The configuration of the DEJ was scalloping rather than a straight line in DD-I teeth.
However, dentinal tubules were fewer in number and smaller in diameter in DD-I teeth than in normal teeth, and some aperture of dentinal tubules of DD-I teeth were occluding (Fig. 4b, d).
In addition, teardrop-shaped lacunae were found near the cervical enamel in DD-I teeth (Fig. 3g).
At higher magnifications, DD-I teeth contained regions of rodless enamel with black and white horizontal stripes (Fig. 4e).
This suggested that the structures of enamel in DD-I teeth may change, although this change in enamel was not extensively found in the current study.
In addition, well-demarcated mantle dentin was found in several areas of all DD-I teeth examined (Fig. 3c, d), and much of the dentin directly adjacent to the enamel had dentinal tubules and a distinctly-differentiated mantle dentin.
In this regard, more studies are needed to determine whether this alteration was an exceptional manifestation of DD-I teeth resulting from a specific mutation, or an artifact of specimen processing.
Further histopathological and ultrastructural studies of dentin in DD-I teeth may help to obtain a better understanding of the pathogenesis, as well as the clinical phenotypes of DD-I.
According to our observations, the scalloped structure of DD-I teeth was larger than in controls and at the same time, results from LM analyses revealed that teardrop-shaped lacuna near the cervical enamel corresponded to regions of rodless enamel.
Examination of ground sections of DD-I and normal teeth under a stereomicroscope and LM revealed that the enamel was of normal thickness in both normal and DD-I teeth and a normal-appearing enamel was continuous with a normal-appearing coronal dentin band of tubules (Figs. 2c, d; 3a, b).
However, dentinal tubules of circumpulpal dentin were fewer compared to the controls, which were fractured and discontiguous in certain areas (Fig. 3c, d), and the thickness of dentin was noticeably thinner in DD-I teeth compared to the controls (Figs. 2d, 3b).
