An open bite is a form of malocclusion, or “bad bite,” where the upper and lower teeth do not make proper contact when the mouth is closed. Unlike a typical bite where the upper front teeth slightly overlap the lower ones, an open bite leaves a noticeable vertical gap. This common dental issue can affect the front teeth, the back teeth, or both, disrupting the normal alignment of the dental arches. The lack of vertical overlap can originate from issues with the teeth themselves or from the underlying growth of the jawbones. Understanding the specific nature of the problem dictates the most effective approach for correction.
Defining the Open Bite Phenomenon
An open bite is characterized by a lack of vertical overlap between the occlusal surfaces of opposing teeth when the jaw is fully closed. This manifests as a space between the upper and lower rows of teeth, preventing them from meeting to shear or grind food. The gap can vary from affecting only a few teeth to spanning the entire dental arch.
The functional impact of this misalignment is often noticeable in daily life. Individuals frequently report difficulty biting into certain foods, such as tearing off a piece of a sandwich, because the front teeth cannot meet to perform the cutting action. An open bite can also affect speech, sometimes leading to a lisp or other pronunciation issues because the tongue cannot articulate against the incisors properly. The open space can interfere with the normal resting position of the lips, potentially leading to lip incompetence, where the lips cannot comfortably close together without strain.
Different Classifications of Open Bite
Open bites are classified primarily by location and underlying cause. Classification by location divides the condition into an anterior open bite or a posterior open bite. An anterior open bite is the most common form, where the front teeth—the incisors and sometimes the canines—do not touch, leaving a space when the back teeth are in contact.
A posterior open bite is rarer and occurs when the back teeth (molars or premolars) fail to meet, even if the front teeth are in contact. This type is particularly disruptive to chewing function.
Classification by etiology differentiates between a dental open bite and a skeletal open bite. A dental open bite is caused by localized factors, such as issues with the positioning or eruption of the teeth themselves, without a significant underlying jawbone abnormality. This form often results from forces that impede the vertical movement of teeth.
A skeletal open bite, conversely, is caused by improper growth of the jawbones, specifically a vertical discrepancy where the facial bones prevent the teeth from meeting. This skeletal pattern frequently involves a long lower facial height and is considered more complex to correct.
Primary Causes and Contributing Factors
The development of an open bite is often multifactorial, stemming from genetic, anatomical, and environmental influences. One of the most common environmental causes, particularly in children, is the persistence of certain habits. Prolonged thumb or finger sucking, as well as extended pacifier use past the age of four or five, creates a continuous force that pushes the teeth outward and prevents normal vertical eruption.
Physiological issues also contribute to the condition. Tongue thrusting is an abnormal swallowing pattern where the tongue pushes forward against or between the front teeth during swallowing. Since an individual swallows hundreds of times a day, this repetitive force pushes the teeth apart and can maintain an existing open bite.
Another factor is mouth breathing, often associated with obstructed airways due to enlarged tonsils or adenoids. When the mouth is habitually open, the tongue rests in a lower, more forward position, disrupting the balance of forces necessary for proper jaw development and tooth alignment.
Finally, a strong genetic component can predispose an individual to a skeletal open bite. This involves an inherited pattern of vertical jaw growth discrepancies, where the bones of the face grow disproportionately, leading to a vertical separation of the dental arches.
Effective Treatment Pathways
The strategy for correcting an open bite is highly individualized, depending heavily on the patient’s age and whether the condition is primarily dental or skeletal.
Habit Modification for Young Patients
For younger patients where the open bite is caused by an oral habit, the initial approach focuses on habit modification. Appliances like a tongue crib—a fixed wire device placed behind the upper front teeth—are often used to physically block the tongue or finger. This allows for spontaneous bite closure as the teeth erupt.
Orthodontic Correction
For dental open bites in older children and adults, orthodontic correction is the standard treatment. This may involve traditional braces or clear aligners, used with specialized mechanics to bring the teeth into contact. Vertical control techniques, such as elastics or temporary anchorage devices (TADs), are employed to either extrude the front teeth or intrude the back teeth, effectively rotating the jaw closed.
Surgical Intervention
In cases of a severe skeletal open bite, where the misalignment is rooted in the jaw structure, a combined approach of orthodontics and orthognathic surgery is often required. Orthognathic surgery involves repositioning the upper jaw (maxilla) and sometimes the lower jaw (mandible) to correct the underlying bony discrepancy. This procedure is reserved for adult patients whose facial growth is complete and whose condition cannot be fully addressed by tooth movement alone.