The effect of changes in reimbursement coverage on the number of brain MRI scan in patients with dizziness in the emergency department

Objective@#This study examined whether the changes in reimbursement coverage of brain magnetic resonance image (MRI) affected practice for patients who visited the emergency department with dizziness as the chief complaint. @*Methods@#Among the 5,423 patients who visited the emergency department for dizziness in 2017, 2019, and 2021, 4,497 patients were included in the study retrospectively and investigated by brain diffusion-weighted MRI and the presence of cerebral infarction on brain diffusion-weighted MRI. This study examined whether there was a significant difference before and after the change. @*Results@#In 2017, 2019, and 2021, 1,489, 1,570, and 1,438 patients with dizziness visited the emergency department, respectively. The number of patients who underwent a brain MRI scan gradually increased from 237 (15.9%) in 2017 to 628 (40.0%) in 2019 and 948 (65.9%) in 2021 (P<0.001). The number of positive findings on brain MRI scan increased gradually from 30 patients (2.0%) in 2017 to 47 patients (3.0%) in 2019 and 53 patients (3.7%) in 2021 (P=0.025). The ratio of positive findings of brain MRI scans to the number of patients who underwent brain MRI scans decreased gradually to 12.7% in 2017, 7.5% in 2019, and 5.6% in 2021 (P=0.001). @*Conclusion@#The changes in the reimbursement coverage of brain MRI affect the number of brain MRI scans and the detection of cerebral infarction.

Evaluation of marginal and internal gaps of Ni-Cr and Co-Cr alloy copings manufactured by microstereolithography

PURPOSE: The purpose of this study was to evaluate the marginal and internal gaps of Ni-Cr and Co-Cr copings, fabricated using the dental µ-SLA system. MATERIALS AND METHODS: Ten study dies were made using a two-step silicone impression with a dental stone (type IV) from the master die of a tooth. Ni-Cr (NC group) and Co-Cr (CC group) alloy copings were designed using a dental scanner, CAD software, resin coping, and casting process. In addition, 10 Ni-Cr alloy copings were manufactured using the lost-wax technique (LW group). The marginal and internal gaps in the 3 groups were measured using a digital microscope (160 ×) with the silicone replica technique, and the obtained data were analyzed using the non-parametric Kruskal-Wallis H test. Post-hoc comparisons were performed using Bonferroni-corrected Mann-Whitney U tests (α=.05). RESULTS: The mean (±standard deviation) values of the marginal, chamfer, axial wall, and occlusal gaps in the 3 groups were as follows: 81.5±73.8, 98.1±76.1, 87.1±44.8, and 146.8±78.7 µm in the LW group; 76.8±48.0, 141.7±57.1, 80.7±47.5, and 194.69±63.8 µm in the NC group; and 124.2±52.0, 199.5±71.0, 67.1±37.6, and 244.5±58.9 µm in the CC group. CONCLUSION: The marginal gap in the LW and NC groups were clinically acceptable. Further improvement is needed for CC group to be used clinical practice.

Ceramic molar crown reproducibility by digital workflow manufacturing: An in vitro study

PURPOSE: This in vitro study aimed to analyze and compare the reproducibility of zirconia and lithium disilicate crowns manufactured by digital workflow. MATERIALS AND METHODS: A typodont model with a prepped upper first molar was set in a phantom head, and a digital impression was obtained with a video intraoral scanner (CEREC Omnicam; Sirona GmbH), from which a single crown was designed and manufactured with CAD/CAM into a zirconia crown and lithium disilicate crown (n=12). Reproducibility of each crown was quantitatively retrieved by superimposing the digitized data of the crown in 3D inspection software, and differences were graphically mapped in color. Areas with large differences were analyzed with digital microscopy. Mean quadratic deviations (RMS) quantitatively obtained from each ceramic group were statistically analyzed with Student's t-test (α=.05). RESULTS: The RMS value of lithium disilicate crown was 29.2 (4.1) µm and 17.6 (5.5) µm on the outer and inner surfaces, respectively, whereas these values were 18.6 (2.0) µm and 20.6 (5.1) µm for the zirconia crown. Reproducibility of zirconia and lithium disilicate crowns had a statistically significant difference only on the outer surface (P<.001). The outer surface of lithium disilicate crown showed over-contouring on the buccal surface and under-contouring on the inner occlusal surface. The outer surface of zirconia crown showed both over- and under-contouring on the buccal surface, and the inner surface showed under-contouring in the marginal areas. CONCLUSION: Restoration manufacturing by digital workflow will enhance the reproducibility of zirconia single crowns more than that of lithium disilicate single crowns.