固定桥不同桥体龈端形态修复下颌第一磨牙的三维有限元分析

目的 应用三维有限元分析法探讨不同桥体龈端形态对固定桥基牙及牙周膜应力分布的影响.方法 利用健康成人牙列的锥形束CT(CBCT)原始数据,通过三维建模软件建立下颌第一磨牙缺失,第二前磨牙与第二磨牙为基牙的双端固定桥,并模拟三种不同桥体龈端形态,即改良鞍式、改良盖嵴式、船底式.利用Ansys 17.0对已建立的三种不同龈...     

低(牙合)龈距下颌第一磨牙全冠有限元模型的建立

目的:建立低(牙合)龈距下颌第一磨牙全冠三维有限元模型.方法:用Micro-CT扫描离体下颌第一磨牙,再用Mimics10.0、Geomagic studio8等图像处理软件,Pro/ENGINEER实体建模设计软件,以及有限元分析软件Abaqus建立模型.结果:建立了低(牙合)龈距下颌第一磨牙具有根管和临床常用的辅助固位形的全冠修复牙体预备体、金属冠、牙周膜和牙槽骨的三维有限元模型.结论:用该方法建模方便、快捷、有效,所得模型真实、准确,能够满足各种生物力学分析的需要.     

下颌第一磨牙分根术后冠修复三维有限元模型的建立

目的建立下颌第一磨牙分根术后单冠和联冠修复的三维有限元模型,为冠修复的生物力学分析奠定基础。方法通过CBCT扫描获取断层图像,利用Mimics软件读取图像并进行初步处理,Geomagic软件精修,造型软件UG装配各模块及有限元软件Ansys划分网格。结果建立下颌第一磨牙、分根术后联冠与单冠修复下颌第一磨牙以及牙周支持组织的三维有限元模型。结论利用CBCT扫描结合逆向工程软件Mimics、Geomagic,造型软件UG,有限元软件Ansys能够快捷有效地建立三维有限元模型。     

基于CBCT图像建立磨牙分根术后冠修复的三维有限元模型

目的 建立下颌第一磨牙分根术后单冠和联冠修复的三维有限元模型,为冠修复的生物力学分析奠定基础。方法通过CBCT扫描获取断层图像,利用Mimics软件读取图像并进行初步处理, Geomagic软件精修,造型软件UG装配各模块及有限元软件Ansys划分网格。结果 建立下颌第一磨牙、分根术后联冠与单冠修复下颌第一磨牙以及牙周支持组织的三维有限元模型。结论 利用CBCT扫描结合逆向工程软件Mimics、Geomagic,造型软件UG,有限元软件Ansys能够快捷有效的建立三维有限元模型。     

上颌第一磨牙根管预备后的有限元模型的建立和受力分析

目的：采用有限元方法建立上颌磨牙根管预备后的三维有限元模型并进行受力分析。方法：采用Micro-CT扫描,应用Mimics 8.1、Geomagic studio 8、Unigraphics NX及Ansys9.0软件分别得到根管预备后上颌第一磨牙三维外形、实体模型和有限元模型,并对建立的模型进行了可靠性验证。结果：重建的三维有限元模型与实体模型具有高度的几何及力学相似性,网格质量较好。结论：将Micro-CT扫描技术、数字图像处理技术与有限元方法结合起来,建立了有效的根管预备后上颌第一磨牙三维有限元模型,为口腔生物力学提供了研究手段。     

运用Micro-CT技术建立上颌第一磨牙根管系统的有限元模型

目的：采用有限元的方法建立上颌磨牙根管系统的三维有限元模型。方法：采用Micro-CT扫描,应用Mimics8.1、Geomagic studio8、Unigraphics NX及Ansys9.0等逆向工程软件分别得到上颌第一磨牙根管系统三维外形、实体模型和有限元模型。结果：重建了根管系统的三维有限元模型,网格质量好,具有高度的精确度,并由此证实模型的可行性。结论：将Micro-CT扫描技术、数字图像处理技术与有限元方法结合起来,建立出高精度的上颌第一磨牙根管系统的三维有限元模型,为口腔生物力学提供了研究手段。     

下颌前牙金属烤瓷桥三维有限元模型的建立

目的：建立下颌前牙金属烤瓷桥的三维有限元模型，为其生物力学特性的研究提供基础。方法：采用螺旋CT扫描，应用Mimics8．1、Geomagic studio8及Ansys10．0软件分别得到下颌前牙金属烤瓷桥三维外形、实体模型和有限元模型，并对建立的模型进行了可靠性验证。结果：重建的三维有限元模型与实体模型具有高度的几何相似、力学相似性，网格质量较好，并由此证实模型的可行性。结论：将CT扫描技术、数字图像处理技术与有限元方法结合起来，建立出有效的下颌前牙金属烤瓷桥三维有限元模型，为口腔生物力学提供了研究手段。     

下颌第一磨牙平台转移种植体三维有限元模型的建立

目的 构建下颌第一磨牙平台转移种植体的三维有限元模型.方法 选择健康成年男性下颌骨1例进行螺旋CT扫描,将得到的DICOM数据导入Mimics 10.01软件中,建立下颌骨及牙齿的三维几何模型,并用Geomagic studio12软件进行曲面优化;利用UG NX6.0软件建立平台转移种植系统(韩国DIO种植体系统)的三维几何模型;最后将各部分模型导入Hypermesh10.0软件中进行装配组合、网格划分以及材料属性赋值.结果 成功建立了下颌第一磨牙平台转移种植体的三维有限元模型,该模型与实际模型有高度的几何相似性,其网格质量较高、力学性能好.结论 结合CT扫描技术和多种有限元建模软件能够快速、精确地建立下颌第一磨牙平台转移种植体的三维有限元模型,为后续平台转移种植体进行有效的生物力学研究提供基础.     

建立下颌第一二磨牙缺失三基牙双端固定桥修复三维有限元模型

目的:建立下颌第一磨牙和第二磨牙缺失三基牙双端固定桥的三维有限元模型,为其力学分析提供数字模型。方法:采用螺旋CT扫描获得断层图像,用Mimics软件进行三维重建,导入Ansys软件中建立下颌第一磨牙和第二磨牙缺失三基牙双端固定桥的三维有限元模型。结果:建立的有限元模型包括牙齿、修复体、牙周膜和牙槽骨,共4260835个单元和739986个节点。结论:该模型有较好的力学和几何学相似性,可用来进行固定桥修复的生物力学研究。     

上颌快速扩弓的颅面复合体三维有限元模型的建立

目的建立上颌快速扩弓的颅面复合体三维有限元模型。方法利用螺旋CT扫描获取颅面复合体二维图像原始DICOM数据,结合Mimics10.0、ProE Wildfire 4.0、MSC.Marc.mentat 2005 R3和Geomagic studio10.0软件,建立包含上颌第一前磨牙、第一磨牙及其牙周膜、带环的颅面复合体三维有限元模型。结果所建三维有限元模型单元数达到522 800,具有良好的几何和生物相似性,可以导入到CAD软件中进行处理。结论应用螺旋CT结合Mimics10.0、MSC.Marc.mentat 2005 R3和Geomagic Studio10.0软件建立颅面复合体三维有限元模型的方法是可行和有效的。     

Evidence of the validity of a model of determinants of quality of restorative dental care

A model describing the relationship between self-reported quality of restorative dentistry and dentist characteristics for 119 Montana general dentists is presented. The best predictors formed a significant model explaining 22% of the variance of the quality measure. Results are contrasted with a previous estimation of the model for 102 Washington general practitioners. Evidence for the external validity of the model is presented.     

Experimental evidence of formation of imines in the course of reduction of hydrazones

The reduction of hydrazones is generally suggested to proceed through a reductive cleavage of the nitrogen–nitrogen bond followed by a reduction of the carbon–nitrogen bond. This sequence of reduction processes is here supported for fluorenone (V) and benzophenone (VI) hydrazones as well as by a comparison of the reduction of fluorenone and benzophenone hydrazonium ions (I,III) with corresponding imines (II,IV). Another proof of the presence of imines as intermediates is the splitting of four-electron waves of hydrazones V and VI and hydrazonium ions I and VIII into two waves at pH < 2. This has been interpreted as due to differences in slopes dE_1/2/dpH and pK_a-values of protonated hydrazine derivatives on one side and corresponding imines on the other. In this pH-range imines formed in reductions of VI and VIII are reduced in a single two-electron wave, those of I and V in two one-electron steps. Fluorenone imine (II) is sufficiently stable to allow recording of time-independent current–voltage curves between pH 6 and 11. In this pH-range the imine (II) is reduced in two one-electron steps. Benzophenone imine (IV) has been found stable between pH 4.6 and 12. At pH 4.6–8 the reduction of the imine IV takes place in a single two-electron step, at pH 8–12 in two one-electron steps. Final proof of the initial cleavage of the N–N bond is presented by comparison with the reduction of nitrones.     

不同剂型玻璃离子水门汀溶解性比较研究

目的:研究、比较不同剂型玻璃离子水门汀的溶解性和表面微观形态改变,为临床使用提供依据.方法:将3M树脂加强型玻璃离子水门汀(水粉剂型)、GC玻璃离子水门汀(水粉剂型)及GC玻璃离子水门汀(双糊剂型)分别在人工唾液中浸泡30 d,冷热循环15000次,烘干测重,比较前后质量变化,计算溶解率,并用扫描电镜观察表面微观改变.结果:不同剂型的玻璃离子水门汀溶解率由高到低分别为3M树脂加强型玻璃离子水门汀(水粉剂型)、GC玻璃离子水门汀(水粉剂型)、GC玻璃离子水门汀(双糊剂型).3种玻璃离子水门汀经浸泡溶解后,SEM扫描表面微观形态可观察到GE玻璃离子水门汀(双糊剂型)表面形态改变较少,其他2组玻璃离子水门汀表面微观改变较多.结论:双糊剂型玻璃离子水门汀理化性能及溶解率均低于传统水粉剂型,是未来临床修复治疗的的良好选择.     

Evaluation of efficacy of chemiluminescence for diagnosis of leukoplakia

ObjectiveLeukoplakia is the most common potentially malignant disorder preceding oral cancer. Chemiluminescence has been developed as an adjunct to conventional examination for the diagnosis of these potentially malignant disorders. This study was conducted to assess the efficacy of chemiluminescence in the diagnosis of leukoplakia and to compare the results with histopathological examination.Study designA total of 50 patients with leukoplakia were included from the outpatients attending the Department of Oral Medicine and Radiology, Dental Hospital, Bengaluru, Karnataka, India. These patients were subjected to conventional oral examination followed by chemiluminescent examination with Vizilite (Zila, Fort Collins, CO, USA) and biopsy for histopathological confirmation.ResultsThe sensitivity, specificity, positive predictive value, and negative predictive value of chemiluminescence were 93.75%, 55.56%, 78.95%, and 83.3%, respectively. The overall accuracy of chemiluminescence was 80%. A statistically significant association was observed between histopathology results and chemiluminescence results.ConclusionAlthough it is an easy, safe, minimal time consuming, and noninvasive technique, it has only adjunctive utility and it does not replace biopsy for the diagnosis of leukoplakia.     

颌骨动静脉畸形的栓塞治疗

目的：总结直接穿刺结合经血管内介入栓塞治疗颌骨动静脉静脉畸形的经验。方法：收治凳骨动静脉畸形患者6例,均进行了介入栓塞治疗。采用的栓塞材料为附凝血棉纤毛的螺圈,聚乙烯醇泡沫微粒和二氰基丙烯酸对丁酯。数字减影颈动脉造影在PHILIPSV300下完成。结果6例颌骨动静脉畸形患者中4,例急性出血得到了快速、有效控制,1例慢性渗血的右下 骨动静脉畸形患者,介入栓塞治疗,拔除松动的右下凳第一磨牙,有效地控制了出血,另1例伴局部软组织搏动性膨隆的上凳骨动静脉畸形患者,介入治疗后膨隆的搏动性得到明显改善,栓塞治疗后分别随访3－24个月,均未发现有口腔内渗血或出血。随访的X线片上,病灶区可见新骨形成。结论：局部穿刺结合经血管内介入栓塞治疗颌骨动静畸形是一种安全、有效的治疗方法。     

Design of clinical trials of traditional therapies of periodontitis

The present paper on the design of clinical trials of periodontal therapy first addresses the issue of the etiology of periodontal disease. It is suggested that most if not all forms of destructive periodontal disease are caused by microorganisms and that there are different forms of disease with different microbial etiologies. The progressive nature of destructive periodontal disease is subsequently discussed and it is emphasized that, in a given patient, periodontal sites which show signs of inflammation and attachment loss may not over a period of several months and years show further sign of attachment loss. The present methods of assessing periodontal disease do not allow us to discriminate between potentially active and inactive sites in untreated patients. The significance and variability of indicators of periodontal disease such as bleeding on probing, probing pocket depth and probing attachment level measurements are discussed. The errors inherent in the various measurements are analyzed and suggestions are presented describing how alterations in any of the above parameters could be identified and presented in a clinical trial. Of concern for the statistical analysis of clinical data of periodontal disease is the definition of the "experimental unit". For a number of years, the "experimental unit" in periodontal trials was the patient. It is clear, however, that different sites within the same individual show different patterns of disease progression and lesion morphology and often respond differently to periodontal therapy. Statistical analyses must consequently be designed which recognize differences in site-to-site infection and lesion morphology within a common host. Until such analyses are available, the investigator should be wary of pooling data within the same individual, since such pooling may obscure meaningful alternatives which may take place in individual periodontal sites. Some goals of periodontal therapy are subsequently identified. 4 goals are discussed more in detail, namely: to establish conditions which will allow the patient to maintain a dentition without further breakdown of the periodontium; to reduce pocket depth to establish an anatomy in the dentogingival region which with proper maintainance care will prevent the re-establishment of the subgingival infection; to gain attachment as a result of treatment; to assess the effect of a certain chemotherapeutic agent on periodontal disease.     

正畸患者切牙影像失真发生情况分析

目的研究正畸患者曲面体层片上的切牙影像失真发生情况，并分析其原因。 方法从中山大学附属口腔医院放射科影像数据库中选取500例正畸患者的曲面体层片和头影测量侧位片，所有曲面体层片均采用咬合杆投照，分别从切牙牙体影像放大、缩小、牙根变短、根尖模糊等评价指标分析上下颌切牙影像失真的发生情况，在头影测量侧位片上测量中切牙根尖-对颌切牙切缘的距离，探讨切牙影像失真发生的原因。采用SPSS 19.0统计软件对所得数据进行统计学检验。 结果500例患者中，切牙牙体影像正常者共417例，切牙牙体影像失真者共83例，影像失真发生率16.6%，其中切牙牙体影像放大17例、牙体影像缩小0例、牙根变短30例，牙根影像变短伴模糊36例。影像失真患者的根尖-切缘距离大于影像正常的患者，差异有统计学意义（F = 5 187.18，P = 0）；影像失真患者的覆盖值大于影像正常的患者，差异有统计学意义（F>477，P = 0）。 结论严重牙颌面畸形如反 、深覆盖是导致曲面体层片的切牙影像失真的主要原因之一。     

正常青年Monson球面半径的测量研究

目的测量正常青年Monson球面半径。方法选择60名(男30名,女30名)正常青年制取全口印模,应用立体摄影成像的原理与方法对Monson球面半径进行测量和统计学处理。结果Monson球面的半径平均为10.173 cm,大于理论值10.160 cm,差异有显著性(P<0.01);男、女性球面半径差异无显著性。结论本实验所得到的数据可作为全口义齿修复中记录颌位关系的一个参量。     

鼻测量法的进展

唇裂术后继发畸形是指唇裂修复术后,仍遗留或继发于手术操作和生长发育变化而表现出来的一类畸形[1]。包括唇畸形、鼻畸形和颌骨畸形。其修复较原发性唇裂修复更复杂,更灵活多变。而导致其修复复杂性的一个重要原因即是局部组织结构复杂变异和缺乏可靠的三维测量手段[2],鼻畸形     

口底癌34例临床分析

目的探讨口底癌的临床特性、治疗方法及预后。方法对我院自1992—2002年住院治疗的34例口底癌患者进行回顾性分析。结果34例口底癌患者中,男28例(82.4%),女6例(17.6%),男女比为4.7∶1,平均发病年龄58岁。发病部位:前口底22例(64.7%),后口底12例(35.3%)。淋巴结转移率41.2%。单纯手术组、化疗加手术组、放疗加手术组、化疗加手术加放疗组的5年生存率分别为45.5%、60.0%、50.0%、62.5%。结论口底癌以中老年患者好发,男性居多。易发生淋巴结转移,综合疗法疗效较好。