Computed tomography appearance of mandibular para-radicular third molar radiolucencies

Mandibular para-radicular third molar radiolucencies (MPRs) were first described in 2004 by Bohay et al (Bohay RN, Mara TW, Sawula KW, Lapointe HJ. A preliminary radiographic study of mandibular para-radicular third molar radiolucencies. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004; 98: 97-101) as a well-defined oval radiolucency surrounded by a thin sclerotic border located immediately distal to the mandibular third molar roots. Bohay et al's analysis was undertaken using panoramic radiographs. The purpose of this study was to confirm Bohay et al's findings on panoramic radiographs and to identify and document the appearance of MPRs on cross-sectional CT.Panoramic films and CT images of the lower third molar regions from 143 patients were reviewed.MPR was identified on panoramic film in 12 patients with a total of 14 MPRs. A number of factors were recorded from panoramic films and CT.This study confirmed the findings of Bohay et al and concluded that the relative lucent appearance on panoramic radiographs can be explained by the presence of one or a combination of factors: (i) an area of decreased density in trabecular bone, (ii) thinning of the inner surface of the buccal cortex, (iii) thinning of the inner surface of the lingual cortex or (iv) a depression in the external surface of the lingual cortex