An open bite is a specific kind of malocclusion, or “bad bite,” that affects both the function and appearance of the teeth. This dental condition involves a vertical space between the upper and lower teeth when the mouth is closed, preventing the arches from meeting properly. While the rest of the teeth may be in contact, the open space compromises essential functions like biting and speaking. Understanding the nature of this misalignment, its causes, and the available solutions is the first step toward correcting it.
Defining the Open Bite
An open bite is characterized by a lack of vertical overlap or contact between opposing teeth when the jaw is fully closed. In a properly aligned bite, the upper teeth should slightly overlap the lower teeth, but with an open bite, a distinct gap remains. This gap can leave the tongue visible between the upper and lower dental arches when the person bites down.
The absence of proper tooth contact impacts several daily activities. Individuals often struggle to incise, or cleanly bite into, foods like sandwiches or apples because the front teeth cannot meet to shear the material. Speaking can also be affected, as the open space may interfere with the creation of certain sounds, potentially leading to a lisp or other articulation difficulties.
Classifying Open Bites by Location
Open bites are classified based on where the vertical gap occurs within the dental arches. The most commonly recognized form is the anterior open bite, where the space is located between the upper and lower front teeth. This type significantly affects the aesthetics of the smile and is strongly associated with speech impediments, such as lisping, because the tongue can protrude through the gap during speech production. It is often the result of dental habits that push the front teeth outward or prevent their proper eruption.
A less frequent variation is the posterior open bite, which occurs when the back teeth, typically the premolars or molars, fail to meet while the front teeth may be in normal contact. This condition severely reduces chewing efficiency because the primary grinding surfaces of the teeth are not engaging. Its functional impact on mastication is profound, sometimes leading to uneven wear on the teeth that do touch.
Primary Causes of Open Bites
The development of an open bite is generally attributed to two distinct categories of factors: skeletal factors and persistent oral habits. Skeletal factors involve abnormal jaw growth patterns, often with an excessive vertical growth of the facial bones. This vertical growth discrepancy, which may be genetically influenced, means the upper and lower jaws develop in a way that naturally separates the teeth. These skeletal open bites are typically more challenging to correct using only orthodontics because the problem lies in the bone structure itself.
Acquired, or habitual, factors are common causes, particularly in children and adolescents whose jaws are still developing. Prolonged thumb or finger sucking, or extended use of a pacifier beyond toddler age, creates persistent pressure against the developing teeth and jawbones. This pressure physically pushes the teeth out of alignment, preventing the normal vertical eruption of the anterior teeth. Another major habitual cause is tongue thrusting, where the tongue pushes forward against or between the front teeth during swallowing or speaking.
Treatment Approaches for Open Bites
Treatment for an open bite is highly individualized and depends on the patient’s age and the underlying cause, whether it is dental, habitual, or skeletal. In younger patients, early intervention focuses on habit modification to eliminate the cause before permanent teeth are fully established. Specialized habit-breaking appliances, such as a tongue crib, can be fitted to the upper arch to prevent the tongue from pushing forward or a finger from entering the mouth, which allows the teeth to erupt naturally and close the gap.
For open bites caused primarily by tooth misalignment, orthodontic correction is the standard approach in both adolescents and adults. Traditional braces or clear aligners, sometimes with the aid of auxiliary devices like elastics or temporary anchorage devices (TADs), are used to physically intrude (push back into the gum line) or extrude (pull out) the teeth to achieve vertical contact. Orthodontic treatment aims to move the teeth into a position that closes the vertical space.
In cases where the open bite is severe and caused by a significant skeletal discrepancy, especially in adults whose growth is complete, orthognathic surgery is often required. This procedure involves surgically repositioning the jawbones, typically the upper jaw, to ensure the upper and lower arches align correctly. Surgery is combined with orthodontics to align the teeth within the newly corrected jaw position, resulting in a stable and functional bite.