[Recent concepts on amelogenesis: towards a molecular understanding of the pathology of human enamel]

Recent studies concerning amelogenesis demonstrate the key role of ameloblasts in the elaboration of mature enamel; this highly differentiated epithelial cell elaborates a specific extra-cellular proteic matrix, secondarily mineralized and participating in the elaboration of mature enamel. While the matrix of immature enamel is essentially made of two main classes of proteins--amelogenins and enamelins--specific proteins are found in mature enamel, the tuft proteins as well as enamelin-type proteins. In light of recent results concerning enamel proteins, we will review the different pathological processes of human enamel. In fact, the clinical observation of various forms of imperfect amelogenesis enables to recognize several aetiological mechanisms. This could either be a pathological process of genetic nature originating in the ameloblast--imperfect, mendelian-type amelogenesis--or secondary abnormalities of the calcification process, without anomalies of the genes responsible for the protein framework, which could be called post-ameloblastic pathological process.