#BEAM HARDENING ARTIFACT MEANING PLUS#

The mandible was inserted into a plastic receptacle and filled with water to simulate soft tissue attenuation of the X-ray beam. A block of homogeneous condensation silicone impression material (Precise SX, Dentsply Sirona, Sao Paulo, Brazil) was attached to the buccal cortical region of the mandible to allow the selection of the same slice on the contralateral side to serve as a control area for subsequent image analysis. For CBCT scan acquisition, the right second premolar socket of the dry mandible was enlarged to fit the tooth passively. Scans were acquired for each intracanal condition: after root canal instrumentation without filling, 1 day after root canal filling, and after metal post placement. Metal post fitting was observed by visual inspection and periapical radiography.

#BEAM HARDENING ARTIFACT MEANING PLUS#

A nickel-chromium (NiCr) post was cast using a FIT CAST-SB Plus alloy (Talmax Ltda, Curitiba, Brazil). The metal post was molded using a direct technique with a standard dowel made of Duralay acrylic resin. The root canal was subsequently prepared for metal post placement by removal of the root filling from the initial two-thirds of the root using #2 and #3 piezo drills (Peeso Long Drill, Dentsply Sirona Endodontics). The root canal was filled along its entire length using gutta-percha and the endodontic cement sealer AH Plus (Dentsply Sirona Endodontics, Charlotte, NC, USA) according to the lateral condensation technique. A root canal instrumentation was implemented according to the MTwo (VDW GmbH, Munich, Germany) protocol (size/taper: 10/0.04, 15/0.05, 20/0.06, and 25/0.06) with distilled water irrigation between rotatory files. The tooth was disinfected with 70% alcohol, was scaled to remove calculus and soft tissue remnants, and had its crown sectioned along the cemento-enamel junction with a diamond saw (Isomet 1000, Buehler Ltd., Lake Bluff, IL, USA). 10 However, information on how such algorithms influence the image is limited.Īs such, the aim of this study was to evaluate the magnitude of artifacts produced due to the beam-hardening phenomenon by gutta-percha and metal posts in CBCT scans obtained with different tube currents and with or without the usage of MAR. 15, 16 Metal artifact reduction (MAR) tools are post-processing algorithms developed by the manufacturers of some CBCT devices to improve image quality during the reconstruction process by reducing beam-hardening artifacts. 12, 13, 14 As the current is increased, image noise is expected to decrease, but no clear relationship with the presence of beam-hardening artifacts has been found. Since the tube current is directly related to the administered radiation dose, it should be set as low as diagnostically acceptable. 1, 2, 6, 7 As different materials produce artifacts of different magnitude and as endodontic materials typically have a high atomic number, 11 studying how the artifacts relate to these materials throughout the volume of the CBCT scan is relevant. 1, 2 Further investigation of this possibility is important for confirming whether errors in the reconstructed data can affect the image quality in regions distant from the artifact-generating material.Īlthough the presence of metal posts and gutta-percha is very common in dental examinations, until now, studies investigating the magnitude of the artifacts in CBCT images have only focused on dental implants. 9, 10 However, recent reports have begun to address the spread of artifacts to different regions of the CBCT volume. The production of artifacts in regions adjacent to high-density materials is relatively well understood. Restorations and crowns create artifacts at the level of dental crowns, which may affect the diagnosis of carious lesions, 4 while the other materials generate artifacts at the level of dental roots and alveolar bone, negatively influencing the ability of clinicians to detect conditions such as root fractures, 5, 6 root resorptions, 7 and bone defects. Such materials include dental restorations and metal crowns, dental implants, gutta-percha, and metal posts. Among the types of artifacts on CBCT scans, those derived from the beam-hardening effect may critically impact diagnosis and are caused by high-density materials located inside 1, 2 or outside 3 the field of view. Artifacts impair the image quality of cone-beam computed tomography (CBCT) scans and may hinder the diagnosis of numerous conditions.

Beam hardening artifact meaning