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1.
《Dental materials》2022,38(1):204-213
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. 相似文献
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《Dental materials》2022,38(4):e83-e93
ObjectivesThe aim was to investigate the fatigue performance of endodontically treated (ET) molars restored by various dentin-replacing materials and material configurations. Moreover, the impact of additional adhesive treatment with glass-ionomer cement (GIC) was evaluated.Methods250 intact molars were collected and randomly distributed into ten groups (n = 25). After endodontic procedure standard Class I cavities were prepared and restored with different direct restorative techniques and dentin-replacing materials. Two-group were restored with either packable or flowable short fiber-reinforced composites (SFRCs). Two-group were restored by experimental fiber-reinforced GIC with and without adhesive treatment. Four-group were restored by conventional and resin-modified GICs with or without adhesive treatment. One-group was restored with a dual-cure composite resin and last group was restored with only conventional composite resin (control). Fatigue-survival was measured for all specimens using a cyclic-loading machine until fracture occurred or a number of 40.000 cycles were achieved. Kaplan-Meyer survival analysis was conducted, followed by pairwise log-rank post hoc comparisons. Fracture mode was then examined by means of optical microscopy and SEM.ResultsGroup restored with flowable SFRC showed significantly higher survival (p < 0.05) compared to all of the groups, except for group restored with packable SFRC (p > 0.05). Group restored with fiber-reinforced GIC had significantly (p < 0.05) higher survival rates compared to other commercial GICs. SEM demonstrated change of the fracture line when fracture reached the SFRC layer.SignificanceDirect restoration of Class I in ET molars with the use of SFRCs as dentin-replacing materials demonstrated its ability to reinforce the dental structures and to increase the fatigue resistance in this specific clinical situation. 相似文献
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《Pancreatology》2022,22(7):1035-1040
ObjectivesThis study aims to assess the prevalence of preoperative fatigue, depression and anxiety among patients undergoing pancreatic surgery for pancreatic cancer (PC), and possible relationship with postoperative outcomes.MethodsProspective data from 162 consecutive patients undergoing pancreatectomy for PC at a third-level referral centers for pancreatic surgery were collected. All patients preoperatively completed four questionnaires assessing depression (PHQ-9), anxiety (STAI-Y2), chronic illness fatigue (FACIT-F) and cancer therapy fatigue (FACT-G).ResultsForty patients (25%) where in the first quartile for chronic illness (FACIT-F ≤34) and/or cancer therapy (FACT-G ≤78) fatigue, 26 patients (16%) met the criteria for major depression (PHQ-9 ≥10) and 34 patients (21%) had anxiety symptoms (STAI-Y2 ≥40). Cancer therapy fatigue was significantly associated with higher rates of morbidity (70% vs 49%), major morbidity (Clavien-Dindo ≥3) (28% vs 11%), post-pancreatectomy hemorrhage (18% vs 4%), pulmonary complications (20% vs 9%) and mortality (8% vs null) (all P ≤ 0.01). Major depression was associated with higher rates of post-pancreatectomy hemorrhage and readmission (23% vs 5%). Multivariable logistic regression analysis of preoperative factors confirmed diabetes (OR 2.71, 95%CI 1.01–7.20; P = 0.04), ASA score ≥3 (OR 4.12, 95%CI 1.52–11.21; P < 0.01) and cancer therapy fatigue (OR 2.95, 95%CI 1.01–8.74; P = 0.04) to be independent predictors of major morbidity.ConclusionsHigher levels of fatigue (in particular cancer therapy fatigue) strongly correlates with worse postoperative outcomes. 相似文献
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背景 全科医师是初级医疗保健体系和分级诊疗的重要支点,全科专业住院医师规范化培训(以下简称全科住培)是培养高素质全科医师最重要的渠道,但目前我国的执业现状使学员易产生职业倦怠,分析其职业倦怠影响因素可为完善全科住培管理和壮大全科医师队伍提供依据。目的 了解全科住培学员职业倦怠现状,并分析其影响因素。方法 2019年3-4月,从江苏省13个市各抽取1家国家级全科住培基地,基地内全科学员全样本调查,共抽取682名学员。采用自制社会人口学调查表、职业倦怠普适量表调查学员的职业倦怠情况,采用多元线性回归分析探讨全科住培学员职业倦怠的影响因素。结果 共发放问卷682份,回收有效问卷604份,有效问卷回收率为88.6%。职业倦怠3个维度情绪耗竭维度得分为(15.34±7.02)分、去个性化维度得分为(9.17±6.36)分、个人成就感低落维度得分为(13.61±8.12)分。零倦怠检出率为43.7%(264/604),轻度职业倦怠检出率为27.3%(165/604),中度职业倦怠检出率为21.5%(130/604),重度职业倦怠检出率为7.5%(45/604)。体育锻炼次数、睡眠时长是全科住培学员情绪耗竭的影响因素(P<0.05);学历、体育锻炼次数、睡眠时长、参加住培年度、收入水平是全科住培学员去个性化的影响因素(P<0.05);性别、身份归属和体育锻炼次数是全科住培学员个人成就感低落的影响因素(P<0.05)。结论 全科住培学员职业倦怠检出率较高。体育锻炼次数、睡眠时长、参加住培年度、收入水平、学历、性别、身份归属是全科住培学员职业倦怠的影响因素。建议加强全科住培学员体育锻炼和心理建设、探索构建“行业社会人”的培养模式、夯实基层基地的建设、提高全科住培学员薪资待遇等,来缓解或降低其职业倦怠程度。 相似文献
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目的 探索多维疲乏目录(Multidimensional Fatigue Inventory,MFI-20)对脑卒中后疲乏(post-stroke fatigue,PSF)的诊断价值。方法 采用方便抽样法抽取328例脑卒中患者作为研究对象,以疲乏严重度量表(Fatigue Severity Scale,FSS)结果为诊断标准,评估MFI-20诊断PSF的效能。结果 328例患者中,136例使用FSS诊断PSF(41.5%),153例应用MFI-20诊断PSF(46.6%)。以FSS为标准,MFI-20对PSF的诊断符合率为91.8%,Kappa值为0.833,灵敏度为96.3%,特异度为88.5%,阳性预测值为85.6%,阴性预测值为97.1%。MFI-20诊断PSF的ROC曲线下面积为0.924。结论 MFI-20具有良好的诊断价值,其多维的特点与PSF的复杂性相契合,可作为PSF的诊断工具。 相似文献
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L.M. Abbassi M. Laurans A. Gasnier A. Smulevici H. Tournat J.-E. Bibault A. Huertas E. Jouglar A. Suissa S. Kreps P. Giraud C. Durdux 《Cancer radiothérapie》2019,23(4):316-321
PurposeTo evaluate prospectively asthenia and the quality of life in patients treated by stereotactic body irradiation and to determine their predictive factors.Methods and materialsQuality of life was assessed by the EORTC QLQ-C30 and asthenia was evaluated with the Brief Fatigue Inventory (BFI), on the first day (T1), last day (T2) and 1–3 weeks after the end of treatment (T3).ResultsSixty-three patients were treated with stereotactic body irradiation from February 2017 to May 2017 and 41 were included in the analysis (22 patients excluded for lack of understanding, organization, psychologic disorders or refusal). The mean number of fractions was 5 (± 2). The compliance to quality of life assessment was 98%, 95% was 81% at T1, T2 and T3, respectively. An increase of asthenia and a worsened quality of life were found in 12 (29%) and 14 (34%) patients between T1 and T2. Univariate analysis demonstrated a correlation between asthenia and quality of life were correlated with performans status (P = 0.03 and 0.05 respectively), hemoglobin level (p = 0.01 and 0.004), albumin level (P = 0.01 and 0.06), distance between home and radiotherapy department (P = 0.05 and 0.02). Multivariate analysis demonstrated a correlation between female gender (P = 0.012), albumin level (P < 0.001), distance over 25 km (P < 0.001) with asthenia, and albumin level (P = 0.003), hemoglobin level (P = 0.004) and previous chemotherapy (P = 0.003) with quality of life. No influence of stereotactic body ratiotherapy parameters was seen.ConclusionDespite hypofractionation, stereotactic body radiotherapy induced asthenia and deterioration of quality of life. 相似文献
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