An open bite is a rare type of malocclusion (misalignment) that only affects 0.6 percent of the U.S. population.
This form of misalignment occurs when the upper and lower front teeth slant outwards and do not touch when the mouth is closed. It can develop in the front of the mouth (anterior) or the back of the mouth (posterior).
An open bite is caused by dental or skeletal factors:
An anterior open bite occurs when the incisors (front teeth) in the upper and lower jaws do not overlap. It can affect all front teeth or just a few teeth. Treatment is typically necessary because patients are unable to or have trouble tearing food with their front teeth. Speaking may also be difficult for some patients.
Treatment can help reduce speech problems, but it is not guaranteed. This is because speech is established in early childhood, and if the permanent teeth have already grown in, it may not be possible.
A posterior open bite is the opposite of an anterior open bite. It occurs when the back teeth, including the molars and premolars, do not touch when in occlusion (biting down). This form of malocclusion does not involve an overjet or overbite. In a normal bite, the back teeth in the upper jaw should be positioned slightly on the outside of the teeth in the lower jaw.
Treatment is usually necessary because patients cannot chew properly.
A dental open bite results from a tooth eruption impediment, while a skeletal open bite is due to abnormal facial growth (genetics). This may include irregular development of the molars or jawbones that grow away from each other.
If an open bite is not caused by genetics, it can be due to poor oral habits. For example, babies have a natural instinct to suck, but they should stop by age 3 or 4. If a child developed this form of malocclusion due to excessive thumb or finger sucking, the condition can still be reversed if the child’s permanent teeth have not grown in yet.
Other causes include:
Many children have open bites during the primary and mixed dentition phase, which is when baby teeth are falling out and permanent teeth begin to grow in.
Children may outgrow it once permanent teeth fully erupt unless the malocclusion formed due to genetic reasons (skeletal). For example, an open bite may self-correct if childhood habits (e.g. thumb sucking) diminish early on and the jaw and permanent teeth develop normally.
Common treatment plans for open bites include:
High pull headgear attaches to the top of the head, back of the head, and the upper jaw.
The appliance controls jaw growth and improves teeth alignment. Headgear is used in combination with braces.
Clear aligners, such as Invisalign, can be effective in treating minor anterior open bites. This treatment is less commonly used, though.
A vertical chin cup is a common orthopedic appliance that is used to correct an open bite. The appliance controls the growth of the lower part of the face and prevents the chin from growing backward or downward.
Roller appliances help prevent tongue thrusting against the front teeth, which can encourage an open bite and upper front teeth protrusion (overjet). The appliance consists of a small roller-type bead that strengthens the tongue muscles and is connected to two braces on the molars in the upper jaw.
Bite blocks can be placed on the two back molars in the lower jaw (both sides) to slowly correct an anterior open bite. The appliance moves the teeth back over time and removes the space between the upper and lower teeth.
Adults with skeletal open bites typically need surgery, since their jaw and teeth are fully developed. Children may also require surgery if their permanent teeth are fully grown in and the jaw is fully developed. During surgery, an oral surgeon places the patient’s upper and lower jaws in the correct position. Then plates and screws are inserted to keep the jaws in place.
Cobourne, Martyn T., and Andrew T. DiBiase. Handbook of Orthodontics E-Book. Elsevier, 2015.
Rohit, Kulshrestha. “Open Bite Malocclusion: An Overview.” Journal of Oral Health and Craniofacial Science, 2018, pp. 011–020., doi:10.29328/journal.johcs.1001022., https://www.heighpubs.org/johcs/johcs-aid1022.php