Accuracy and Reliability of Cone-Beam Computed Tomography for Linear and Volumetric Mandibular Condyle Measurements. A Human Cadaver Study

Abstract

The accuracy of Cone-Beam Computed Tomography (CBCT) on linear and volumetric measurements on condyles has only been assessed on dry skulls. The aim of this study was to evaluate the reliability and accuracy of linear and volumetric measurements of mandibular condyles in the presence of soft tissues using CBCT. Six embalmed cadaver heads were used. CBCT scans were taken, followed by the extraction of the condyles. The water displacement technique was used to calculate the volumes of the condyles and three linear measurements were made using a digital caliper, these measurements serving as the gold standard. Surface models of the condyles were obtained using a 3D scanner, and superimposed onto the CBCT images. Condyles were isolated on the CBCT render volume using the surface models as reference and volumes were measured. Linear measurements were made on CBCT slices. The CBCT method was found to be reliable for both volumetric and linear measurements (CV < 3%; CCI > 0.90). Highly accurate values were obtained for the three linear measurements and volume. CBCT is a reliable and accurate method for taking volumetric and linear measurements on mandibular condyles in the presence of soft tissue, and so a valid tool for clinical diagnosis.

Figure 1

Water displacement method to calculate physical volumes using a pycnometer.

Figure 2

Anatomical landmarks and linear measurements on dry condyles.

Figure 3

CBCT image orientation and slice selection for linear measurement calculations.

Figure 4

Linear measurements taken on the coronal (L1 and L3) and axial (L2) views of the CBCT image.

Figure 5

3D scanning procedure using iTero (left) and surface model obtained (right).

Figure 6

Surface model superimposed onto DICOM reconstruction in Dolphin Imaging® software.