Abstract
Purpose Accurate growth assessment in orthodontics requires three-dimensional (3D) methodologies. However, studies using cone-beam computed tomography (CBCT) for long-term, longitudinal 3D growth assessments remain scarce. Furthermore, few studies have utilized 3D registration based on planes traditionally used in two-dimensional (2D) cephalography, such as the Sella (S)-Nasion (N) and Basion (Ba)-N planes. This study aimed to develop a 3D registration method using the pterygoid point (PT) and Dorsum Sellae (DS) from the onset to the completion of growth.Materials and methods 12 skeletal Class I patients (6 males, 6 females) treated at Nezu Orthodontic Clinic from 2002 to 2022 were included. CBCT scans were performed at four intervals from the initial consultation to the end of treatment, classified as T1–T4. Seven measurement points (Nasion[N], anterior nasal spine [ANS], pogonion [Pog], bilateral PTs, and bilateral dorsum sellae [DSs]) were identified. PT-based and DS-based registration methods were utilized for qualitative and quantitative assessments.Results Qualitative analysis revealed PT-based registration demonstrated anteroinferior movement of the maxilla and mandible, while DS-based registration showed downward movement. Quantitatively, movement tendencies for N, ANS, and Pog were highly consistent with no significant differences across all axes and periods. Localized significant differences in 3D cumulative magnitudes were limited to only two specific landmarks.Conclusion PT-based and DS-based registrations allowed effective superimposition for evaluating 3D growth. Differences in movement trends suggest cranial base registration points facilitate quantitative assessment of growth-related changes over time.