Recent advancement in the historadiographic techniques has made it possible to observe the calcified tissues with comparative ease, thus enabling a fair number cf researchers to conduct work on the fine structures of bony and dental tissues. Although there is much published literature on dentin structures by the use of historadiography, an effort which compares our knowledge gained by the historadiography with that of optical microscopy is yet scarce. NALBANDIAN et al. [1], in 1960, reported their comparison of photomicrographs of opaque dentin with historadiographs. In 1964, HARCOURT [2] published a study on the sclerotic dentin in terms of historadiographs. TODA et al. (1966) [3], members of our department, published the historadiographs and photomicrographs of the exposed dentinal tubules of human dentin recently.
The present study is concerned with the historadiographs of some human dentin structures that have been fairly familiar to us optical microscopically.