Peritubular hypercalcified zone of mammalian dentin.

According to FUJITA (1957) and TAKUMA (1960), the structure of the dentinal tubule wall in human dentin has been studied by KOLLIKER, NEUMANN, WALKHOFF, FLEISCHMANN, HANAZAWA, MEYER and ORBAN. Recently, TAKUMA and TSUCHIKURA (1950) found by means of the electron microscope that the dentinal tubules were lined with a hypercalcified area, and designated it as peritubular hypercalcified matrix. This area was also described as peritubular hypercalcified zone or ring by SHROFF, WILLIAMSON and BERTAUD (1954 and 1956), FEARNHEAD (1957) and FRANK (1959) who studied it with the electron microscope. The last mentioned author was able to show the zone in a very thin undecalcified section of human dentin. MILLER (1954), BERGMAN and ENGFELDT (1955), AMPRINO and CAMANNI (1956), BLAKE (1958), VAN HUYSEN (1961) and ATKINSON and HARCOURT (1961) also studied the hypercalcified zone with a historadiographic method. BERGMAN ane ENGFELDT (1955), ROCKERT (1956), BLAKE (1958) and BRADFORD (1958) reported that the occurrence of the zone was due to aging. However, the corresponding zone was also recognized in the dentin of young people by TAKUMA (1960), NALBANDIAN et al. (1960) and VAN HUYSEN (1961). BLAKE (1958), TAKUMA (1958) and ATKINSON and HARCOURT (1961) did not find the peritubular hypercalcified zone in some parts of the dentin. HARCOURT (1964) detected well developed peritubular hypercalcified zones in sclerotic and translucent human dentins and ascribed them a role of protection for the tooth pulp. It was thought by ISOKAWA et al. (1964) that the peritubular hypercalcified zone was a true structure in human adult dentin. As for the peritubular area of animals, however, the available literature comprises only a limited number of historadiographic studies (ISOKAWA et al. 1964; BLAKE, 1958; TAKUMA and his group, 1950, 1958, 1960). It is the purpose of this study to examine by means of a historadiographic method the peritubular zones of the dentin in a larger variety of mammals.