When the upper and lower teeth fail to meet, it can be a source of confusion and concern. This common misalignment issue is medically termed a malocclusion, and specifically, the absence of vertical overlap is known as an open bite. An open bite creates a noticeable gap between the dental arches, which can occur even when the jaw is fully closed. Understanding why the teeth do not touch is the first step toward finding an appropriate solution. This condition arises from a complex interaction of genetic, habitual, and developmental factors.
Understanding the Open Bite
An open bite is a form of dental misalignment where a segment of the upper and lower teeth cannot make contact. In a normal bite, the upper teeth slightly overlap the lower teeth, allowing for efficient biting and chewing. The condition is primarily categorized based on where the lack of contact occurs in the mouth.
An Anterior Open Bite is the most commonly recognized type, involving a gap between the front teeth (incisors) when the back teeth are touching. Conversely, a Posterior Open Bite is less frequent, involving a separation between the back teeth (molars or premolars), even when the front teeth are in contact.
Primary Causes of Non-Contact
The development of an open bite is attributed to a combination of factors related to jaw structure, habitual behaviors, and tooth eruption. Skeletal factors involve the inherent growth pattern of the jawbones, which is often influenced by genetics. A vertical growth pattern in the jaw can lead to an increased lower facial height, preventing the front teeth from coming together. This structural discrepancy is rooted in the way the maxilla and mandible developed.
Habitual factors are chronic, repetitive behaviors that exert pressure on the teeth and surrounding bone, mechanically pushing them out of alignment. One of the most common is prolonged thumb or finger sucking, which, when continued past the age of four, applies persistent force to the front teeth. Another significant behavior is tongue thrusting, where the tongue pushes forward against or between the front teeth during swallowing or speaking. Chronic mouth breathing, often associated with a low resting tongue posture, can also contribute by altering the balance of forces within the mouth.
Dental factors relate directly to issues with the teeth themselves, rather than the jawbone structure or habits. These include the failure of certain teeth to fully erupt into their correct position, a condition sometimes seen in a posterior open bite. In children, a transitional open bite may be temporary, occurring during the shift from primary to permanent dentition. If this transient condition does not resolve spontaneously, it is often due to underlying skeletal or habitual issues.
Consequences for Oral Function
When teeth fail to meet, the functional consequences impact daily activities like eating and speaking. People with an open bite find it difficult to bite into and incise food, such as apples or sandwiches, due to the lack of contact between the upper and lower front teeth. This difficulty in the initial stage of chewing can lead to less efficient digestion, as food may not be properly prepared for the stomach.
The inability to fully close the bite also places abnormal forces on the teeth that do contact, typically the back molars. This concentrated force leads to excessive and premature wear on the surfaces of the contacting teeth, potentially causing discomfort. The strain on the bite can also contribute to issues with the temporomandibular joints (TMJ). Speech function is frequently affected, as the gap allows air to escape during articulation, resulting in a lisp or difficulty pronouncing sounds like “s” and “z.”
Treatment Pathways
The approach to correcting an open bite depends on the underlying cause identified by a dental professional. For open bites rooted in behavioral causes, the first step involves Habit Modification to eliminate the force pushing the teeth apart. This may include myofunctional therapy to retrain the tongue to rest and swallow correctly. Another element is the use of specific appliances, such as a tongue crib, to physically block the tongue from thrusting forward.
Once harmful habits are controlled, or when the open bite is primarily dental, Orthodontic Correction is the standard pathway. Braces, clear aligners, and specialized appliances move the teeth into proper vertical alignment. Forces can be applied to intrude (push up) the back teeth or extrude (pull down) the front teeth to close the gap. Temporary Anchorage Devices (TADs), which are small mini-implants, provide a stable anchor point for effective tooth movement in complex cases.
In severe cases involving significant Skeletal Discrepancies that cannot be corrected by orthodontics alone, a combined approach is necessary. This involves Surgical Intervention, known as orthognathic surgery, often performed on the upper jaw (maxilla). The procedure typically involves surgically repositioning the jawbone to establish a correct skeletal relationship, which then allows the teeth to meet properly. This surgical correction is performed in conjunction with a course of orthodontic treatment to fine-tune the final tooth positions.