Posterior Open Bite - Causes and Management

What Is Posterior Open Bite?

Posterior open bite (POB) is a condition that is characterized by clinical features mainly occurring due to a lack of posterior occlusal contact that results in reduced contact or synchronization with each other while biting or chewing. Posterior open bite is frequently accompanied by additional complications like facial asymmetry.

• The anterior teeth; the upper and lower front teeth do come in contact, but the posterior teeth or the molars/premolars are mainly responsible for maintaining the correct bite and also responsible for the maximum chewing, and grinding movements that are accomplished in this segment of the jaw.

• Dental POB or dental origin POB can be treated by orthodontic treatment like myofunctional appliances, and habit-breaking appliances, though the elimination of the underlying pathology or causative, skeletal malocclusions is more challenging and may require orthognathic surgery.

• Dental Research also implies that both anterior as well as posterior open bites may more often be a result of the hyperactivity of the tongue. The axial inclinations of the incisors lead to an open bite.

• When the anterior teeth contact prematurely, it becomes a reason for the loss of contact between posterior teeth.

What Are the Causes of Posterior Open Bite?

Following are the few common causes of posterior open bite:

• Failure of teeth to erupt.

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• Disorders associated with the temporomandibular joint.

• Cases of several known systemic or medical syndromes.

The prevalence of POB is elusive and low in comparison to the commonly occurring anterior open bite (AOB). Despite the functional consequences that occur in severity with POB. The etiology according to dental research still remains unclear. This is because the occurrence of the most severe malocclusions would impair the masticatory functions in patients.

Firstly, it is a condition that would be associated with several trigger factors or causative factors stated above. Multiple factors are associated with posterior open bite.

The main pathological factors include the following conditions:

• Primary failure of tooth eruption (PFE), tongue thrust habit, or specifically lateral tongue thrusting.

• Pathologies of the temporomandibular joints need to be effectively eliminated either by providing prosthetic appliances.

• Treating the habit that has caused POB or treating the underlying medical and local temporomandibular joint pathology or joint issue associated with POB.

• The complex interplay of environmental or genetic factors leads to this condition.

• It is clinically challenging for the dental operator or the orthodontist to treat it from the origin of the disorder.

What Are the Causative Factors of Posterior Open Bite?

Given below are the causative factors that can cause Posterior open bite:

• Mechanical Failure of eruption (MFE) may either be due to tooth fusion with the bone or ankylosis, in such cases, the cementum would be fused to the alveolar bone resulting in an eventual interference in the eruption pattern causing tooth eruption defects or loss of tooth eruption altogether in the affected region. MFE usually affects only one tooth and is responsible for subluxation on application of orthodontic forces.

• Primary failure of eruption (PFE) is termed as an incomplete eruption of the affected teeth and unerupted teeth that are actually non-ankylosed. In a few cases, normal eruption pattern is hampered. PFE unlike MFE does not impact only one tooth to erupt and often multiple posterior teeth would be involved creating a phenomenon of infra occlusion.

• Genetic mutations are noted as interference within several genes that play a role in normal tooth eruption. For example, according to dental research, genes encoding the parathyroid hormone receptor 1 (PTH1R) or the histone methyltransferase 2C (KMT2C) when impacted would result in PFE.

• Tongue-thrusting is a detrimental habit in infants or in early childhood that can be termed an environmental and direct cause of POB. In specific lateral tongue thrusting habit would be capable of causing POB.

• Skeletal malocclusion can be due to unilateral mandibular hyperplasia condition or even in Class III skeletal relationships that occur alongside posterior crossbite.

• Temporomandibular joint pathologies can in fact be a major cause or reason for the posterior teeth not to being in proper contact; the potential displacement of the mandibular condyles from the normal position can cause a posterior open bite.

• Patients on mandibular advancement therapies and patients who are using functional mandibular appliances used for mandibular advancement are recommended by the dentist or orthodontist for conditions like obstructive sleep apnea, and hypopnea. However, case reports have implicated these devices to be a potential cause of POB.

What Are the Management Strategies for Posterior Open Bite?

For treating the cause of primary failure in eruption (PFE), the extraction of the tooth of concern can be followed up with a prosthetic replacement. Procedures like segmental osteotomy in the cases of young adults and children, myofunctional appliances, and orthodontic treatment like aligners can exert the right forces in correcting the posterior jaw bite.

Minor cases of posterior open bite like lack of contact between the upper and lower molars would require only appliances like temporary anchorage devices with the adjunct of habit-breaking appliances. In cases where the child or adolescent has a particular habit associated with a posterior open bite like lateral tongue thrust. Several research studies propose that temporary anchorage devices (TAD) would not only provide anchorage for the extrusion and intrusion in posterior teeth but can also help in the adjustment of facial symmetry eliminating the need for orthognathic or facial surgeries that may be also needed in case of skeletal malocclusions.

Conclusion

Posterior open bite is frequently accompanied by additional complications like facial asymmetry. Dental POB or dental origin POB can be treated by orthodontic treatment like myofunctional appliances, habit-breaking appliances, and elimination of the underlying pathology or cause. Skeletal malocclusions are more challenging and may require orthognathic surgery.

The management of open bite posteriorly in cases where the upper and lower molar and premolars have altered contact or lack of contact is clinically challenging. But it is still a condition with a good prognosis with regular orthodontic therapy, habit-breaking appliances, addressing the underlying local or systemic pathology, and the patient's cooperation.