There are two types of cross-bite, anterior and posterior.
Anterior cross bite
This is the term used when a patient’s front teeth close the wrong way around with the upper incisors behind the lower incisors instead of in front of them. This is sometimes referred to as a scissors bite. Patients with anterior cross bites often shift the lower jaw into an unusual but more comfortable position when they close their teeth together. This is called a mandibular shift. Anterior cross bites can be treated with either fixed or removable appliances.
A removable appliance like the one shown, consists of an acrylic base plate, clasps for retention and springs to move teeth. A removable appliance was used to treat the case shown below. It was worn full-time for 6 months then for a further 4 months just at night as a retainer.
Posterior cross bite