The purpose of this article is to report 20 cases of ossifying fibroma involving the jaw bone and to review the literature of this lesion. All the cases had adequate radiographs and clinical information. Varying shapes of the lesion including cystic lesion and mixed density lesion are presented, including two massive expansile lesions, which measured more than 10 cm.

Objectives: This study was undertaken to investigate the relationship between radiographic appearance and epithelial cell proliferations in keratocystic odontogenic tumours (KCOTs). Methods: A retrospective radiographic analysis was performed on 284 cases of KCOT to gain insight into the radiographic characteristics. Expression of Ki-67 in 30 of the 284 cases was detected by the labelled streptavidin-biotin (LSAB) method and evaluated by an image analysis system. Results: The radiographic presentation of KCOT was divided into four types: unilocular, multilocular, multiple and naevoid basal cell carcinoma syndrome (NBCCS). The expression of Ki-67 in NBCCS was significantly different from the solitary and multiple KCOTs (P 5 0.018, 0.002). In multilocular KCOTs it was also significantly different from the unilocular and syndrome-associated lesions (P 5 0.000). In contrast, no significant differences were observed between the solitary and multiple lesions (P 5 0.220). Conclusions: A high correlation exists in KCOT between its biological behaviour and imaging features. The solitary KCOT seems less biologically aggressive and it should be classified as a cyst rather than a tumour. This means that more than half of KCOTs manifest themselves as ordinary cysts.