Enamel caps are recognized as isolated projections on the intact enamel surfaces in normal human permanent teeth. We observed small dome-shaped projections forming parts of overlapping perikymatas with the isolated projections, small granule-shaped projections attached to the perikymatas, and smaller enamel cap-like projections in Tomes' process pits (TPP), besides the enamel caps. We also indicated that the cap-like projections in TPP may seal the punched-out deep pits in TPP as well as the enamel caps occluding the focal holes. On the enamel surfaces adjacent to hypoplastic enamel defects, the enamel caps and various-shaped and sized enamel projections or enamel-like deposits were observed. The floors of minor irregular enamel defects in a tooth showed large granule-shaped enamel crystallites or enamellike deposits. The floor layer of a large enamel defect was occupied with granule-shaped deposits composed of afibrillar cementum. Thus, some enamel-like deposits in the hypoplastic enamel may be such an afibrillar cementum.
Deformity of the jaw may be caused by the functional disharmony of the masticator muscle and malocclusion. The purposes of this study are to define the characteristics and to measure the thickness of the masseter muscle of the patients with jaw deformity using ultrasonography. Ten patients with jaw deformity and ten normal volunteers were examined using a 7.5 MHz linear array transducer to measure the thickness of the muscle on the axial plane and the echo level of the area defined in the center of the muscle in the rested and maximal clenching conditions. The results showed that 1) the thickness in the maximal clenching condition was thicker than that in the relaxed condition for the normal and the affected side of the patients although the significant change in thickness was not observed in the unaffected side of the patients, 2) the echo level in the maximal clenching condition was lower than that in the rested condition for the normal and the affected side of the patients although the significant decrease was not observed in the unaffected side of the patients, and 3) the thickness of the affected side in the relaxed condition was thinner than that of the normal. The results indicate that the patients with jaw deformity show the different properties of the a masseter muscle and the ultrasonography may be useful to analyze the jaw deformity.
Surface-overlapping projections with aggregated granular to dome-shaped structures, forming part of the abnormal perikymata region, were observed on the hypoplastic enamel surface with keyhole-shaped prisms by scanning electron microscopy. These projections ranging from about 4 to 6 pm in diameter were formed independently of the positions of the keyhole-shaped prisms and gradually changed into the surface prismless enamel with regular perikymatas towards the cervical margin. It is concluded, therefore, that the surface-overlapping projections are enamel structures, although the surface crystallites showed a fine sand-grain shape while the keyhole-shaped prisms consisted of larger needle-shaped crystallites.
Five cases of second branchial cleft cyst were evaluated with computed tomography (CT). One case of them was also evaluated with magnetic resonance imaging (MRI). CT and MRI were helpful to diagnosis and surgery because of their demonstrating exact locations of these masses related to the deep structures in the neck, as reported previously.