外生性骨疣是一种比较常见的情况，多见于下颌前磨牙区舌侧 (torus mandibularis) 及上颌腭部 (torus palatinus) 以及上下颌颊侧骨皮质 (Buccal exostoses (“buttressing bone”))。固定桥桥体下方亦可出现类似情况。
A nodular mass of bone has grown up beneath the pontics of this mandibular fixed bridge. (from Color Atlas of Oral and Maxillofacial Diseases)
The reactive subpontine exostosis is a rare type of osseous hyperplasia that develops beneath the pontic of a fixed bridge. In almost all instances, such lesions occur in association with a posterior mandibular bridge. It is theorized that occlusal stresses carried through the abutment teeth of the bridge may stimulate the formation of new cortical bone under the central pontic. Such exostoses usually are discovered incidentally and do not require any treatment. However, if continued growth of the exostosis places pressure against the pontic or if it interferes with oral hygiene, then surgical removal can be performed.