Purpose: This study investigated the effect of increasing slice thickness and applying sharpening filters on the diagnosis of bone graft loss in regions adjacent to zirconia implants using cone-beam computed tomography (CBCT). Materials and Methods: Twelve zirconia implants were inserted into mandibles, followed by bone graft application.Graft loss was then simulated in half of the samples. CBCT scans were obtained using 2 devices (OP300 and Eagle 3D) with parameters set at 90 kVp, 8 mA, and a 133 μm voxel size. Five examiners assessed the scans under different conditions: original thickness, 1 mm, 2 mm, no filter, Sharpen 1 × , and Sharpen 2 × . The area under the receiver operating characteristic curve (AUC), sensitivity, and specificity were calculated and compared using 2-way analysis of variance (α = 5%). Results: For the OP300 device, increasing slice thickness to 1 mm impaired AUC, sensitivity, and specificity metrics(P<0.05). Overall, filter application reduced this impairment (P<0.05). For the Eagle device, slice thickness didnot affect diagnostic metrics, but specificity values increased with sharpening filter application on scans at originalthickness or with 1 mm slices (P<0.05). Conclusion For 1 device, a 1 mm increase in slice thickness impaired the diagnosis of bone graft loss in areasadjacent to zirconia implants. However, the application of sharpening filters helped mitigate this impairment.

Purpose: The aim of this study was to evaluate image artifacts in the vicinity of dental implants in cone-beam computed tomography (CBCT) scans obtained with different spatial orientations, tube current levels, and metal artifact reduction algorithm (MAR) conditions. Materials and Methods: One dental implant and 2 tubes filled with a radiopaque solution were placed in the posterior region of a mandible using a surgical guide to ensure parallel alignment. CBCT scans were acquired with the mandible in 2 spatial orientations in relation to the X-ray projection plane (standard and modified) at 3 tube current levels: 5, 8, and 11 mA. CBCT scans were repeated without the implant and were reconstructed with and without MAR. The mean voxel and noise values of each tube were obtained and compared using multi-way analysis of variance and the Tukey test (α = 0.05). Results: Mean voxel values were significantly higher and noise values were significantly lower in the modified orientation than in the standard orientation (P<0.05). MAR activation and tube current levels did not show significant differences in most cases of the modified spatial orientation and in the absence of the dental implant (P>0.05). Conclusion Modifying the spatial orientation of the head increased brightness and reduced spatial orientation noise in adjacent regions of a dental implant, with no influence from the tube current level and MAR.

Purpose: This study evaluated the impact of artifacts generated by metal crowns on the detection of proximal caries lesions in teeth at various distances using cone-beam computed tomography (CBCT). Additionally, the diagnostic impacts of tube current and metal artifact reduction (MAR) were investigated. Materials and Methods: Thirty teeth were arranged within 10 phantoms, each containing 1 first premolar, 1 second premolar, and 1 second molar. A sound first molar (for the control group) or a tooth with a metal crown was placed. Of the 60 proximal surfaces evaluated, 15 were sound and 45 exhibited enamel caries. CBCT scans were acquired using an OP300 Maxio unit (Instrumentarium, Tuusula, Finland), while varying the tube current (4, 8, or 12.5 mA) and enabling or disabling MAR. Five observers assessed mesial and distal surfaces using a 5-point scale. Multi-way analysis of variance was employed for data comparison, with P<0.05 indicating statistical significance. Results: The area under the curve (AUC) varied from 0.40 to 0.60 (sensitivity: 0.28-0.45, specificity: 0.44-0.80). The diagnostic accuracy was not significantly affected by the presence of a metal crown, milliamperage, or MAR (P>0.05). However, the overall AUC and specificity were significantly lower for surfaces near a crown (P<0.05). Conclusion CBCT-based caries detection was not influenced by the presence of a metal crown, variations in milliamperage, or MAR activation. However, the diagnostic accuracy was low and was further diminished for surfaces near a crown. Consequently, CBCT is not recommended for the detection of incipient caries lesions.