Radiographic changes on panoramic imaging following intensity-modulated radiation therapy

To document radiographic changes visible on panoramic radiographs following intensity-modulated radiation therapy (IMRT).

This is a retrospective study including 143 patients (120 males and 23 females) with a history of oropharyngeal cancer treated with IMRT at Memorial Sloan Kettering Cancer Center between 2005 and 2015 and seen at our Dental Service prior to starting radiation therapy. For each patient, one pre-IMRT panoramic radiograph closest to the IMRT start date and one post-IMRT panoramic radiograph that was most recent were evaluated, for a total of 286 panoramic radiographs.

There was no significant relationship found in the maxilla between any of the radiographic changes following IMRT either in the ipsilateral or the contralateral side of the primary tumor. In the mandible, there was significant relationship between the development of periodontal ligament space widening without epicenter (p = 0.046) and radiographically visible vertical defects (p = 0.029) in the ipsilateral IMRT. There was no significant association found between radiographically visible furcation, localized horizontal bone loss, vertical defects, and perio-endo lesions with ipsilateral IMRT.

These results indicate that subclinical radiographic changes in the mandible are common after IMRT and that they should be monitored closely as they likely indicate the level of devitalization of the periodontium after IMRT. These patients should be scheduled for frequent recall visits with their dentists to minimize the risk of future oral surgical interventions that could lead to debilitating conditions such as osteoradionecrosis of the jaw.