A radiological conundrum

Sir, a 19-year-old male patient was reviewed in our maxillofacial outpatient clinic nine months following a bi-maxillary osteotomy with advancement genioplasty. His only complaint was a clicking sensation below his nose, ongoing for one month. No abnormalities were found on clinical examination, along with a good result for facial profile and occlusion of teeth.

Although post-operative dental panoramic tomogram (DPT) and posterior-anterior mandible (PA mandible) radiographs had been taken the day after surgery, a repeat DPT and PA mandible were taken to assess the maxillofacial plating and bone to ensure fixation had remained adequate. As can be seen in Figure 1, a horizontal radiopaque line was detected in the Le Fort I osteotomy surgical site, traversing the mid-face titanium mini-plates. This abnormality was not present in the DPT radiograph (Fig. 2), nor was it present in the initial post-operative DPT and PA mandible radiographs nine months before.

Fig. 1

Post-operative posterior-anterior (PA) mandible radiograph - nine months following bi-maxillary osteotomy and advancement genioplasty

Fig. 2

Post-operative dental panoramic tomograph (DPT) - nine months following bi-maxillary osteotomy and advancement genioplasty

Initial differential diagnoses were:

a) Retained 'Raytec X-ray detectable swab' in Le Fort I osteotomy site

b) Orthodontic wire.

After due consideration, the attending clinician had an epiphany. It was confirmed that at this clinic appointment, when the patient attended the radiology department, he had been wearing a fluid resistant surgical face mask in an effort to adhere to hospital trust infection control policy, during the current COVID-19 pandemic. This face mask was worn for the PA mandible but not for the OPG radiograph. Figure 3 demonstrates the aluminium wire within the face mask, which allows adaptation around the nose and mid-face for better fit and seal. The artefact seen on the PA mandible (Fig. 1) was indeed this metal wire.

Fig. 3

Fluid resistant surgical face mask - demonstrating the aluminium metal wire extruded from its superior horizontal margin

I hope my letter raises awareness to colleagues regarding this radiographical COVID-19 conundrum so that they might prevent its recurrence by advising patients to remove their face mask before facial radiographs.

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Correspondence to M. Watts.

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Watts, M. A radiological conundrum. Br Dent J 229, 636 (2020).

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