铸造支架联合NITI悬臂梁矫正舌倾下颌磨牙的临床效果评价

目的 评价NITI悬臂梁在矫正舌倾下颌磨牙中的临床效果。方法 选择16例单侧下颌第二磨牙舌倾的病例为研究对象,带垫铸造支架连接双侧下颌后牙,提供颌内支抗、解除咬合锁结,0.018英寸×0.025英寸或0.019英寸×0.025英寸NITI悬臂梁提供颊向旋转力矩和压低力。采用Graphpad Prism 6.0 软件对治疗前、后所测数据进行配对 t 检验。结果 所有患牙均获得直立,牙轴变化24°±1.2°（P<0.01）,近中舌尖到正中矢状面垂直距离变化（3±0.8） mm（P<0.05）,牙周状况良好,咬合关系稳定。结论 铸造支架联合NITI 悬臂梁可提供有效力学机制,矫正舌倾下颌磨牙。     

Resin-retained bridges in the treatment of traumatized dentition*

Abstract Resin-retained bridges can be used as the definitive treatment, as well as for interim treatment. Compared with conventional fixed prostheses, there are some advantages which make this treatment especially useful in traumatized dentition. The ultra conservative approach makes the adhesive bridge a standard treatment option in cases of uncertain prognostic factors. However, in such specific situations as traumatized dentition some complicating factors may be present. These complicating factors must be recognized and eliminated to create situations in which this kind of restoration can be succesful. Therapeutic and patient-related factors are discussed using data from longitudinal clinical studies. Available clinical information indicates the anterior adhesive bridge to be a permanent restoration'. However, a benefit-cost analysis is necessary to weigh the value of this restorations.     

Organic interlamellar layers,mesolayers and mineral nanobridges: Contribution to strength in abalone (Haliotis rufescence) nacre

The contributions of mesolayers, organic interlamellar layers and nanoasperities/mineral bridges to the strength of nacre from red abalone (Haliotis rufescens) shell nacre are investigated. Samples were demineralized and deproteinized to separate the organic and mineral components, respectively. Tensile tests were performed on both the isolated organic constituent and the isolated mineral. The strength of the isolated organic component suggests that growth bands play an important role in the mechanical behavior as they are thick regions of protein that are a significant fraction (∼0.4) of the total organic content. The thickness variation of the nacre tablets was measured and found to be a small fraction of the mean tablet thickness (0.568 μm); the standard deviation is 26 nm, indicating that the wedge mechanism of toughening does not operate in the nacre investigated. Results obtained from the isolated mineral validate the importance of the organic constituent as the mechanical properties decline greatly when the organic component is removed. The results presented herein add to the understanding of the mechanical response of the organic interlayers and growth bands and their effect on the toughness of the abalone nacre.     

守土尽责,致敬新冠肺炎疫情防控一线的放射工作者

2019年12月底以来,湖北武汉暴发的新型冠状病毒肺炎(novel coronavirus pneumonia,NCP)迅速扩散至全国各地及境外24个国家,1月30日世界卫生组织(WHO)将疫情列为“国际关注的突发公共卫生事件(PHEIC)”,到2月2日死亡人数已超过2003年的重症急性呼吸综合征(SARS)。放射影像CT检查是病例诊断和疗效评估不可或缺的一环。广大放射诊断医务人员日夜奋战在新冠肺炎防控一线,为保障患者和放射诊断工作人员安全和健康,各地放射卫生技术机构与放射卫生监督工作者忠实地履行着自己的职责。     

动态载荷下种植体位置和直径对悬臂梁种植固定义齿应力影响的三维有限元研究

目的 应用三维有限元法分析动态加载下种植体植入位置和直径对悬臂梁种植固定义齿应力的影响。方法 建立左下颌第二前磨牙、第一磨牙、第二磨牙缺失种植固定义齿的三维有限元模型,远中种植体的位置和直径保持不变;近中种植体依次向远中移动形成中轴与第一前磨牙远中面距离D分别为5.5、8.0、10.5、13.0 mm的悬臂梁种植固定义齿,分别采用4.1和4.8 mm两种直径的种植体;以250 N 牙合力模拟咀嚼周期0.875 s的动态载荷加载于颊尖和舌尖上,应用有限元分析软件MSC.Marc和Partran分析种植体-骨组织界面的Von Mises应力情况。结果 随着近中种植体逐渐向远中移动,近远中种植体Von Mises应力均有不同程度增高,近中种植体中轴与第一前磨牙远中面距离D≤8.0 mm范围内种植体最大Von Mises应力增幅缓和,D>8.0 mm时应力急剧加大;近中种植体直径增大,则近远中种植体的应力减小;各加载阶段最大Von Mises应力均处于近远中种植体颈部与皮质骨交界处;斜向加载种植体应力显著大于垂直加载。结论 种植体植入位置是影响悬臂梁种植固定义齿应力的重要因素,悬臂梁长度不超过前磨牙宽度时行种植固定义齿设计是可行的,直径的选择要考虑骨量和悬臂梁长度双重因素。     

南京“5.7” 192Ir源放射事故患者的生物剂量估算

目的 用3种方法估算南京"5.7" ¹⁹²Ir源放射事故患者的生物剂量,为核与辐射事故受照者的临床救治提供剂量资料。方法 受照后第5天采集患者外周血,分别进行外周血淋巴细胞染色体"双着丝粒+环"("dic+r")畸变分析、胞质分裂阻滞微核(CBMN)分析、核质桥(NPB +FHC)分析,并估算生物剂量。用双着丝粒畸变在细胞间的泊松分布情况检验照射的均匀性。结果3种方法估算的该患者受到的一次全身等效剂量分别为"dic+r"畸变分析1.51 Gy (95% CI 1.40~1.61),CBMN 分析1.47 Gy (95% CI 1.36~1.60),NPB+FHC分析1.30 Gy(95% CI 1.00~1.60)。泊松分布检验结果显示,该患者"dic+r"畸变偏离泊松分布,受到了不均匀照射。结论 外周血淋巴细胞染色体"dic+r"畸变分析、CBMN分析、NPB+FHC分析均是有效的生物剂量估算手段,对本例急性局部不均匀照射患者估算的一次全身等效剂量与临床诊断结果相符。     

Tooth‐to‐Implant Connection: A Systematic Review of the Literature and a Case Report Utilizing a New Connection Design

Background: In the treatment of partially edentulous patients, implants have often been connected to natural teeth. Numerous studies have reported significant complications and problems, while others have demonstrated favorable outcomes. Purpose: The purpose of this article was to systematically review the literature regarding the splinting of implants and teeth. The difference in the biomechanical behavior between osseointegrated implants and teeth and the efficacy of the different modes of connection that have been employed are explored. Materials and Methods: A MEDLINE search between 1966 and October 2006 was performed to retrieve relevant articles. A further manual search from the bibliographies of the former articles was performed to include as many references as possible. Prospective and retrospective clinical studies, as well as laboratory and computer‐generated research, were included. Results: A pronounced difference in the biomechanics of teeth and implants has been revealed in theoretical models. This disparity has also been supported by the majority of the experimental work published. As a result, principal complications, such as intrusion of teeth and higher risk of overload and greater marginal bone loss around the implants have been reported. Among the several types of connections utilized, the rigid connection showed fewer complications but unfortunately did not eliminate them. Conclusion: Totally implant‐supported prostheses should be the treatment of choice. However, there are cases where combining teeth and implants is inevitable. The authors propose a rationale design of connecting implants and teeth. This design minimizes the biologic and technical complications.