Cemento-Osseous Dysplasia: A Detailed Comparison of the 2005 and 2017 WHO Classifications and Case Analysis

The WHO substantially redefined cemento-osseous dysplasia (COD) in 2017. The descriptions of COD in the 2005 and 2017 WHO classifications are quite different. In this study, we compared the difference in COD description between the 2005 and 2017 editions of the WHO classifications in detail. There are remarkable differences in the terminology, definition, synonyms, epidemiology, classifications, clinical features, radiation/pathology, prognosis, and predictive factors of COD between the two versions. At present, the surgical treatment of COD is less defined, and there is no clear guidance for the treatment of sclerotic bone. In this study, we extracted the affected teeth without removing the sclerotic bone when the bone absorption line can be only found between the root and the lesion, and we extracted the teeth as well as the lesion and curetted the granulation tissue when a bone absorption line could be seen between the lesion and the alveolar bone. According to our observation, the position of the bone absorption line can be used as a reference for the selection of sclerotic bone treatment. Sclerotic bone preservation did not increase its volume and density after tooth extraction. Sclerotic bone was composed of highly mineralized tissue with less blood vessels and cells. The position of the bone resorption line can be used as a basis for treatment selection. The high mineralization of the lesion may weaken its anti-infection ability.