As explained in Chapter 25, a variety of conditions that can affect the jaws are radiopaque relative to the surrounding bone, although the degree of opacity can be very variable. A step-by-step guide, similar to that suggested for radiolucent lesions in Chapter 26, is outlined to emphasize the importance of a methodical approach when producing a differential diagnosis. The suggested approach is summarized in Fig. 27.1. Although most lesions are still detected using plain radiographs, this process can be greatly facilitated in many cases if advanced imaging modalities, described in Chapters 16 and 18, such as computed tomography (CT), cone beam CT or magnetic resonance (MR) are available.
• Site or anatomical position – is the opacity actually within bone or is it within the surrounding soft tissues and thus superimposed on the bone? To localize the opacity, two radiographs are usually required, ideally at right angles to one another.
|Abnormalities of the teeth|
|Unerupted and misplaced teeth including supernumeraries|
|Odontomes — Compound
— Complex (see odontogenic tumours)
|Conditions of variable radiopacity affecting the bone|
|Developmental||Exostoses including tori — mandibular or palatal|
|Inflammatory||Low grade chronic infection — sclerosing osteitis
Osteomyelitis — sequestra; involucrum formation
|Calcifying epithelial odontogenic tumour (CEOT)
Adenomatoid odontogenic tumour (AOT)
Calcifying cystic odontogenic tumour (calcifying odontogenic cyst)
Odontomes — Compound
|Non-odontogenic||Benign — Osteoma
Malignant — Osteosarcoma
— Osteogenic secondary metastases
|Periapical osseous dysplasia
Focal osseous dysplasia
Florid osseous dysplasia
Familial gigantiform cementoma
|Other lesions||Ossifying fibroma
|Bone diseases||Paget’s disease of bone
|Superimposed soft tissue calcifications|
|Calcified lymph nodes|
|Calcified acne scars|
|Within the soft tissues|
|On or overlying the skin|
Compare the radiological features of the unknown opacity with the typical radiological features of these possible conditions. Then construct a list showing, in order of likelihood, all the conditions that the lesion might be. As mentioned in Chapter 26, this list forms the radiological differential diagnosis.
The typical radiographic features of the important radiopacities are described below using a similar style to that adopted in Chapter 26. It must be emphasized that this is a simplified approach and that most lesions can produce a variety of appearances.
Although both compound and complex odontomes are more accurately classified as epithelial odontogenic tumours with odontogenic ectomesenchyme showing dental hard tissue formation (WHO Classification 2005), they are often also described as dental developmental anomalies (see Ch. 24).
Deciduous and permanent root remnants remaining in the alveolar bone, following attempted extraction, are common. The site, shape and density make radiographic identification relatively simple. Additional diagnostic radiographic features include the surrounding radiolucent line of the periodontal ligament shadow and sometimes evidence of a root canal.
The formation of excessive amounts of cementum, usually around the apical portion of the root, is common. The cause is unknown, but it is sometimes seen in Paget’s disease of bone and is then typically craggy and irregular. Diagnostically hypercementosis is not a problem – the resultant opacity being part of the tooth root and producing an alteration to the root outline.
Exostoses are small, irregular overgrowths of bone sometimes developing on the surface of the alveolar bone. They consist primarily of compact bone and produce an ill-defined radiopacity when superimposed over the bulk of the alveolar bone. Usually two views are required to establish the exact site (see Fig. 27.7).