Comparison of Ultrasonography and Cone-beam Computed Tomography for Quantitative Assessment of Midpalatal Suture Opening after Rapid Palatal Expansion: A Pilot Study.

Background: The study was to compare the ultrasonographic (USG) and cone-beam computed tomographic (CBCT) measurements of the width of anterior midpalatal suture (MPS) opening following rapid palatal expansion (RPE).

Methods: The study included 13 patients (boys: 6; girls: 7) with a mean age of 11.85 ± 1.82 years who underwent RPE therapy for maxillary transverse deficiency. The width of the anterior MPS opening was measured in real-time USG, postscan USG image, and CBCT that were obtained immediately after maxillary expansion. The postscan USG and CBCT measurements were performed twice by two examiners at different times. The intraclass correlation coefficient (ICC), Bland-Altman plot, and paired t-test were performed to evaluate intra- and inter-examiner reliability, level of agreement, and systematic error between different measurements.

Results: On serial USG evaluation, the MPS opening was seen as the discontinuity in the margins of the maxillary cortical bone, which was not evident before expansion or after the retention period. The intra- and inter-examiner reliability was high (ICC >0.9) for all the measurements. The Bland-Altman plot showed considerable agreement between the different methods, with maximum observations having a mean difference which was within the 95% limits of agreement (real-time vs. postscan USG: ±0.75 mm; CBCT vs. real-time USG: ±0.93 mm; and CBCT vs. postscan USG image: ±1.09 mm). The systematic differences were not statistically significant (P < 0.05) for all the computed measurements.

Conclusion: USG can be used as a reliable nonionizing imaging modality to assess the anterior MPS opening following RPE.