医学影像存储的色彩模式和文件格式的比较

本文介绍了不同的影像色彩模式和影像文件常见存储格式的特点及其在应用上的优缺点，分析了影像色彩模式、文件存储的格式与影像质量、用途的关系。     

两种后牙根管预备方法的临床效果比较

目的 :评估 2种后牙根管预备方法的临床效果。方法 :采用机用镍钛扩大锉 (ProFile)和手用不锈钢扩大锉 (K file)扩大后牙根管 ,并对 2组病例术后疼痛以及充填情况加以比较。结果 :发现机用镍钛扩大锉扩大后牙根管 ,具有去除根管感染物质彻底 ,根管形态保持良好 ,速度快 ,术后疼痛率较低的优点 ,但易出现断针。而手用不锈钢扩大锉扩大后牙根管速度较慢 ,术后疼痛率略高 ,但不易出现断针 ,操作上容易掌握。结论 :2种后牙根管方法都有优缺点 ,可结合起来使用。     

根管细菌渗漏体外模型的建立

目的：建立检测微细菌培养模型，以用于评价根管充填封闭情况。方法：牙根的冠根两端各连接一细菌培养储室，冠方储室置1mL无菌培养基并接种0．1mL菌液，根方储室起始为无菌培养基。每隔3d将冠方储室中菌液吸出1mL，并注入1mL新鲜BHI培养基，共90d。当根尖储室中培养基发生浑浊即为细菌渗漏发生，记录细菌渗漏发生时的天数。选择18个直根管前牙，其中牙胶充填组6个，用冷牙胶侧方加压充填技术充填；空管组6个，根管只预备不充填；根管密封组6个，根管充填并严密封闭根管口和根尖孔。用设计的模型检测密封状况。结果：全部空管组6个样本在1d内根方储室中出现浑浊；根管密封组6个样本的根方储室在90d内均未发生浑浊。牙胶充填组有2个样本分别在44d和46d发生浑浊。结论：此模型方法简单易行且实用有效，具有一定的临床相关性和可行性。     

Transition from Film to Electronic Media in the First-Year Medical School Gross Anatomy Lab

For the benefit of the first-year gross anatomy students, we digitized and published on a Web site images that had been collected over a 30-year period. We provided a CD-ROM (compact disk, read-only media) containing the image set in higher quality format to students and faculty. We supplemented basic images with hot topics such as CT angiography, virtual colonography, computer-aided diagnosis, and 3D post-processing. Full motion video and moving JPEG (Joint Photo Expert Group) animations were integrated into the atlas. On the post course questionnaire medical students reported that the images on CD-ROM were helpful during the course and for review prior to examinations. Faculty and medical students used the CD-ROM for problem-based learning sections and facilitator training. The images were clear and easily projected during review sessions and were useful for the small group sessions, where they served as examples of normal anatomy.     

数字化三维牙颌模型中牙齿边界的自动提取

目的在计算机辅助口腔正畸治疗的软件设计中实现对牙齿边界的自动提取。方法首先,对获取的数字化牙颌模型STL文件进行分析,针对后期处理的需要设计出拓扑重建后的数据结构;然后,通过对牙颌模型的三角网格离散曲率的估算获得初步提取的边界;最终,根据牙齿轮廓的特点提出一种修正方法,经修正后完成对牙齿边界的自动提取。结果自动提取出的牙齿边界线已基本符合实际需要。结论对数字化牙颌模型进行自动边界提取是可行的,并能提高牙齿分割的效率和精度。     

上颌窦对上颌后牙显微根尖手术的影响

显微根尖手术是临床上保存牙髓根尖周病患牙的有效手段之一,也是治疗其疑难病例的必备技术。但由于位置靠后操作空间狭小、根尖与上颌窦毗邻,导致在上颌后牙区进行根尖外科手术仍存在一定挑战。本文就上颌窦与上颌后牙解剖关系、对显微根尖手术影响以及辅助技术如:3D打印手术导板、超声骨刀等在上颌后牙区手术中的应用进行总结。文献复习结果表明,上颌后牙根尖与上颌窦空间关系通常分3类:根尖突进上颌窦底;根尖与上颌窦底相接触;根尖和上颌窦底之间有间隙或空间。术前CBCT检查后结合患牙根尖周和上颌窦状态以及根尖病损到上颌窦距离评估手术难度,术中应用导板、内窥镜、超声骨刀等以使手术更加安全可靠和精准微创,但后者在临床上的普及仍需进一步推广。目前尚缺乏高质量的上颌后牙区现代显微根尖手术长期疗效的临床研究。     

Influence of post fit and post length on fracture resistance

Aim  To investigate (i) the impact of post fit (form-congruence) and (ii) the influence of post length on the fracture resistance of severely damaged root filled extracted teeth.
Methodology  Ninety-six single-rooted human teeth were root filled and divided into four groups ( n  = 24 per group). Post spaces were prepared with a depth of 6 mm (group 1, 3) and 3 mm (group 2, 4). Form-congruence with a maximal fit of the post within the root canal space was obtained in groups 1 and 2, whereas there was no form-congruence in groups 3 and 4. In all groups, glass fibre reinforced composite (FRC) posts were adhesively cemented and direct composite crown build-ups were fabricated without a ferrule. After thermo-mechanical loading (1200000×, 5–50 °C), static load was applied until failure. Loads-to-failure [in N] were compared amongst the groups.
Results  Post fit did not have a significant influence on fracture resistance, irrespective of the post length. Both groups with post insertion depths of 6 mm resulted in significantly higher mean failure loads (group 1, 394 N; group 3, 408 N) than the groups with post space preparation of 3 mm (group 2, 275 N; group 4, 237 N).
Conclusions  Within the limitations of this study, the fracture resistance of teeth restored with FRC posts and direct resin composite crowns without ferrules was not influenced by post fit within the root canal. These results imply that excessive post space preparation aimed at producing an optimal circumferential post fit is not required to improve fracture resistance of roots.     

利用Toad解决Oralce数据库表空间错误问题

数据库是整个信息系统的核心，传统方式的数据库管理一般采用Sqlplus等命令行工具书写SQL命令。相比之下，使用数据库管理工具Toad连接数据库，通过图形化界面解决数据库问题，减少操作失误和繁琐程度，有效降低数据库管理成本。     

Effectiveness and Safety of Computer-controlled Periodontal Ligament Injection System in Endodontic Access to the Mandibular Posterior Teeth

Objective To evaluate the effectiveness and safety of a computer-controlled periodontal ligament （PDL） injection system to the local soft tissues as the primary technique in endodontic access to mandibular posterior teeth in patients with irreversible pulpitis. Methods A total of 162 Chinese patients who had been diagnosed with irreversible pulpitis in their mandibular posterior teeth without acute infection or inflammation in the periodontal tissues were enrolled in this clinical study. The patients were divided into 3 groups according to the position of the involved tooth： the premolar group （PM, z2=38）, first molar group （FM, n=66）, and second molar group （SM, n=58）. All the patients received computer-controlled PDL injection with 4% articaine and 1 ＇ 100 000 epinephrine. Immediately after the injection, endodontic access was performed, and the degree of pain during the treatment was evaluated by the patients using Visual Analogue Scale for pain. The success rates were compared among the 3 groups. The responses of local soft tissues were evaluated 3-8 days and 3 weeks after the procedure. Results The overall success rate was 76.5%. There was a significant difference in success rates among the PM, FM, and SM groups （92.1%, 53.0%, 93.1%, respectively; 2 X =34.3, P〈0.01）. Both the PM and SM groups showed higher success rates than that of the FM group （v=l, f=16.73, P〈0.01, v=l, Z = 4.5, X2 2 P〈0.01）. No irreversible adverse effects on the periodontal soft tissues at the injection sites were observed in the follow-up visits in any of the groups. Conclusion The computer-controlled PDL injection system demonstrates both satisfactory anesthetic effects and safety in local soft tissues as primary anesthetic technique in endodontic access to the mandibular posterior teeth in patients with irreversible pulpitis.     

学术论文作者机构规范文档构建

以中国生物医学文献数据库为基础,面向基于学术论文开展机构检索、分析与评价相关知识服务需要,对学术论文作者机构名称规范目标与内容、体系结构与组织方式以及构建过程与实现策略进行研究、实践总结。