不同材料桩核对IPS-Empress2全瓷冠颜色的影响

目的研究不同材料桩核对IPS- Empress 2全瓷冠不同部位颜色的影响规律。方法制作全瓷桩核、氧化锆桩树脂核、金合金桩核、镀金镍铬合金桩核和镍铬合金桩核各3个,用PR- 650光谱扫描色度仪测量不同桩核背景下IPS- Empress 2全瓷冠唇面切1/3、中1/3和颈1/3的L*、a*、b*颜色参数,研究不同材料桩核对全瓷冠颜色的影响。结果全瓷桩核和镀金镍铬合金桩核背景的L*、a*、b*值均高于其他桩核背景,氧化锆桩树脂核背景的L*、a*值较高,b*值较低,金合金桩核背景的L*、a*、b*值较低,镍铬合金背景的L*、a*、b*值最低。结论应用IPS- Empress2全瓷冠修复根管治疗后的上前牙时,推荐使用全瓷桩核和氧化锆桩树脂核,也可以考虑使用镀金镍铬合金桩核或金合金桩核,不推荐使用镍铬合金桩核。     

粘接材料对渗透铝瓷全瓷修复体颜色的影响

目的 探讨不同粘接材料对渗透铝瓷全瓷修复体颜色的影响。方法 制作12个A2色直径12.5 mm、底层厚度0.5 mm的GI－Ⅱ渗透铝瓷试件,在其上烧结A2色1.0 mm厚的 Vitadur α饰面瓷完成渗透铝全瓷试件,并制作12个直径12.5 mm、厚2 mm的铸造Ni-Cr合金背景试件。将全瓷试件和背景试件分别用树脂粘接剂、玻璃离子粘固粉、磷酸锌粘固粉粘接,根据粘接材料的不同分为3组,每组4个。用JY9800型白度色度计测量各组粘接前、后的L*、a*、b*颜色参数。结果 粘接材料对全瓷修复体的最终颜色有一定的影响,其中树脂对修复体的颜色影响最小,磷酸锌粘固粉的影响最大,其粘接前后的色差可肉眼分辨。结论 全瓷修复体的粘接推荐使用树脂粘接剂,以减小粘接材料对全瓷修复体最终颜色的影响。     

背景颜色对3种牙科全瓷底层材料颜色的影响

目的:探讨不同桩核材料背景色对3种全瓷底层材料的颜色影响。方法:采用色差计测量各组试样在贵 金属、镍铬合金、银汞合金和树脂背景上的色度值并计算组间色差值。结果:3种EmpressⅡ铸瓷试样在不同背景之 间的色差值均能够为人眼所识别(ΔE>1.5),而渗透氧化铝和氧化锆陶瓷的组间色差值不能为人眼所识别。结 论:AL1色系渗透氧化铝和EmpressⅡ铸瓷材料受背景色影响较大,应采用适当的遮蔽背景色的方法。AL2色系选 用树脂材料作为核桩材料时不须遮蔽背景色。而AL3、AL4色系渗透氧化铝和氧化锆材料不受背景色的影响。     

不同桩核材料对四种牙科底层瓷颜色的影响

目的 探讨3种桩核材料对4种牙科底层瓷颜色的影响,以期为修复医师正确选择适宜的修复材料提供参考.方法 制作A2色热压铸二硅酸锂玻璃陶瓷(Empress Ⅱ,A组)、Z2色瓷沉积氧化锆陶瓷(B组)、氧化锆陶瓷(Cercon base color,C组)、氧化锆陶瓷(Cereon base,D组)底层瓷试件各5个,A组试件厚度为0.80 mm,B～D组试件厚度为0.50 mm.采用色差计测量4组底层瓷试件在金铂合金、镍铬合金和复合树脂背景上的色度值,并计算每种底层瓷在不同背景间的色差值(△Eab*).结果 B、C和D组试件在不同背景间的色差均值分别为(0.14±0.08)、(0.90±0.20)和(0.99±0.09),不易为人眼所辨别(△Eab*<1.5),而A组试件在不同背景间的色差均值为(2.83±0.70),能够为人眼所辨别(△Eab*>1.5).结论 玻璃陶瓷易受背景颜色的影响,宜在与牙齿颜色相近的桩核条件下使用;氧化锆的遮色能力强,适用于基牙严重变色或染色以及各类非牙色桩核等情况.     

瓷贴面厚度及试色糊剂对IPS e.max铸瓷贴面色彩效果的影响

目的:观察不同瓷片厚度及试色糊剂对IPS e.max瓷贴面修复体颜色的影响,从而为临床提供理论依据。方法:将不同厚度A1色IPSe.max铸瓷片覆盖ND5色树脂块模拟瓷贴面修复变色基牙。电脑比色仪在标准白背景下分别测定对照组(瓷试样和树脂试样间加用水)、试色糊剂组(瓷试样和树脂试样间使用试色糊剂剂)色度值L~*、a~*、b~*值,计算明度差△L~*值及色差△E值,应用SPSS11.5软件行统计学分析。结果:相同瓷片厚度下,各试色糊剂组与对照组间△E>1.5NBS,肉眼可辨;其中使用+3、-3试色糊剂引起的明度差△L~*较大,色差△E亦较大,而其他几种试色糊剂引起的明度和色差变化较小;随着瓷贴面厚度的增加,同一色糊剂组与对照组明度差△L~*及色差△E均逐渐减小,当瓷贴面厚度为1mm时,试件明度差及色差变化最小。试色糊剂组与对照组色差值差异受到瓷贴面厚度和试色糊剂种类的显著影响(P<0.05)。结论:瓷贴面厚度及试色糊剂种类均影响修复体最终颜色。瓷厚度增加,遮色能力增强,试色糊剂对修复体颜色影响减小;而所有试色糊剂中+3、-3号试色糊剂调节颜色的能力较强。     

不同金属基底和遮色瓷厚度对金瓷修复体色彩的影响

目的　对比不同金属基底和遮色瓷厚度对金瓷修复体色彩的影响,力求找出能有效遮住底层冠金属色的 最佳遮色瓷厚度。方法　制作贵金属合金、金沉积与镍铬合金片,分别以其为基底依次制作遮色瓷厚度为0·05、 0·1、0·2、0·3、0·4、0·5 mm的试件。用CR-321色差计对试件测色,计算色差并进行统计分析。结果　以镍铬合金与 贵金属合金为基底的瓷修复体遮色瓷厚度为0·3 mm时可以完全遮住底色,色差值小于1·5 NBS;金沉积为基底的 修复体遮色瓷厚度为0·1 mm即可完全遮住底色,色差值小于1·5 NBS。结论　对于不同的金属基底材料,有不同 的遮色瓷厚度要求;随遮色瓷厚度的增加,以镍铬合金与贵金属合金为基底的修复体彩度增加,金沉积为基底的修 复体彩度略有下降。     

烧结次数对两种合金烤瓷颜色的影响

目的:探讨烧结次数对金铂合金烤瓷及镍铬合金烤瓷颜色的影响。方法:制作直径14mm,厚度0.35mm的金铂合金烤瓷及镍铬合金烤瓷2组标准试件各15个,每组再分为3小组,分别上遮色瓷(A2色)0.2mm和不同厚度的体瓷(A2色)0.3mm,0.6mm,0.9mm。用美能达CR-100色度计测量试件上遮色瓷、体瓷烧结1、3、5、7次后的L*a*b*均值,计算两种合金烤瓷颜色(A2色)烧结次数间的色差△E。结果:金铂合金烤瓷及镍铬合金烤瓷均为体瓷烧结3次时色差△E最小,烧结5次时色差△E增大,烧结增至7次色差△E稍有降低。结论:临床金属烤瓷修复时,虽然烧结次数达到7次时对色差的影响都较小,但还是适宜控制在7次内。随着烧结次数增加,金铂合金烤瓷的色泽稳定性较镍铬合金烤瓷更佳。     

背景材料对3种牙科全瓷底层材料饰瓷后颜色的影响

目的：探讨不同桩核材料背景色对3种全瓷材料饰瓷后的颜色影响。方法：采用色差计测量各组饰瓷后试样在贵金属、镍铬合金、银汞合金和树脂背景上的色度值并计算组间色差值。结果：EmpressⅡ材料在贵金属背景色与两种非贵金属和树脂背景色之间,出现明度值和色品值的组间显著差异（P〈0．05）,渗透氧化铝陶瓷在不同背景色下,只出现了色品值的组间显著差异（P〈0．05）。4组氧化锆试样不同背景色下的色度值无组间显著性差异（P〉0．05）。结论：饰瓷后,EmpressⅡ铸瓷修复体透明度较高,受背景色的影响较大,人眼可以辨别;渗透氧化铝陶瓷受背景色影响较小,人眼不能辨别。氧化锆陶瓷不受背景色的影响。     

不同桩核对Lava锆瓷冠颜色影响的实验研究

目的:研究遮色钴铬合金桩核、氧化锆桩核、纤维桩树脂核、钴铬合金金属桩核对二氧化锆全瓷冠(Lava)颜色的影响。方法:选取因牙周炎拔除的完整上颌中切牙,在釉牙骨质界冠方2.0 mm处截冠,完善根管充填治疗和桩道预备,分别制作4种不同桩核预备体各10个,每个桩核再相应制作1个Lava二氧化锆全瓷冠,内冠厚0.5 mm,饰面瓷0.7mm。采用Minolta CM一700d分光测色仪,测试4种桩核背景下Lava锆瓷冠唇面中1/3 区域L^*、a^*、b^*值,分别进行完全随机设计的单因素方差分析和两两比较的LED检验,并根据公式计算和比较色差△E。结果:4种不同桩核背景下Lava锆瓷冠的L^*、a^*、b^*值间差异有统计学意义(FL=136.206,PL=0.000;Fa= 3.454,Pa=0.026;Fb=6.172,Pb=0.000)。3组牙色桩核的色差则均不能为肉眼所识别(△E< 1.5),钴铬合金桩核组的色差超过临床可接受水平(△E>2)。结论:临床应用锆瓷冠(Lava)进行修复时(特别是前牙区),不建议使用金属桩核。     

金铂合金与镍铬合金烤瓷颜色和金瓷结合强度的比较研究

目的 探讨金铂合金烤瓷与镍铬合金烤瓷颜色和金瓷结合强度的差别,为临床选择修复材料 提供理论依据。方法 ①制作不同体瓷厚度的金铂、镍铬合金烤瓷圆盘试件各15件,用美能达CR-100色 度计测量试件上遮色瓷、体瓷后的L、a、b值,计算两种金属烤瓷颜色(A2)间的色差△E。②制作金铂、镍铬 合金烤瓷棒盘试件各5件,通过剪切实验测量金瓷结合强度。结果 ①金铂合金烤瓷颜色比镍铬合金烤瓷颜 色要偏黄、偏红,明度小,两种金属烤瓷颜色(A2)的色差△E在遮色瓷时最大,随体瓷增厚而减小。②金铂合 金烤瓷金瓷结合强度85.08±15.16MPa,镍铬合金烤瓷金瓷结合强度54.76±8.74MPa,统计学分析P<0.05。结论 金铂合金烤瓷不仅金瓷结合强度高,不易崩瓷,而且颜色更接近天然牙。     

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。     

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。     

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.