A crossbite is more than a cosmetic issue. Left untreated, it can wear down tooth enamel, cause gum recession, affect speech clarity, and lead to jaw pain. About 14% of children in their primary teeth have a posterior crossbite, making it one of the more common bite problems orthodontists see.
What a Crossbite Actually Is
In a normal bite, your upper teeth sit slightly outside your lower teeth when you close your mouth. A crossbite is the reverse: one or more upper teeth sit inside the lower teeth instead. This can happen in the front teeth (anterior crossbite) or the back teeth (posterior crossbite). There’s also a less common variation called a buccal crossbite or Brodie bite, where upper back teeth bite completely outside the lower teeth rather than meshing with them.
A crossbite can involve a single tooth or an entire section of teeth, and it can occur on one side of the mouth or both. The severity matters. A mild crossbite where teeth are off by a millimeter or two creates different risks than one where the upper teeth are halfway or more behind the lower ones.
How a Crossbite Damages Teeth Over Time
The most consistent problem with an untreated crossbite is abnormal enamel wear. When teeth don’t line up properly, they grind against each other at angles they weren’t designed for. In a buccal crossbite, for example, the inner surfaces of the upper premolars get worn down during side-to-side chewing movements. This wear happens gradually, so you may not notice it for years, but it thins the enamel in ways that can’t be reversed.
Beyond enamel loss, the uneven forces from a crossbite can push teeth into positions that irritate the gums. Over time, this contributes to gum recession, where the gum tissue pulls away from the tooth and exposes the root. Receded gums don’t grow back on their own, and the exposed root surface is softer and more vulnerable to decay than enamel-covered tooth surfaces.
Jaw Pain and Functional Problems
A crossbite forces your jaw to shift slightly when you close your mouth, compensating for the misalignment. Do this thousands of times a day while chewing and swallowing, and the jaw joint and surrounding muscles take on stress they aren’t built to handle. This can lead to jaw pain, clicking, headaches, and in some cases symptoms associated with temporomandibular joint disorders.
Chewing efficiency also takes a hit. When back teeth don’t meet properly, food doesn’t get broken down as effectively, which means your jaw muscles work harder for the same result. Some people with crossbites also develop speech difficulties. The misalignment can change tongue placement during speech, reducing clarity and fluency, particularly with sounds that require precise tongue-to-tooth contact.
Why Timing Matters for Treatment
Crossbites are far easier to fix in childhood than in adulthood. The most effective window for palatal expansion, the standard treatment for posterior crossbites, is between ages 7 and 10. At that age, the two halves of the upper jaw haven’t yet fused together at the midline. A palatal expander applies gentle, consistent pressure to widen the upper jaw, and the bone responds by growing into the gap. The American Association of Orthodontists recommends children have their first orthodontic evaluation by age 7, partly to catch issues like crossbites early.
By the teenage years, the midpalatal suture has often fused, which makes nonsurgical expansion harder or impossible. Adults with crossbites can still be treated, but the options become more limited. Mild posterior crossbites in adults, where the misalignment is roughly 1 to 3 millimeters, can sometimes be corrected with orthodontic appliances alone. More severe cases, where the upper molar sits halfway or more behind the lower molar, often require jaw surgery to achieve the same result a simple expander could have accomplished in a child.
The Prevalence Drop From Childhood to Adulthood
Posterior crossbites affect about 14% of children in their baby teeth. By the time the permanent teeth come in, that number drops to around 7%. The decline is largely due to early orthodontic treatment, particularly palatal expanders used during childhood and the mixed dentition years. This pattern reinforces that crossbites don’t tend to self-correct. The ones that disappear from the statistics were treated, not outgrown.
What Treatment Looks Like
For children, the most common approach is a palatal expander, a device cemented to the upper back teeth with a small screw that gets turned daily or every few days. Most kids wear an expander for several months while the jaw widens, followed by a holding period to let new bone fill in. The process is generally painless, though there’s mild pressure after each adjustment.
For older teenagers and adults, treatment depends on the severity. Braces or clear aligners can correct crossbites that involve tooth position rather than jaw width. When the jaw itself is too narrow, surgically assisted expansion or orthognathic surgery may be necessary. These are bigger procedures with longer recovery times, which is one of the strongest arguments for catching crossbites early.
A single-tooth crossbite, especially an anterior one, is sometimes the simplest to fix. It may only require a few months of targeted orthodontic movement. But even a single misaligned tooth can cause localized enamel wear and gum damage if left alone long enough, so “it’s just one tooth” isn’t a reason to skip evaluation.