Histological Typing of Odontogenic Tumours (WHO. World Health Organization. International Histological Classification of Tumours)

This new edition is extensively illustrated with photomicro- graphs in colour, together with clinical radiographs and photographs of operation specimens where these help to show the distinctive features of various lesions. Inter-relationships of the Dental Tissues The tooth germ has three main components -the enamel organ, the dental papilla and the dental follicle (Fig. 1). The enamel organ is an epithelial structure derived from the ectoderm that lines much of the oral cavity. The dental papilla and the dental follicle are ectomesen­ chymal (mesectodermal), being partly derived from cells that mi­ grated from the neural crest early in embryogenesis. Both the gross morphology of the tooth germ and the differentiation of its cells de­ pend upon a complex pattern of inductive interactions between the epithelium and the ectomesenchyme. The sites in which the teeth will form appear to be determined before the commencement of epithelial downgrowth from the oral epithelium to form the odontogenic epithelium. This epithelial downgrowth (the dental lamina), the development of the enamel or­ gans of the individual teeth, and the morphology of each enamel organ, are controlled by the ectomesenchyme. The enamel organ is responsible for the formation of enamel and comprises four layers: outer dental epithelium, stellate reticulum, stratum intermedium and inner dental epithelium (Figs. 1 and 2a).

Retaining the same scope as the first edition, this new edition deals with the classification and characteristics of tumours and tumour-like lesions. Similar information is also given on odontogenic and non-odontogenic cysts of the jaws. It is extensively illustrated with photomicrographs in colour, together with clinical radiographs and photographs of operation specimens to show the distinctive features of various lesions. The classification has been updated to reflect the present state of knowledge and changes in views, and includes a number of newly recognised entities.