What does crossbite mean?
A crossbite is a type of malocclusion — a misalignment of the teeth — in which some of the upper teeth close on the wrong side of the lower teeth. In a normal bite, the upper teeth sit slightly outside and in front of the lower ones; with a crossbite, one or more upper teeth fall inside the lower teeth instead. Crossbites are usually described as anterior, involving the front teeth, or posterior, involving the back teeth, and they may affect one side of the mouth or both. Causes include inherited jaw shape, delayed loss of baby teeth, and habits such as prolonged thumb-sucking. Left untreated, a crossbite can lead to uneven tooth wear, gum problems, jaw strain, and even asymmetrical facial development in children, so dentists often recommend correcting it early with braces, expanders, or other orthodontic appliances. Though chiefly a clinical term, "crossbite" appears regularly in orthodontic advice and general health coverage.
nounA dental malocclusion in which one or more upper teeth bite on the inside of the lower teeth rather than outside them, occurring when the jaws or dental arches are misaligned.
- A malocclusion in which one or more upper teeth occlude inside (lingual to) the corresponding lower teeth when the jaws are closed.
- More generally, any transverse misalignment between the upper and lower dental arches.
"The orthodontist recommended a palatal expander to correct the child's crossbite before it affected jaw growth."
"A posterior crossbite on the left side had caused her lower jaw to shift slightly when she closed her mouth."
"Early treatment of an anterior crossbite in children can prevent abnormal wear on the enamel and asymmetric jaw development."
Regular plural; used mainly in clinical and statistical contexts, e.g. discussing prevalence rates.
"Posterior crossbites are among the most common skeletal discrepancies seen in paediatric orthodontics."
A crossbite can quietly reshape a growing face — orthodontists often treat it in childhood precisely because the longer it goes uncorrected, the more the jaw itself adapts to the error.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of crossbite
The word "crossbite" is formed transparently within English from "cross," meaning across or contrary to, and "bite," the act or manner in which the teeth meet. It emerged in dental and medical writing, likely in the late nineteenth century as modern orthodontics developed its descriptive vocabulary for malocclusions alongside terms such as overbite and underbite. Its components trace further back: "cross" comes from Old Norse "kross" (ultimately Latin "crux"), while "bite" derives from Old English "bītan," of Germanic origin.
Related word forms
How crossbite is actually used
"Crossbite" is primarily a clinical and technical term used by dentists, orthodontists, and in health writing; it is uncommon in everyday conversation. It is frequently classified as anterior (front teeth) or posterior (back teeth), and as unilateral or bilateral depending on how many teeth are involved. Unlike "overbite," it carries no figurative or informal usage.
Easily confused with crossbite
An overbite is excessive vertical overlap of the upper front teeth over the lower teeth, whereas a crossbite is a sideways (transverse) misalignment in which upper teeth close inside the lower teeth.
An underbite occurs when the lower front teeth protrude beyond the upper front teeth, while a crossbite refers to individual teeth or arch segments closing on the wrong side, which may affect back teeth as well.