Relationships between changes in skeletal and integumental points A and B following orthodontic treatment.

The purpose of this study was to explore the changes in points A' and B' which occur in the soft-tissue profile of the face and their interrelationship to concomitant changes in the underlying hard tissue after orthodontic treatment. Pre- and posttreatment lateral cephalometric radiographs of forth Class II. Division 1 patients were studied to determine the relationships between the distal movements of osseous points A and B and the corresponding overlying labial soft tissues. Perpendicular lines were drawn to sella, point A, superior labial sulcus (point A'), point B, and the inferior labial sulcus (point B') from the Frankfort horizontal plane. Linear measurements were taken from the above-mentioned four intersects to the sella intersect. Pretreatment and posttreatment measurements were analyzed statistically and it was found that the average ratios between hard- and soft-tissue changes were point A to point A', 1.40 to 1.00, and point B to point B', 1.09 to 1.00.