[On the Peculiar Dentin Existing in the Gutter-shaped Root]

The purpose of this study is to investigate the histological structure of the gutter-shaped root. Materials investigated in this study deal with 15 japanese lower molars of adults having gutter-shaped roots and 2 of them of children. Buccolingual, mesiodistal, and horizontal ground sections of them were prepared and observed with binocular microscopy, polarizing microscopy, phase microscopy, fluorescent microscopy, microradiograph, and scanning electron microscopy. It is thought that the lingual dentin of the gutter-shaped root is transparent and roentgenopaque because it has primarily slender and sparse dentinal tubules. It is considered that the lingual dentin differs from the transparent dentin of which dentinal tubules were secondarily filled with calcified substance. It is considered that the lingual dentin of the gutter-shaped root is thinner than the buccal dentin because the forming time of the lingual dentin isn't brief but the forming speed of it is late. It is thought that the peculiar dentin is formed at the lingual part because one odontoblast shares more broad forming space of the dentin there than the other part.