The metal post material influences the performance of artefact reduction algorithms in CBCT images

Abstract

This study aimed to assess the effect of the MAR tool on the expression of artefacts in different regions of a tooth restored with different types of metal posts. Alveolar sockets (anterior, and posterior region) of a mandible and an unirradicular tooth were used. Cone beam computed tomography scans of the tooth without a metal post, and with cobalt-chromium (Co-Cr), nickel-chromium (Ni-Cr), or silver-palladium (Ag-Pd) were individually obtained, with 2 MAR conditions: disabled, and enabled. In an axial reconstruction, lines of interest (LOIs) were set around the canal: 4 in oblique (mesiobuccal, distobuccal, mesiolingual, distolingual) directions, and 4 in orthogonal (mesial, distal, buccal, lingual) directions. Beam-hardening artefacts expression was determined by calculating the difference in the mean of gray values (DMGV) between the experimental and control groups for each LOI. There was no significant difference in the DMGV values between “without MAR” and “with MAR” for any LOI, in neither anterior nor posterior mandible (p>0.05), for the Ni-Cr and Co-Cr groups. For the Ag-Pd, significant differences in the DMGV values were observed between “without MAR” and “with MAR” for most LOIs (p<0.05), mainly in oblique directions in the anterior region, and mesio-distal direction in the posterior region. MAR acted mostly in hypodense artefacts (negative DMGV). The effectiveness of the MAR tool of the OP300 CBCT unit varied according to the post material tested. It was effective in reducing the expression of artefacts raised by the Ag-Pd post, mainly in the tooth regions affected by hypodense artefacts, regardless of the mandibular region.

A Quantitative Evaluation of the Effectiveness of the Metal Artifact Reduction Algorithm in Cone Beam Computed Tomographic Images with Stainless Steel Orthodontic Brackets and Arch Wires: An Ex Vivo Study

“…Artifacts were assessed using SD of gray values and CNR in six ROIs with different distances (10 to 35 mm) and angulations (70 to 135) from the implants. The authors concluded that both modes of using MAR reduce the amount of artifacts in CBCT images, especially when the impact of artifacts in the images is more significant [23]. This finding is not completely in line with our findings.…”

“…In 2022, Gomes et al investigated the effect of the artifact reduction algorithm in teeth restored with different posts and found that in the case of nickel-chromium and chromecobalt posts, these algorithms did not significantly reduce the amount of artifacts. However, in the case of silver-palladium posts, the effect of the MAR algorithm was significant [23]. This indicates that the material and alloy of the restoration were a significant factor in the effectiveness of MAR algorithms.…”

“…CBCT allows for the examination of structures in three dimensions and with high resolution with a relatively low radiation dose [7]. However, one of the challenges of CBCT imaging is the presence of metallic artifacts around objects with a high atomic number [23]. For example, in cases where metallic orthodontic brackets are attached to the surface of adjacent teeth, due to their high atomic number, artifacts are created around them.…”

Vertical root fracture diagnosis in teeth with metallic posts: Impact of metal artifact reduction and sharpening filters

“…Previous objective analyses have concluded that hypodense and hyperdense streaks are smoothed when MAR is enabled. 22 23 However, this homogenization of gray values in areas affected by beam-hardening artifacts does not necessarily impact diagnostic tasks. Some studies have shown that activating MAR did not enhance the detection of dehiscence and fenestration defects, nor did it aid in identifying fractured endodontic instruments.…”