Chairs:
anastasia mitsea
paul van der stelt
120: IMPACT OF COMMON DENTAL MATERIALS ON METAL ARTIFACT REDUCTION IN MAXILLO-FACIAL MDCT EXAMINATION
S. Antic1, B. Markovic Vasiljkovic2, M. Lezaja Zebic3, J. Kuzmanovic Pficer4, D. Bracanovic2, A. Janovic2
1School of Dental Medicine, University of Belgrade, Center for Radiological Diagnostics, Beograd, Serbia, 2School of Dental Medicine, University of Belgrade, Center for Radiological Diagnostics, Belgrade, Serbia, 3School of Dental Medicine, University of Belgrade, Implant Research Center, Belgrade, Serbia, 4School of Dental Medicine, University of Belgrade, Statistics, Belgrade, Serbia
Aim: To investigate the impact of common dental materials on metal artifacts during MDCT examination.
Material and methods: A mandibular model, comprising restored human teeth, was created. Six dental materials were molded as teeth coverage to uniform thickness: A-Silicones (Elite HD+, and Vonflex S Putty), Alginate (Tropicalgin), Pink wax (MBwax1), C-Silicon (Zetaplus) and Zinc-oxide (COE-PAK). The model alone (control), and with teeth covered by each of the materials, underwent MDCT scanning (Philips Ingenuity 64), using standard, and a low dose protocol. Each dataset included original, and images reconstructed with O-MAR algorithm. Two experienced radiologists analyzed obtained datasets: quantitatively- by measuring standard deviations (SD) within the selected region of interest (ROI), and qualitatively (using a five-point Likert scale). The data were analyzed using standard one-way analysis of variance (ANOVA). Inter-rater reliability was examined.
Results: Intraclass Correlation Coefficient for all measurements was between 0.806- 0.996. Excluding Alginate (with both protocols) and C-silicon (low dose protocol), each material significantly differed from the control (p<00.1). Vonflex showed the lowest SD values in both protocols, while the highest values were recorded for control, and for Alginate at standard protocol. With O-MAR, all SD values decreased- the most drastically for Alginate, and higher scores were reached in qualitative analysis. Qualitative analysis did not show significant differences between the control and any of the tested materials.
Conclusion: Covering teeth with certain dental materials, especially Vonflex, quantitatively reduced image noise. Still, in contrast to O-MAR algorithm, they did not show a visible, qualitative impact on the artifact reduction.
209: EXPOSURE OF PSP PLATES WITH RED, BLUE AND GREEN LIGHT BEFORE SCANNING: DOES CHANGING ORDER AFFECT SIGNAL LOSS?
H. Amasya1, K. Orhan2
1Istanbul University-Cerrahpaşa, Oral and Dentomaxillofacial Radiology, Istanbul, Turkey, 2Ankara University, Oral and Dentomaxillofacial Radiology, Ankara, Turkey
Aim: This research aims to investigate the effect of changing the order of the colors by conducting twelve various sequences of light exposure in red, green or blue colors.
Material and Methods: Human-related material was not included. An Arduino-based experimental tool was developed with 3D printed light-tight platform. Plates were irradiated using same parameters and metallic coins were used as contrast material. The plates were exposed to red, green and blue colors, with variable color order and time interval (20 seconds, 1 second, 100 milliseconds, 10 milliseconds). Total delay before scanning and total time of light exposure was fixed, twelve sequences were conducted, and each experiment was repeated twice. Resulting radiographs were imported to ImageJ software and Signal-to-noise (SNR) and Contrast-to-noise (CNR) values were calculated by combining the ROIs dedicated for each contrast region.
Results: SNR values were found in the range of 128.6-155.6, while CNR values were found between 63.2-74.7. Second experiment (R-B-G, 20 seconds) resulted in the lowest SNR (128.6) and CNR (63.2) values, while the twelfth experiment (R-B-G, 10 milliseconds) resulted in the highest SNR (155.6) and CNR (74.7) values. For 20 seconds, administration of the red color first resulted in greater signal loss than green and blue colors.
Conclusion: Results of this experiment suggests that, despite the total delay and light exposure was the same, changing color order and time interval effected the resulting signal. Testing this phenomenon with different PSP systems or investigating the logic behind it may be the subject of future studies.
54: IMPACT OF DOSE-LOWERING CBCT PROTOCOLS ON HEIGHT AND WIDTH MEASUREMENTS IN THE MANDIBLE – AN EX VIVO STUDY IN HUMAN CADAVERIC SPECIMENS
L. Schropp1, L.A. Kaaber1, R. Spin-Neto1, L.H. Matzen1 (alt presenter: Laurits Kaaber)
1Aarhus University / Department of Dentistry and Oral Health, Section for Oral Radiology and Endodontics, Aarhus, Denmark
Aim: To compare linear bone measurements for implant planning in the mandible based on low-dose(LD), standard(SR), and high resolution(HR) CBCT protocols.
Material and Methods: Forty-two posterior implant sites were scanned in three CBCT units (AXEOS, Dentsply-Sirona, Germany; X1, 3Shape, Denmark; and VISO, Planmeca, Finland) using three protocols (HR, SR, and LD), and supplemented with ultra-low dose (ULD) for VISO. Three observers measured the height from the top of the alveolar crest to the upper border of the mandibular canal in sagittal and coronal plane images (420 of each), and the width three mm from the alveolar crest in the coronal images. Paired t-tests were applied to test differences in height and width measurements among the various protocols.
Results: Overall, the linear measurements for the three protocols did not differ significantly using AXEOS or X1. However, one observer measured the width in X1 significantly larger for HR than for SR (0.11 mm, p=0.04) and for HR compared to LD (0.12 mm, p=0.02). For VISO, the height and width measurements in the coronal plane did not differ significantly among the four protocols. The height measurements in the sagittal plane differed for observer 1 (HR vs SR: 0.16 mm, p=0.02), observer 2 (HR vs ULD: -0.18 mm, p=0.02), and observer 3 (HR vs LD: 0.48 mm, p=0.03).
Conclusion: Dose-lowering protocols did not impact significantly on linear bone measurements for implant planning. A tendency to a difference between HR and the other protocols for the height measurements in sagittal images was disclosed for VISO.
100: DIAGNOSTIC IMAGE QUALITY OF LOW-DOSE, STANDARD, AND HIGH-RESOLUTION CBCT FOR ALVEOLAR BONE MEASUREMENTS: AN EX VIVO STUDY IN HUMAN SPECIMENS
L. Kaaber1, L.H. Matzen1, L. Schropp1, R. Spin-Neto1
1Aarhus University, Department of Dentistry and Oral Health, Aarhus, Denmark
Aim: To assess the impact of dose-lowering (LD) cone beam computed tomography (CBCT) protocols on the diagnostic image quality when performing linear bone height measurements for implant planning compared to standard (SR) and high-resolution (HR) protocols.
Material and methods: Forty-two potential posterior implant sites in human cadaveric mandibular specimens were selected and subsequently scanned in three CBCT units. Radiographic examinations included LD, SR, and HR protocols based on a small field-of-view (FOV) and factory set exposure parameters. Images of the implant sites were prepared and replicated for all protocols in dedicated software. Three blinded observers, independently and in randomised order, judged if the image quality was adequate for performing bone height measurements or not. Intra- and inter-observer reproducibility were expressed with kappa statistics for the number of non-measurable cases. Frequencies of non-measurable cases were compared for the units and their respective protocols.
Results: Interpretation of the intra-observer reproducibility for cases that were judged as non-measurable ranged from fair (0.328) to almost perfect (0.933). The inter-observer reproducibility among observer pairs ranged from fair (0.322) to substantial (0.668). Trends in frequencies of non-measurable cases were similar for protocols within each unit independent of observer, however, the high-resolution protocol of one unit resulted in the most non-measurable cases consistently among observers.
Conclusion: Diagnostic image quality when performing linear bone height measurements for implant planning was similar in volumes acquired with LD protocols compared to SR and HR protocols. It was not always the highest resolution protocol that provided the best diagnostic image quality.