Influence of the patient's head spatial orientation on the expression of artifacts arising from a dental implant in cone beam computed tomography: an ex-vivo study

Abstract

Image artifacts are defined as alterations contained in cone-beam computed tomography (CBCT) scans that do not belong to the scanned object and represent a major limitation of this imaging modality. The formation of image artifacts depends on numerous factors, being the acquisition parameters and the composition of the scanned material the most frequent. Considering that the spatial orientation of the patient's head at the time of obtaining the CBCT scan affects the projection of the X-ray beam on the structures, the objective of the present study will be to evaluate the influence of the spatial orientation of the patient's head at the time of CBCT acquisition on the expression of artifacts from dental implants. A phantom will consist of a dry human skull and jaw; in the mandible, a set consisting of two polypropylene tubes and a titanium dental implant will be fixed. The propylene tubes will be filled with an aqueous solution of dipotassium phosphate (K2HPO4), which allows the evaluation of the expression of artifacts in CBCT. The phantom will be scanned using the OP300Maxio unit under two spatial orientations: traditional (long axis of the tooth perpendicular to the radiation beam) and reclined (long axis of the tooth parallel to the radiation beam). Then the implant will be removed and all acquisitions will be repeated. All volumes will be reconstructed with and without the application of the metal artifact reduction tool, resulting in 40 volumes (5 replicates × 2 spatial orientations × 2 implant conditions × 2 FRA conditions). The images will be evaluated in the OnDemand 3D imaging software regarding the expression of artifacts from the mean gray and standard deviation values. To obtain these values, regions of interest will be selected in the center of each of the polypropylene tubes. Data will be analyzed using SPSS software, with a significance level of 5%. Mean gray values and standard deviation will be compared by means of the analysis of variance (two-way ANOVA) with Tukey's posthoc test. The reproducibility of the study will be evaluated through the intraclass correlation coefficient.(AU)