Can we estimate root axis using a 3-dimensional tooth model via lingual-surface intraoral scanning?

Area of Science:

• Orthodontics
• Dental Imaging
• Biomedical Engineering

Background:

• Accurate root axis estimation is crucial for orthodontic treatment planning and monitoring.
• 3D tooth models derived from intraoral scans and CBCT offer detailed visualization.
• Comparing different scanning methods for 3D model creation is essential for clinical application.

Purpose of the Study:

• To compare the root axis estimation error between whole-surface scan (WSS) and lingual-surface scan (LSS) methods at the midtreatment stage.
• To evaluate the clinical significance of any observed differences in estimation error.

Main Methods:

• Constructed 3D tooth models by merging intraoral scan crowns and CBCT scan roots.
• Superimposed 3D models onto midtreatment intraoral scans (WSS and LSS) to estimate root axis.
• Used midtreatment CBCT as the gold standard for real root axis determination.
• Measured mesiodistal angulation and buccolingual inclination estimation errors.

Main Results:

• Both WSS and LSS methods yielded estimation errors below 2.0° for root axis angulation and inclination.
• The LSS method showed statistically larger, yet clinically insignificant, estimation errors compared to WSS.
• Specific differences were noted in mandibular canines and overall teeth for mesiodistal angulation and buccolingual inclination.

Conclusions:

• Both WSS and LSS methods provide clinically acceptable root axis estimation using 3D tooth models.
• The choice between WSS and LSS may depend on specific clinical needs, with WSS showing slightly lower errors.
• These findings support the use of both scanning techniques for monitoring orthodontic tooth movement.