established. Abnormalities Odontomes Odontomes are considered to be developmental anomalies resulting from the growth of completely differentiated epithelial and mesenchymal cells that give rise to ameloblasts and odontoblasts. Histologically, they are composed of different dental tissues including enamel, dentine, cementum and in some cases, pulp tissue, therefore if the enamel organ is not arranged in its proper fashion, an odontome may form. Odontomes are categorised as either: Compound this malformation is anatomically like a normal tooth, and has dental tissues (enamel, dentine, cementum) placed in an orderly fashion. These are more frequent than complex odontomes. Complex this malformation results in dental tissues being arranged in a disorderly fashion, forming an irregular mass. Odontomes are rare entities and usually asymptomatic; they are often incidental findings on routine dental radiographic examinations. The complex odontome appears as an irregular mass of calcified material surrounded by a thin radiolucent area with smooth periphery, and the compound type shows calcified structures resembling teeth in the centre of a well-defined radiolucent lesion. Some factors related to the development of odontomes are: Changes in genetic components responsible for tooth development Trauma at primary dentine period Inherited conditions such as Gardner's Syndrome Infection Inflammation Hyperactivity of odontoblasts. The first reported case of an odontome erupting in the oral cavity was in 1980. Dens Invaginatus Dens Invaginatus is a dental anomaly which means that the affected tooth (dilated odontome) contains a cavity that is completely or partially lined by enamel, radiographically resembling a tooth within a tooth (dens in dente). There is a lack of consensus on the aetiology of dens invaginatus. It is suggested that dens invaginatus arises because during odontogenesis, there is proliferation and ingrowth of the cells of the enamel organ into the dental papilla during development. Another proposed theory is that the distortion of the enamel organ during tooth development and subsequent protrusion of a part of the enamel organ will lead to the formation of an enamel-lined channel ending at the cingulum or occasionally at the incisal tip. Histologically, there are differences in the structure and composition between the external and internal enamel in dens invaginatus. The internal enamel exhibits atypical and more complex rod shapes and its surface has the typical honeycomb pattern but no perikymata. The invagination can be: Coronal type: slight pitting involving the enamel organ infolding into the dental papilla Radicular type: occupying most of the crown and root involving