Patients can present with different forms of malocclusion, each unique to the individual. On a case-by-case basis, clinicians will also encounter new parafunctional habits – nail biting, pen chewing, thumb sucking – that can impact occlusion over time depending on the frequency and severity of the action.
With so many unique problems presenting in the dental chair, it’s important to be able to recognise when a patient can be considered ‘high-risk’ for developing a malocclusion, or when an existing condition will present future problems. Clinicians that are able to identify such problems early can begin to implement an effective treatment plan.
Posterior open bites are a rare form of malocclusion that can present a number of aesthetic and functional problems. Clinicians must assess the risk of such a condition developing early in order to provide interceptive care, and be able to aid patients that have surpassed this point to prevent damage to the dentition and general health.
Identifying causation
The aetiology of a posterior open bite could be linked to failed tooth eruption, a lateral tongue-thrusting habit, or as a result of changes to the temporomandibular joints, amongst other factors.[i] Dissecting the balance of genetic and environmental factors is complex, as seen in a 2020 study that focused on a family with a generation of children that all exhibited posterior open bites.i
Despite its small sample size, it reasons that as treatment had been successful in some of the family, failure of eruption would not be the cause in this case, ruling out ankylosis – where the cementum is fused to the alveolar bone, limiting tooth eruption – as a potential cause. Instead, it highlighted a common similarity of retruded upper and lower lips, increased muscle tones, retroclined incisors and lateral tongue thrust. Together, the case could be made that genetics had affected the increased muscle tone of the lips, which is known to cause upper incisor retroclination, reducing the anterior-posterior length of both arches and forcing the tongue to exhibit pressure laterally.i Alternatively, another genetic or environmental component could have a stronger contribution to the common posterior open bites through an as yet undiscovered mechanism.
Lateral tongue thrust is a habit that has been described widely throughout the literature in connection with posterior open bitesi, and tongue thrust is seen as a potential cause of open bites in other areas of the dentition.[ii] It creates a mechanical interference in posterior tooth eruption, which, if intercepted early, could be corrected by cessation of the habit. Without it, occlusal contacts may not meet over time. Cessation is also necessary for effective outcome retention. It must be noted that lateral tongue thrusting is commonly present alongside other known risk factors, suggesting that it could be a contributing factor that is aided by similarly detrimental dental or skeletal conditions.i
There is also evidence to suggest that a posterior open bite may be caused by the use of mandibular advancement devices. A 2014 study[iii] into the use of mandibular advancement splints to treat obstructive sleep apnoea observed 51% of participants developing a posterior open bite. The devices in question could protrude the lower incisors after prolonged treatment and regular use, causing premature anterior contacts that leave the posterior teeth unable to fully close.
The need for treatment
There are a number of ways a posterior open bite may be detrimental to the dentition. A lack of posterior support has been seen to affect anterior tooth wear, and a greater severity of it – though this is debated in some results.[iv] Patients may experience defective speech, which can be an issue in social interactions, prompting psychological issues in turn.[v] Mastication challenges are also reported, which could affect digestion and wider general health issues.v
Treatment will differ depending on each case. Orthodontic care that aligns the dentition is common, but some cases may need more invasive surgical intervention to create space. No matter the case, clinicians must exhibit a developed understanding of optimising occlusion, and create a treatment plan that considers a resolution within the existing dentition.
Dental professionals could develop their knowledge by taking the Occlusion: Basics & Beyond course from the IAS Academy, led by Dr Jaz Gulati and Dr Mahmoud Ibrahim. The online course can be accessed and taken at your desired pace, covering occlusion in comprehensive detail to inform your clinical judgements. With an OBAB Starter Kit containing an autoclavable Huffman Leaf Gauge and a pack of 8 microns Hanel Shimstock Foil, and OBAB Hardback Textbook included, it is the perfect source for clinicians looking to develop.
Though posterior open bites are rare, it is essential to understand how they can occur in order to confidently provide interceptive care that restores the occlusion. This is only possible through diligent education for all practitioners.
For more information on upcoming IAS Academy training courses, please visit www.iasortho.com or call 01932 336470 (Press 1)
[i] Huang, W., Shan, B., Ang, B. S., Ko, J., Bloomstein, R. D., & Cangialosi, T. J. (2020). Review of Etiology of Posterior Open Bite: Is There a Possible Genetic Cause?. Clinical, Cosmetic and Investigational Dentistry, 233-240.
[ii] de Castro Cabrera, M., Cabrera, C. A. G., de Freitas, K. M. S., Janson, G., & de Freitas, M. R. (2010). Lateral open bite: treatment and stability. American Journal of Orthodontics and Dentofacial Orthopedics, 137(5), 701-711.
[iii] Pliska, B. T., Nam, H., Chen, H., Lowe, A. A., & Almeida, F. R. (2014). Obstructive sleep apnea and mandibular advancement splints: occlusal effects and progression of changes associated with a decade of treatment. Journal of Clinical Sleep Medicine, 10(12), 1285-1291.
[iv] Wazani, B. E., Dodd, M. N., & Milosevic, A. (2012). The signs and symptoms of tooth wear in a referred group of patients. British dental journal, 213(6), E10-E10.
[v] Alyami, B. (2020). Diagnosis and Management of a Unilateral Posterior Open Bite Using a Temporary Anchorage Device (TAD): Case Report and Review of the Literature. Case reports in dentistry, 2020(1), 9814949.
