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Figure 8. Coronal T1 weighted scans show the roots of the molar teeth are well visualized with their pulp chambers in vertical cross-section. The most posterior scan slices through the third molar region. The unerupted lower wisdom teeth (H) are seen with their crowns angled lingually and roots angled buccally in close approximation with the buccal cortex of the mandible. There is high signal from their pulp chambers and there is a band of high signal immediately surrounding the crown, demarcated by a lower signal edge of bone. This band or "halo" enveloping the crown is an eruption follicle (Q) developed from the remnants of cells left over from the formation of the enamel and crown of the tooth, and usually disappears on eruption of the tooth into the mouth. It is sometimes referred to as an eruption cyst and occasionally enlarges and is termed a dentigerous cyst, which has to be surgically marsupialized.
