Aim: To evaluate and compare the accuracy of digital models created by two scanning modalities; CBCT and extraoral optical scanner.
Methodology: Twenty-four stone models were fabricated, and then digital models were created using the “3D model " protocol featured in Planmeca, Promax 3D Mid CBCT machine, and Medit T500 optical scanner. 3-Matic Medical software assessed 6 linear measurements on the digital models including mesiodistal width till the first molars, 2 arch length readings and arch width measured in 3 readings: inter-canine, inter-premolar and inter-molar width. They were then compared to their reference standard “plaster model" using the digital caliper. Numerical data were presented as mean with 95% confidence intervals, standard deviation, minimum and maximum values. Shapiro-Wilk's test was used to monitor data distribution. Normally distributed data was analyzed using repeated measures ANOVA followed by Bonferroni post hoc test to monitor the difference in accuracy between the two modalities. Intra-observer and inter-observer reliability were analyzed using ICC.
Results: The measurement error of the two scanning modalities showed no statistically significant difference except for some readings, however they were clinically irrelevant. For optical scanner models, the average mean error calculated values were (0.58 mm), (0.49 mm), and (0.20mm). while for CBCT models, the average mean error values were (0.65 mm), (0.66mm), and (0.29 mm) for arch width, arch length, and mesiodistal width respectively. The study showed an excellent intra-observer and inter-observer correlation.
Conclusions: EOS and CBCT showed high degree of accuracy and reproducibility in arch space analysis compared to the gold standard.