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Objectives: To assess the effect of standard filtered back projection (FBP) and iterative reconstruction (IR) methods on CBCT image noise and processing time (PT), acquired with various acquisition parameters with and without metal artefact reduction (MAR). Methods: CBCT scans using the Midmark EIOS unit of a human mandible embedded in soft tissue equivalent material with and without the presence of an implant at mandibular first molar region were acquired at various acquisition settings (milliamperages [4mA-14mA], FOV [5 × 5, 6 × 8, 9 × 10 cm], and resolutions [low, standard, high] and reconstructed using standard FBP and IR, and with and without MAR. The processing time was recorded for each reconstruction. ImageJ was used to analyze specific axial images. Radial transaxial fiducial lines were created relative to the implant site. Standard deviations of the gray density values (image noise) were calculated at fixed distances on the fiducial lines on the buccal and lingual aspects at specific axial levels, and mean values for FBP and IR were compared using paired t-tests. Significance was defined as p < 0.05. Results: The overall mean for image noise (± SD) for FBP was 198.65 ± 55.58and 99.84 ± 16.28 for IR. IR significantly decreased image noise compared to FBP at all acquisition parameters (p < 0.05). Noise reduction among different scanning protocols ranged between 29.7% (5 × 5 cm FOV) and 58.1% (5mA). IR increased processing time by an average of 35.1s. Conclusions: IR significantly reduces CBCT image noise compared to standard FBP without substantially increasing processing time. [ABSTRACT FROM AUTHOR]

To assess the reproducibility of a wedge-guided bitewing image receptor-holding device (IRHD-WG) compared to a commercially available bitewing image receptor-holding device (IRHD-XCP). Ten operators randomly acquired bitewing radiographs of four posterior regions (Premolar, Molar 1, Molar 2, Molar 3) distributed in two dry bone skulls and mandibles using 2 IRHDs (IRHD-WG and IRHD-XCP). The radiographs corresponding to the same region and IRHD but acquired by different operators were paired for reproducibility comparison. A total of 360 pairs of radiographs were randomized for analysis. Objective analysis consisted of extracting the pixel values from each radiograph and comparing the values between each pair by intraclass correlation coefficient. For subjective analysis, the IRHDs images were digitally removed. Five oral radiologists blinded for the study conditions classified the radiograph pairs according to their similarity and diagnostic value. The answers' relative frequencies were compared by the chi-square test (α = 0.05). The IRHD-WG presented a higher reproducibility (Mean = 0.850; SD = 0.144) than the IRHD-XCP (Mean = 0.615; SD = 0.287) in the objective analysis. Radiographs acquired with the IRHD-WG were more similar than those acquired with the IRHD-XCP (p < 0.001). The diagnostic value of bitewing radiographs acquired with the IRHD-WG was considered superior to those acquired with the IRHD-XCP (p < 0.001). For the objective and subjective analyses of reproducibility, the IRHD-WG performed better than the commercial IRHD-XCP. [ABSTRACT FROM AUTHOR]

The objectives of the present study were to compare measurements of pharyngeal airway subregions on lateral cephalometric (LC) and cone beam computed tomographic (CBCT) images in relation to skeletal classes and discuss the advantages and disadvantages of these imaging formats for this type of assessment. The CBCT images were assessed via both multiplanar reconstruction (MPR) and 3-dimensional (3D) reconstruction. The LC and CBCT images from 107 patients were classified according to skeletal class: 1, n = 35: 11, n = 35; and 111, n = 37. Linear measurements of the subdivisions of the upper airway were performed on the LC, MPR, and 3[) images. In addi:tion, area and volumetric measurements were performed on the MPR images. The relationships among imaging methods, skeletal class, and pharyngeal thirds were assessed by means of a 1-way analysis of variance (a = 0.05). No statistically sign:ificant differences in the linear, area, or volumetric measurements of the upper airway subregions were found among the skeletal classes (P > 0.05). For the linear measurements in the oropharynx and hypo pharynx, greater values were observed for the LC images than for the MPR and 3D images (P £ 0.05). Based on the study findings, MPR images should be preferred for visualization of the pharyngeal airway subregions. However, LC imaging is preferable to 3D reconstruction. [ABSTRACT FROM AUTHOR]

Objective: To assess the reproducibility of a wedge-guided bitewing image receptor-holding device (IRHD-WG) compared to a commercially available bitewing image receptor-holding device (IRHD-XCP)., Methods and Materials: Ten operators randomly acquired bitewing radiographs of four posterior regions (Premolar, Molar 1, Molar 2, Molar 3) distributed in two dry bone skulls and mandibles using 2 IRHDs (IRHD-WG and IRHD-XCP). The radiographs corresponding to the same region and IRHD but acquired by different operators were paired for reproducibility comparison. A total of 360 pairs of radiographs were randomized for analysis. Objective analysis consisted of extracting the pixel values from each radiograph and comparing the values between each pair by intraclass correlation coefficient. For subjective analysis, the IRHDs images were digitally removed. Five oral radiologists blinded for the study conditions classified the radiograph pairs according to their similarity and diagnostic value. The answers' relative frequencies were compared by the chi-square test (α = 0.05)., Results: The IRHD-WG presented a higher reproducibility (Mean = 0.850; SD = 0.144) than the IRHD-XCP (Mean = 0.615; SD = 0.287) in the objective analysis. Radiographs acquired with the IRHD-WG were more similar than those acquired with the IRHD-XCP ( p < 0.001). The diagnostic value of bitewing radiographs acquired with the IRHD-WG was considered superior to those acquired with the IRHD-XCP ( p < 0.001)., Conclusion: For the objective and subjective analyses of reproducibility, the IRHD-WG performed better than the commercial IRHD-XCP.