Evaluation Of The Changes Of Orbital Volume In Adult Female Patients Treated With Miniscrew Assisted Rapid Palatal Expansion

ObjectivesIn this study,CBCT scan images were used to reconstruct the bone orbit and periorbital skeletal bones and then measure the orbital volume and periorbital bone widths.To evaluate the effect of miniscrew assisted rapid palatal expansion（MARPE）on the orbital volume and the widths between the periorbital bones in the treatment of adult female patients with maxillary transverse deficiency.At the same time,a new automatic segmentation method based on a convolutional neural network was proposed to achieve accurate and efficient bony orbital segmentation,and the accuracy and sensitivity of the automatic segmentation were analyzed.MethodsA total of 20 adult female patients（average age:22.6±6.29 years,18-44years）with maxillary transverse deficiency（MTD）were selected from September 2016 to May 2021 in the Orthodontic Department of Shandong University.CBCT scans were performed on each patient before（TO）and within three weeks after the end of the expansion（T1）respectively.We obtained DICOM data and imported the data into Mimics 21.0 software to reconstruct the bony orbit and periorbital bones and measure the orbital volume and periorbital bone widths.The results were statistically analyzed by SPSS 20.0,all of which were in line with the normal distribution.The measurement data before and after maxillary skeletal expansion were compared by paired sample t-test.The ANS and PNS expansion were tested by an independent sample t-test.P<0.05 indicates that the difference is significant.In addition,a total of 36 adult patients with no history of craniofacial trauma and congenital developmental malformations who underwent CBCT at Shandong University Stomatological Hospital were selected to construct the segmentation model,of which 28 were used as the training set and 8 as the validation set.CBCT of 20 cases before and after the expansion was used as the test set to evaluate the performance of the automatic segmentation model.All datasets were manually segmented by a trained orthodontist according to the same annotation criteria.Results1.After MARPE,the average opening of the helical expander was（6.21±1.45）mm.The increase of midpalatal suture in ANS and PNS was（2.62±0.60）mm and（2.45±0.60）mm respectively.Compared with T0,the orbital volume increased by（346.80±275.31）mm3 in T1（P<0.05）.2.After MARPE,the widths between the right and left zygomaticomaxillary sutures increased by（1.69±0.57）mm（P<0.05）.The widths between the right and left infraorbital points increased by（1.711±0.70）mm（P<0.05）.However,the widths between the right and left frontozygomatic sutures increased by（0.15±0.32）mm（P>0.05）.The widths between the right and left supraorbital points increased by（0.23±0.52）mm（P>0.05）.3.The Dice similarity coefficient,hausdorff₉5,sensitivity and specificity of the convolutional neural network reached 0.9685,0.8560,0.9642,and 0.9998,respectively.There was a statistically significant difference in orbital volume before and after MARPE by automatic segmentation（P<0.05）.There was no statistical difference between the manual segmentation and the automatic segmentation before and after expansion（P>0.05）.Conclusions1.Miniscrew assisted rapid palatal expansion can successfully split the midpalatal suture of female adults with maxillary transverse deficiency.After expansion,the midpalatal suture expands in parallel,and the orbital volume increases slightly.During the expansion process,the widths between the periorbital bones also increase,and the closer to the expander,the greater the expansion.2.Compared with manual segmentation,the model based on convolutional neural network proposed in this paper can segment the orbit accurately and efficiently with excellent performance,which is an effective tool to assist in evaluating the effect of MARPE.