Dental long axes using digital dental models compared to cone-beam computed tomography

Area of Science:

• Orthodontics and Dental Imaging
• Biomedical Engineering
• Radiology

Background:

• Current methods for evaluating tooth long axes, including digital dental models (DDMs) and radiographic techniques, have limitations in comparability or involve significant radiation exposure.
• Cone-beam computed tomography (CBCT) provides detailed 3D imaging but exposes patients to ionizing radiation, raising concerns about cumulative dose.
• Accurate assessment of tooth long axis changes is crucial for effective orthodontic diagnosis and treatment planning.

Purpose of the Study:

• To compare the angular measurements of tooth long axes between digital dental models (DDMs) and cone-beam computed tomography (CBCT).
• To evaluate the reproducibility and agreement of measurements obtained from DDMs compared to CBCT.
• To explore the potential of DDMs as a radiation-free alternative for orthodontic tooth movement assessment.

Main Methods:

• A secondary data analysis was performed on digital dental models (DDMs) and cone-beam computed tomography (CBCT) scans from 24 patients.
• Scans were acquired before and after orthodontic treatment involving piezocision.
• Angular changes in tooth long axes (mesiodistal angulation and buccolingual inclination) were measured using specific landmarks on molars, canines, and incisors. Statistical analyses included Wilcoxon test, intraclass correlation coefficient (ICC), and Bland-Altman plots.

Main Results:

• Digital dental model (DDM) measurements for mesiodistal angulation and buccolingual inclination demonstrated good reproducibility.
• The mean differences between DDM and CBCT measurements were not statistically significant for all teeth (mesiodistal angulation: 1.9°±1.5°; buccolingual inclination: 2.2°±2.2°).
• Intraclass correlation coefficients (ICC) indicated good to excellent agreement between DDM and CBCT measurements (0.85 for molars, 0.94 for canines, 0.96 for incisors), with a high percentage of measurements falling within a 5° range.

Conclusions:

• Assessment of tooth long axis changes using digital dental models (DDMs) is reproducible and provides measurements comparable to cone-beam computed tomography (CBCT) within a 5° margin of error.
• DDMs offer a viable alternative to CBCT, significantly reducing patient exposure to ionizing radiation.
• These findings support the development of machine learning algorithms for orthodontic treatment planning that integrate crown and root canal data from DDMs, eliminating the need for radiation-based scans.