There’s no single threshold your teeth need to cross before you can get braces. If you want braces for cosmetic reasons, any amount of misalignment qualifies. But if you’re looking for insurance coverage or trying to figure out whether your situation is serious enough to warrant treatment, orthodontists and insurers use specific measurements and scoring systems that draw clear lines between mild, moderate, and severe cases.
What Orthodontists Actually Measure
During an evaluation, your orthodontist takes X-rays of your skull from the side and front, along with photos and impressions of your teeth. The side X-ray, called a cephalometric radiograph, lets them measure the exact angles between your upper jaw, lower jaw, and skull base. These angles reveal whether your bite problem comes from your teeth, your jaw position, or both. A normal relationship between the upper and lower jaw produces an angle of about 2 degrees. Significant deviations from that number point toward more complex treatment.
Beyond the skeletal measurements, your orthodontist looks at several specific features of your bite: how far your upper teeth stick out past your lower teeth (overjet), how much your upper teeth overlap the lower ones vertically (overbite), whether any teeth bite in the wrong direction (crossbite), how crowded your teeth are, and whether any teeth are trapped beneath the gums or erupting in the wrong position.
Overjet, Overbite, and Open Bite Thresholds
Most people’s upper front teeth naturally sit about 2 millimeters ahead of their lower front teeth. That’s considered normal. Once that gap exceeds 2 millimeters, it’s technically an overjet. Mild overjets of 3 to 5 millimeters are common and may not cause functional problems, but they’re enough to justify braces if you want them corrected. Severe overjet, around 8 to 10 millimeters or more, often requires braces combined with other interventions, and sometimes jaw surgery.
For overbite, an overlap of 2 to 4 millimeters is typical. When your upper front teeth cover more than about 30% of your lower front teeth (roughly 4 to 6 millimeters), that’s classified as an overbite worth treating. In extreme cases, the lower teeth bite into the roof of the mouth, causing tissue damage. That level of overbite is considered automatically qualifying for treatment under most insurance scoring systems.
Open bite is the opposite problem, where your upper and lower teeth don’t meet at all when you close your mouth. Even a few millimeters of open bite can make it difficult to bite through food and may affect speech. Severe anterior open bite, where teeth only touch in the back, creates significant chewing and speaking problems.
How Crowding Severity Is Graded
Crowding is measured by the gap between how much space your teeth need and how much space your jaw provides, calculated in millimeters. Orthodontists generally classify crowding into mild, moderate, and severe categories based on that discrepancy. You can often see crowding as overlapping or twisted teeth, but the millimeter measurement determines what kind of treatment you’ll need and how long it will take.
Crowding matters beyond appearance. Overlapping teeth trap food and make flossing difficult or impossible in certain spots. Over time, this leads to more plaque buildup, a higher risk of cavities between teeth, and a greater chance of gum disease. Misaligned teeth also wear unevenly, gradually eroding tooth surfaces in ways that can’t be reversed.
When Insurance Considers Braces Medically Necessary
This is where the question of “how bad” really matters for most people. Cosmetic braces come out of pocket, but insurance coverage (particularly Medicaid and many private plans) requires proof that your misalignment is severe enough to be a health issue. Many states use a scoring system called the Handicapping Labio-Lingual Deviation index, or HLD, to make that determination.
Under this system, certain conditions qualify you automatically, with no further scoring needed:
- Cleft palate or other craniofacial anomalies
- Deep overbite where the lower teeth are actively damaging the tissue on the roof of the mouth, with visible tissue injury
- Anterior crossbite that’s causing gum recession and attachment loss around the affected teeth
- Severe traumatic injury to the dental structures
- Overjet greater than 9 millimeters with lips that can’t close comfortably, or a reverse overjet (lower teeth ahead of upper) greater than 3.5 millimeters with chewing and speech difficulty
If you don’t meet any of those automatic qualifiers, the scoring system assigns points for each problem you do have. Your overjet is measured in millimeters. Your overbite is measured. Crowding counts if the arch length shortage exceeds 3.5 millimeters. Teeth that are more than 50% blocked out of the arch score points. A posterior crossbite involving at least two adjacent teeth, one of which is a molar, adds to the total. All of these scores are added together, and you need a combined score of 26 or more to qualify as medically necessary.
The practical takeaway: mild crowding or a slightly protruding bite typically won’t meet insurance thresholds. You generally need a combination of problems, or one problem that’s quite pronounced, to hit that score.
How Orthodontists Classify Bite Problems
Beyond measuring individual features, orthodontists classify your overall bite into one of three categories based on how your back molars line up. Class I means your molars meet correctly but your individual teeth may be crooked or crowded. This is the most common type and the easiest to treat. Class II means your lower jaw sits too far back relative to your upper jaw, creating a profile where the chin looks recessed and the upper teeth protrude. Class III is the reverse, where the lower jaw juts forward and the lower teeth sit ahead of the upper teeth.
Class II and III problems tend to be more functionally significant because they affect not just how your teeth look but how your jaw operates. Misalignment at this level can cause difficulty chewing, speech changes, a shift from nose breathing to mouth breathing, and habitual cheek or tongue biting.
The Link to Jaw Pain
People often wonder whether their bite is bad enough to cause jaw joint problems. Research on this connection is nuanced. Certain specific bite features have been identified as risk factors for temporomandibular joint issues: overjet greater than 6 to 7 millimeters, anterior open bite, unilateral posterior crossbite, and missing five or more back teeth. However, most people with these features never develop jaw pain or dysfunction. A bad bite increases your statistical risk but doesn’t guarantee problems.
Screening Age for Children
The American Association of Orthodontists recommends children have their first orthodontic evaluation by age 7. That sounds early, since most kids still have a mix of baby and adult teeth at that age, but the point isn’t necessarily to start treatment. It’s to catch specific problems that benefit from early intervention: abnormally narrow arches causing crowding, anterior crossbites that could affect jaw growth, and adult teeth trapped beneath the gums that need help erupting.
Most kids evaluated at 7 are told to come back in a year or two for monitoring. But for the ones who do need early treatment, catching the problem while the jaw is still growing can simplify or even eliminate the need for more extensive work later. Phase one treatment at this age typically focuses on guiding jaw development rather than straightening individual teeth.
Do You Need Braces If Your Teeth Are “Not That Bad”?
Plenty of people get braces for teeth that fall well below the medical necessity threshold. Mild crowding, small gaps, or a slight overjet won’t damage your health, but they’re still valid reasons to pursue treatment if they bother you. The distinction between cosmetic and medically necessary only matters for insurance purposes.
On the other hand, some people with clearly misaligned teeth skip treatment and do fine for decades. The real risks of leaving moderate to severe misalignment untreated are cumulative: harder-to-clean teeth gradually develop more cavities and gum problems, uneven wear slowly erodes enamel, and functional issues like difficulty chewing or mouth breathing can affect nutrition and sleep quality over time. The worse the misalignment, the faster those consequences tend to accumulate.
If you’re unsure where you fall, an orthodontic consultation will give you specific measurements and a clear picture of what treatment would accomplish. Most orthodontists offer free or low-cost initial evaluations, and there’s no obligation to proceed.