Invisalign treats most of the same orthodontic issues as traditional braces: crowding, gaps, overbites, underbites, crossbites, and open bites. For mild cases like minor crowding or small gaps, treatment typically wraps up in 3 to 6 months. Complex cases involving significant bite correction or heavy rotation can take 18 to 24 months. Here’s a closer look at each condition and how the aligners handle it.
Crowding and Spacing
Crowding, where teeth overlap because there isn’t enough room in your jaw, is the most common reason people start Invisalign. The aligners work by applying incremental pressure across a series of trays, each one shifting teeth fractions of a millimeter until they line up. Gaps between teeth (including a gap between the two front teeth, sometimes called a diastema) are corrected the same way, with each tray gradually closing the space.
Mild crowding or a single gap responds quickly and predictably. More severe crowding sometimes requires the orthodontist to slim down the sides of certain teeth by tiny amounts to create room, a painless process called interproximal reduction. If teeth are severely overlapping, traditional braces may still be the faster option, but most moderate crowding falls well within Invisalign’s range.
Overbites and Underbites
An overbite means the upper front teeth sit too far ahead of the lower ones when you bite down. An underbite is the reverse, with the lower teeth jutting forward. Invisalign corrects both using a combination of aligner trays and small rubber bands (elastics) hooked between upper and lower teeth.
For an overbite, elastics typically run from the upper canines down to the lower molars, pulling the upper teeth back and the lower teeth forward. For an underbite, the pattern flips: rubber bands hook from the top back molars to the lower canines. The elastics apply a steady directional force that the aligners alone can’t generate. You attach them yourself, and they’re replaced daily.
Bite correction adds complexity and time. Expect treatment closer to the 18 to 24 month range rather than the shorter timelines for simple alignment cases.
Open Bites
An open bite means your front teeth don’t touch when you close your mouth, leaving a visible gap between the upper and lower rows. It can make biting into food difficult. Invisalign addresses this by slowly pushing the front teeth downward (extruding them) until they meet. At the same time, the plastic covering on the back teeth helps prevent the molars from drifting further apart, which would make the open bite worse.
The mechanism differs depending on the cause. When the open bite is primarily dental (caused by tooth position rather than jaw structure), treatment focuses on bringing the upper incisors down. When it has a skeletal component, the lower incisors are extruded instead, and the overall angle of the lower jaw shifts slightly. Aligners are considered a viable option for open bite treatment because the material itself acts as a bite block on the back teeth, giving the orthodontist better vertical control than you might expect from plastic trays.
Crossbites
A crossbite occurs when some of your upper teeth sit inside the lower teeth instead of outside them. It can happen in the front (anterior crossbite) or on the sides (posterior crossbite). Left untreated, crossbites can cause uneven wear, jaw pain, and gum recession on the affected teeth.
Invisalign treats crossbites by widening the arch or shifting individual teeth into their correct positions. Studies on younger patients in early mixed dentition (a mix of baby and adult teeth) have shown reliable correction of both anterior and posterior crossbites with clear aligners, particularly when the arch only needs about 5mm of expansion. In adults, the approach works similarly for dental crossbites, though a skeletal crossbite caused by a narrow upper jaw may need additional intervention.
Rotated Teeth
A rotated tooth is one that has twisted in its socket so it faces the wrong direction. Invisalign handles rotations up to about 20 to 30 degrees reliably. Beyond 30 degrees, the aligners lose their grip on the tooth and struggle to generate enough torque. Small, round teeth like lower premolars are especially tricky because the aligner has less surface area to push against.
To improve control over rotations, orthodontists bond tiny tooth-colored bumps called attachments onto specific teeth. These are roughly the size of a sesame seed and act as handles, giving the aligner something to push on so force transfers more precisely. Attachments are also used for other difficult movements like pulling a tooth downward or tilting a root into place. They’re removed at the end of treatment without damaging enamel.
Treatment for Children
Invisalign isn’t only for adults and teens. A version designed for younger children (roughly ages 6 to 10) addresses issues in the early mixed dentition stage, when baby teeth and permanent teeth coexist. At this age, the goals are typically arch development, correcting crossbites, managing crowding before it worsens, and closing small gaps caused by early tooth loss.
A prospective study of 100 young patients found clear aligners effective for anterior crossbite, posterior crossbite, deep bite, crowding, and spacing in this age group. Cases involving mild jaw constriction (up to about 5mm of expansion needed) and certain bite patterns with functional shifts responded particularly well. For children who feel self-conscious about metal braces during formative social years, clear aligners offer a less visible alternative without sacrificing results in appropriate cases.
How Results Compare to Traditional Braces
A randomized controlled trial comparing Invisalign to conventional braces found no statistically significant difference in final treatment outcomes. Both groups scored similarly on a standardized grading system used to evaluate tooth alignment, bite fit, and root angulation. After six months of retention, the results still held steady with no meaningful difference between the two groups.
Where braces tend to have an edge is speed. The same trial noted braces finished faster on average. Invisalign also depends more heavily on patient compliance: you need to wear the trays 20 to 22 hours a day and swap to the next set every 7 to 14 days as prescribed. Falling behind on wear time is the most common reason treatment stalls.
What Invisalign Can’t Fix
Invisalign has expanded its range significantly over the past decade, but some situations still call for braces or even surgical intervention. Tooth rotations beyond 30 degrees, large vertical discrepancies caused by skeletal jaw growth, and cases requiring significant tooth movement in three dimensions simultaneously can exceed what the aligners deliver. Severe skeletal underbites or overbites where the jaw bones themselves are misaligned (rather than just the teeth) typically need more than any orthodontic appliance alone.
Your orthodontist will take scans and X-rays to determine whether your specific case fits within Invisalign’s capabilities. Many cases that would have required braces five or ten years ago are now treatable with aligners, but the evaluation matters.
Keeping Results After Treatment
Teeth have a natural tendency to drift back toward their original positions after any orthodontic treatment, whether you had braces or Invisalign. Retainers are essential for preventing this. Most orthodontists recommend wearing a retainer full-time for the first few months after treatment, then transitioning to nighttime-only wear indefinitely. The retainers look and feel similar to aligner trays, so the adjustment is minimal if you’ve already spent months wearing Invisalign.