Accuracy of artificial bone defects measurements on two cone beam computed tomography scanners. A comparative study

Introduction

Several CBCT systems are currently on the market variable in their image quality and ability to visualize anatomic structures. Those systems differ from each other in detector design, patient scanning settings, and data reconstruction parameters. Moreover, other scanning and reconstruction factors including scan field of view (FOV), voxel size and the number of basis projections used for reconstruction have significant influence on image quality in CBCT. The aim of this study is to compare two CBCT systems regarding their linear measurements accuracy.

Materials and methods

Eighteen bone defects were created in one dry skull by using a round diamond bur mounted on a high speed hand piece. The defects were fully injected with polyvinyl siloxane impression. The skull was scanned using Planmeca ProMax 3D (Planmeca, Helsinki, Finland) and i-CAT next generation (Imaging Sciences international, Hatfield, PA, USA). Images were uploaded to a third party software (On Demand, Cyber med Inc. South Korea) for applying the measurements. Several measurements of each rubber impression material were done using the measurement tool on the cross sectional images in order to determine the maximum diameter. Then the impression material was removed carefully from the mandible by a dental probe and all the rubber balls were measured with a digital caliber to determine the actual maximum diameter (gold standard). Numerical collected data were explored for normality by checking the data distribution.

Results

The results of the present study showed that the overall measurements by Planmeca showed statistically significantly higher mean measurement than the standard reference while i-CAT measurements showed non-statistically significant difference from the standard reference at all areas and also regarding the overall measurement. Regarding the overall error measurement and error percentage; Planmeca showed statistically significantly higher mean error and error percentage than I-CAT.

Conclusion

CBCT is highly accurate and reproducible in linear measurements in the axial and coronal image planes and in different areas of the maxillofacial region. According to the findings of the present study I-CAT is recommended when the purpose of the CBCT scan is to measure linear distances. This will result in lower patient radiation dose and faster scan time.