Comparative Analysis of Alignment Accuracy in Dental CAD Software for Morphologically Altered Digital Models

Area of Science:

• Digital dentistry
• Computer-aided design (CAD)
• 3D modeling and alignment

Background:

• Accurate spatial alignment of altered digital dental models is essential for precision digital workflows.
• Various alignment protocols exist across different CAD platforms, with varying degrees of accuracy.

Purpose of the Study:

• To evaluate the trueness and precision of different spatial alignment protocols for virtually altered digital dental models.
• To compare the performance of landmark-based and reference-based alignment methods across three dental CAD platforms.

Main Methods:

• Generated a morphologically altered digital model from a lower dentition cast.
• Displaced and aligned the altered model to the original using five protocols across BlueSky Plan, Exocad, and Blender for Dental (B4D).
• Quantified accuracy using root mean square (RMS) error, 3D deviation, and landmark deviation, with repeated measurements and statistical analysis.

Main Results:

• Significant differences in alignment accuracy were observed between methods (P<.001).
• Exocad's landmark-based with best-fit optimization yielded the highest accuracy (12 μm RMS error).
• Landmark-based methods alone showed poor performance and high variability (152-250 μm RMS error).

Conclusions:

• Alignment method selection critically impacts accuracy in processing altered digital dental models.
• Optimized landmark-based and reference-based alignment methods achieve clinically acceptable accuracy.
• Standard landmark-based alignment alone is unsuitable for precision digital workflows due to unacceptable errors.