Mandibular Radiolucencies; A systematic approach to diagnosis

Dr. Ahmed M. Adawy Professor Emeritus, Dep. Oral & Maxillofacial Surg.

Former Dean, Faculty of Dental MedicineAl-Azhar University

Mandibular lesions

Conventional radiography may reveal a variety of intraosseous lesions in the mandible. These represent a broad spectrum of odontogenic and non-odontogenic lesions with a varying degree of malignant potential. Mandibular lesions can be described as having either a radiolucent, radiopaque, or mixed appearance. The vast majority of jaw lesions (more than 80%) are radiolucent (1)

Various mandibular lesions. Panoramic radiographs Show radiolucent, radiopaque, or mixed appearance

Based on another classification, intraosseous lesions can be classified as inflammatory lesions, cysts, benign tumors, malignant neoplasms and osseous manifestations of systemic conditions. Differentiation of these lesions from normal anatomic structures of the jaws is of particular importance and since a dentist might be the first individual to diagnose these lesions, it is very important to have a proper knowledge of the prevalence and characteristics of these lesions for diagnosis and treatment planning

Mandibular lesions

Mandibular RadiolucenciesInterpretation of radiolucent lesions of the mandible can be challenging either because the clinical presentation may be non-specific or because the lesion may be detected incidentally (2). Further, interpretations may vary from one examiner to another (3). Thus, systematic approach to the evaluation of radiolucent jaw lesions is necessary to diagnose the lesion or at least provide a meaningful differential diagnosis. Such approach should focus on specific radiographic parameters (4), which could allow greater diagnostic accuracy, mainly in the case of lesions of difficult radiographic interpretation

Location (5)Certain lesions have a predilection for a particular site, whereas others can occur anywhere in the jaw. Non-odontogenic lesions usually have no specific relationship to the dentition or can involve the bone around two or more teeth, whereas odontogenic lesions typically involve only one tooth or a specific part of the tooth. A tooth-related lesion may also arise or persist at the site of a congenitally absent or extracted tooth. A single periapical radiolucency of an anterior mandibular tooth would suggest a diagnosis of periapical inflammatory disease, while multiple periapical radiolucencies would be more consistent with cemento-osseous dysplasia

Step1 – Location

A B

C D

A- Single periapical lesion B- Multiple periapical lesions C- At the site of extracted molar D- Paradental

The relative position of the lesion can also be extremely helpful. Some lesions might be located around the tooth root, around the crown and in the inter-radicular area, whereas others might have no relation with teeth

Step1 - Location

Relationship of the lesion with respect to the inferior alveolar canal indicates tissue types that compose the lesion. Lesions above the canal are likely to be odontogenic, whereas lesions below it are usually non-odontogenic in nature. Lesions close to the inferior alveolar canal would be suggestive of a neural origin

Step1 - Location

Lesion below the inferior alveolar canal

Lesion within the inferior alveolar canal.

Similarly, unilateral defects are more suggestive of a disease process while bilateral symmetrical defects would most likely represent normal (or variations of normal) structures. If the abnormal appearance affects all the structure of maxillofacial region, systemic disorders such as metabolic or endocrine abnormality should be considered.

Step1 - Location

Bilateral numerous mandibular radiolucencies

Step 2 – MarginsMargins (5)The margins can either be described as well-defined or ill-defined. Well-defined margins usually represent benign processes. They may have corticated margins, a thin radio-opaque line around the periphery of the defect (sclerotic margins), and a wider, non-uniform radio-opaque periphery. A lesion with an ill-defined (diffuse) border is suggestive of a lesion enlarging by invading the surrounding bone, such as in aggressive inflammatory or neoplastic pathology

Well-defined margin

Ill-defined margin

Measure the lesion with a ruler. If you must estimate, use surrounding structures as guide. Measurements should include the width and height in mm or cm

Step 3 – Size and Shape

Small radiolucency

Large midline radiolucent lesion

The shape of the lesion (5) can provide pertinent clues for diagnosis. Regular shapes like round, triangular and rhomboid are mostly seen. Irregular shape like circular or scalloped-multilocular appearance is sometimes encountered. A unilocular, well-demarcated defect would be most consistent with a slow proliferating benign process. A multilocular radiolucent lesions with well-defined borders, also referred to as honeycomb, soap-bubble, tennis racket or scalloped pattern, with well-defined borders would be highly suggestive of a benign yet aggressive process such as an ameloblastoma, or odontogenic myxoma. Moth eaten osteolytic pattern signals either an inflammatory condition, such as chronic osteomyelitis or a primary or metastatic malignant lesion

Step 3 – Size and Shape

Unilocular radiolucency Multilocular, soap-bubble radiolucency

Moth eaten osteolytic pattern

Step 4 – Effect on surrounding structures Evaluating the effect of the lesion on the surrounding structures is a good measure of the clinical behavior of the disease process (6). Slow growing benign processes frequently result in tooth displacement. Dentigerous cyst, for example, displace the tooth apically. Chronic inflammatory processes would result in tooth resorption rather than displacement. However, malignant lesions also occasionally resorb teeth. Slow-growing lesions often cause expansion with cortical bowing, while cortical destruction denotes aggressive inflammatory or neoplastic lesions. Presence of periosteal reaction is also suggestive of an inflammatory or malignant aetiology. Some types of periosteal reactions are quite specific, like the sunburst type in osteosarcoma

Large radiolucent lesion involving mandibular angle and ramus.

Note displacement of third molar

Large mandibular radiolucency.Tooth resorption is clearly seen

Multilocular radiolucency. The lesion causes expansion of buccal and lingual plates

Mandibular lesion causing destruction of the buccal cortex

Step 5 – Forming an interpretationSystematic radiographic interpretation should be started by placing the “lesion” in the category of either normal or abnormal. If the lesion is abnormal, then it is either developmental or acquired. This step is followed by adding a description to the disease process, such as benign, malignant, slow-growing, inflammatory, or fibro-osseous. Obviously, however, diagnosis of a lesion should never be made exclusively on the basis of radiographic interpretation. Appropriate radiographic interpretation should be used along with clinical information and other tests to formulate a differential diagnosis. The best way to establish a definitive diagnosis is to perform a biopsy

1. DelBalso AM. An approach to the diagnostic imaging of jaw lesions, dental implants, and the temporomandibular joint. Radiol Clin North Am, 36: 855, 1998.2. Dunfee BL, Sakai O, Pistey R, et al. Radiologic and pathologic characteristics of benign and malignant lesions of the mandible. Radiographics 26: 1751, 2006.3. Stheeman SE, Mileman PA, Hof M van’t, et al. Room for improvement? The accuracy of dental practitioners who diagnose bony pathoses with radiographs. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 81: 251, 1996.4. Mourshed F. An approach to the teaching of radiographic interpretation of bone lesions. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 50: 92, 1980.5 . Neyaz Z, Gadodia A, Gamanagatti S, et al. Radiographical approach to Jaw lesions. Singapore Med J. 49: 165, 2008.6 . Theodorou S, Theodorou D, Sartoris D. Imaging characteristics of neoplasms and other lesions of the jaw bones Part 1. Odontogenic tumors and tumor like lesions. J Clin Imaging. 31: 114, 2007.

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