Two cases of posterior open bite caused by the thickness of retrodiscal tissue in the temporomandibular joint

Clinical characteristics of temporomandibular disorders presenting posterior open bite - A report of 12 cases

Background/purpose

There is a paucity of comprehensive information about posterior open bite (POB) in patients with temporomandibular disorders (TMD) because of its rare prevalence. The purpose of this study was to investigate the etiologies, clinical characteristics, and treatment outcomes of patients with TMD presenting POB.

Materials and methods

This study includes a careful review of medical records and imaging findings of 12 patients with TMD (seven men and five women, 50.9 ± 19.2 years, 15–72 years) complaining of POB.

Results

In total, 11 had unilateral POB, whereas 1 had bilateral POB. In 11 patients, POB was caused by inflammatory disorders of temporomandibular joint (TMJ). In the remaining one patient, TMJ medial disc displacement (MDD) was responsible for POB. Of 11 patients with inflammatory conditions of TMJ, four patients had unilateral TMJ internal derangement (ID), two had bilateral TMJ ID, and one had rheumatism. POB was resolved in 10 of 11 patients with TMJ inflammation following the administration of non-steroidal anti-inflammatory drugs and self-management instructions. Prosthodontic treatment was needed in one patient to resolve POB. POB was resolved in the patient with TMJ MDD after stabilization splint therapy.

Conclusion

POB in patients with TMD was mostly caused by inflammatory disorders of TMJ. TMJ MDD could also be a reason. Although almost all POB was resolved by conservative treatments including medications, the possibility of prosthodontic, orthodontic, or surgical treatments also must be considered.

Review of Etiology of Posterior Open Bite: Is There a Possible Genetic Cause?

Posterior open bite (POB) is one of the most severe malocclusions that can impair patients' masticatory functions, yet it is also a condition that is poorly understood and not well studied. Most reported cases are either sporadic or idiosyncratic with a diverse yet poorly understood etiology. Although primary failure of eruption (PFE), lateral tongue thrust, and certain medical syndromes or pathology of the temporomandibular joints have all been shown to cause POB, the complex interplay of environmental and genetic factors makes its etiopathogenesis a difficult subject to understand and investigate. Here, we provide a comprehensive review of the etiology of posterior open bite. Additionally, a genetic cause for POB is proposed through a report of an apparently non-syndromic familial case series with high POB penetrance across two generations. Further investigations of the gene(s) and mechanism(s) involved can not only provide a unique opportunity to better understand POB and the intricate muscular-occlusal relationship, but also offer powerful insight into the most effective approaches to clinical management of these (and potentially other) malocclusions.

Temporomandibular dislocation caused by pancreatic cancer metastasis: A case report

Metastasis-induced dislocation of the temporomandibular joint (TMJ) is rare. The present study describes a case of TMJ dislocation caused by metastasis from pancreatic cancer, and discusses this in the context of literature on occlusal abnormality and/or dislocation due to metastasis. In the present case, unilateral TMJ dislocation was suspected when the patient first presented; destructive bone changes were not observed on conventional radiographs, and magnetic resonance imaging (MRI) revealed a tumorous lesion. The present case suggests that healthcare professionals should consider whether a malignant disease is present in cases of occlusal abnormality and/or dislocation of the TMJ, and that, in patients with TMJ dislocation that cannot easily be repositioned, additional imaging examinations, including MRI, should be performed as soon as possible, regardless of whether destructive bone changes are present. Metastasis to the TMJ is typically associated with generalized skeletal metastasis in the final stage of malignancy. Therefore, it is crucial to consider the possibility of cervical spine metastasis in order to decrease the risk of cervical fracture when attempting reduction of a TMJ dislocation, particularly in patients with a history of cancer.