![]() ![]() Reduced plaque accumulation and accelerated biocompatibility around zirconium implants have diminished the inflammatory and allergic reactions compared to titanium implants. Zirconium implants are preferable in the esthetic area due to their tooth-like color. Metal-free implants such as zirconium have recently become a feasible alternative to titanium implants. Therefore, CBCT is not an inerrant protocol for post-implant evaluations due to the inherent limitations of the imaging process. Īs one of the high-density materials used in dentistry, traditional titanium implants are accounted for artifact formation in CBCT images, which may prevent proper analysis of the peri-implant area. This difference in the attenuation level causes streaking artifacts to happen. When the beam passes through both objects at a particular tube position, it is more hardened than when it passes through one of the objects at another tube position. Due to the rotational position of the tube, beam hardening occurs at different rates leading to the formation of these artifacts. ĭark bands or streaks are artifacts that appear in an image between two high-density objects. The hardened beam that reaches the detectors is less attenuated than expected, and this difference between the attenuation level of the ideal projection and projection with beam hardening results in the cupped shape artifact formation surrounding the cylindrical object. ![]() Since the central part is composed of more material than edges, it can absorb more low-energy photons. In the process of imaging a cylindrical object, x-rays passing through the middle part of the object are hardened more than those passing through the edges. This phenomenon, known as beam hardening, is one of the prominent causes of artifacts, including cupping artifacts and dark bands or streaks. Thus, the beam reaching the detector is mainly composed of higher-energy photons. When the x-ray beam passes through an object, lower-energy photons are absorbed more rapidly than higher-energy ones. ![]() Īn X-ray beam is composed of Individual photons with various levels of energy. Factors involved in inducing the artifacts can be classified as follows: 1) artifacts caused by the physical structure of the CBCT system, such as the mathematical format used in the 3-dimensional reconstruction, 2) artifacts related to the image acquisition, such as patient movement, exposure settings including milliamperage (mA) and peak kilovoltage (kVp), and presence of high-density elements. Artifacts are visualized structures formed in the image through the data reconstruction process that do not represent the subject being studied. The most commonly encountered problem is the formation of image artifacts. īesides the numerous advantages of the CBCT technique, some problems limit its application. It enables the accurate localization of anatomical structures, quantification of the remaining bone, and exact measurements of both depth and height of the implantation site. CBCT is recommended as a preoperative examination of dental implants. In implantology, preoperative surgery planning and postoperative evaluation are critical steps. We also concluded that the artifacts could be minimized using the larger FOV and voxel size.Ĭone-beam computed tomography (CBCT) has developed as a three-dimensional imaging system used in various specialties of dentistry to provide precise diagnosis and treatment plans. Our results suggest that zirconium implants induce higher amounts of artifacts than titanium ones. The amount of artifacts was increased when using the 133 µ voxel size in both groups, which was only significant in the zirconium group ( P < 0.001). The larger FOV (6 × 8 cm 2) resulted in a lower amount of artifacts in both groups, although the results were only statistically significant in the zirconium group ( P < 0.001). The results showed that titanium implants caused lower amounts of artifacts than zirconium implants, which was statistically significant ( P < 0.001). Data were analyzed by paired t test and independent t test using SPSS 21 and the 0.05 significance level. Subsequently, two observers assessed the images and detected the amount of artifacts around the implants through gray values. CBCT images were taken in two different fields of view (FOV: 4 × 6 cm 2 and 6 × 8 cm 2) and at two resolutions (133 µ and 200 µ voxel size). In this experimental study, 30 zirconium and 30 titanium implants were placed in bovine rib bone blocks. This study aimed to compare the amount of artifacts induced by the titanium and zirconium implants on cone-beam computed tomography (CBCT) and assess the effect of different exposure settings on the image quality for both materials. ![]()
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