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.

Finite element method, as a verified numerical simulation method, has been widely applied in the biomechanical research of clear aligner treatment. The accuracy of its calculation results is closely related to the construction method of the finite element model. This paper takes the finite element modeling process of clear aligner treatment as a clue, and reviews the modeling methods of relevant research in recent years, aiming to provide reference for subsequent studies.

Finite element method, as a verified numerical simulation method, has been widely applied in the biomechanical research of clear aligner treatment. The accuracy of its calculation results is closely related to the construction method of the finite element model. This paper takes the finite element modeling process of clear aligner treatment as a clue, and reviews the modeling methods of relevant research in recent years, aiming to provide reference for subsequent studies.

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:Using the method-point-factor to construct a system of evaluation indexes for clinician positions in county-level public hospitals to assess the relative value of clinician positions in county-level public hospitals in Anhui province.Methods:Questionnaire survey was used for a questionnaire survey of 12 county-level public hospitals in northern Anhui, central Anhui and southern Anhui in the province from July to August 2019. The content of the questionnaire survey mainly includes such doctor′s basic information as gender, age, and department, as well as the doctor′s score on the four dimensions of " post qualification, skills, risks and responsibilities, work intensity and environment" . In this study, Excel 2010 and SPSS 16.0 were used to perform descriptive statistical analysis on the collected data.Results:In this study, a job evaluation system for doctors in county-level public hospitals was established, covering 4 level-1 indicators, 10 level-2 indicators, and 37 level-3 indicators. Among the 1 895 clinical doctors participating in the survey in 12 county-level public hospitals, the average score of doctor′s job evaluation was 768.4 points, of which the neurosurgeons had the highest average score of 800.90 points and endocrinologists had the lowest average score of 735.40 points. There were differences in the overall score rate in the four dimensions of job evaluation, in the order of " risk and responsibility, work intensity and environment, skills, job qualification" (80.09%>79.49%>79.24%>66.72%).Conclusions:The results and grades of clinical doctors′ job evaluation were reasonable. The overall trend of the scores was in line with the job characteristics of doctors, and provided a theoretical basis for improving the internal performance salary distribution system of county-level public hospitals.

Objective:To form the workload relative value of 10 general surgery projects in Anhui province based on the theoretical framework of resource-based relative value scale(RBRVS).Methods:Cluster sampling was used to identify the 12 county-level public hospitals surveyed from July to August 2019; Expert consultation method was used to select the benchmark project of general surgery and the measured projects; Magnitude estimation was used by doctors surveyed to find the relative evaluation of the surgeries selected, and RBRVS principle was used to find surgeon workload relative value of the 10 surgeries; Pearson correlation analysis was used to analyze the relationship between the charging price of surgeries and the relative value of surgeons′ workload in Anhui province.Results:The study found the time consumption, work intensity relative value and surgeon work load relative value of 10 general surgeries; The relative value of the current surgical item price was positively correlated with the relative value of the doctor′s workload, and the correlation coefficient was r=0.928, P<0.01(bilateral). But in some surgeries, the pricing fails to represent the relative value of the workload. Conclusions:Based on RBRVS theory, 10 localized relative value scales of general surgeons′ workload were developed via empirical studies from such dimensions as time consumption, mental labor, physical labor and risk stress; Pearson′s correlation analysis found part of the pricing in general surgeries as groundless.

Objective To establish a bioiflm (BF) models of Haemophilus inlfuenza in vitro, and to observe the changes of antibiotic susceptibility after the BF fromation. Methods Thirty strains Haemophilus inlfuenzae isolated from adenoids of children with adenoidal hypertrophy and cultured in a 96-well plate. The BF was identiifed by crystal violet staining and scanning electron microscopy (SEM). The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and the minimum bioiflm bacteria bioiflm clear concentration (MBEC) of ampicillin (AMP), ceftriaxone (CRO), levolfoxacin (LVFX) and azithromycin (AZM) were individually detected. Result All of 30 strains of Haemophilus inlfuenzae formed various BF. After BF is formed, the increase of MBEC for different antibiotics was inconsistent with the increase of MIC and MBC. The difference was statistically signiifcant (MBEC/MBC, H=91.54;MBEC/MIC, H=87.91;all P<0.001). The MBEC of AMP was the highest, up to 100 times than the MBC and MIC. The MBEC of CRO was dozens of times than the MBC and MIC. The MBEC of LVFX and AZM were most close to those of MBC and MIC. Conclusion After the formation of BF, resistance to antibiotics of Haemophilus inlfuenzae is enhaced. LVFX and AZM showed more favorable effect on Haemophilus infuenzae BF.