An open bite is a type of dental misalignment, or malocclusion, where certain upper and lower teeth fail to make contact when the mouth is closed, creating a visible gap. This condition affects both the appearance of a smile and the function of the bite. It is a common dental issue that can arise from various factors impacting oral development.
Defining Open Bites
An open bite is characterized by a lack of vertical overlap between the upper and lower teeth when the jaw is closed. A space remains between them instead of the upper teeth slightly overlapping the lower. This condition can manifest in different areas of the mouth, leading to distinct classifications.
Two primary types of open bites exist: anterior and posterior. An anterior open bite occurs when the front teeth, including incisors and sometimes canines, do not touch. This leaves a noticeable gap at the front of the mouth, even when the back teeth are fully closed. Conversely, a posterior open bite involves the back teeth, such as molars and premolars, failing to meet, creating a space in the chewing areas while the front teeth may still make contact.
Open bites are also distinguished by their origin: skeletal or dental. A skeletal open bite stems from an issue with jawbone growth, where the upper and lower jaws grow apart rather than parallel, often influenced by genetics. This type can lead to significant gaps between the upper and lower teeth and may present with an increased lower anterior facial height and a hyperdivergent facial type.
In contrast, a dental open bite is due to the position of the teeth themselves rather than jaw structure. This can result from improper tooth eruption or issues like crowding or spacing within the dental arches. While skeletal open bites often present with specific facial characteristics, dental open bites occur with a more balanced craniofacial pattern.
Underlying Causes
Several factors contribute to the development of an open bite, ranging from persistent habits to genetic influences. Prolonged thumb sucking or pacifier use can exert continuous pressure on the developing teeth and jaw. This external force can physically push the front teeth forward or prevent their proper vertical eruption, leading to an anterior open bite.
Another common behavioral cause is tongue thrusting, an orofacial myofunctional disorder where the tongue pushes against or between the front teeth during swallowing, speaking, or at rest. This constant pressure can prevent the proper alignment of the teeth, contributing to the formation of a gap.
Genetic predispositions also play a role, particularly in skeletal open bites. Inherited growth patterns can lead to an abnormal development of the jawbones. These skeletal discrepancies create an inherent lack of contact between the upper and lower teeth. Less common factors, such as temporomandibular joint (TMJ) disorders or certain medical conditions affecting jaw growth, can also contribute to open bite development.
Corrective Treatments
Correcting an open bite involves various approaches, tailored to the type and severity of the misalignment. For milder cases, non-surgical orthodontic options are effective. These include traditional braces, which use brackets and wires to gradually move teeth into their correct positions.
Clear aligners, such as Invisalign, represent another popular non-surgical choice, particularly for mild to moderate open bites. These custom-made, removable trays apply gentle pressure to shift teeth over time to close the gap. Habit appliances can be used to retrain tongue posture and eliminate habits like thumb sucking or tongue thrusting, which are employed in conjunction with braces or aligners.
For more severe skeletal open bites, where the jaw structure is misaligned, orthognathic surgery (jaw surgery) may be necessary. This surgical intervention repositions the upper jaw, lower jaw, or both, to achieve proper alignment and bite. Orthognathic surgery is performed in adults after growth has completed and is combined with orthodontic treatment, with braces worn before and after the surgical procedure to fine-tune tooth positioning. The overall goal of these treatments is to achieve a functional bite, improve chewing and speech, and enhance facial aesthetics.