Application of the moiré method to three-dimensional measurements of the lingual surface of the upper central incisors.

Moire 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 moire 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.