反3/4冠抗切向脱位力的实验研究

目的:通过测量并比较金属3/4冠与金属烤瓷反3/4冠修复离体上颌中切牙抗切向脱位力的差异,论证金属烤瓷反3/4冠的抗切向脱位力能否满足临床固位要求.方法:选择20颗牙冠完整的离体上颌中切牙行牙体预备,制作金属3/4冠并就位于对应离体牙上,用万能试验机测量并统计各个样本的切向脱位力.再对20颗离体上颌中切牙行牙体预备,制作金属烤瓷反3/4冠金属底冠并就位于对应离体牙上,用万能试验机测量并统计各个样本的切向脱位力.用SPSS14.0统计软件包对测量结果进行配对T检验(parired-samples T Test).结果:①金属3/4冠的切向脱位力为0.545±0.487N.②金属烤瓷反3/4冠金属底冠的切向脱位力为2.96±1.58N.③金属3/4冠的抗切向脱位力和金属烤瓷反3/4冠金属底冠的切向脱位力差异有显著统计学意义(P<0.01).后者抗切向脱位力大于前者.结论:金属烤瓷反3/4冠修复离体上颌中切牙,其抗切向脱位力能够满足临床要求.     

Clinical and SEM evaluation of all-ceramic chair-side CAD/CAM-generated partial crowns

The effect of hardware and software on the quality of Cerec all-ceramic partial crowns was investigated in this cross-sectional study. Partial crowns (n = 818) had been adhesively placed in 496 patients between 1993 and 1997 using Cerec 1 and Cerec 2 units (groups 1 and 2) as well as Cerec 2 with wall-spacing software (group 3). From each group, 25 randomly selected partial crowns were evaluated using modified United States Public Health Service (USPHS) criteria. Of these, 12 were randomly selected in each group, replicas taken and examined in a scanning electron microscope for marginal interfacial width and for continuous margin adaptation. Interfacial width of group 1 (308 +/- 95 micro m) was significantly larger than those of groups 2 (243 +/- 48 micro m) and 3 (207 +/- 63 micro m). Continuous margin adaptation at the tooth-luting composite and luting composite-restoration interfaces showed only minor differences in groups 1 (94.5 +/- 8% and 95.5 +/- 2%), 2 (98.1 +/- 1% and 97.5 +/- 1.4%) and 3 (96.8 +/- 3% and 96.8 +/- 2%). Pooled clinical rating was excellent or good at 97% for all groups, indicating acceptable restoration quality except for one breakage in group 1.     

Clinical evaluation of a carbon fibre reinforced carbon endodontic post

This study reports a prospective clinical trial comparing a carbon fibre reinforced carbon (CFRC) endodontic post with a conventional prefabricated post. Twenty-seven single rooted maxillary anterior teeth in 18 patients (nine males and nine females; age range 18-60 years) were restored either with a CFRC post or a wrought precious alloy control. Cast type III gold alloy cores were used in conjunction with both post groups. The CRFC posts (n = 16) were cemented with a composite luting agent and the conventional posts (control) were cemented with zinc phosphate. Four failures were recorded in the CFRC post group at 24, 29, 56 and 87 months, compared with one failure in the control group at 84 months. These results suggest that post-retained crowns utilizing a CFRC material and a composite resin luting agent do not perform as well as conventional wrought precious alloy posts.     

角膜散光与软性角膜接触镜配适评估的相关性分析

目的探讨角膜散光的大小、轴向与球性、散光软性角膜接触镜的配适状态、舒适度之间的关系。设计前瞻性随机区组对照临床研究。研究对象284例自愿受试者,现在或曾经配戴软性角膜接触镜。方法受试者的平均近视屈光度为(-5.18±2.53)D,平均散光度为(0.81±0.50)D。每位受试者在接受眼部检查、验光、角膜地形图检查后,于其左眼间隔一定的时间先后配戴球性和散光软性接触镜。根据受试者左眼角膜散光的轴向将人群分为三组:第一组,顺规散光组(132眼);第二组,逆规散光组(76眼);第三组,斜轴散光组(76眼)。同时,根据受试者角膜散光度数的不同分为以下三组:第四组,<0.75D共153眼;第五组,≥0.75D、<1.50D,共106眼;第六组,≥1.50D共25眼。主要指标镜片中央定位、覆盖度、活动度、散光镜片的旋转性和稳定性以及舒适度。结果在前三组和后三组对比中,镜片覆盖度、活动度、旋转性及稳定性指标组间均无显著性差异。散光镜片的稳定性在3分钟、15分钟明显优于第1分钟。散光镜片的中央定位优于球性软镜(P=0.00),最佳中央定位的比例分别为54%与48%;散光镜片活动度大于球镜(P=0.02),两者活动度不良所占的比例分别为18%与19%;散光镜片舒适度差于球镜(P=0.00),不可接受的比例散光片为14%,球镜片为5%。结论软性角膜接触镜的配适与舒适度较少地受到角膜散光的影响。球性软镜可在一定程度上作为首选配戴。     

ED-NM-MO三联法对丹参三七配比的多目标优化研究

[目的]采用ED-NM-MO三联法对经基线等比增减设计的丹参、三七不同配比的药效学数据进行非线性拟合和多目标优化。[方法]对经基线等比增减设计的丹参、三七不同配比的药效学数据,以心肌缺血程度Σ-ST、心肌缺血程度(缺血区左室)等7个分别反映心肌缺血、心脏状态和血流动力学的指标作为待优化的药效目标,进行非线性拟合和多目标优化。[结果]分别得到针对7个药效指标和6个药效指标(不包含血清中心肌钙蛋白)的Pareto最优配比。[结论]ED-NM-MO三联法是一种适合复方特点的优化方法,可以应用于由多饮片多组分多成分复方药物的剂量配比优化。     

Technical failure rates of double crown-retained removable partial dentures

Removable partial dentures (RPD) can be retained using conical crowns or parallel-sided telescopic double crowns. The purpose of this study was to evaluate and compare the technical failure rate of the two retainer systems. One hundred seventeen dentures made by dentists of the medical school were included. Seventy-four RPD were retained with parallel-sided crowns (n=251) and 43 with conical crowns (n=160). Following the medical report follow-ups from January 1992 to December 1998, technical RPD failures were noted and analyzed. Technical problems occurred during the observation time in 48.8% of the conical retained dentures and 34.2% of the parallel-sided retained dentures. In both cases, loss of cementation was most frequently noted, while loss of the facings occurred only with conical crowns. Other technical failures did not depend on the type of retainer system used. These were most frequently problems with the denture base, e.g., fracture of artificial teeth or the metal framework. We conclude that there were different technical failures of both double crown retainer systems. These problems were not insignificant in number but treatable. Received: 14 December 1999 / Accepted: 19 January 2000     

A comparative study of the audiological outcomes with Retro-X (semi-implantable hearing aid system) and conventional open fitting hearing aids

The objective of this study was to compare the results of hearing augmentation with the Retro-X semi-implantable hearing aid to a conventional non-implantable open canal hearing aid using the same software technology (Titan-X, auric Hearing Systems, HiKaNo.:13.20.03.0047). Nineteen subjects (20 ears) with mild to moderate high-frequency sensory-neural hearing loss were included in this clinical study. All the subjects were first fitted with a conventional open canal hearing aid (Titan-X). After a period of 4-6 weeks audiological evaluations were performed using standardized speech tests in quiet and noise. Subjective evaluation was performed with the help of standardized questionnaires. After this phase the patients received the semi-implantable Retro-X device under local anaesthesia and 4 weeks later were fitted with a hearing module with the same software technology as the conventional Titan-X hearing aid. Four weeks following the first fitting the same audiological evaluations were performed under similar conditions and the patients were evaluated again using the same questionnaires in order to compare the results of the Retro-X semi-implantable system with the conventional open canal hearing aid. Audiological evaluations revealed better results with the semi-implantable Retro-X in the adaptive speech in noise test; however, the results of the monosyllabic word test in quiet were similar for the Retro-X and conventional open canal hearing aid. The patients subjectively preferred the improved wearing comfort of the semi-implantable device. The Retro-X semi-implantable hearing aid provides better speech perception in noise and higher wearing comfort in comparison to the conventional open canal hearing aids. Considering the simple implantation procedure under local anaesthesia with low complication rate, Retro-X is an alternative to the conventional open canal hearing aids in patients with mild to moderate high frequency sensory-neural hearing loss.     

一种滤毒通风装置的研制

目的：研制一种能够对悬浮在空气中的生物气溶胶、化学毒气等有害物质进行过滤并向医疗方舱内提供清洁新风的滤毒通风装置。方法：采用模块化设计方法，将过滤净化单元和送风动力单元按照可操作性和可维修性原则组合成为整体。结果：减小了该装置的结构尺寸，降低了风机的振动噪声，提高了可操作性和可维修性。结论：该装置能够满足医疗方舱对生物及化学防护的要求，快速装卡等结构设计能适应快速反应的需要。     

硫酸钡比浊法测定水中硫酸盐的不确定度评估

目的分析和评估硫酸钡比浊法测定水中硫酸盐含量的不确定度。方法依据测量不确定度评定与表示（JJF1059-1999），建立数学模型，得出测定硫酸盐的合成小确定度和扩展不确定度。结果水中硫酸盐的合成不确定度为0．33mg／L，扩展不确定度为0．7mg／L。结论通过对硫酸钡比浊法测定水样中硫酸盐含量不确定度的来源分析，找出影响测量结果的各种因素，计算不确定度分量及合成不确定度，有效掌握了测量结果的可信程度和准确性，保证检测工作和检测结果的质量。     

Linearly optimum seeking K-value in the fitting of exponential and geometric

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