Comparison of Tooth Size Measurements in Orthodontics Using Conventional and 3D Digital Study Models.

Area of Science:

• Orthodontics
• Dental Imaging
• Biometrics

Background:

• Alginate impressions are the orthodontic gold standard for plaster models.
• Assessing digitization method accuracy is crucial for reliable 3D tooth size analysis.
• Evaluating deviations in 3D tooth size measurements from various digitization techniques.

Purpose of the Study:

• To determine which digitization method yields the greatest deviation in 3D tooth size measurements.
• To compare digital models from intraoral scans and digitized plaster casts (alginate, silicone) against conventional plaster models.
• To evaluate the accuracy of 3D tooth size measurements using different impression and digitization techniques.

Main Methods:

• 30 subjects (10 male, 20 female) included in the study.
• Measurements of mesio-distal (MD) and buccal/labial-lingual/palatal (BL) dimensions on reference teeth.
• Comparison of four model types: intraoral scan digital, digitized alginate, digitized silicone, and conventional plaster models.
• Statistical analysis using repeated measures ANOVA, Friedman test, and intraclass correlation coefficient (ICC).

Main Results:

• Similar agreement levels observed between digital and conventional models across both jaws and segments.
• Mesio-distal (MD) measurements showed better agreement (r=0.337-0.798) than Buccal/Labial-Lingual/Palatal (BL) measurements (r=0.016-0.542).
• Smaller mean differences and measurement errors were found for MD dimensions compared to BL dimensions.

Conclusions:

• Differences between digital and conventional plaster models are small and clinically acceptable.
• Digital models demonstrate reliable accuracy for orthodontic tooth size measurements.
• Intraoral scanning and digitized models offer a viable alternative to conventional plaster models.