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Abstract Background/purpose: Computer aided implant surgery has been widely adopted in modern implant dentistry. However, absence of reliable anatomic landmarks for superimposing digital data sets for patients with terminal dentition or complete edentulism remained challenging. Utilization of additional fiducial markers intraorally as the reference points for the improvement of accuracy became crucial in implant digital workflow. Nevertheless, the choice of the material for fiducial markers should present the least radiographic artifacts under cone beam computed tomography (CBCT) for better accuracy. The aim of this in vitro study was to investigate the volume of radiographic artifacts generated through different materials under the image of CBCT. Materials and methods: Fifteen dental materials were selected and configured into cubic shape. All the materials were scanned initially with the laboratory scanner as the control groups. The samples were scanned by CBCT machine as test groups and the volume of artifact generated under CBCT images were compared and analyzed using 3D modeling software. Results: Eleven out of fifteen materials could be recognized under CBCT images. Volumetric analysis reported that statistically significant differences among the materials could be noted, and the flowable composite resin presented the least volumetric difference. Lithium disilicate glass-ceramic, flowable composite resin, and gutta-percha presented the least deformation and maintained their cubic shapes. Conclusion: The results of the present study may imply that flowable composite resin compared to all ceramic materials, amalgam and gutta-percha may be a preferable choice when utilized as fiducial markers under CBCT images.

Objectives: To compare unilateral versus bilateral antegrade cerebral perfusion (ACP) techniques on cerebral protection during acute type A aortic dissection repair. Methods: Using an institutional database, we retrospectively reviewed patients who underwent acute type A aortic dissection repair with selective ACP techniques from October 2008 to December 2019. Primary end point was the detection of neurologic dysfunctions. The secondary end point was mortality. For baseline adjustment, the propensity score matching method was used. Multivariable logistic regression analysis was performed to determine the predictor of neurologic events. Results: Among 522 patients (aged 62.0 ± 14.9 years; 45.7% women), unilateral and bilateral ACP techniques were used in 357 (64.7%) and 165 (35.3%) patients, respectively. Transient (19.6% vs 21.2%; P = .65) and permanent (7.0% vs 10.3%; P = .70) neurologic dysfunction rates were not significantly different in patients with unilateral versus bilateral ACP, respectively. Observed mortality rate was higher in the patients with bilateral ACP (hazard ratio, 2.05; 95% CI, 1.33-3.14; P = .001). Propensity-score matching yielded 94 pairs of patients. In matched analysis, bilateral ACP did not significantly lower the risks for transient (odds ratio, 0.87; 95% CI, 0.42-1.81; P = .71) and permanent (odds ratio, 1.42; 95% CI, 0.55-3.85; P = .47) neurologic dysfunction or death (hazard ratio, 1.65; 95% CI, 0.87-3.15; P = .13). In the multivariable analysis, the ACP technique was not significantly associated with perioperative neurologic deficit. Conclusions: Despite additional supply, the patients undergoing bilateral ACP during acute type A aortic dissection repair did not have superior outcomes in neurologic and death events compared with the patients undergoing unilateral ACP.

Alveolar ridge preservation (ARP) is indicated to attenuate anatomic and physiologic changes following tooth extraction. A properly contoured ovate pontic placed immediately into an extraction socket may be adequate to maintain alveolar ridge architecture for improved esthetic results. This prospective clinical study evaluated the ability of immediately placed ovate pontics in conjunction with ARP to attenuate postextraction tissue dimensional changes in the esthetic zone and maintain alveolar ridge contour. Ten patients (11 sites) completed the study. All subjects received a combination of socket grafting with allogeneic particulate graft material and socket sealing with an ovate pontic provisional restoration. A set of clinical linear and volumetric outcomes were assessed after a 6-month healing period. At 6 months postoperative, the linear measurements for the mean ridge dimensional loss were 0.9 ± 0.6 mm (range: 0.2 to 1.8 mm) in height and 1.4 ± 0.6 mm (range: 0.1 to 2.4 mm) in width. The mean volumetric tissue loss observed was 24.4 ± 15.4 mm³ (range: 2.6 to 50.1 mm³) at 3 months postoperative and 32.2 ± 14.2 mm³ (range: 3.8 to 50.5 mm³) at 6 months postoperative. Resorption pattern assessment showed the overall cervical area to have less resorption than the apical areas at 6 months postoperative, with the least amount of resorption in the midbuccal cervical section. When compared to the data of a previous pilot study, no statistically significant difference was seen between the dimensional losses when using ovate pontics with and without ARP. This may be evidence that the use of an ovate pontic provisional restoration immediately after extraction effectively attenuates postextraction dimensional changes. [ABSTRACT FROM AUTHOR]