Incidental Finding of Bilateral Ponticulus Posticus on a Dental Panoramic Radiograph

Case at a Glance

A 30-year-old female presented for a routine dental check-up, where a panoramic radiograph revealed unusual bilateral, ring-like calcifications near the cervical spine, incidentally identified as ponticulus posticus.

Patient's Story

A 30-year-old female patient, with no significant past medical history, attended a routine dental appointment. During the visit, a panoramic radiograph (OPG) was taken for a general dental assessment. The patient was completely asymptomatic with no history of headaches, dizziness, or neck pain. After reviewing the X-ray, the dentist, a practitioner with 40 years of experience, expressed significant confusion about a specific finding, noting he had never encountered it before. He pointed out two symmetrical, circular, "lifesaver-like" opacities on the far edges of the image, near the spinal column, and asked the patient about them. The patient was equally perplexed and had no information to offer.

Initial Assessment

The patient was alert, cooperative, and presented for a standard dental evaluation. The clinical dental examination was unremarkable. The unexpected finding was purely radiographic. The panoramic X-ray showed all expected dental and gnathic structures. However, located bilaterally and projected on the lateral aspects of the film were two well-defined, corticated, ring-like radiopacities. These structures were located in the expected region of the first cervical vertebra (C1). The dental staff confirmed that the patient had removed all jewelry, including earrings, prior to the imaging, ruling out common artifacts.

The Diagnostic Journey

The dentist was initially unable to identify the structures. The primary differential considerations for such an unusual radiopacity included foreign body artifacts (ruled out), calcified lymph nodes, or a rare anatomical anomaly. Due to the distinct ring-like shape, symmetrical bilateral appearance, and location relative to the cervical spine, the radiographic features were highly suggestive of a ponticulus posticus (also known as an arcuate foramen or Kimmerle's anomaly) of the C1 vertebra. This is an anatomical variant where the posterior atlanto-occipital membrane, which normally covers the vertebral artery groove, becomes ossified. On a panoramic radiograph, due to the tomographic technique and patient positioning, the posterior arch of the atlas is often projected at the extreme lateral edges of the image, which explains the bilateral appearance of the single anatomical structure.

Final Diagnosis

Bilateral Ponticulus Posticus (Arcuate Foramen) of the Atlas (C1) Vertebra.

Treatment Plan

The patient was educated about the nature of the finding. It was explained that ponticulus posticus is a relatively common (present in up to 15% of the population) and benign congenital anatomical variant. Since she was asymptomatic, no treatment or further investigation was required. The patient was reassured that the finding was incidental and not pathological. In very rare instances, this anomaly has been loosely associated with vertebrobasilar insufficiency or cervicogenic headaches, but given the patient's lack of symptoms, these were not a concern.

Outcome and Follow-up

The patient was relieved to understand the benign nature of the finding. Her planned dental treatment proceeded without any changes. No further radiological follow-up for the ponticulus posticus was recommended. This case serves as an important reminder for dental practitioners to be aware of common non-dental anatomical variants that can appear on panoramic radiographs to prevent unnecessary patient anxiety and referrals for further, often invasive, investigations.