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BackgroundTemporomandibular joint (TMJ) ankylosis in children often leads to facial deformity, functional deficit, and negative influence of the psychosocial development, which worsens with growth. The treatment of TMJ ankylosis in the pediatric patient is much more challenging than in adults because of a high incidence of recurrence and unfavorable growth of the mandible.Case reportThis is a case report describing sequential management of the left TMJ ankylosis resulted from trauma in early childhood. The multiple surgeries including a costochondral graft and gap arthroplasty using interpositional silicone block were performed, but re-ankylosis of the TMJ occurred after surgery. Alloplastic TMJ prosthesis was conducted to prevent another ankylosis, and signs or symptoms of re-ankylosis were not found. Additional reconstruction surgery was performed to compensate mandibular growth after confirming growth completion. During the first 3 years of long-term follow-up, satisfactory functional and esthetic results were observed.ConclusionsThis is to review the sequential management for the recurrent TMJ ankylosis in a growing child. Even though proper healing was expected after reconstruction of the left TMJ with costal cartilage graft, additional surgical interventions, including interpositional arthroplasty, were performed due to re-ankylosis of the affected site. In this case, alloplastic prosthesis could be an option to prevent TMJ re-ankylosis for growing pediatric patients with TMJ ankylosis in the beginning.

Background While global health agencies have listed asthma as a vulnerability for severe cases of coronavirus disease 2019 (COVID-19), the evidence supporting this is scarce. Methods A nationwide cohort study was conducted using the validated Korean national health insurance claim data of patients diagnosed with COVID-19 between January 1 and April 8, 2020. Asthma comorbidity was determined using a diagnosis code assigned by the physician and the prescription of asthma-related medications. The clinical course of COVID-19 was classified into three severity grades according to the requirements for oxygen supply and mechanical ventilation. We also evaluated the association of asthma with overall and in-hospital mortality of COVID-19. Results Asthma morbidity was a significant risk factor for severe COVID-19 (grade 2 requiring oxygen supply) (adjusted odds ratio [aOR]=1.341, 95% confidence interval [CI], 1.051−1.711, P=0.018) and grade 3 requiring mechanical ventilation or leading to death (aOR=1.723, 95% CI: 1.230−2.412, P=0.002) multinomial logistic regression adjusting co-risk factors. Asthma was also significantly associated with mortality of COVID-19 (aOR=1.453, 95% CI: 1.015−2.080, P=0.041) and was revealed to have a shorter time to in-hospital mortality of COVID-19 (P<0.001). Patients with recent asthma exacerbation showed more severe COVID-19 of grade 3 (OR=7.371, 95% CI: 2.018−26.924, P=0.003) and higher mortality (OR=9.208, 95% CI: 2.597−32.646, P<0.001) in univariable analysis, but the statistical significance was not found in multivariable analysis. Conclusion Asthma morbidity was associated with severity and mortality of COVID-19. Patients with asthma should pay more attention to avoid worsening of COVID-19.

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This study investigates the effects of students' intrinsic motivation and prior knowledge on student achievement in learning Chinese in a game-based learning environment. A total of 140 fourth-grade students from an elementary school in South Korea participated in this study. An instructional game called "Hanjamaru," which is designed to teach Chinese characters, was implemented for four weeks. During the experiment, students' prior knowledge, intrinsic motivation in gaming, and achievements learning Chinese were quantitatively measured. Findings from this study demonstrate that both students' prior knowledge and intrinsic motivation affect their achievements in learning Chinese. Also, there students' prior knowledge and intrinsic motivation affected each other; that is, a group low in intrinsic motivation but with higher prior knowledge showed comparatively higher student achievements. These findings suggest that students' prior knowledge should also be considered while designing and adopting game-based learning in order to engage students with different levels of intrinsic motivation.