Fatigue analysis of restored teeth longitudinally cracked under cyclic loading

ObjectiveTo investigate the fatigue behavior of restored teeth, in particular the mechanisms of longitudinal dentinal cracking under cyclic mechanical loading, using finite element analysis (FEA) and the stress-life (S-N) approach.MethodsTen root-filled premolars restored with resin composites were subjected to step-stress cyclic loading to produce longitudinal cracks. Fracture loads and number of cycles completed at each load level were recorded. FEA was used to predict the stress amplitude of each component under the global cyclic load. Both intact and debonded conditions were considered for the dentin-composite interface in the FEA. The predicted stress concentrations were compared with the fracture patterns to help elucidate the failure mechanisms. The S-N approach was further used to predict the lifetimes of the different components in the restored teeth. Cumulative fatigue damage was represented by the sum of the fractions of life spent under the different stress amplitudes.ResultsLongitudinal cracks were seen in ~50% of the samples with a mean fracture load of 770 ± 45 N and a mean number of cycles to failure of 32,297 ± 12,624. The longitudinal dentinal cracks seemed to start near the line angle of the cavity, and propagated longitudinally towards the root. The sum of fractions of life spent for the dentin-composite interface exceeded 1 after ~7000 cycles when that for dentin was much lower than 1, indicating that interfacial debonding would occur prior to dentin fracture. This was supported by micro-CT images showing widened interfacial space in the cracked samples. In the debonded tooth, FEA showed dentinal stress concentrations at the gingival wall of the cavity, which coincided with the longitudinal cracks found in the cyclic loading test. The sum of fractions of life spent for dentin was close to 1 at ~30,000 cycles, similar to the experimental value.SignificanceDebonding of the dentin-composite interface may occur prior to longitudinal cracking of dentin in root-filled teeth under cyclic loading. The approximate time of occurrence for these events could be estimated using fatigue analysis with stresses provided by FEA. This methodology can therefore be used to evaluate the longevity of restoration designs for root-filled teeth.     

Exploring peer tutoring from the peer tutor's perspective

IntroductionChanging working practices, student numbers, workforce demands, and deficits, have created a need to consider new ways of radiography student training. One suggestion could be to implement Peer Assisted Learning (PAL) during clinical placements. PAL utilises social constructivist theories, where peer tutors teach lower or same level tutees, reinforcing and practicing material formally taught. The aim of this study was to trial an intervention of PAL, co-designed between the university and students and evaluated to identify opportunities and challenges.MethodsUsing participatory action research 8 final year student volunteers trialled a 3-week intervention, where they delivered PAL to first years, tutoring on first year radiographic clinical practice. Focus groups were held pre and post intervention to gather qualitative data.ResultsFocus group discussions were transcribed and collectively thematically analysed. Two students and the primary researcher took part in the analysis.ConclusionStudents identified benefits and challenges to PAL. Issue around preparing for and being a peer tutor are also discussed.Further study involving experiences of first year students and clinical colleagues is required.Implications for practicePeer-tutoring has potential benefits to students to facilitate the development of skills related to image analysis and critique as well as radiographic anatomy and patient positioning.     

河南省非订单定向全科住院医师规范化培训结业学员的就业状况及影响因素研究

背景 全科医生数量和质量是人力资源管理的两个重要维度，其中，医生数量的新增、保持和流失，是全科人力动态规划、管理和评价的重要考量，也是全科住院医师规范化培训（简称全科住培）的绩效指标。探讨全科住培学员的就业状况及影响因素，可以为今后住培政策和激励机制的制定提供参考，但目前针对非订单定向全科住培学员的相关研究较为缺乏。 目的 了解河南省非订单定向全科住培学员的就业状况，分析学员结业后未从事全科医学相关工作的原因，从而为完善培训管理和人力资源激励机制提供参考。 方法 于2021年8月，采用分层随机整群抽样法，在河南省选取2014—2017年入培且已结业的非订单定向全科住培学员326例进行问卷调查。问卷由课题组自行设计，主要内容为学员的基本信息、全科住培情况、目前工作情况及结业后从事与未从事全科医学相关工作的原因。问卷通过"问卷星"平台发放，由学员自行填写。 结果 共发放问卷326份，回收有效问卷271份（83.1%）。结业后，从事全科医学相关工作者77例（28.4%），从事非全科医学相关工作者194例（71.6%）。多因素Logistic回归分析结果显示，年龄、文化程度、生源类型、全科住培基地所在区域是学员结业后是否从事全科医学相关工作的影响因素（P<0.05）。与结业后未从事全科医学相关工作的学员相比，结业后从事全科医学相关工作学员注册为全科医学专业的比例更高〔70.1%（54/77）比32.0%（62/194），P<0.05〕，在乡镇卫生院/社区卫生服务中心执业的比例更高〔49.4%（38/77）比6.2%（12/194），P<0.05）〕。194例未从事全科医学相关工作的学员中，从事内科学工作者78例（40.2%），从事急诊及危重症医学工作者33例（17.0%），从事外科学工作者17例（8.8%）。不选择从事全科医学相关工作的前3位原因分别为：单位安排〔34.5%（67/194）〕，所在单位没有全科医学科〔29.9%（58/194）〕，薪酬低〔26.8%（52/194）〕。 结论 非订单定向全科住培学员选择从事全科医学相关工作的比例较低，年龄、文化程度、生源类型及基地所在区域是影响因素。建议加大全科医学理念宣传，加快综合医院全科医学科建设，提高全科医生薪酬待遇，以此增加全科医生的职业吸引力。     

Factors influencing the rating of sonographer students’ clinical performance

IntroductionLittle is known about the factors influencing clinical supervisor-assessors’ ratings of sonographer students’ performance. This study identifies these influential factors and relates them to professional competency standards, with the aim of raising awareness and improving assessment practice.MethodsThis study used archived written comments from 94 clinical assessors describing 174 sonographer students’ performance one month into their initial clinical practice (2015–6). Qualitative mixed method analysis revealed factors influencing assessor ratings of student performance and provided an estimate of the valency, association, and frequency of these factors.ResultsAssessors provided written comments for 93 % (n = 162/174) of students. Comments totaled 7190 words (mean of 44 words/student). One-third of comment paragraphs were wholly positive, two-thirds were equivocal. None were wholly negative. Thematic analysis revealed eleven factors, and eight sub-factors, influencing assessor impressions of five dimensions of performance. Of the factors mentioned, 84.6 % (n = 853/1008) related to professional competencies. While 15.4 % (n = 155/1008) were unrelated to competencies, instead reflecting humanistic factors such as student motivation, disposition, approach to learning, prospects and impact on supervisor and staff. Factors were prioritised and combined independently, although some associated.ConclusionClinical assessors formed impressions based on student performance, humanistic behaviours and personal qualities not necessarily outlined in educational outcomes or professional competency standards. Their presence, and interrelations, impact success in clinical practice, through their contribution to, and indication of, competence.Implications for practiceSonographer student curricula and assessor training should raise awareness of the factors influencing performance ratings and judgement of clinical competence, particularly the importance of humanistic factors. Inclusion of narrative comments, multiple assessors, and broad performance dimensions would enhance clinical assessment of sonographer student performance.     

Reporting radiographer academy training model; an evaluation of the impact for trainees and clinical service

IntroductionDemand on imaging services continues to increase on a background of complex issues and barriers to care. Collaborative cross organisational working through the development of imaging networks is recommended to address these issues including managing reporting workloads. Standardisation of reporting practices and collaborative cross region reporting radiographer training has been recommended to be supported by a regional reporting radiographer academy model to achieve these aims. This research explores the perceptions of trainees and their managers/mentor who undertook radiographer academy training model with a view to integrated imaging network formalisation in the region.MethodsAn online questionnaire was designed to capture qualitative and quantitative data with three phases; 1) trainees perception of the academy model, 2) trainees perception of the differences in training models and 3) the perceptions of the managers/mentors related to the academy model.ResultsThere were overwhelmingly positive opinions of the academy training model from both cohorts in this study, with the two main benefits emerging being the protected study time away from clinical departments and minimal disruption to clinical services due to reduced onus on the local mentors. Peer support was also highlighted as a positive aspect of the model which would facilitate future integrated imaging network working.ConclusionThe academy model has been well received by both cohorts in this study with positive outcomes highlighted and the model being seen as promoting and facilitating integrated imaging network working between departments. The small sample size of the study requires consideration when extrapolating the results to wider academy models, however some themes may be applicable.Implications for practiceInvestment in the reporting radiographer academy model is justified and provides a practical alternative to the traditional model.