Mixed odontogenic tumours and odontomas. Considerations on interrelationship. Review of the literature and presentation of 134 new cases of odontomas.

Based on a world-wide literature survey of published cases of "mixed odontogenic tumours" (ameloblastic fibroma, fibrodentinoma and fibro-odontoma) and complex/compound odontomas (including 134 own cases of odontomas) the authors present data showing the complex nature of these lesions. The authors suggest the following work hypothesis regarding the pathogenesis and relationship between the "mixed odontogenic tumours" and the odontomas. The tumours develop along two separate lines: (I) the neoplastic line comprising only one tumour, the ameloblastic fibroma (AF) and the closely related ameloblastic fibrodentinoma (AFD). (II) The hamartomatous (or the developing complex odontoma (DCO) line comprising: (1) The AF (and AFD). Differences in age and biological behaviour indicate that some AF are true benign neoplasms, whereas others are hamartomas presenting the first stage in the DCO-line. (2) The AF-O represents the second stage of the DCO-line developing into (3) the fully mineralized complex odontoma. Lastly, the authors suggest that the compound odontoma should be considered not as an alternative final stage to the complex odontoma but rather as a malformation (with a high degree of histomorphological differentiation) pathogenetically closely related to the process producing hyperodontia, "multiple schizodontia" or locally conditioned hyperactivity of the dental lamina.