We are pleased that our article attracted attention and would like to clarify some misunderstandings.
In our study, the penetration rate was estimated based on 60 mini-implants; the 25 mentioned in the letter was for a different rate. In relation to the exclusion criteria, subjects with thickened sinus membranes were excluded before insertion in our study, since the penetration rate is high in the infrazygomatic crest, and those with sinus inflammation are not suitable for a mini-implant. We used the term “incidence” with reference to previous articles.
To investigate the interobserver agreement, 2 examiners made each measurement. Because of the inherent correlation of 2 outcomes for each measurement, the paired t test was apparently more appropriate than the 2-sample t test. P values should be complemented by other statistical parameters. That’s why we reported interval estimations. In addition, as mentioned in the ASA statement, it was released mainly because of the controversies in some journals on the P value cutoff to claim significance. We checked recent articles in the AJO-DO , and it still usually supports 0.05 as the significance cutoff. In addition, means and standard deviations are summary statistics to show the distribution features of observations without any hypothesis involved, whereas the nonparametric tests mentioned in the article were testing specified scientific hypotheses.
Although we agree that CBCT is not the most accurate method to measure the soft tissues, histologic examination of Schneiderian membrane thickness is not feasible in the clinic, especially in a retrospective study. Until now, CBCT is still a common method to evaluate the Schneiderian membrane thickness. Three CBCT images were obtained in each of the 25 mini-implant sites, and the voxel size was 0.15 mm. All CBCT imaging was prescribed to benefit patient care, enhance patient safety, or improve clinical outcomes during treatment, but not to satisfy this retrospective study.
The influence of membrane perforation over the graft and implant survival rates remains a controversy, and few authors have investigated the reaction of the sinus to the penetration of mini-implant anchorage. The thick sinus membrane might imply inflammation and be related to mini-implant failure. Thus, we take the change of the membrane thickness as a potential indicator for harmful stimulation. Many orthodontists, including us, can present cases with the thickened sinus membrane affected by penetration of mini-implant anchorage during treatment and recovered several months after removal of the mini-implant. However, we also think less harm is important to the patient and regard the thickened sinus membrane by the mini-implant as an adverse reaction that should be prevented by precise operations, such as a guide plate. So, the relatively safe depth of mini-implant penetration must be stated first. We found that a 1-mm penetration into the sinus is the boundary of a thickened or unthickened membrane with a mini-implant in the infrazygomatic alveolar ridge. That is 1 key point in the article.
∗ The viewpoints expressed are solely those of the author(s) and do not reflect those of the editor(s), publisher(s), or Association.