锆瓷基底表面形貌对锆瓷饰瓷间结合强度影响的研究

目的：探讨锆瓷基底表面形貌对其与饰瓷结合强度的影响.方法：切削制备1 1mm×10mm×5mm锆瓷烧结瓷块40块,随机均分至4组即对照组（烤瓷面烤瓷前经过常规打磨、喷砂及抛光处理）,垂直组（与对照组不同处在于剪切加载方向与切削瓷面的刀路方向垂直）,平行组（与对照组不同处在于剪切加载方向与切削瓷面的刀路方向一致）,突起组（与对照组不同处在于烤瓷面制备有2个直径2mm,高0.3mm的圆柱状突起）.各组试件烤瓷面涂布粘接瓷,堆积4mm厚饰瓷后烧结.以万能试验机测试饰瓷与锆瓷基底间的剪切强度.结果：对照组、垂直组、平行组、突起组锆瓷与饰瓷间的剪切强度均数与标准差分别为24.1±2.64 MPa、27.9±4.53MPa、27.5±4.79MPa和37.2±7.03MPa,单因素方差分析显示差异有统计学意义,突起组强度显著高于垂直组、平行组（P＜0.05）及对照组（P＜0.01）.结论：锆瓷烤瓷面切削刀路方向对锆瓷与饰瓷间的烧结剪切强度无显著影响;锆瓷烤瓷面制备出适当的突起可显著增强饰瓷抗剥脱的能力.     

喷砂处理对氧化锆陶瓷基底与饰瓷结合强度的影响

目的 探讨喷砂处理对氧化锆陶瓷基底与饰瓷结合强度的影响.方法 选择批号相同未烧结的VITA In-Ceram 2000 YZ氧化锆陶瓷块切割成方块,打磨后分成两组,烧结硬化,实验组进行喷砂处理,对照组不作任何处理,表面烧结VITA VM9饰瓷,扫描电镜观察和平行剪切实验比较两组的差异性.结果 烧结面扫描电镜观察示两组间...     

3种锆瓷表面形貌对氧化锆瓷与饰瓷结合强度的影响

目的探讨计算机辅助设计/计算机辅助制造(CAD/CAM)切削表面形貌对氧化锆瓷与饰瓷结合强度的影响。方法将40个Upcare氧化锆基底材料以CAD/CAM切削烧结瓷块试件,随机等分为4组。其中对照组按常规操作进行打磨、喷砂及抛光等处理。实验组均采用CAD/CAM时预设程序,分别使切削产生的刀路与剪切强度测试加力方向呈垂直(A组)、平行(B组)及突起(C组),并对试件进行喷砂处理。测量并比较各组试件的表面粗糙度和剪切强度。扫描电镜观察断裂界面的情况。结果各组的剪切强度分别为:A组(27.64±4.24)MPa、B组(27.12±5.32)、C组(36.86±7.21)MPa、对照组(24.14±2.74)MPa,其中对照组与A组、B组之间差异均无统计学意义(P>0.05),对照组与C组之间的差异具有统计学意义(P<0.05)。各组的表面粗糙度分别为:A组(5578.34±1165.58)Ra、B组(5227.98±1440.29)Ra、C组(5699.97±1234.28)Ra、对照组(5964.92±1013.834)Ra,各组之间的差异无统计学意义(P>0.05)。Pearson相关性分析显示,试件表面粗糙度与剪切强度之间无线性相关关系(P>0.05)。扫描电镜观察显示C组较其他组氧化锆瓷与饰瓷结合更致密,未见气泡,无孔隙存在。结论固位突起的锆瓷表面形貌可有效增加锆瓷与饰瓷间的结合强度,而表面粗糙度对界面的结合强度无明显影响。     

高半透性氧化锆基底的不同处理对锆-瓷结合强度的影响

目的探讨高半透性氧化锆的不同表面处理对其与饰瓷界面结合强度的影响,为临床提高氧化锆全瓷修复体的锆-瓷结合强度提供研究基础。方法制作30个高10 mm、直径为10 mm的圆柱形KATANA氧化锆试件,分为四组,每组7个:(1)C组(对照组)打磨后直接堆塑饰瓷粉;(2)S组(喷砂组)打磨后喷砂,堆塑饰瓷粉;(3)B组(结合层组)打磨后先烧结一薄层饰瓷粉,再堆塑饰瓷粉;(4)SB组(喷砂+结合层组)打磨后喷砂,烧结一薄层饰瓷粉,再堆塑饰瓷粉;剩余2个试件观察喷砂前后氧化锆的表面形貌。烧结后包埋成剪切试件,采用剪切强度测试法测定各组的剪切强度值,并进行统计学分析。体视显微镜观察瓷层断裂模式。结果C组剪切强度值为(21.86±3.18)MPa;S组为(22.12±3.06)MPa;B组为(19.19±1.46)MPa;SB组为(27.76±1.95)MPa。C组、S组和B组剪切强度两两比较无显著差异,各组与SB组比较剪切强度值差异有统计学意义(P<0.05)。体视显微镜下观察各组饰瓷断裂模式以混合破坏为主。结论单独喷砂处理不能显著增加锆-瓷结合强度,薄涂饰瓷作为结合层对锆-瓷结合强度没有明显影响,喷砂与结合层结合可显著提高锆-瓷结合强度。     

氧化锆表面制备衬里层对锆-瓷结合力影响的初步研究

目的:初步探讨氧化锆陶瓷表面制备衬里层对其锆-瓷结合力的影响.材料方法:16片氧化锆陶瓷试件致密烧结后随机分为两组,标记为C组和L组,C组空白对照、L组预先烧结一薄层衬里层即Vita VM9Effect Bonder(Eb).全部试件表面烧结饰瓷后应用平行剪切实验进行锆-瓷结合强度测试,并通过扫描电镜观察破坏界面的表面形貌.结果:L组的平行剪切强度为26.96±2.78MPa、C组剪切强度为22.15±2.29MPa,两组锆-瓷界面破坏方式均以粘接破坏为主.在氧化锆表面制备衬里层后其剪切强度显著提高,二者差异有统计学意义(P＜0.05).结论:在致密烧结后氧化锆表面预先烧结一薄层Vita VM9 Effect Bonder(Eb)来制备衬里层,能一定程度提高锆瓷结合强度.     

不同表面处理方式对Kavo氧化锆基底与饰瓷结合强度的影响

目的:研究不同表面处理方法对Kavo氧化锆底层材料与Noritake Cerabien饰面瓷结合强度的影响。方法:选择Kavo氧化锆陶瓷作为底层材料,随机分为4组,每组8个试件。A组为染色液浸泡着色+表面不喷砂;B组为染色液浸泡着色+表面喷砂;C组为不浸泡染色液+表面不喷砂;D组为不浸泡染色液+表面喷砂。4组底层材料采用粉浆涂塑法烧结饰面瓷后,使用材料试验机测试其剪切强度,采用SPSS10.0软件包对数据进行统计学分析。结果:采用喷砂处理的2组(B组和D组)材料,其剪切强度均高于未喷砂的2组(A组和C组),差异具有显著性(P<0.01);浸泡染色处理对剪切强度的无显著影响,A组与C组、B组与D组之间的差异无显著性(P>0.05)。结论:对Kavo氧化锆基底表面进行喷砂处理,可以提高基底冠与饰面瓷的结合强度;而浸泡染色则对两者结合力的强度无显著影响。     

四种饰瓷与Vitablocs MarkⅡ瓷结合强度的比较

目的:测试并比较4种饰瓷与Vitablocs MarkⅡ瓷的结合强度,为临床使用提供依据.方法:将成品Vitablocs Mark Ⅱ瓷块切割成12 min×6 mm×2 mm的试件24个,随机分为4组,分别在其表面烧结E-maxceram、Vintage ZR、Cercon ceram kiss及VM9饰瓷,剪切实验测试各组结合强度,电镜观察确定试件的断裂方式.结果:E-max ceram、Vintage ZR、Cercon ceram kiss、VM9 4组的抗剪强度值分别为(41.07±12.42)MPa、(43.44±11.32)MPa、(35.81±8.69)MPa、(37.35±9.71)MPa;试件的断裂67%以上均发生于基底瓷;经单因素方差分析得出F=0.641,P>0.05,表明4组抗剪强度无显著性差异;单样本t检验结果显示,4组饰瓷与Vitablocs Mark Ⅱ瓷的结合强度值均高于ISO9693:1999规定的强度值(25 MPa).结论:4种饰瓷与Vi-tablocs MarkⅡ瓷的结合强度均能满足临床需要,可作为Vitablocs Mark Ⅱ的个性化饰瓷使用.     

核瓷表面处理对二硅酸锂、氧化锆双层瓷失效行为的影响

目的 探讨核瓷表面处理对二硅酸锂、氧化锆双层瓷失效行为的影响,为其临床加工制作提供依据.方法 二硅酸锂和氧化锆核瓷试件均按随机数字表分为4个组(每组样本量为12),碳化硅砂纸逐级打磨至1 000目(A组)、600目(B组)、320目(C组)或行喷砂后不打磨(D组)处理并测定表面粗糙度.两种核瓷烧结饰瓷后测定断裂强度并计算韦布尔模数(m值),分析失效模式.结果 对于二硅酸锂双层瓷,4组断裂强度差异无统计学意义(F=0.406,P=0.750),4组m值95％置信区间重叠,各组均以饰瓷内聚失效为主.对于氧化锆双层瓷,D组断裂强度[(640±95) MPa]显著高于其他3组[A、B、C组分别为(541±75)、(533±73)、(529±78) MPa] (P＜0.05),4组m值95％置信区间重叠,各组均以饰瓷剥脱失效为主.结论 二硅酸锂核瓷的表面处理对双层瓷结构失效行为无显著影响;喷砂有助于提高氧化锆双层瓷结构的断裂强度,减少界面处饰-核瓷的分层.     

粘接瓷对纯钛与低熔瓷粉结合强度的影响

目的 通过研究粘接瓷对纯钛与低熔瓷粉结合强度的影响,探讨粘接瓷影响钛-瓷结合的作用机制.方法 根据ISO 9693中三点弯曲法制作钛试件40个,分为4组,每组10个;分别进行砂纸打磨(B组)、打磨+喷砂(S组)、打磨+表而烧结GC Initial Ti粘接瓷(BG组)和打磨+喷砂+表面烧结粘接瓷(SG组)处理;于4组试件中部烧结低熔瓷粉(Vita Titankeramik).测试钛-瓷结合强度,体视显微镜观察钛-瓷断裂模式,并对钛试件剥脱面进行扫描电镜观察.结果 表面烧结粘接瓷的BG组和SG组的钛-瓷结合强度分别为(32.72±4.46)和(34.25±6.52)MPa,均达到ISO9693的临床标准(＞25 MPa),并显著高于不应用粘接瓷的B组和S组[分别为(20.70±3.15)和(23.92±5.02)MPa,P＜0.05].结论 粘接瓷能有效提高钛-瓷结合强度.     

3种粘接瓷对钛瓷结合强度的影响

目的:观察3 种粘接瓷对钛瓷结合强度的影响,分析粘接瓷作用机制.方法:将纯钛试件随机分为3 组分别采用纯钛专用瓷Super Ti22,Duceratin,Titankeramik进行烧结,每种瓷粉又分为涂布粘接瓷组和未涂布粘接瓷组,共6 组.根据ISO9693标准,运用三点弯曲方法测试各组钛瓷结合强度.对钛瓷结合界面进行扫描电镜观察和能谱分析.结果:Super Ti22涂布粘接瓷组结合强度为(35.84±2.17) MPa,Duceratin涂布粘接瓷组结合强度为(35.45±2.37) MPa,均显著大于各自未涂布组(P<0.05);Titankeramik涂布粘接瓷组结合强度为(31.73±1.66) MPa, 略大于其未涂布组(29.86±2.48) MPa,但差异无显著性(P>0.05).电镜观察Super Ti22和Duceratin涂布粘接瓷组钛瓷结合界面结合紧密,未见明显孔隙出现;其余各组均可见明显孔隙.结论:粘接瓷的应用有利于钛瓷结合强度的提高.     

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.     

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.     

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.     

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.     

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.     

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。     

Electrodeposition of bilayers of dithiols

We report an electrochemical method to form a bilayer of dithiol. The cyclic voltammogram of the oxidative deposition of an aromatic dithiol on gold from an alkaline aqueous solution reveals two current peaks separated by more than 400 mV. The integrated charge of the oxidative current peak (B) at the most positive potential is twice that of the other oxidative current peak (A). These two oxidative current peaks were characterized by differential capacitance and electrochemical quartz crystal microbalance (EQCM) measurements. A decrease of the capacity by a factor of two, and an increase of the EQCM frequency change by a factor of two were observed when the potential was scanned from a value where only the first oxidative peak (A) is obtained, to a potential where both oxidative current peaks (A and B) are obtained. Infrared spectra show that the aromatic dithiols adsorb vertically at potentials corresponding to the current peak A and they become tilted for potentials corresponding to the current peak B. The simple relationships between the properties of the two oxidative current peaks are found to be compatible with a step-wise oxidative deposition of a bilayer of dithiol.     

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。     

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。