Cephalometric measurements performed on CBCT and reconstructed lateral cephalograms: a cross-sectional study providing a quantitative approach of differences and bias

Abstract

Background Cephalometric analysis is traditionally performed on skull lateral teleradiographs for orthodontic diagnosis and treatment planning. However, the skull flattened over a 2D film presents projection distortions and superimpositions to various extents depending on landmarks relative position. When a CBCT scan is indicated for mixed reasons, cephalometric assessments can be performed directly on CBCT scans with a distortion free procedure. The aim of the present study is to compare these two methods for orthodontic cephalometry. Methods 114 CBCTs were selected, reconstructed lateral cephalometries were obtained by lateral radiographic projection of the entire volume from the right and left sides. 2D and 3D cephalometric tracings were performed. Since paired t-tests between left and right-side measurements found no statistically significant differences, mean values between sides were considered for both 2D and 3D values. The following measurements were evaluated: PNS-A; S-N; N-Me; N-ANS; ANS-Me; Go-Me; Go-S; Go-Co; SNA, SNB, ANB; BaŜN; S-N^PNS-ANS; PNS-ANS^Go-Me; S-N^Go-Me. Intraclass correlation coefficients, paired t-test, correlation coefficient and Bland–Altman analysis were performed to compare these techniques. Results The values of intra- and inter-rater ICC showed excellent repeatability and reliability: the average (± SD) intraobserver ICCs were 0.98 (± 0.01) and 0.97(± 0.01) for CBCT and RLCs, respectively; Inter-rater reliability resulted in an average ICC (± SD) of 0.98 (± 0.01) for CBCT and 0.94 (± 0.03) for RLC. The paired t-tests between CBCT and reconstructed lateral cephalograms revealed that Go-Me, Go-S, PNS-ANS^Go-Me and S-N^Go-Me measurements were statistically different between the two modalities. All the evaluated sets of measurements showed strong positive correlation; the bias and ranges for the 95% Limits of Agreement showed higher levels of agreement between the two modalities for unpaired measurements with respect to bilateral ones. Conclusion The cephalometric measurements laying on the mid-sagittal plane can be evaluated on CBCT and used for orthodontic diagnosis as they do not show statistically significant differences with those measured on 2D lateral cephalograms. For measurements that are not in the mid-sagittal plane, the future development of specific algorithms for distortion correction could help clinicians deduct all the information needed for orthodontic diagnosis from the CBCT scan.

Accuracy of automated 3D cephalometric landmarks by deep learning algorithms: systematic review and meta-analysis

“…Recently, thanks to the introduction of systems for volumetric rendering and the management of large datasets, the interest has been moved toward cephalometric analysis on 3D images, CT or CBCT [ 44 ]. However, accurate identification of reference points from X-ray images is used to calculate angular and linear measurements, essential to provide quantitative evaluation of craniofacial structures [ 45 ].…”

The Maxilla-Mandibular Discrepancies through Soft-Tissue References: Reliability and Validation of the Anteroposterior Measurement

“…Raw data obtained from the CBCT scan were coded in the file format Digital Imaging and Communications in Medicine (Dicom3). Lateral cephalometric x-rays of the whole volume employing the software 1.8 iCAT Vision (Imaging Sciences International, Inc., Milan, Italy; (accessed on 15 April 2021)) were reconstructed for each raw data according to Baldini et al (2022) [ 5 ].…”

“…Cephalometry is considered for both clinical prediction and growth planning [ 2 ]. The ANB angle obtained from the subspinal-nasion and supramental points and the “Wits appraisal” obtained by projecting the A and B points onto the occlusal plane and considering the linear distance between them, are the most used and described measurements in the literature [ 5 , 6 , 7 ].…”

“…Moreover, the Wits appraisal has been queried because of the difficulties in recognizing the occlusal functional plane and its change in inclination [ 6 ]. As such, other options have been proposed over the years that are based neither on the cranial base nor the occlusal plane [ 5 , 9 ]. Indeed, both measurements evaluate the positions of the maxilla and the mandible relative to each other on the sagittal plane, but while the ANB angle depends also on the relative locations of the cranial base and jaws, the Wits appraisal measures the sagittal jaw relationship independently to cranial landmarks [ 5 , 6 , 10 ].…”

‘Study of the maxillary yaw on cone beam computed tomography: A preliminary report and comparison between two different dento‐skeletal malocclusions’

“…7 The use of cone beam computed tomography (CBCT) in threedimensional diagnosis is boosting the radiographic characterization of different types of facial asymmetry, and the protocols to measure the transverse rotation of the maxillo-facial complex are becoming fast and simple. 7,[11][12][13][14] In this study, we have tested a cephalometric method to assess the yaw on a CBCT three-dimensional reconstructed image of the skull, by evaluating the amount of the maxillary skeletal and dental yawing compensations in two groups of patients clinically affected by a similar malocclusion, a class III with deviation of the lower midline. The aim of the statistical analysis was to compare the measurements of the rotating side with respect to the healthy one in each group, and to analyse if two aetiologically different types of facial asymmetry could significantly affect the transverse maxillary rotation.…”