Abstract: Objective: To evaluate the patterns of midpoints lines of facial axis (FA) point and discuss its relationship with pre-adjusted bracket positioning. Methods: Fifty-nine sets of stone models were prepared from teenagers of normal occlusion. The height of clinical crown was measured with a vernier and the midpoints of the FA point were determined. The horizontal and vertical data of the center point of clinical crown were measured by a simple two-dimensional model measuring instrument. The lines of the midpoints of FA which were drawn with computer software were analyzed. Results: The central points of the clinical crowns of adolescents with normal occlusion in Guangzhou could be summarized into several regular zigzag lines. Conclusion: The FA points between the teeth were not always on the same plane. It was recommended that the ideal position to place the bracket was not the center of the labial surface of the tooth

Key words: clinical height of crown center, bracket placement, normal occlusion