complications, and without in-person evaluations, problems like improper bite shifts may go unnoticed until they’ve progressed. These services are typically designed for mild cosmetic corrections and aren’t equipped to handle bite issues, significant crowding, or jaw discrepancies.
Straight teeth don’t automatically mean a healthy bite. Proper alignment includes even pressure distribution across all teeth, reduced jaw strain, and long-term stability. Orthodontic supervision accounts for full bite function, not just the appearance of the front teeth.
Keeping Your Aligners Clean
Simply rinsing your trays under tap water is the least effective way to clean them. Biofilm (the slimy bacterial layer that builds up on any surface in your mouth) sticks to the plastic and needs more than a rinse to remove.
A systematic review of cleaning methods found that the best approach combines mechanical and chemical cleaning. Brushing the aligners with toothpaste removes the bulk of the biofilm, and pairing that with an antibacterial soak, like effervescent cleaning tablets, improves results further. If you have access to an ultrasonic jewelry-style cleaner, using it with a detergent solution was the single most effective protocol tested.
A few things to watch out for: chlorhexidine-based mouthwashes are effective at killing bacteria but are known to stain surfaces, including both your teeth and your aligners. And while ultrasonic cleaners scored well for biofilm removal, microscopy showed they can roughen the surface of certain aligner plastics, which could make bacterial buildup worse over time. For most people, gentle brushing plus a daily soak in a dedicated aligner cleaning solution strikes the best balance between hygiene and preserving the tray surface.
Cost and Treatment Length
Full clear aligner treatment through an orthodontist or dentist typically costs between $3,000 and $8,000, with most cases falling in the $4,500 to $5,500 range. Minor corrections using limited tray systems can run $1,800 to $3,500, while complex cases requiring comprehensive treatment may reach $8,000 or more. Many dental insurance plans cover a portion of orthodontic treatment, and most providers offer monthly payment plans.
Treatment length depends on how much movement your teeth need. Simple spacing or mild crowding cases may finish in six months. Moderate corrections typically take 12 to 18 months. More complex situations can stretch to two years, especially if refinement trays are needed at the end to fine-tune the result. After active treatment, you’ll wear a retainer (often just at night) to keep your teeth from drifting back toward their original positions.