Examination of Precision of Integrating Three-dimensional Facial and Dental Data

Aim: The purpose of this study was to examine the precision of integrating three-dimensional facial and dental data.Materials and methods: The subject was a 27-year-old male with normal occlusion. Materials consisted of two kinds of facial three-dimensional data: three-dimensional dental cast data and the lateral cephalogram. To confirm the precision of data obtained, measurements were performed three times on different days. Integration of the soft tissue and dental cast data was achieved by using markers. The reference plane was defined with bilateral ear-rods and the left orbital on the soft tissue. The Y axis was the perpendicular line dropped from sella converted from the cephalogram to the reference plane. For analysis of the hard tissue and the soft tissue, cross sections were set up parallel to the reference plane at 2 mm intervals. Radial patterns from the Y axis on each cross section to the hard tissue and the soft tissue were set at 1 degree intervals, and the hard tissue and soft tissue measured values were defined as the distance from the Y axis to the hard and soft tissues, respectively. The mean and standard deviation of the distances among two facial data at gingival exposure and closed lips, and dental cast data in the common region were used to evaluate the precision of the integration. Reproducibility was investigated from the mean and standard deviation of the measured values for the hard tissue and the soft tissue at the same angle of the same cross section.Results: The mean and standard deviation of the distances between two facial data were 0.15 mm and 0.01 mm, and those of the distances between facial data at gingival exposure and dental cast data were 0.37 mm and 0.01 mm. With respect to reproducibility of the integrated three-dimensional data, no significant differences were found in the measured values for the hard tissue and the soft tissue for the same three randomly selected points.Conclusion: The present system is valid for precisely analyzing three-dimensional changes in soft tissue without computerized tomography.