Sir, I wish to report the unusual presentation of an idiopathically fractured mandible.

A 67-year-old female presented for an urgent dental appointment complaining of pain over the right-hand side of her face, which was swollen over the mid-body of mandible. The swelling was allegedly present for the past four days with increasing size and severity. At the time of presentation, it was approximately the size of half a ping pong ball. She attended on the advice of her GP who believed this swelling could have been of dental origin.

Following a stroke six months ago, she was diagnosed with lung cancer, three weeks of radiotherapy ensued and then no other treatment. She was a well-controlled type 2 diabetic and suffered from fibromyalgia. Her current medications included metformin, inhalers, and tramadol, with no history of bone-modifying medication.

She described having been completely edentulous for a number of years. On clinical examination, there was no cervical lymphadenopathy but mild unilateral tracking of the swelling down the neck. Upper and lower comfortable, stable, and retentive complete acrylic dentures were present, and had never caused any concerns. Intra-oral landmarks were unremarkable. Over the Attwood Class V alveolar ridge of the lower right premolar region, there was acute tenderness to palpation, especially buccally directly adjacent to the extra-oral swelling. Here, the swelling was firm, fixed, and contained within well-circumscribed boundaries. No intra-oral fluid-filled swelling, fistula/sinus, bruising or cut was identified.

The patient recalled no history of trauma to the region, nor recent over-zealous eating, and the dentures were intact. Initial discussion included further investigation using a periapical radiograph in order to ascertain the possibility of a potentially unerupted tooth, retained root, other bone pathology or any infectious process. A second opinion was sought from a senior colleague, who could only confirm the original findings and acquiesced with the plan.

We decided to explore further using panoramic radiography to better gauge a larger area for identifying a cause for this idiopathic swelling (Fig. 1).

Fig. 1
figure 1

A full panoramic radiograph identifying the horizontally ectopic lower left premolar and a complete, undisplaced mid-body mandibular fracture on the right-hand side

Full size image

The OPG revealed the presence of a horizontally ectopic lower left premolar and a complete, undisplaced mid-body mandibular fracture.

The patient was informed and extremely surprised. The local SHO in oral and maxillofacial surgery was called and the patient was advised to transfer across to A&E immediately. An initial management plan of intra-venous antibiotics followed by fixation was devised.

Idiopathic fractures of the mandible, most commonly categorised in pathological fractures, are rare and account for 2% of all mandibular fractures.1

There are many risk factors associated with pathological mandibular fractures such as age, gender, existing infection, or bone lesions.1 Identification of such fractures can be beneficial for patient care and should be recognised as a potential differential diagnosis when assessing high risk patients.