At Present, stress corrosion and corrosion fatigue causing durability degradation of concrete structure in the field of civil engineering become an important problem,and thus become a hot topic to study. But the research on it at home and abroad is still in stage of theoretical exploration. This paper using self-designed corrosion fatigue loading test device, studied in magnesium nitrate solution of concrete under the action of erosion strength increasing regularity, results show that the concrete strength by corrosion fatigue than fatigue specimen attenuation extent.

Background/Aim There are no epidemiological reports focused on the oral and maxillofacial surgery emergency department in the West China Hospital of Stomatology. The aim of this study was to analyse the epidemiological characteristics of emergency patients admitted for Trauma and Plastic Surgery Department of the West China Hospital of Stomatology from 2016–2019. Materials and Methods In this retrospective study, 5220 patients with complete medical records were evaluated. The following data were collected: gender, age, etiology, disease type distribution, anatomic injury site and treatment modality. Results There were 3046 males and 2174 females (ratio 1.40:1), with an average age of 16.2 years. The largest group was children aged between 3 and 6 years old (28.3%). Maxillofacial injuries were the most common condition (87.3%), which mostly occurred on the forehead (29.7%), followed by the lips (27.8%). A fall was the leading cause of injury (59.9%), especially in patients younger than 6 years old. There were 327 cases of maxillofacial space infections (MSI), and the mandibular third molars were the most common tooth associated with odontogenic infections (36.2%). Univariable analysis identified that multiple‐space infection, visit time and systemic conditions were the risk factors for being admitted to the hospital for treatment. There were 116 patients (2.2%) with bleeding as the main complaint, and most of the maxillofacial bleeding patients could be stopped by compression (52.6%). Conclusion Males and children aged younger than 6 years were the highest risk populations. Trauma accounted for the majority of emergency patients in maxillofacial surgery. Most maxillofacial injuries involved the forehead and were mainly caused by accidental falls. The proportion of MSI was not high, but serious cases may be life‐threatening. The causes of bleeding were diverse, and the bleeding was easy to control.

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