SLM钴铬合金在含氟人工唾液中的电化学耐腐蚀性能研究

目的通过电化学阻抗谱方法研究选择性激光熔覆（Selective laser melting,SLM）技术制作的钴铬合金在含氟人工唾液中的耐腐蚀性能。方法运用SLM技术和传统铸造（CAST）技术,使用相同成分的钴铬合金,分别制作40个直径10mm×3mm厚度的圆柱形试件。在p H值为2.5和5.0,含氟浓度为0.00%、0.05%、0.1%和0.2%的人工唾液中,利用电化学阻抗谱检测2种加工方法制作的钴铬合金的耐腐蚀性能。结果当p H=5.0时,Na F 0.1%环境下SLM组和CAST组Rp值分别为3.49±0.44和1.59±0.88;Na F 0.2%环境下SLM组和CAST组Rp值分别为5.30±3.29和1.71±1.10。当p H=2.5时,Na F0.00%环境下SLM组和CAST组Rp值分别为6.40±0.26和2.05±0.35;Na F0.05%环境下SLM组和CAST组Rp值分别为5.67±0.25和1.15±0.83;Na F0.1%环境下SLM组和CAST组Rp值分别为4.74±0.50和0.24±0.10;Na F0.2%环境下SLM组和CAST组Rp值分别为4.76±0.97和0.30±0.09。在以上各实验条件下,SLM组和CAST组之间的表面氧化层电阻Rp值差异均具有统计学意义（P〈0.05）。结论 SLM技术制作的钴铬合金耐腐蚀性能优于铸造组。     

牙科铸造钴铬合金氩弧焊接后的力学性能分析

目的 研究牙科铸造用高熔钴铬合金氩弧焊接后的力学性能,为临床口腔修复的应用提供实验依据。方法 用直径2mm蜡线,常规包埋,牙科铸造钴铬合金铸造长约5cm的金属段20根,随机分成2组,每组10根。A组不做处理;B组从中间切断,用同材料做焊丝,氩弧焊接。然后分别测试其维氏硬度（HV10）、拉断力、屈服强度和延伸率等力学性能。结果 焊接后的牙科铸造钴铬合金的维氏硬度、拉断力、屈服强度和延伸率等,几乎与未焊合金相同,经χ²计算,P>0.05。结论 氩弧焊接牙科高熔铸造钴铬合金的力学性能良好,可考虑用于牙科铸造支架断裂焊接,在金属支架上增加人工牙、高熔铸件缺陷修补以及圆锥形套筒冠外冠与支架的焊接等方面。     

选择性激光熔积钴铬合金在含氟口腔环境中电化学腐蚀性能的研究

目的 考量采用区域选择性激光熔化(SLM)技术制作的钴铬合金口腔修复材料在含氟口腔环境中的耐腐蚀性能.方法 选取具有相同成分的Co-Cr合金金属粉末和金属块,分别运用SLM技术(SLM组)和传统的铸造工艺(对照组)各制作5个试件(圆柱形,直径10 mm,厚度3 mm),在模拟含氟口腔环境下(pH值6.8,NaF 0.1％),采用电化学交流阻抗谱(EIS)的方法,分析两组试件的耐腐蚀性能.结果 对照组和SLM组的表面氧化层电阻(Rp)值分别为3.28±1.53和6.69±3.30,组间比较差异无统计学意义(P＞0.05).结论 在模拟含氟口腔环境中,SLM技术制作的钴铬合金与传统铸造方式加工的钴铬合金具有相似的耐腐蚀性能,能够满足临床要求.     

加工参数设置对选择性激光熔积钴铬合金硬度的影响

目的 观测几种加工参数设置对选择性激光熔积(SLM)钴铬合金的表面形貌和表面维氏硬度的影响。方法 使用正交实验设计9组不同的加工参数,即激光功率为2500W、2750W、3000W,扫描速度为5mm/s、10mm/s、15mm/s,送粉速率为3r/min、4.5r/min、6r/min,制备9组选择性激光熔积钴铬合金试件,每组5个(直径10mm,厚度3mm),经抛光处理后分别进行扫描电镜观察和表面维氏硬度测试,采用SPSS16.0软件包进行数据处理。结果 9组不同加工参数制备下SLM钴铬合金试件的扫描电镜图像均呈现均匀而规则的细胞样结构;其平均表面维氏硬度均在345HV以上。结论 当加工参数设置在激光功率2500~3000W,扫描速度5~15mm/s,送粉速率3~6r/min范围内时, SLM钴铬合金具有较为理想的表面形貌和表面硬度,能适合临床应用需求。     

氟离子对两种不同工艺制作的钴铬合金耐腐蚀性能的影响

目的 在模拟口腔环境下研究氟离子对采用选择性激光熔覆（SLM）技术和传统铸造技术两种工艺制作的钴铬合金耐腐蚀性的影响。方法 选择具有相同材料成分的钴铬合金金属粉末和金属块,分别采用SLM（SLM组）和铸造技术（Cast组）各制作15个试件,置于含不同氟离子质量分数（0、0.05%、0.20%）的酸性人工唾液（pH值为5.0）中浸泡24 h进行电化学试验,采用动电位极化曲线法测试合金的自腐蚀电位Ecorr、自腐蚀电流密度Icorr和极化电阻Rp,同时结合扫描电子显微镜（SEM）观察,分析两组试件的耐腐蚀性能。结果 铸造工艺制作的钴铬合金在酸性人工唾液中的Ecorr随着氟离子质量分数的升高而减小。当氟离子质量分数为0.20%时,两种工艺制作的钴铬合金的Ecorr、Icorr、Rp均有明显改变（P<0.05）,SEM结果也显示合金表面均出现腐蚀现象。当氟离子质量分数为0.20%时,Cast组钴铬合金的Icorr高于SLM组,而Ecorr和Rp低于SLM组（P<0.05）。结论 氟离子可降低两种工艺制作的钴铬合金的耐腐蚀性,在氟离子质量分数较高（0.20%）时,SLM技术制作的钴铬合金的耐腐蚀性优于铸造工艺制作的钴铬合金。     

制作方法对钴铬合金金瓷结合性能的影响

目的 比较铸造钴铬合金与选区激光熔化（SLM）钴铬合金金瓷结合强度的差异。方法 用铸造法和SLM技术制作钴铬合金试件各10个,在中间1/3区域熔附瓷粉,采用剪切力试验测试金瓷结合强度并观察断裂类型。采用SPSS 13.0软件中的t检验对结果进行统计学分析。结果铸造组、SLM组剪切力分别为（33.11±4.98）、（30.94±5.98） MPa,二者间差异无统计学意义（P>0.05）。样本的断裂类型为复合断裂。结论 SLM钴铬合金修复体精密度较高,其金瓷结合强度与铸造钴铬合金相近。     

不同工艺制作钴铬合金基底冠适合性的实验研究

目的：：对比3种不同工艺制作的钴铬合金基底冠适合性。方法：制作18个树脂代型,随机分为A、B、C 3组,分别采用传统铸造技术、CAD/CAM技术、直接金属激光烧结技术制作钴铬合金基底冠各6个。将基底冠粘固于对应的树脂代型上并包埋片切。测量钴铬合金基底冠边缘及内部粘固剂的厚度。对实验数据进行统计学分析。结果：3组试件边缘间隙分别为A组(66.08±3.90)μm, B组(29.21±3.31)μm,C组(24.96±2.99)μm(P<0.01);3组试件内部间隙分别为A组(114.10±27.66)μm,B组(73.69±31.31)μm,C组(79.89±33.63)μm(A组与 B或 C组比较, P<0.01, B组与 C组比较, P>0.05)。结论：直接金属激光烧结技术制作的钴铬合金基底冠具有更好的边缘适合性;CAD/CAM技术及直接金属激光烧结技术制作的钴铬合金基底冠具有良好的内部适合性。3种技术制作的基底冠边缘及内部适合性均在临床允许范围内。     

3D打印钴铬合金和铸造钴铬合金的理化性能和生物相容性的比较

目的 比较3D打印和传统铸造钴铬合金的理化性能及生物学影响.方法 实验组和对照组分别用3D打印技术中的选择性激光熔融(SLM)和传统铸造技术,制作钴铬合金试件各10个,采用洛氏硬度计HR-150A和金相显微镜对两组分别进行洛氏硬度测定和金相观察,并在自腐蚀电位下对金属试件进行极化曲线测定.在无菌环境下制备试件的浸提液,...     

选择性激光熔积技术制作钴铬合金基底冠的边缘密合度研究

目的 研究选择性激光熔积(selective laser melting,SLM)制作的钴铬合金基底冠的边缘密合度.方法 分别采用SLM技术和传统铸造法,各制作20个钴铬合金基底冠,用硅橡胶复制其边缘间隙宽度,在体式显微镜下观察其边缘密合度并加以比较.结果 SLM技术制作的钴铬合金基底冠的边缘间隙宽度平均值为49.6μm,显著小于铸造组的90.8μm (P＜0.05);结论 SLM技术制作的钴铬合金基底冠的边缘密合度优于传统铸造组,具有临床应用前景.     

激光熔覆技术烤瓷冠边缘适合性的实验研究

目的通过对传统失蜡铸造和激光熔覆两种技术制作的钴铬合金烤瓷冠以及浅凹型和直角肩台型两种牙体预备形态制作的激光熔覆技术烤瓷冠的边缘适合性进行比较,以探讨激光熔覆技术烤瓷冠的边缘适合性。方法选取上颌前磨牙30颗,随机分成3组,每组10颗,按烤瓷冠要求常规牙体预备。A、B组用浅凹型边缘,C组用直角肩台。A组为传统失蜡铸造钴铬合金烤瓷冠,B、C组为BEGO德贝尔激光熔覆技术钴铬合金烤瓷冠;3组全用聚羧酸锌水门汀粘结剂粘固,经环氧树脂包埋后,沿颊腭向中间剖开烤瓷冠和牙体,用金相显微镜及电子显微镜观察和测量各组的颊、腭侧冠边缘间隙的大小。结果 A组烤瓷冠的水平边缘间隙为79.61±11.45μm,垂直边缘间隙94.90±7.09μm,绝对边缘间隙114.94±8.60μm;B组激光熔覆技术钴铬合金烤瓷冠的水平边缘间隙67.76±9.20μm,垂直边缘间隙82.54±9.92μm,绝对边缘间隙105.35±9.84μm;C组激光熔覆技术钴铬合金烤瓷冠的水平边缘间隙72.72±9.03μm,垂直边缘间隙88.11±9.53μm,绝对边缘间隙102.48±9.15μm。B组与A组比较差异有统计学意义（P〈0.05）;B、C组之间的差异无统计学意义（P〉0.05）。结论激光熔覆技术钴铬合金烤瓷冠边缘水平边缘间隙、垂直边缘间隙、绝对边缘间隙均小于120μm,均达到临床可接受的范围内。激光熔覆技术钴铬合金烤瓷冠比传统失蜡铸造钴铬合金烤瓷冠边缘适合性更好。牙体预备采用浅凹型（B组）和直角肩台型（C组）制作的激光熔覆技术钴铬合金烤瓷冠边缘适合性无明显差异。     

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。