Abstract
Only little has been described so far of three dimensional observation of the enamel tufts, since there have been no adequate technics of their observation. Stereomicroscopic observation was made in order to clarify threedimensional structure of the enamel tufts and their distribution and arrangement of human incisors, premolars and molars.
Now in this study focusing attention on the fact that the enamel tufts are rich in organic substances, the author found a new method of decalcifying whole calcified enamel and leaving enamel tufts, which were observed under the stereomicroscope. Tooth-crown was decalcified after infusing the styrene resin into the crown amputated at its neck and all enamel tufts and lamellae still remained on the surface of dentine after decalcification of the other parts.
Results obtained from the observations are as follows:
1. Sizes of the enamel tufts are dependent upon the form of tooth-crowns. There can be found narrow tufts on both flat and concave surfaces, but not on the broad concave surface at times, while tall and wide tufts are noticed on the prominent convexity. Generally speaking their distribution, arrangement and dimension are definite according to the kind of teeth. Each tuft is delicate in incisors, while big in canines, particularly premolars and molars.
2. Convexity of the crown can be classified into those of horizontal and longitudinal directions and size of tufts and their direction are dependent upon these convexities. Enamel tufts radiate to the middle of the crown from the tip of the cusp on the following strongly convex surfaces to the tooth-axis toward the middle of the crown from the tip: lingual surface of the upper molar and premolar, buccal surface of the lower molar and premolar, and labial surface of the upper canine. On the contrary they run in parallel with tooth-axis on the following equally convex surfaces to the axis in axial direction: lingual surface of the lower molar and premolar.
3. Tufts are largest at the upper half of the crown of each tooth and become delicate at the lower half of the crown. Most of them disappears in the surrounding zone of the neck.
4. Tufts show three-dimensional wavy structure, particularly at the upper half of the crown. Each of adjoining tufts corresponds to its wavy direction and runs linearly at the lower half of the crown.
5. Tufts frequently go over the tip of the cusp to those of the other surface, but this condition can not be noticed in incisors. And they often go over the marginal ridge to the other surface, but rarely in incisors.
6. Tufts on the occlusal surface are complicated in their direction, but they run according to the principle mentioned in 1.
8. Adjoining tufts sometimes unite and show network or membraneous structure near the tip of cusps and the marginal ridge.
