Moiré photographs of the lingual surfaces of eight upper central incisors were taken using a specially designed standard plane. This plane was formed by three points, namely the most protruding points of the lingual tubercle, and the mesial and distal marginal ridges of the lingual surface. When the moiré photographs taken using this standard plane were observed, they showed a high reproducibility. These photographs could be applied to measurement of the depth of the lingual fossa and the three-dimensional distances between the measuring points.
The histological structure of upper-and lower-jaw teeth of Sicyopterus japonicus, a fish known to exhibit rock-climbing behavior, were examined by light microscopy and scanning electron microscopy. The upper jaw teeth and the lower jaw teeth were entirely different in form. The characteristics of the upper jaw teeth were that the enameloid constituting the tip of the tooth had a shovel-like shape and that there were many eruptive teeth behind each of which lay a large number of successional teeth ready for continuous replacement. The shape of the enameloid was suited to the work of scraping algae from the surface of stones. The lower jaw teeth had a hinged structure. It was suggested that the forms of teeth in Sicyopterus japonicus were the result of the fish's adaptation to its feeding habit, rather than its rock-climbing nature.
In this study, the relationship between the results of the caries activity test (Snyder) and salivary IgA level were investigated statistically. There was no significant difference between caries-resistant and slightly caries-active groups (p>0.05), although there were significant differences between moderately active and slightly active and between moderately active and caries-resistant groups at the level of p<0.05. There were statistical relationships between caries-active and moderately active groups, moderately active and slightly active groups, and between slightly active or caries-active and caries-resistant groups at the level of p<0.01.