Dimensional accuracy of 3D printed models using different voxel size CBCT (Comparative Experimental Study)

Document Type : Original articles

Authors

1 Ain shams university egypt

2 Professor of Oral & Maxillofacial Radiology department and Head of Oral Medicine, Periodontology, Diagnosis and Maxiloofacial Radiology, faculty of Dentistry, Ain Shams University

3 faculty of dentistry Ain shams univeristy cairo egypt

Abstract

Aims:
To evaluate the influence of different imaging protocols (voxel sizes) of CBCT on linear measurements accuracy of different printed 3d models.
Methods and Material:
Ten intact casts with complete dentition were selected and anonymously numbered from 1-10. Casts were prepared with round bur size 2 at certain specific points to be used as fixed measurement limits. Casts were then scanned with the same CBCT machine using two voxel size protocols (0.125mm and 0.3mm). Each scan was then imported into ondemand3d app software, segmented by thresholding, and exported as STL file to be transferred to the 3d printer. Each set of reference cast and two printed copies were compared with considering cast as gold standard.
Statistical analysis:
Student t-test was used to compare two independent groups. Agreement between continuous variables was detected using Inter-class correlation considering a correlation coefficient of more than 0.7 to be accepted.
Results:
Different linear measurements throughout the three basic planes were taken using digital caliper of 0.01mm accuracy on each set by two radiologists of nine years’ experience after having set for standardization measures. Each observer had three readings to assess intra-rater variability and resulted in no statistically significant difference and excellent agreement between conventional cast readings with models 0.125 and 0.3. Although measurements taken on models 0.125 were slightly close to the gold standard than measurements of model 0.3.
Conclusions:
Using 0.3 mm voxel size in scanning cast models to obtain 3d printed models showed no statistical significance difference from using 0.125mm voxel size.

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