We appreciate the interest in our article (Kuroda S, Hichijo N, Sato M, Mino A, Tamamura N, Iwata M, et al. Long-term stability of maxillary group distalization with interradicular miniscrews in a patient with a Class II Division 2 malocclusion. Am J Orthod Dentofacial Orthop 2016;149:912-22), and we want to answer Dr Thakkar’s questions.
First, the interradicular space between the maxillary second premolar and first molar looks narrow from the lateral cephalogram (Fig 3); however, from the panoramic and periapical radiographs, there was sufficient space for miniscrew placement. About a quantification of the interradicular area, we have commonly used panoramic and periapical radiographs but not CBCT.
We really appreciate your second suggestion. You are correct: the miniscrews were placed at the mesial alveolus of the first molars and not the mesial alveolus of the first premolars. We want to correct this in the Discussion section. The sentence should have read, “In this patient, the interradicular screws were placed at the mesial alveolus of the maxillary first molars but are shown at the middle part of the second premolar after treatment (Fig 5, B and D ).”
Third, to prevent contact between the screw and dental root, oblique insertion of the miniscrew is effective because the screw tip is then placed where there is a relatively wide area between the roots. Therefore, when placed in the interradicular area, miniscrews are often implanted into the bone at an insertion angle of 30° to 45°. As mentioned above, we commonly take only panoramic and periapical radiographs to check and confirm the position of miniscrew placement.
Finally, we agree that maxillary arch distalization often increases the mandibular plane angle. The increase of the mandibular plane angle would be caused mainly by maxillary molar extrusion. Therefore, we took care to ensure that the direction of force application was backward and upward as parallel to the occlusal plane as possible without molar extrusion. We selected the short hook as the line connecting the miniscrew with the hook that was parallel to the occlusal plane and used light continuous forces (approximate 200 g with a nickel-titanium coil spring).