Fig. 4

Degree of rotation of the occlusal plane as a function of power arm length and tooth movement patterns. a Degree of rotation of the occlusal plane with varying the height of retraction force on power arm from 8 to 14 mm at the completion of space closure for the 0.019 × 0.025-in and the dual-section archwire. b Tooth movement patterns with the 0.019 × 0.025-in archwire and power arms of 8 and 14 mm at the time when the extraction space was closed. Power arm of 14 mm was required to achieve bodily movement of the incisors. However, it caused a large amount of counter-clockwise rotation of the occlusal plane. c Tooth movement patterns with the dual-section archwire and power arms of 8 and 14 mm. Bodily movement of the incisors was produced with a small amount of counter-clockwise rotation of the occlusal plane when 8 mm power arm was used