BACKGROUND:Buccal Multiloop Removable Appliance can interceptively correct mutiple adolescent malocclusions. But the clinical problem of Buccal Multiloop fatigue fracture is not solved yet. How to prolong the fatigue fracture cycle is stil in the research stage. OBJECTIVE: To study the effect of different temperature of heat treatment on the Buccal Multiloop fatigue fracture cycle, thereby to select a relatively optimal method to enhance the fatigue fracture cycle. METHODS: Thirty-five left HL-2 Buccal Mltiloops were divided into seven groups according to different ways of heat treatment. Each group consisted of five samples. They were an untreated group, three pre-bending groups (320, 420, 520℃ heat treatment before bending) and three post-bending groups (320, 420, 520℃ heat treatment after bending). The dental stainless steel wires and Buccal Multiloop were respectively treated by low-temperature annealing. The data were recorded and evaluated after the samples tested by the 3D Simulating Movement of TMJ Testing Machine. The features of fatigue fracture were observed by scanning electron microscope. RESULTS AND CONCLUSION: The mean values of the Buccal Multiloop fatigue fracture cycle from largest to smalest were as folows: 520℃ pre-bending group > 420℃ pre-bending group > 320℃ pre-bending group > untreated group > 520℃ post-bending group > 320℃ post-bending group > 420℃ post-bending group. The fatigue fracture cycle of Buccal Multiloop made of the dental stainless steel wires after 520℃ annealing treatment was longer than others. By the observation of scanning electron microscope, the fracture crack extension area had the tendency to expand, transient interruption was delayed and the tissue structure became more uniform.

OBJECTIVE: To investigate the psychological and behavior status of minor children of medical staff in Hubei province during the coronavirus disease 2019 (COVID-19) epidemic. METHODS: A cross-sectional questionnaire survey was conducted through WeChat from March 13 to 15, 2020, which included a general data questionnaire and Conners parental assessment questionnaire (PSQ). The questionnaires received from outside of Hubei province were excluded through IP address, and the questionnaires with answer time <150 s were also excluded. The influence of parental work status on the psychological behavior was analyzed in children of different age groups. RESULTS: A total of 391 valid questionnaires were collected, there were 207 males (52.9%) and 184 females (47.1%); 91 (23.3%) aged 3 to 6, 183 (46.8%) aged 6 to 10, and 117 (29.9%) aged 10 to 16. Both parents were medical staff in 87 participants(22.3%), one parent was medical staff in 139(35.5%) participants, and no parents were medical staff in 165 (42.2%) participants. In 3-<6 years group, there was no significant difference in the PSQ scores of the children in each factor level (all >0.05) between children with parents as medical staff and those without. In 6-<10 years group, children with both parents as medical staff had higher hyperactivity-impulse factor score, learning problem factor score and total score than those without parents as medical staff (all <0.05), while they had higher learning problem factor score than those with one parent as medical staff (<0.05); the anxiety score of children with one or both parents as medical staff was higher than that of those without parents as medical staff (all <0.05). In 10 to 16 years group, the behavior problems, learning problems, hyperactivity-impulse, more dynamic index and the total score in children with one parent as medical staff were lower than those with both parents as medical staff or without parents as medical staff (<0.05 or <0.01); while there were no significant differences in psychosomatic problems, anxiety factor scores between children with one parent as medical staff and other two groups (all >0.05). CONCLUSIONS s During COVID-19 epidemic period, the psychological and behavior status of minor children of Hubei medical staff with different ages shows differences with those without parents as medical staff, particularly in 6-<10 years and 10 to 16 year groups. It is necessary to pay attention to the psychological and behavioral status of children of medical staff in these age groups.
Adolescent ; Betacoronavirus ; Child ; Child, Preschool ; China ; epidemiology ; Coronavirus ; Coronavirus Infections ; Cross-Sectional Studies ; Female ; Humans ; Male ; Medical Staff ; statistics & numerical data ; Mental Health ; statistics & numerical data ; Pandemics ; Pneumonia, Viral ; Surveys and Questionnaires