臭氧老化作用对SY-28硅橡胶机械性能的影响

目的：评估臭氧老化作用对SY-28硅橡胶机械性能的影响。方法：按照国家标准，对SY-28和MDx-4-4210硅橡胶臭氧老化前后的扯断强度、扯断伸长率、永久变形率（3min后）、撕裂强度、硬度（邵氏A）进行测试，并对其老化性能加以评价。结果：经臭氧老化作用处理，SY-28硅橡胶的永久变形率和邵氏硬度优于MDX-4-4210硅橡胶：扯断强度、扯断伸长率和撕裂强度与MDX-4-4210硅橡胶相似。结论：SY-28硅橡胶机械性能优良，同时具有良好的耐臭氧老化性能。     

三种硅橡胶的机械性能实验

目的 :对比SY 2和MDX 4 42 10、SY 1硅橡胶的机械性能。方法 :按国家标准要求对SY 2和MDX 4 42 10、SY 1硅橡胶扯断强度、扯断伸长率、永久变形率 ( 3min)、撕裂强度、硬度 (邵氏A)进行测试 ,对其机械性能加以评价 ,并进行统计学分析。结果 :3种硅橡胶的扯断强度、永久变形率无显著差异(P >0 .0 5 ) ;SY 2的扯断伸长率、邵氏硬度均优于MDX 4 42 10硅橡胶 (P <0 .0 5 ) ;SY 1和SY 2的撕裂强度优于MDX 4 42 10硅橡胶 (P <0 .0 5 )。结论 :SY 2硅橡胶可以满足颌面软组织缺损赝复材料的机械性能要求 ,并在扯断伸长率、撕裂强度、邵氏硬度指标方面优于MDX 4 42 10。     

臭氧老化作用对SY-20硅橡胶机械性能的影响

目的:评估臭氧老化作用对SY-20硅橡胶机械性能的影响.方法:按照国家标准要求,对SY-20和MDX-4-4210硅橡胶臭氧老化前后的扯断强度、扯断伸长率、永久变形率(3 min后)、撕裂强度、硬度(邵氏A)进行测试,对其老化性能加以评价,并进行统计学分析.结果:臭氧老化百分率结果显示,SY-20硅橡胶的扯断强度、永久变形率和邵氏硬度优于MDX-4-4210硅橡胶;扯断伸长率和撕裂强度与之相似.结论:SY-20硅橡胶机械性能优良,同时具有良好的耐臭氧老化性能.     

SY-1和MDX4-4210硅橡胶拉伸性能、邵氏硬度的测定

目的 :测定SY 1和MDX4 42 10硅橡胶的拉伸性能和邵氏硬度。方法 :在相同条件下对 2种硅橡胶进行了扯断强度、扯断伸长率及永久变形率 ( 3min后 )、撕裂强度、邵氏硬度测定 ,并对结果进行t检验分析。结果 :2种硅橡胶材料的扯断强度、永久变形率无显著差异 (P >0 .0 5 ) ;SY 1硅橡胶的扯断伸长率、邵氏硬度优于MDX4 42 10硅橡胶 (P <0 .0 1)。结论 :SY 1在拉伸性能和邵氏硬度上具有与MDX4 42 10同样的或更为良好的性能指标 ,可以满足作为面部软组织缺损赝复材料的要求。     

三种颌面赝复硅橡胶耐热氧老化性能的对比测定

目的：对比研究ZY-1、SY-1及A-2186三种赝复硅橡胶热氧老化前后的机械性能,评价ZY-1硅橡胶的耐热氧老化性能。方法：在相同条件下分别对三种硅橡胶材料老化前后的机械性能进行测定,并对结果进行统计学分析。结果：ZY-1、A-2186和SY-1硅橡胶在热氧老化后,拉伸强度、扯断伸长率、撕裂强度以及硬度均呈现下降趋势,ZY-1热氧老化后性能变化百分率和A-2186无明显差异,ZY-1、A-2186硅橡胶的扯断伸长率、永久变形率（3 min后）、撕裂强度的老化百分变化率明显小于SY-1硅橡胶。结论：ZY-1加成型赝复硅橡胶具有良好的耐热氧老化能力。     

热氧老化作用对SY-28、SY-20和MDX4-4210硅橡胶机械性能的影响

目的:评估热氧老化作用对SY-28、SY-20和MDX4-4210硅橡胶机械性能的影响。方法:按照国家标准,对SY-28、SY-20和MDX4-4210硅橡胶热氧老化前后的扯断强度、扯断伸长率、永久变形率(3min)、撕裂强度、硬度(邵氏A)进行测试,对其老化性能加以评价,并进行统计学分析。结果:SY-28硅橡胶的扯断伸长率、永久变形率(3min)、邵氏硬度优于MDX4-4210硅橡胶;扯断强度、撕裂强度与之相似。SY-20硅橡胶的扯断强度、永久变形率(3min)、邵氏硬度优于MDX4-4210硅橡胶;扯断伸长率与之相似,撕裂强度差于MDX4-4210硅橡胶。结论:SY-28和SY-20硅橡胶机械性能优良,同时具有良好的抗热氧老化性能,可以满足作为颌面软组织缺损赝复材料的要求。     

不同固化方式对硅橡胶机械性能的影响

目的：考察不同的固化方式对SY—1硅橡胶的机械性能的影响。方法：采用常温24h，升温70℃ 1．5h，微波700W 3min 3种固化方式制备硅橡胶试件，按国家标准要求进行扯断强度、扯断伸长率、永久变形率（3min）、撕裂强度、硬度（邵氏A）测试。结果：3种固化方式下，各组间硅橡胶的5项机械性能都没有统计学差异俨〉0．05）。结论：在赝复体的制作中，可以考虑采用升温或微波固化的方式，加快赝复体的制作周期，为临床患者的特殊需要提供选择。     

SY-1和MDX4-4210硅橡胶热老化性能试验

目的 对比SY-1和MDX4-4210硅橡胶的热老化性能。方法 在相同条件下对两种硅橡胶材料进行了热老化试验,对其老化性能加以评价。结果 热老化后,SY-1硅橡胶的扯断强度性能变化百分比与MDX4-4210硅橡胶无显著差异(P>0.05);SY-1硅橡胶的邵氏硬度、扯断伸长率、永久变形率(3min后)、撕裂强度的性能变化百分比优于MDX4-4210硅橡胶(P<0.01)。结论 SY-1硅橡胶热老化性能略优于MDX4-4210硅橡胶,热老化性能可以满足作为面部软组织缺损赝复材料的要求。     

纳米CeO2对SY-1硅橡胶臭氧老化性能影响的初步研究

目的初步研究纳米CeO2(纳米二氧化铈)对SY-1硅橡胶臭氧老化性能的影响及纳米CeO2的最适加入量,并探讨其机制。方法将纳米CeO2分别按ω(CeO2)=0.00%、0.50%、1.00%、1.50%、2.00%、2.50%加入SY-1硅橡胶中,在相同条件下,按国家标准要求,对6组硅橡胶进行臭氧老化实验,并评价其老化性能。结果按照纳米CeO2与SY-1硅橡胶胶料质量分数为1.50%的比率,在SY-1硅橡胶中加入纳米CeO2,臭氧老化后,SY-1硅橡胶的断后伸长率、永久变形率及撕裂强度的百分变化率与对照组存在显著差异,邵氏硬度与抗张强度的百分变化率与对照组无显著差异。结论纳米CeO2能够显著提高SY-1硅橡胶在断后伸长率、永久变形率及撕裂强度3个方面的耐臭氧老化性能。     

不同SY-1硅橡胶被覆厚度对三明治式硅橡胶结构拉伸性能的影响

目的：比较不同SY-1硅橡胶被覆厚度的三明治硅橡胶结构的拉伸性能。方法：在相同条件下对表面被覆SY-1厚度分别为0mm,1mm,1.5mm,2mm的三明治式硅橡胶试件进行拉伸强度、扯断伸长率的测定,并对结果进行统计学分析。结果：被覆1mm SY-1硅橡胶的试件与单纯的GP-084泡沫硅橡胶试件拉伸强度及扯断伸长率的差异有显著性（p〈0.05）;被覆1.5mm SY-1试件与被覆1mm的SY-1试件的拉伸强度的差异无显著性（p〉0.05）,但是扯断伸长率的差异具有显著性（p〈0.05）;被覆2mmSY-1试件与被覆1mm SY-1试件的拉伸强度及扯断伸长率的差异有显著性（p〈0.05）。结论：由SY-1硅橡胶和GP-084泡沫硅橡胶组成的三明治式结构可以明显增加泡沫硅橡胶较低的拉伸强度和扯断伸长率。     

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.     

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.     

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。     

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