It is a common discovery to find that your back teeth, the molars and premolars, do not meet fully when you close your mouth. This failure of the back teeth to make contact points to a specific dental misalignment. This alignment problem can interfere with fundamental functions like eating and speaking, and understanding why it occurs is the first step toward finding a solution for a complete and functional bite.
Understanding the Posterior Open Bite
The condition where the posterior teeth fail to make contact when the jaw is closed is specifically termed a posterior open bite (POB). This mechanical reality means that while your front teeth, the incisors and canines, may touch, a vertical gap remains between the upper and lower back teeth. Patients often report a sensation of the front teeth bearing all the pressure, with the back teeth feeling “out of play.”
This is distinct from the more commonly discussed anterior open bite, where a gap is present between the front teeth when the jaw is closed. This failure of the back segments to reach occlusion compromises the stability of the entire bite.
Primary Causes for Misalignment
The origins of a posterior open bite are diverse, ranging from early childhood behaviors to structural and growth-related issues. One frequent category of causes is habitual or behavioral, often stemming from improper oral muscle function. Persistent habits like prolonged thumb-sucking or pacifier use, especially past the age of four, exert constant pressure that can push the erupting teeth out of alignment.
Another common behavioral factor is a tongue thrust, where the tongue pushes against the teeth during swallowing or speaking instead of resting properly on the palate. This continuous, gentle force can prevent the back teeth from fully erupting into their correct vertical position. Skeletal discrepancies also contribute to this problem, such as when the upper and lower jaws grow at different rates or in an incorrect vertical dimension.
Dental causes can involve issues with the teeth themselves, not just the jaw structure. This includes mechanical failure of eruption (MFE), which is most often caused by ankylosis, where the tooth cementum fuses directly to the alveolar bone. A more complex issue is primary failure of eruption (PFE), which involves a defective eruption mechanism that can affect multiple posterior teeth. A posterior open bite can occasionally be an unintended consequence of prior dental work, such as poorly fitted restorations or certain types of orthodontic mechanics.
Consequences of an Uncorrected Bite
When the back teeth do not meet, the primary consequence is a significant reduction in the efficiency of chewing, a process called mastication. The premolars and molars are designed to grind food, and without proper contact, food particles are not broken down adequately, potentially leading to digestive strain. This functional deficit forces the front teeth to take on the entire biting load, a task they are not structurally designed for.
The excessive pressure exerted on the anterior teeth can lead to premature or increased wear and tear. This uneven distribution of force may result in chipped enamel, fractures, or a general breakdown of the front teeth over time. Additionally, the jaw may attempt to shift or posture itself to find a more comfortable or functional position, which can strain the temporomandibular joints (TMJ) and surrounding muscles.
This chronic strain on the jaw system can manifest as discomfort, pain, or frequent tension headaches. An uncorrected posterior open bite also compromises the long-term stability of the overall occlusion. The lack of posterior support can also affect speech articulation, sometimes causing difficulties with certain sounds or a slight lisp.
Treatment Pathways for Correction
The pathway for correcting a posterior open bite depends entirely on an accurate diagnosis of the underlying cause. For cases rooted in habitual issues, such as tongue thrusting or prolonged sucking, habit modification is the initial focus. This often involves the use of specialized myofunctional appliances designed to retrain the tongue and oral muscles to promote a correct swallowing pattern.
Orthodontic solutions are frequently employed to physically move the teeth into proper alignment. Traditional metal or ceramic braces are highly effective, applying constant, controlled forces to extrude (move down/up) the teeth into occlusion. Clear aligners are also utilized, often requiring the strategic use of attachments and elastic bands to generate the necessary vertical movement.
In cases where the misalignment is due to a severe skeletal discrepancy, orthognathic surgery (jaw surgery) may be the necessary intervention. This procedure is typically reserved for adult patients after their growth has been completed, as it involves surgically repositioning the jaw bones to achieve a proper functional bite. For minor vertical discrepancies, treatments like selective removal of aligner material or the application of composite build-ups can be used to facilitate the natural settling of the teeth into contact.