Objective To analyze the effects of different traction sites and directions on the maxilla and upper dentition when using clear aligners combined with protraction for the treatment of maxillary deficiency.Methods A three-dimensional(3D)finite element model including the zygomaticomaxillary complex,maxillary dentition,and clear aligners was constructed.The models were divided into Group 1(traction hook at the distal of the lateral incisor)and Group 2(traction hook at the distal of the canine).Each group was analyzed under four loading conditions with protraction angles of 0°,10°,20°,and 30° relative to the occlusal plane.A unilateral protraction force of 500 g was applied.The differences in stress distribution and displacement of the maxillary bone and dentition under different loading conditions were analyzed.Results When the protraction angle was 30°,both groups showed forward and downward displacement of the maxilla,while other angles resulted in counterclockwise rotation.Under the same protraction direction,the total displacement of the maxilla and displacements in all directions in Group 2 were greater than those in Group 1.The upper central incisors in Group 1 showed lingual displacement,which increased with the protraction angle.The maxillary dentition in Group 2 showed forward displacement,with the minimum total and sagittal displacements at a protraction angle of 30°.Stress concentration was mainly observed in the zygomaticomaxillary suture and anterior alveolar bone regions in both groups,decreasing as the protraction angle increased.Conclusions Clear aligners combined with protraction can be applied to skeletal Class Ⅲ patients with mild maxillary deficiency.When the protraction site is located at the distal of the canine with a 30° downward and forward angle to the occlusal plane,the maxilla can achieve ideal forward and downward displacement with the minimum labial movement of the upper anterior teeth.

Objective To analyze the effects of different traction sites and directions on the maxilla and upper dentition when using clear aligners combined with protraction for the treatment of maxillary deficiency.Methods A three-dimensional(3D)finite element model including the zygomaticomaxillary complex,maxillary dentition,and clear aligners was constructed.The models were divided into Group 1(traction hook at the distal of the lateral incisor)and Group 2(traction hook at the distal of the canine).Each group was analyzed under four loading conditions with protraction angles of 0°,10°,20°,and 30° relative to the occlusal plane.A unilateral protraction force of 500 g was applied.The differences in stress distribution and displacement of the maxillary bone and dentition under different loading conditions were analyzed.Results When the protraction angle was 30°,both groups showed forward and downward displacement of the maxilla,while other angles resulted in counterclockwise rotation.Under the same protraction direction,the total displacement of the maxilla and displacements in all directions in Group 2 were greater than those in Group 1.The upper central incisors in Group 1 showed lingual displacement,which increased with the protraction angle.The maxillary dentition in Group 2 showed forward displacement,with the minimum total and sagittal displacements at a protraction angle of 30°.Stress concentration was mainly observed in the zygomaticomaxillary suture and anterior alveolar bone regions in both groups,decreasing as the protraction angle increased.Conclusions Clear aligners combined with protraction can be applied to skeletal Class Ⅲ patients with mild maxillary deficiency.When the protraction site is located at the distal of the canine with a 30° downward and forward angle to the occlusal plane,the maxilla can achieve ideal forward and downward displacement with the minimum labial movement of the upper anterior teeth.

Lysine methyltransferase 2A( KMT2A) rearrangement (KMT2A-r) is a high-risk gene subtype of acute lymphoblastic leukemia (ALL) in children with a high relapse rate, poor prognosis and suboptimal response to conventional chemotherapy.Improving the treatment and prognosis of childhood KMT2A-r ALL is an urgent problem.In recent years, with an in-depth understanding of the mechanism of KMT2A-r, more accurate risk stratification of KMT2A-r ALL has been carried out, and great progress has also been made in its immune and targeted therapy.In this article, the genetic and biological characteristics, risk stratification, treatment strategies and prognosis of children KMT2A-r ALL were reviewed in order to provide theoretical support for clinical work and future research.

【Objective】 To investigate the factors influencing the production of platelet antibody and its effect on clinical platelet transfusion. 【Methods】 This is a single-center prospective observational study. The research subjects were patients with hematological diseases in West China Hospital of Sichuan University from October 1, 2018 to September 30, 2019, and their plasma were collected before platelet transfusion to detect platelet antibodies using solid-phase agglutination method. According to the results of platelet antibody screening, the patients were divided into platelet antibody positive group and negative group. The t test and nonparametric Mann-Whitney U test were used to compare the transfusion efficacy of two groups. Patients’ demographic and clinical information, including age, gender, diagnosis, the units of platelets and RBC transfused, were collected via HIS6.2.0 and whole process management system of blood in clinical (version 3.0) to analyze the influence of age, gender and the disease on the positive rate of platelet antibodies, as well as the profile of platelet antibodies in patients with different diseases, the correlation between the positive rate of platelet antibodies and the history of blood/platelets transfusion. In additional, the platelet transfusion process was observed on site. 【Results】 A total of 316 patients with hematologic diseases were included in this study, mainly with acute myeloid leukemia(188/316, 59.5%). All patients were transfused 1671 U platelet [1~17(5.3±3.1)U each person] and 1896 U RBC products [0~38(7.8±4.6)U each person] during the treatment. Out of the 316 patients, platelet antibodies were found in 85 (26.9%) of them. No significant differences in the positive rates of platelet antibody after transfusion were notice by genders or ages(P>0.05). The incidence of platelet antibody was related to diseases (P<0.05), with MDS as the highest (57.1%), followed by aplastic anemia (36.4%) and myeloid leukemia (27.7%). In additional, the positive rate of platelet antibody increased with the number of previous platelet transfusions(P<0.05). The 316 patients were divided into positive group and negative group according to the results of platelet antibody screening. The corrected count of increment (5.2×10⁹/L vs 11.5×10⁹/L, P<0.01) and absolute platelet increase(8×10⁹/L vs 17×10⁹/L, P<0.01)in positive group were lower than those in negative group. The positive group were transfused more units of platelets(1.7 U vs 1.2 U, P<0.01)and red blood cells(1.5 U vs 1.1 U, P<0.05)per week than negative group. The platelet transfusion interval was shorter in positive group than negative group (3.1 days vs 3.6 days, P<0.05), but there was no significant difference in red blood cell transfusion interval (3.1 days vs 3.8 days, P>0.05) between two groups. The minimum PLT count(5×10⁹/L vs 9×10⁹/L, P<0.01), average PLT count(27×10⁹/L vs 40×10⁹/L, P<0.01)and average Hb(71 g/L vs 77 g/L, P<0.05)in positive group were lower than those in negative group during hospitalization, but there was no significant difference in the minimum Hb(56 g/L vs 59 g/L, P>0.05)between two groups. According to transfusion events on site, the incidence of acute adverse reactions to transfusion was 13% (169/1 291). 【Conclusions】 The positive rates of platelet antibodies in patients with hematologic diseases were relatively high. In addition, the efficacy of platelet transfusion in positive group were worse than that in the negative group. It is recommended that platelet antibody testing should be routinely performed before transfusion in hematologic disease patients to select crossmatch-compatible platelets in order to improve the effectiveness of platelet transfusion.