Important radiographic features in the identification of osseous dysplasiaÀrelated osteomyelitis Chen Nadler, DMD, PhD, a,1 Susanne E. Perschbacher, DDS, MSc, Dipl ABOMR, FRCD(C), b,1 Daniel Septon, DMD, c Ragda Abdalla-Aslan, DMD, d Michael Pharoah, DDS, MSc, FRCD(C), b and Linda Lee, DDS, MSc, Dipl ABOP, FRCD(C) b Objectives. The aims of this study were to identify radiographic features that distinguish osseous dysplasiaÀrelated osteomyelitis (OD-related OM) from OD without OM and to detect possible causes of OD-related OM. Study Design. Seventeen OD cases with and without OM were examined on planar and volumetric (cone beam computed tomography or multidetector computed tomography) imaging. Cases were divided into 3 groups based on clinical data: symptom- atic OM, incidental (asymptomatic) OM, and control (OD without OM). Images were reviewed by 3 precalibrated observers, blinded to clinical information, for OD characteristics (location and extent); radiographic features of OD-related OM; and possi- ble causes. Radiographic features of OD-related OM chosen by at least 2 observers were statistically analyzed within and between groups. Results. Discontinuity of the cortical plates, widening of the radiolucent rim, decreased attenuation of the radiolucent rim, and sequestrum formation were significantly more common in symptomatic and incidental OM groups than in the control group (P  .05). Two causes, atrophy of the edentulous ridge and presence of a periapical lesion, were also correlated with OD-related OM (P  .05, P  .01, respectively). Conclusions. Radiographic features can distinguish OD-related OM from OD. Familiarity with these radiographic features and possible causes may help improve the identification of secondarily infected OD. (Oral Surg Oral Med Oral Pathol Oral Radiol 2020;000:1À8) Osseous dysplasia (OD) is a nonneoplastic condition in which normal cancellous bone is replaced by irregular trabeculae of woven bone and fibrous tissue. 1,2 OD lesions in the jaws, confined to tooth-bearing regions, are most often asymptomatic and may present as incidental findings on radiographs. 3 OD is typically known to affect middle-aged women and is known to be common among African Americans and those of Asian descent. 3-7 The prevalence of OD cases is unknown; however, one Korean study found it to be greater than 1% in women over the age of 40. 8 Lesions have characteristic radio- graphic features, including multifocal involvement 9 ; location in the periapical region of teeth; well-defined, sclerotic, or corticated borders with radiolucent inner rims; maturation of the internal structure over time from radiolucent, to mixed, to radiopaque; and, in most cases, no effect on the surrounding structures. 3 Three variants of OD have been described: periapical, focal, and florid. 10-12 These variants differ primarily in their anatomic location and number of sites involved but present with overlapping radiographic features and behavior. 10-12 They also share the same histologic presentation. 10-12 For these reasons, for the purpose of this study, the term osseous dysplasia is used to encompass all 3 variants. Osteomyelitis (OM) is inflammation of the osseous medulla 13,14 representing different stages of bone inflammation along a continuous spectrum from acute to chronic phases. 14,15 All stages may be characterized by pain, swelling, fever, lymphadenopathy, and leuko- cytosis. However, in the chronic stage, symptoms are less severe and have a longer history. In the jaws, OM appears predominantly in the mandible with radio- graphic characteristics including ill-defined, gradual blending of mixed sclerotic or radiolucent regions. The hallmark feature of OM is the presence of sequestra. Other associated features may include widened peri- odontal ligament spaces, root and/or cortical bone Statement of Clinical Relevance We identified 4 significant radiographic features in planar and volumetric imaging of osseous dysplasia (OD) complicated by osteomyelitis. Awareness of these features can help imaging specialists to improve their clinical decision making during diag- nosis and follow-up of patients with OD lesions. This work was presented at the IADFR conference in Taiwan in 2017. 1 Both author are equally contributed. a Oral Maxillofacial Imaging Unit, Oral Medicine Department, the Hebrew University, Hadassah School of Dental Medicine, Ein Kerem, Jerusalem, 91120, Israel. b Discipline of Oral and Maxillofacial Radiology, Faculty of Den- tistry, University of Toronto, Toronto, ON, Canada. c Researcher, Oral Maxillofacial Imaging Unit, Oral Medicine Department, the Hebrew University, Hadassah School of Dental Medicine, Ein Kerem, Hadassah Medical Center, Jerusalem, Israel. d Department of Oral and Maxillofacial Surgery, Rambam Health Care Campus, Haifa, Israel. Received for publication Dec 22, 2019; returned for revision Sep 7, 2020; accepted for publication Sep 19, 2020. Ó 2020 Elsevier Inc. All rights reserved. 2212-4403/$-see front matter https://doi.org/10.1016/j.oooo.2020.09.008 1 ARTICLE IN PRESS Vol. 00 No. 00 && 2020