Since the introduction of the “new X-ray technique” for cephalometric analysis by Broadbent in 1931, cephalograms have been widely used for measuring the size and shape of craniomaxillofacial structures and evaluating their growth and development1. Lateral cephalograms are the “gold standard” tool in the evaluation of craniofacial growth, orthodontic diagnosis, treatment planning, assessment of treatment results, and craniofacial growth prediction2,3. However, since the conventional cephalometric radiograph displays a three-dimensional (3D) structure on a 2D plane, it may produce inaccurate results when quantitative evaluation is required. For example, when structures on both sides overlap and have distinct magnifications, it is difficult to distinguish between the left and right sides. This may result in inter-examiner discrepancy and differences according to time between the same inspectors. In addition, depending on the transmission of radiation, the structures in the midsagittal region may have an ambiguous shape, thereby lowering the measurement accuracy in the overlapping structures.
Recently, owing to the innovative development of 3D radiographic techniques, such as cone-beam computed tomography (CBCT), 3D images have been used for orthodontic diagnosis. CBCT has minimal image distortion because there is no difference in magnification by region, and important parts can be observed in detail without overlapping images. Furthermore, compared to the conventional radiographs, CBCT has a higher resolution and can distinguish between tissues only when there is a difference of 10% in tissue density. In addition, images can be refined using multiplanar reformatting, surface rendering, and volume rendering through computer reconstruction, and evaluation in various directions is possible through image rotation. Clearly, CBCT has advantages over plain lateral cephalometric radiographs, but conventional cephalograms are easier to access than CBCT in many ways. CBCT has been able to address some of the limitations of conventional CT and provides high-resolution images at low radiation dosage and cost, but still exposes patients to greater doses of radiation than conventional lateral cephalometric radiographs4. With the rapid improvement in CBCT technology, the gap between accessible scientific data and the lawful use of CBCT is narrowing. This holds especially true for children who are more sensitive to radiation and frequently present with difficult diagnoses5,6. When considering radiation exposure for diagnosis, the three basic principles of radiological protection should always be followed: justification, optimization, and dose limitation5,7.
If the DICOM data obtained from CBCT are reconstructed, a 2D image, such as the conventional lateral cephalometric radiograph, can be obtained. The advantage of this technique is that there is no additional need to record a lateral cephalometric radiograph, skull anteroposterior radiograph, or submentovertex radiograph. Furthermore, when recording a conventional radiograph, the position of the radiographic film is fixed, but in CBCT, the position of the image can be modified using software. In addition, it is possible to reduce the error caused by the magnification of the left and right sides of a conventional 2D image.
Lateral cephalogram measurements can be performed manually or with a computer. Manual measurement methods are time-consuming, have a large measurement error, and are greatly affected by the expertise of the operator. In addition, although cephalometric analysis is typically performed by orthodontists trained in clinical practice, there have been many reports of significant intra- and inter-observer variability8,9. In computer-assisted cephalometric analysis, computerized cephalometric tracing programs, such as V Ceph (CyberMed, Inc., Seoul, Korea), Rainbow Ceph (Dentium Co, Gyeonggi-do, Korea), and Dolphin Imaging Version 8.0 (Dolphin Imaging, Chatsworth, CA), automatically evaluate the selected landmarks and calculate the distance and angles, thereby reducing inaccuracies that can arise with manual measurement10. However, an error might still occur in identifying the landmarks according to the skill level of the examiner in using such software11.
Therefore, the need for a fully automated tracing software program to improve the accuracy and reliability of cephalometric measurements is continuously increasing. Artificial intelligence (AI) is widely used in everyday applications. AI-based algorithms are found in almost every technology and used in spam filtering or online voice assistants, internet search engines, and image recognition on social media platforms. Several AI-based programs for automatically identifying anatomical measurement points are being studied currently. These include AI-based orthodontic and orthognathic online platforms, such as WebCeph (Assemble Circle, Gyeonggi-do, Korea), WeDoCeph (Audax, Ljubljana, Slovenia), and Ceph X (ORCA Dental AI, Las Vegas, NV). These are gaining popularity because of their ability to plan orthodontic treatment and obtain patient information quickly. WebCeph™ includes automated cephalometric tracing, cephalometric analysis, automatic superimposition, visual treatment simulation, photo gallery, and image archiving. Additionally, it enables manual landmark modification and automatic measurement computation.
In this study, conventional lateral cephalograms and lateral cephalograms generated from CBCT data were analyzed using the AI-based landmark measurement program WebCeph™. The purpose of this study was to evaluate the applicability of lateral cephalograms generated from CBCT images using an AI-based cephalometric analysis program.