Experimental evaluation of aerosol mitigation strategies in large open-plan dental clinics

BackgroundAerosols are generated routinely during patient care in dentistry. Managing exposure risk requires understanding characteristics of aerosols created during procedures such as those performed using high-speed drills that operate at 200,000 revolutions per minute.MethodsA trained dentist performed drilling procedures on a manikin’s incisors (teeth nos. 8 and 9) using a high-speed drill and high-volume evacuator. The authors used high-speed imaging to visualize the formation and transport of aerosol clouds and particle sampling to measure aerosol concentration and size distribution at several locations. The authors studied several aerosol mitigation strategies.ResultsAerosols produced during high-speed drilling were erratic and yielded high concentrations that were at least an order of magnitude above baseline. High-speed imaging showed aerosols initially travelled at 1 m per second. Owing to erratic behavior of aerosols, supplemental suction was not effective at collecting all aerosols; however, barriers were effective.ConclusionsBarriers are the most effective mitigation strategy. Other methods studied have limitations and risks. To the authors’ knowledge, this article presents the first characterization of aerosols generated during high-speed drilling by a dentist.Practical ImplicationsWith thorough preoperative planning and the use of this investigation’s findings about effectiveness of mitigation strategies as a guide, dental offices may be able to return to prepandemic productivity.     

Accuracy of drilling guides for transfer from three-dimensional CT-based planning to placement of zygoma implants in human cadavers

Abstract: The accuracy of surgical drilling guides was assessed for placement of zygoma implants. Six zygoma fixtures of length 45 mm (Nobel Biocare, Göteborg, Sweden) were placed in three formalin‐fixed human cadavers using surgical drilling guides. The fabrication of these custom‐made drilling guides was based on three‐dimensional computerized tomography (3D‐CT) data for the maxillary‐zygomatic complex. The installation of the implants was simulated preoperatively using an adopted 3D‐CT planning system. In addition, anatomical measurements of the zygomatic bone were performed on the 3D images. The preoperative CT images were then matched with postoperative ones in order to assess the deviation between the planned and installed implants. The angle between the planned and actually placed implants was < 3° in four out of six cases. The largest deviation found at the exit point of one of the six implants was 2.7 mm. The present study showed that the use of surgical drilling guides should be encouraged for zygoma implant placement because of the lengths of the implants involved and the anatomical intricacies of the region.     

失血性休克紧急手术模拟演练在新入职护士培训中的应用效果分析

目的:探讨失血性休克紧急手术模拟演练在新入职护士培训中的应用效果。方法:选取2019年医院外科手术室新入职护士31人为对照组,另选2020年医院新入职护士31人为观察组,对照组实施常规培训方法,观察组在对照组基础上实施失血性休克紧急手术模拟演练,比较两组应用效果。结果:干预后观察组护士急救相关核心制度、急救抢救药物知识、抢救流程、紧急手术各类应急预案评分均高于对照组(P<0.05);干预后观察组护士除颤仪、呼吸机、心肺复苏仪、徒手心肺复苏操作技能评分均高于对照组(P<0.05);干预后观察组护士抢救配合能力、案例分析能力、应急处理能力、学习兴趣、沟通能力评分均高于对照组(P<0.05);观察组护士工作能力优良率为96.77%,高于对照组的70.97%(P<0.05)。结论:失血性休克紧急手术模拟演练应用于新入职护士培训中,不仅可有效提高其理论知识水平、操作技能及综合能力,还能提高其工作能力优良率。     

高频超声射频回波信号高速数据传输系统的设计

目的:为提高超声诊断设备数据传输的实时性和准确性,设计一种高频超声射频回波信号高速数据传输系统.方法:该系统基于现场可编程门阵列(field programmable gate array,FPGA)和单阵元高频宽带换能器设计,由FPGA控制处理模块、超声探头模块、射频回波信号处理模块、USB传输模块以及上位机组成.采...     

天然产物分离中高速逆流色谱溶剂体系的研究进展

根据溶剂体系的极性与分离的天然产物的关系,本文对高速逆流色谱中使用的溶剂系统进行了归纳总结,不仅对快速选择溶剂体系分离天然产物起到了一定的指导作用,而且为今后高速逆流色谱溶剂体系的研究提供了方便。     

大孔吸附树脂-高速逆流色谱法分离纯化玄参中哈巴俄苷和斩龙剑苷A

目的 以玄参的干燥根为原料,建立大孔吸附树脂-高速逆流色谱法(HSCCC)分离纯化玄参中哈巴俄苷与斩龙剑苷A的方法。方法 玄参粗提物先经过大孔吸附树脂初步分离,富集目标化合物。然后以正丁醇-乙酸乙酯-水(1∶9∶10)为溶剂体系,上相为固定相,下相为流动相,流速1.5 mL·min^-1,检测波长210 nm,利用制备型HSCCC分离纯化哈巴俄苷和斩龙剑苷A。结果 经过大孔吸附树脂-高速逆流色谱法分离后,一次性得到哈巴俄苷和斩龙剑苷A,经HPLC检测其纯度分别为98.1%和97.2%。经¹H-NMR和¹³C-NMR鉴定结构为哈巴俄苷和斩龙剑苷A。结论 该方法能够简便、高效地制备玄参中的哈巴俄苷和斩龙剑苷A。     

Effect on implant drills and postoperative reactions for pre-extraction interradicular implant bed preparation during the COVID-19 pandemic and beyond

The aim of the present study was to observe the abrasion of implant drills and postoperative reactions for the preparation of the interradicular immediate implant bed during the COVID-19 pandemic and beyond.Thirty-two implant drills were included in four groups: blank, improved surgery, traditional surgery, and control. In the improved surgery group, a dental handpiece with a surgical bur was used to decoronate the first molar and create a hole in the middle of the retained root complex, followed by the pilot drilling protocol through the hole. The remaining root complex was separated using a surgical bur and then extracted. Subsequently, the implant bed was prepared. Implant drills were used in the traditional surgery group to complete the decoronation, hole creation, and implant-drilling processes. The tooth remained intact until the implant bed was prepared. The surface roughness of the pilot drill was observed and measured. Surgery time, postoperative reactions (swelling, pain, and trismus), and fear of coronavirus disease 2019 scale (FCV-19S) were measured and recorded, respectively.Statistical analysis revealed significant difference with surface roughness among blank group (0.41 ± 0.05 μm), improved surgery group (0.37 ± 0.06 μm), traditional surgery group (0.16 ± 0.06 μm), and control group (0.26 ± 0.04 μm) (P < .001). Significant differences were revealed with surgery time between improved surgery group (5.63 ± 1.77 min) and traditional surgery group (33.63 ± 2.13 min) (P < .001). Swelling, pain, and trismus (improved group: r ≥ 0.864, P ≤ .006; traditional group: r ≥ 0.741, P ≤ .035) were positively correlated with the FCV-19S.This study proved that a new pilot drill could only be used once in traditional surgery but could be used regularly in improved surgery. Improved surgery was more effective, efficient, and economical than the traditional surgery. The higher FCV-19S, the more severe swelling, pain, and trismus.     

Study on the Interaction between Wheel Polygon and Rail Corrugation in High-Speed Railways

The wheel polygonization and rail corrugation are typical wheel–rail periodic wear problems, which seriously affect the safe operation of high-speed railways. In the present paper, the interaction between the wheel polygon and the rail corrugation in the long-slope section of high-speed railways is mainly studied based on theory of friction coupling vibration. Firstly, the simulation model of the wheel–rail contact model is established, as well as the polygonal wear of the wheel and the corrugated wear of the rail. Then, the stability analyses of the wheel–rail system with periodic wear are studied, in which the four working conditions of smooth rail–smooth wheel, polygonal wheel–smooth rail, smooth wheel–corrugated rail and polygonal wheel–corrugated rail are compared. Finally, the competition mechanisms between the wheel polygon and rail corrugation under different parameters are discussed, including the wheel–rail friction coefficient and the depth of periodic wear of the wheel–rail system. The numerical results show that both the periodic wear of the wheel and rail with certain relevance will increase the friction coupling vibration of the wheel–rail system, which may aggravate the subsequent relevant wheel polygonal and rail corrugation wear. With the increase of the friction coefficient between wheel and rail, as well as the depth of the wheel polygon and rail corrugation, the vibration trend of the friction coupling vibration of the wheel–rail system increases gradually. Moreover, the proportion of the wheel polygon’s influence on the friction coupling vibration of the wheel–rail system is greater than that of rail corrugation.     

微创拔除阻生下颌第三磨牙时高速涡轮手机车针断裂30例临床分析

目的    探讨拔除阻生下颌第三磨牙时高速涡轮手机车针断裂的原因及处理对策。方法    收集苏州大学附属第一医院口腔科从2010年2月至2019年10月拔除阻生下颌第三磨牙时高速涡轮手机车针断裂的30例患者病例资料，对断针留存的部位及取出方法进行总结分析。结果    所有断针全部取出，20例患者无明显术后反应，10例患者术后第2天复诊局部有明显肿胀及张口受限。2例患者术后第2天出现下唇及舌尖麻木。1周后复诊，创口均一期愈合，无感染和张口受限。1个月后复诊，2例唇舌麻木的患者完全恢复。结论    在使用高速涡轮手机拔牙时应及时更换车针，避免车针使用次数过多；在操作中切勿使用暴力，尽量保护舌侧骨板的完整性；在车针断针后，行相关影像学检查辅助定位，切莫盲目手术；采用多学科交叉的方法有利于断针的取出。