Purpose: The purpose of this study was to evaluate the fracture strength of zirconia crowns of varying margin thicknesses. Materials and Methods: A model of the maxillary right first molar (Nissin, Kyoto, Japan) was prepared to create an abutment, which was fabricated into a metal die via a 3D metal printer. CAD software (exocad GmbH, Darmstadt, Germany) was used to design the crowns. A total of eight groups were generated: initially separated by margin thickness (0.1 mm and 0.8 mm), and then further divided by horizontal margin widths of 0.1 mm, 0.2 mm, 0.3 mm, and 0.4 mm. Zirconia crowns were designed for each group’s working models (N=10). Crown fracture strength was assessed using a universal testing machine (Shimadzu, Kyoto, Japan), applying a compressive load until fracture and recording the maximum load. A scanning electron microscope was employed to observe fracture patterns. Fracture strength results were analyzed using one-way ANOVA, with the Tukey HSD test applied for post-hoc analysis (α=0.05). Results: Zirconia crown fracture strength significantly improved with increased horizontal margin width (P<0.001). However, margin thickness had no statistically significant effect on fracture strength (P=0.513). Conclusion Optimizing the horizontal margin width of zirconia crowns enhances their durability and performance.

Purpose: The purpose of this study was to evaluate the fracture strength of zirconia crowns of varying margin thicknesses. Materials and Methods: A model of the maxillary right first molar (Nissin, Kyoto, Japan) was prepared to create an abutment, which was fabricated into a metal die via a 3D metal printer. CAD software (exocad GmbH, Darmstadt, Germany) was used to design the crowns. A total of eight groups were generated: initially separated by margin thickness (0.1 mm and 0.8 mm), and then further divided by horizontal margin widths of 0.1 mm, 0.2 mm, 0.3 mm, and 0.4 mm. Zirconia crowns were designed for each group’s working models (N=10). Crown fracture strength was assessed using a universal testing machine (Shimadzu, Kyoto, Japan), applying a compressive load until fracture and recording the maximum load. A scanning electron microscope was employed to observe fracture patterns. Fracture strength results were analyzed using one-way ANOVA, with the Tukey HSD test applied for post-hoc analysis (α=0.05). Results: Zirconia crown fracture strength significantly improved with increased horizontal margin width (P<0.001). However, margin thickness had no statistically significant effect on fracture strength (P=0.513). Conclusion Optimizing the horizontal margin width of zirconia crowns enhances their durability and performance.

Purpose: The purpose of this study was to evaluate the fracture strength of zirconia crowns of varying margin thicknesses. Materials and Methods: A model of the maxillary right first molar (Nissin, Kyoto, Japan) was prepared to create an abutment, which was fabricated into a metal die via a 3D metal printer. CAD software (exocad GmbH, Darmstadt, Germany) was used to design the crowns. A total of eight groups were generated: initially separated by margin thickness (0.1 mm and 0.8 mm), and then further divided by horizontal margin widths of 0.1 mm, 0.2 mm, 0.3 mm, and 0.4 mm. Zirconia crowns were designed for each group’s working models (N=10). Crown fracture strength was assessed using a universal testing machine (Shimadzu, Kyoto, Japan), applying a compressive load until fracture and recording the maximum load. A scanning electron microscope was employed to observe fracture patterns. Fracture strength results were analyzed using one-way ANOVA, with the Tukey HSD test applied for post-hoc analysis (α=0.05). Results: Zirconia crown fracture strength significantly improved with increased horizontal margin width (P<0.001). However, margin thickness had no statistically significant effect on fracture strength (P=0.513). Conclusion Optimizing the horizontal margin width of zirconia crowns enhances their durability and performance.

Purpose: The purpose of this study was to evaluate the fracture strength of zirconia crowns of varying margin thicknesses. Materials and Methods: A model of the maxillary right first molar (Nissin, Kyoto, Japan) was prepared to create an abutment, which was fabricated into a metal die via a 3D metal printer. CAD software (exocad GmbH, Darmstadt, Germany) was used to design the crowns. A total of eight groups were generated: initially separated by margin thickness (0.1 mm and 0.8 mm), and then further divided by horizontal margin widths of 0.1 mm, 0.2 mm, 0.3 mm, and 0.4 mm. Zirconia crowns were designed for each group’s working models (N=10). Crown fracture strength was assessed using a universal testing machine (Shimadzu, Kyoto, Japan), applying a compressive load until fracture and recording the maximum load. A scanning electron microscope was employed to observe fracture patterns. Fracture strength results were analyzed using one-way ANOVA, with the Tukey HSD test applied for post-hoc analysis (α=0.05). Results: Zirconia crown fracture strength significantly improved with increased horizontal margin width (P<0.001). However, margin thickness had no statistically significant effect on fracture strength (P=0.513). Conclusion Optimizing the horizontal margin width of zirconia crowns enhances their durability and performance.

Background: and Purpose In young patients (aged 18–60 years) with patent foramen ovale (PFO)- associated stroke, percutaneous closure has been found to be useful for preventing recurrent ischemic stroke or transient ischemic attack (TIA). However, it remains unknown whether PFO closure is also beneficial in older patients. Methods: Patients aged ≥60 years who had a cryptogenic stroke and PFO from ten hospitals in South Korea were included. The effect of PFO closure plus medical therapy over medical therapy alone was assessed by a propensity-score matching method in the overall cohort and in those with a high-risk PFO, characterized by the presence of an atrial septal aneurysm or a large shunt. Results: Out of the 437 patients (mean age, 68.1), 303 (69%) had a high-risk PFO and 161 (37%) patients underwent PFO closure. Over a median follow-up of 3.9 years, recurrent ischemic stroke or TIA developed in 64 (14.6%) patients. In the propensity score-matched cohort of the overall patients (130 pairs), PFO closure was associated with a significantly lower risk of a composite of ischemic stroke or TIA (hazard ratio [HR]: 0.45; 95% confidence interval [CI]: 0.24–0.84; P=0.012), but not for ischemic stroke. In a subgroup analysis of confined to the high-risk PFO patients (116 pairs), PFO closure was associated with significantly lower risks of both the composite of ischemic stroke or TIA (HR: 0.40; 95% CI: 0.21–0.77; P=0.006) and ischemic stroke (HR: 0.47; 95% CI: 0.23–0.95; P=0.035). Conclusion Elderly patients with cryptogenic stroke and PFO have a high recurrence rate of ischemic stroke or TIA, which may be significantly reduced by device closure.

Background and Objectives: Concerns remain that early aspirin cessation may be associated with potential harm in subsets at high risk of ischemic events. This study aimed to assess the effects of P2Y12 inhibitor monotherapy after 3-month dual antiplatelet therapy (DAPT) vs.prolonged DAPT (12-month or longer) based on the ischemic risk stratification, the CHADSP2A2RC, after percutaneous coronary intervention (PCI). Methods: This was a sub-study of the SMART-CHOICE trial. The effect of the randomized antiplatelet strategies was assessed across 3 CHADS-P2A2RC risk score categories. The primary outcome was a major adverse cardiac and cerebral event (MACCE), a composite of all-cause death, myocardial infarction, or stroke. Results: Up to 3 years, the high CHADS-P2A2RC risk score group had the highest incidence of MACCE (105 [12.1%], adjusted hazard ratio [HR], 2.927; 95% confidence interval [CI], 1.358–6.309; p=0.006) followed by moderate-risk (40 [1.4%], adjusted HR, 1.786; 95% CI, 0.868–3.674; p=0.115) and low-risk (9 [0.5%], reference). In secondary analyses, P2Y12 inhibitor monotherapy reduced the Bleeding Academic Research Consortium (BARC) types 2, 3, or 5 bleeding without increasing the risk of MACCE as compared with prolonged DAPT across the 3 CHADS-P2A2RC risk strata without significant interaction term (interaction p for MACCE=0.705 and interaction p for BARC types 2, 3, or 5 bleeding=0.055). Conclusions The CHADS-P2A2RC risk score is valuable in discriminating high-ischemicrisk patients. Even in such patients with a high risk of ischemic events, P2Y12 inhibitor monotherapy was associated with a lower incidence of bleeding without increased risk of ischemic events compared with prolonged DAPT.

Background: The risk of device thrombosis and device-oriented clinical outcomes with bioresorbable vascular scaffold (BVS) was reported to be significantly higher than with contemporary drug-eluting stents (DESs). However, optimal device implantation may improve clinical outcomes in patients receiving BVS. The current study evaluated mid-term safety and efficacy of Absorb BVS with meticulous device optimization under intravascular imaging guidance. Methods: The SMART-REWARD and PERSPECTIVE-PCI registries in Korea prospectively enrolled 390 patients with BVS and 675 patients with DES, respectively. The primary endpoint was target vessel failure (TVF) at 2 years and the secondary major endpoint was patientoriented composite outcome (POCO) at 2 years. Results: Patient-level pooled analysis evaluated 1,003 patients (377 patients with BVS and 626 patients with DES). Mean scaffold diameter per lesion was 3.24 ± 0.30 mm in BVS group.Most BVSs were implanted with pre-dilatation (90.9%), intravascular imaging guidance (74.9%), and post-dilatation (73.1%) at proximal to mid segment (81.9%) in target vessel.Patients treated with BVS showed comparable risks of 2-year TVF (2.9% vs. 3.7%, adjusted hazard ratio [HR], 1.283, 95% confidence interval [CI], 0.487–3.378, P = 0.615) and 2-year POCO (4.5% vs. 5.9%, adjusted HR, 1.413, 95% CI, 0.663–3.012,P = 0.370) than those with DES. The rate of 2-year definite or probable device thrombosis (0.3% vs. 0.5%, P = 0.424) was also similar. The sensitivity analyses consistently showed comparable risk of TVF and POCO between the 2 groups. Conclusion With meticulous device optimization under imaging guidance and avoidance of implantation in small vessels, BVS showed comparable risks of 2-year TVF and device thrombosis with DES.

Background: Recent reports have suggested that pneumonitis is a rare complication following vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).However, its clinical features and outcomes are not well known. The aim of this study was to identify the clinical characteristics and outcomes of patients with vaccine-associated pneumonitis following vaccination against SARS-CoV-2. Methods: In this nationwide multicenter survey study, questionnaires were distributed to pulmonary physicians in referral hospitals. They were asked to report cases of development or exacerbation of interstitial lung disease (ILD) associated with the coronavirus disease 2019 vaccine. Vaccine-associated pneumonitis was defined as new pulmonary infiltrates documented on chest computed tomography within 4 weeks of vaccination and exclusion of other possible etiologies. Results: From the survey, 49 cases of vaccine-associated pneumonitis were identified between February 27 and October 30, 2021. After multidisciplinary discussion, 46 cases were analyzed. The median age was 66 years and 28 (61%) were male. The median interval between vaccination and respiratory symptoms was 5 days. There were 20 (43%), 17 (37%), and nine (19%) patients with newly identified pneumonitis, exacerbation of pre-diagnosed ILD, and undetermined pre-existing ILD, respectively. The administered vaccines were BNT162b2 and ChAdOx1 nCov-19/AZD1222 each in 21 patients followed by mRNA-1273 in three, and Ad26.COV2.S in one patient. Except for five patients with mild disease, 41 (89%) patients were treated with corticosteroid. Significant improvement was observed in 26 (57%) patients including four patients who did not receive treatment. However, ILD aggravated in 9 (20%) patients despite treatment. Mortality was observed in eight (17%) patients. Conclusion These results suggest pneumonitis as a potentially significant safety concern for vaccines against SARS-CoV-2. Clinical awareness and patient education are necessary for early recognition and prompt management. Additional research is warranted to identify the epidemiology and characterize the pathophysiology of vaccine-associated pneumonitis.

Background/Aims: While switching strategies of P2Y12 receptor inhibitors (RIs) have sometimes been used in acute myocardial infarction (AMI) patients, the current status of in-hospital P2Y12RI switching remains unknown. Methods: Overall, 8,476 AMI patients who underwent successful revascularization from Korea Acute Myocardial Infarction Registry-National Institute of Health (KAMIR-NIH) were divided according to in-hospital P2Y12RI strategies, and net adverse cardiovascular events (NACEs), defined as a composite of cardiac death, non-fatal myocardial infarction (MI), stroke, or thrombolysis in myocardial infarction (TIMI) major bleeding during hospitalization were compared. Results: Patients with in-hospital P2Y12RI switching accounted for 16.5%, of which 867 patients were switched from clopidogrel to potent P2Y12RI (C-P) and 532 patients from potent P2Y12RI to clopidogrel (P-C). There were no differences in NACEs among the unchanged clopidogrel, the unchanged potent P2Y12RIs, and the P2Y12RI switching groups. However, compared to the unchanged clopidogrel group, the C-P group had a higher incidence of non-fatal MI, and the P-C group had a higher incidence of TIMI major bleeding. In clinical events of in-hospital P2Y12RI switching, 90.9% of non-fatal MI occurred during pre-switching clopidogrel administration, 60.7% of TIMI major bleeding was related to pre-switching P2Y12RIs, and 71.4% of TIMI major bleeding was related to potent P2Y12RIs. Only 21.6% of the P2Y12RI switching group switched to P2Y12RIs after a loading dose (LD); however, there were no differences in clinical events between patients with and without LD. Conclusions In-hospital P2Y12RI switching occurred occasionally, but had relatively similar clinical outcomes compared to unchanged P2Y12RIs in Korean AMI patients. Non-fatal MI and bleeding appeared to be mainly related to pre-switching P2Y12RIs.

Background/Aims: Minimising total ischemic time (TIT) is important for improving clinical outcomes in patients with ST-segment elevation myocardial infarction who have undergone percutaneous coronary intervention (PCI). TIT has not shown a significant improvement due to persistent pre-hospital delay. This study aimed to investigate the risk factors associated with pre-hospital delay. Methods: Individuals enrolled in the Korea Acute Myocardial Infarction Registry-National Institutes of Health between 2011 and 2015 were included in this study. The study population was analyzed according to the symptom-to-door time (STDT; within 60 or > 60 minutes), and according to the type of hospital visit (emergency medical services [EMS], non-PCI center, or PCI center). Results: A total of 4,874 patients were included in the analysis, of whom 28.4% arrived at the hospital within 60 minutes of symptom-onset. Old age (> 65 years), female gender, and renewed ischemia were independent predictors of delayed STDT. Utilising EMS was the only factor shown to reduce STDT within 60 minutes, even when cardiogenic shock was evident. The overall frequency of EMS utilisation was low (21.7%). Female gender was associated with not utilising EMS, whereas cardiogenic shock, previous myocardial infarction, familial history of ischemic heart disease, and off-hour visits were associated with utilising EMS. Conclusions Factors associated with delayed STDT and not utilising EMS could be targets for preventive intervention to improve STDT and TIT.