Evaluation of vertical magnification coefficients of potential dental implant site in cone-beam computed tomography images: An ex vivo study

Abstract

Purpose: This study aimed to investigate whether the vertical magnification coefficient (MC) changes with errors in head positioning in cone-beam computed tomography (CBCT), which is increasingly used for measurements in implantology. Materials and Methods: CBCT images were obtained in 15 different positions (5° in one or two planes) with the help of a positioner that allowed angular movement in coronal, sagittal, and horizontal planes, using a dry skull, in which three steel spheres were placed in the alveolar bone of each tooth region. An observer measured the vertical dimensions of the spheres in the images twice. Vertical MCs were calculated by dividing the measurements by the real diameter lengths of the spheres. The inter-class correlation coefficient (ICC) was used to compare the measurements repeated twice. Moreover, the Kolmogorov–Smirnov, Levene, one-way analysis of variance, Kruskal–Wallis and least significant difference, Tukey, and Tammhane binary comparison tests were performed in the statistical analysis. Results: A total of 1260 measurement values were used. There was high reliability between the first and second measurement values (ICC = 0.986). The measurements in the images taken in the ideal position were quite close to the physical size. A statistically significant difference was found between the ideal position and the images taken in other positions. The most affected regions by the different positions were the anterior regions for both jaws. Conclusions: Vertical measurements in CBCT images are reliable; however, especially in the anterior regions, such measurements can vary significantly with errors in positioning of patients' heads.

Keywords

• cone beam computed tomography
• dental implants
• magnification coefficient
• vertical dimension