Re: Response to: Does proclination of maxillary incisors really affect the sagittal position of point A? Ali Altug Bicakci, Ozkan Semih Cankaya, Serhat Mertoglu, Nurbengu Yilmaz and Burcu Kocoglu Altan. The Angle Orthodontist. 2013;83(6):943-947
To: Editor, The Angle Orthodontist
We congratulate and appreciate the authors of this article for bringing up the important issues regarding the relationship between maxillary incisor proclination and the sagittal position of point A. We do have a couple of questions regarding this study.
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As the authors mentioned, the axial inclination of the upper incisors could be changed in different ways by varying the center of rotation around which the teeth are proclined. The authors said that patients in the study group underwent incisor proclination with a center of rotation closer to the apex than the bracket. What treatment method and mechanism of proclination did the authors perform in subjects involved in this study?
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A non-significant decrease of SNA angle after proclination was found in the study. The authors attributed this to the movement of Nasion in a forward and downward direction during treatment. How did the growth of the maxilla contribute to this finding? Forward growth of the maxilla could reduce the apparent backward movement of A point caused by posterior movement of the incisor apices.
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As written in the end of the Results section of the manuscript, “A point moved 0.48 mm forward but 1.04 mm backward in the control and study groups, respectively.” However, as shown in Table 1, the Vert T-A values of both the study group and the control group showed a decrease at T2 (−1.04 mm in the study group and −0.48 mm in the control group).
Thank you for presenting this interesting study.