Prosterior Crossbite

Prosterior Crossbite

Posterior crossbite occurs in cases of a narrow palate (upper jaw) which affects the posterior teeth (premolars and / or molars) of the mouth and is one of the most common orthodontic problems.

Clinical picture – Diagnosis

The term crossbite characterizes the condition in which the teeth of the upper jaw close (bite) more inwards (more lingually) than the teeth of the lower jaw, in such a way that a kind of cross is formed. Depending on which teeth (anterior or posterior) have the problem, we have the anterior and posterior crossbite. Thus, in the anterior crossbite, the anterior teeth of the upper jaw are located further back (more lingual) than the teeth of the mandible, while in the posterior crossbite, the posterior teeth of the upper jaw are deeper, more lingual than those of the mandible. Bear in mind that, normally, all the teeth of the upper jaw close a little further out than those of the lower jaw.


The main cause of crossbite is the lack of space in the mixed dentition when a new (permanent) tooth is about to erupt and take its place. Also, thumb sucking in children, as well as breathing through the mouth due to adenoids can cause a narrow palate and crossbite.


Crossbite may appear on one (unilateral) or both sides (bilateral posterior crossbite) of the palate. In the unilateral crossbite, one of the upper sides “closes” through the lower teeth, while in the bilateral, both sides of the upper jaw close through the lower ones. In cases of unilateral crossbite, when closing the mouth, the upper middle line does not coincide with the lower one, thus, asymmetry is created which requires a special effort to fix during adolescence or adulthood.


In the posterior crossbite, either the upper jaw is narrow or the lower jaw is unusually wide or the teeth of the upper and lower jaw are ectopic leading to a crossbite.

Treatment of Posterior Crossbite

Treatment for crossbite should begin as early as possible – it can begin before the permanent teeth erupt, during infancy. If the problem is left untreated, it can develop into a serious skeletal abnormality with several difficulties in its treatment.


The treatment consists of addressing the cause of the crossbite and is determined and applied by a specialist, the orthodontist, who will perform the application of removable or fixed orthodontic appliances.

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