Immunohistochemical localization of bone morphogenetic protein (BMP) in calcifying fibrous epulis

Immunohistochemical detection of bone morphogenetic protein (BMP) in calcifying fibrous epulis was performed to elucidate the biological process of ossification and cemento-ossification. In a total 25 cases, 15 (60%) showed positive BMP staining in bone forming areas. Histopathological features of developing hard tissues were varied, consisting of structures such as woven bone and cemento-osseous formations. BMP immunostaining was limited to osteoblasts and fibrous connective tissue surrounding the bone matrix. BMP was concentrated in the periodontal fibres and in dense fibrous structures in the cemento-osseous masses. On the basis of histopathological and immunohistochemical features, the histogenesis of ossifying and cemento-ossifying processes appear to be of two possible origins; the excessive proliferation of periodontal ligament and a metaplastic process occurring in the connective tissue fibres (non-periodontal in origin), with the former being more common.