Novel intraoral ultrasonography to assess midpalatal suture anatomy

Abstract

<h3>Background</h3> Evaluation of the midpalatal suture is key when planning for skeletal maxillary expansion with orthodontic appliances in young adults. Non-ionizing ultrasonography is a promising alternative to cone beam computed tomography (CBCT) to assess suture patency. <h3>Objective</h3> The objective of this study was to investigate and validate the accuracy of intraoral ultrasound (iUS) to assess the midpalatal suture in animal models. The null hypothesis is that iUS is as accurate as the CBCT to assess midpalatal suture. <h3>Study Design</h3> The sample comprised the cadaveric maxillae of 4 piglets and 5 young pigs. iUS scans were performed using a clinical ultrasound scanner (ZS3, Mindray) paired with our prototype probe (L25-8). Multiple cineloops along the midpalatal suture were acquired at a speed of 2mm/s. CBCT scans (J.Morita) and intraoral (IO) scans (3Shape Trios) were also obtained for each maxilla. 3D Slicer software was used to obtain multiplanar reconstructions of iUS, superimpose then on the CBCT and IO images, and measure the width of the patent suture and soft tissue thickness on the iUS and CBCT scans. <h3>Results</h3> Suture patency was identified on iUS as a hypoechoic gap between the two hyperechoic palatal bony plates (≥6 dB contrast difference), with end-to-end, beveled, or overlapped appearance. Suture patency was clearly visualized in the most anterior portion of the premaxilla in all CBCT images. Limited width (0.4mm) of the suture was noted in the posterior aspect of the premaxilla and an interdigitated suture was observed towards the posterior maxilla. In iUS, the suture was visible with a soft tissue thickness of 2.444mm, but not visible when thicker than 3.636mm. Suture patency width measurement differences between iUS and CBCT ranged from 0.0076mm-0.15mm. <h3>Conclusion</h3> The iUS is a feasible method to assess patency of the midpalatal suture when soft tissue thickness is <3.5mm, but may have limitations when sutures are interdigitated. <b>Statement of Ethical Review</b> Ethical Review or exemption was not warranted for this study