Does proclination of maxillary incisors really affect the sagittal position of point A?

Abstract

Objective: To examine the effect of maxillary incisor proclination due to orthodontic treatment upon the sagittal position of point A and evaluate the effect of this possible movement of point A on sella-nasion-point A (SNA) angle. Materials and Methods: A study group was formed from 25 subjects (12 male and 13 female) who had Class II division 2 malocclusion with retroclined upper incisors, and a control group was formed from 25 subjects (12 male and 13 female) who had minor crowding in the beginning of the treatment and required no or minimal maxillary anterior tooth movement. Treatment changes in maxillary incisor inclination, sagittal position of point A, SNA angle, and movement of incisor root apex and incisal edge were calculated on pretreatment and posttreatment lateral cephalographs. Results: Maxillary incisors were significantly proclined (17.33 degrees) in the study group and not significantly proclined (1.81 degrees) in the control group. This proclination resulted in 2.12-mm backward movement of the root apex and 5.76-mm forward movempnt of the incisal edge of maxillary incisors. Point A moved 1.04 mm backward (P = .582) and 0.48 mm (P = .811) forward in the study and control groups, respectively. Incisor root apex and incisal edge almost remained stable in the control group. No significant change was observed in the value of the SNA angle in both the study and control groups. Conclusions: Proclination of maxillary incisors accompanied by backward movement of incisor root apex caused posterior movement of point A. However, this posterior movement does not significantly affect the SNA angle.