The construction of angles is needed for soft tissue analysis and the angles can be made by drawing lines connecting anatomic points or tangent lines. The purpose of the present study is to ,Compare the two drawing methods and show the difference between them. Soft tissue outlines were traced in the lateral cephalograms of 40 normal occlusion individuals, 20 males and 20 females. On the traced cephalograms, angles were constructed by means of both drawing methods. The procedure was repeated twice in a two-week period by the same investigator, and then performed once more by another. In each procedure, angular forms of profile was digitized and 10 angular measurements were computed. The two sets of measurement by the first investigator were compared to study ´differences due to the interval between drawings, while the two sets of measurement by the two investigators were compared to show any differences resulting from the drawers. The obtained results were as follows:
1. The comparison of the measurements between the anatomic point and tangent line group showed a statistically significant difference in nine of ten measurements.
2. The comparison for the reproducibility through correlation analysis showed a high reproducibility in both the anatomic point group and tangent line group.
3. In the analysis of the measurement difference according to the drawing time, two measurements showed significant difference in the anatomic point group and four measurements represented significant difference in the tangent line group.
4. In the analysis of the measurement difference according to the drawers, five measurements showed significant difference in the anatomic point group and six measurements represented significant difference in the tangent line group.
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