An erupted odontoma associated with pigmentation: a histogenetic and histological perspective.

Odontomas are hamartomatous malformations of odontogenic origin composed of all the structures that form the tooth. Pigmentation associated with odontomas is rare, with only two cases reported in the literature. The genesis of this composite malformation is attributable to the organizational failure of the developing odontogenic apparatus leading to abnormal morphodifferentiation.

Gene deployment for tooth replacement in the rainbow trout (Oncorhynchus mykiss): a developmental model for evolution of the osteichthyan dentition.

Repeated tooth initiation occurs often in nonmammalian vertebrates (polyphyodontism), recurrently linked with tooth shedding and in a definite order of succession. Regulation of this process has not been genetically defined and it is unclear if the mechanisms for constant generation of replacement teeth (secondary dentition) are similar to those used to generate the primary dentition. We have therefore examined the expression pattern of a sub-set of genes, implicated in tooth initiation in mouse, in relation to replacement tooth production in an osteichthyan fish (Oncorhynchus mykiss).

Periodontal ligament: structural and clinical correlates.

This paper reviews certain structural aspects of the periodontal ligament. These include collagen (type, crimping and fibril diameters), ground substance (functions), cells (fibroblast morphology, cell heterogenicity and distinguishing of cell phenotypes, cell kinetics, 'foetal' characteristics), nerves (presence of neuropeptides) and blood vessels (presence of fenestrations). Attention is drawn to recent advances in our understanding of the development of the periodontal ligament, especially cementum formation, and in the presence of bioactive molecules such as growth factors and cytokines.