title: Mandibular changes on panoramic imaging after head and neck radiotherapy.
abstract: OBJECTIVE
  Changes to the radiographic appearance of the jaws after head and neck radiotherapy have not been thoroughly characterized. This retrospective study examines changes to the appearance of the mandible on panoramic images following intensity-modulated radiotherapy (IMRT) and relates these changes to medical co-morbidities and radiation dose.
  
  
  METHODS
  The medical and dental charts, and panoramic images of 126 patients who received IMRT at the Princess Margaret Hospital between January 1, 2005, and December 31, 2008, were analyzed independently by three observers.
  
  
  RESULTS
  Of the 126 patients, 75 (60%) had post-IMRT changes, as seen on panoramic images; most, 66 (88%), consisted of widened periodontal ligament space (WPLS). The median time to WPLS was 29 months after IMRT. Female gender and radiation dose correlated with decreased time to WPLS.
  
  
  CONCLUSIONS
  These results indicate that WPLS is a common radiographic sequela after head and neck radiotherapy, underscoring its clinical significance as a reliable marker of irradiated bone. Furthermore, this type of WPLS needs to be differentiated from odontogenic inflammatory disease and cancer recurrence to avoid unnecessary treatment that may precipitate osteoradionecrosis.
authors.affiliation: Clinical Assistant Professor, Department of Oral and Maxillofacial Pathology, Radiology and Medicine, New York University College of Dentistry, New York, New York, USA. Electronic address: kcc5@nyu.edu.
authors.forename: King Chong
authors.initials: KC
authors.lastname: Chan
authors.affiliation: Assistant Professor, Discipline of Oral and Maxillofacial Radiology, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Susanne E
authors.initials: SE
authors.lastname: Perschbacher
authors.affiliation: Professor and the Dr. Lloyd & Mrs. Kay Chapman Chair in Clinical Sciences, Discipline of Oral and Maxillofacial Radiology, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Ernest W N
authors.initials: EW
authors.lastname: Lam
authors.affiliation: Staff Radiation Oncologist, Department of Radiation Oncology, Princess Margaret Hospital, University Health Network, Toronto, Ontario, Canada.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Hope
authors.affiliation: Staff Medical Physicist, Department of Radiation Oncology, Princess Margaret Hospital, University Health Network, Toronto, Ontario, Canada.
authors.forename: Andrea
authors.initials: A
authors.lastname: McNiven
authors.affiliation: Staff Biostatistician, Department of Biostatistics, Princess Margaret Hospital, University Health Network, Toronto, Ontario, Canada.
authors.forename: Eshetu G
authors.initials: EG
authors.lastname: Atenafu
authors.affiliation: Staff Dentist, Department of Dental Oncology, Ocular and Maxillofacial Prosthetics, Princess Margaret Hospital, University Health Network, Toronto, Ontario, Canada.
authors.forename: Linda
authors.initials: L
authors.lastname: Lee
authors.affiliation: Professor, Discipline of Oral and Maxillofacial Radiology, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pharoah
mesh_terms: D005260:Female; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging* / Q000528:radiation effects*; D010513:Periodontal Ligament / Q000000981:diagnostic imaging* / Q000528:radiation effects*; D011862:Radiography, Panoramic; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated; D012189:Retrospective Studies