Distortion or magnification? An in vitro cone-beam CT study of dimensional changes of objects with different compositions

Abstract

Objectives: To assess whether dimensional changes occur as shape distortion (unevenly), contraction or magnification (evenly) in cone beam computed tomography (CBCT) considering materials, anatomical regions, and metal artefact reduction algorithms (MAR). Methods: Four cylinders of amalgam (Am), cobalt-chromium (Co-Cr), gutta-percha (Gu), titanium (Ti) and zirconium (Zi) were inserted inside a polymethylmethacrylate phantom in anterior and posterior regions for acquisitions in Picasso Trio and OP300 with MAR enabled and disabled. Two observers measured the dimensions of each cylinder in three axes: Y (height), Z (antero posterior diameter), and X (latero-lateral diameter). Repeated measures ANOVA with Tukey post-hoc test compared the data (α = 5%). Results: Shape distortion occurred for all materials in anterior region of Picasso Trio without MAR (p < 0.05). With MAR enabled, Gu and Ti contracted, while the others showed distortion (p ≥ 0.05). In posterior region, all materials distorted in both MAR conditions (p < 0.05), except Gu, which magnified without MAR (p ≥ 0.05) and contracted unevenly with MAR (p < 0.05). In anterior region of OP300, all materials magnified without MAR, (p ≥ 0.05), and had shape distortion with MAR (p < 0.05). In posterior region, only Am showed magnification without MAR (p ≥ 0.05), while all materials presented shape distortion with MAR (p < 0.05). Conclusion: Dimensional changes of high-density materials in CBCT can be either a magnification, a contraction or a distortion; the last condition is the most prevalent. Furthermore, changes differ considering material, anatomical region and MAR condition.

The impact of implant‐related characteristics on dental implant blooming: An in vitro study

“…There was statistically significant distortion when measuring zirconium implants on NWT images, whereas for ACC the distortion was significant only in the anterior region. Our results are compatible with research recently published by Coelho‐Silva et al (2021), suggesting that MAR algorithms work well on titanium but may be inadequate when zirconium is present, resulting in image distortion.…”

“…was significant only in the anterior region. Our results are compatible with research recently published byCoelho-Silva et al (2021), suggesting that MAR algorithms work well on titanium but may be inadequate when zirconium is present, resulting in image distortion.Each of the findings related to implant variables is based on eight measurements of a single implant. To reduce the influence of confounding factors as much as possible, each configuration was scanned using two CBCT devices and two measurements were performed by two experienced observers, using the same workstation and lighting conditions.…”

“…Distortion is defined as a difference in the amount of blooming between the mesiodistal and buccolingual measurement directions. As previous research has shown that distortion may depend on the anatomical region (Coelho‐Silva et al, 2021), this aspect was also verified. To assess distortion for each anatomical region (anterior vs. posterior) and implant material (titanium vs. zirconium), a linear mixed effects model was applied using the difference between mesiodistal and buccolingual measurements with device and material as fixed factors and jaw as random factor.…”

“…gutta‐percha, metal posts and crowns, and dental implants) (Fontenele et al, 2018; Gaêta‐Araujo et al, 2020). These artifacts include streaking, beam hardening, scatter, photon starvation, and blooming or volumetric distortion (Coelho‐Silva et al, 2021; de Faria Vasconcelos et al, 2020; Schulze et al, 2011).…”

Influence of Exposure Parameters and Implant Position in Peri-Implant Bone Assessment in CBCT Images: An In Vitro Study

“…Its presence has been confirmed on both periapical and panoramic radiographs [21][22][23]. Surprisingly, dimensional changes were also observed in CBCT, which is considered one of the most accurate techniques in dental radiology [24]. These distortions may be related to beam hardening, partial volume effects, and metallic artifact reduction algorithms [25].…”