ProTaper和K3预备对上颌前磨牙根管形态影响的研究

目的比较Pro Taper和K3预备对根管形态的影响。方法选取正畸减数拔除含颊舌双根管的上颌前磨牙40颗,把80个根管随机分为2组,分别采用机用镍钛器械Pro Taper和K3预备根管,预备前后分别三维成像,记录预先设立的根管横断面、颊舌向切面、近远中向切面三个位点的三维数据,根据预备前后的三维图像评价根管预备的效果。结果 K3组相对于Pro Taper组对牙本质的切削量少,对根管形态的影响较小,Pro Taper组和K3组有显著性差异(P<0.01)。结论 K3组预备后的根管形态优于Pro Taper组。K3预备后能较好的保持根管形态,对根管壁牙本质的切削量少,较少地削弱了余留牙体组织的抗折力。     

上颌第一磨牙不同根管预备方法的三维影像分析

目的:通过建立上颌第一磨牙模型,三维分析根管预备后根管中心的偏移。方法:7个离体上颌第一磨牙,随机分为2组。ProTaper预备组(n=4)和K锉预备组(n=3),根管预备前和预备后行Micro-CT扫描,建立三维模型及根管中心线模型,比较预备前、后根管中心线之间的三维空间距离。统计分析采用t检验。结果:建立了上颌第一磨牙的三维模型及根管中心线模型,腭根和近颊根管距离根尖1 mm层面上,Pro-Taper组根管中心线偏移明显小于K锉组,远颊根管距离根尖2 mm层面上,K锉组根管中心线偏移明显小于ProTaper组(P<0.05)。结论:上颌第一磨牙三维模型及根管中心线模型的建立,能三维测量、比较根管预备后的中心偏移,为根管预备效果的评价提供有效的量化数据参考。     

两种镍钛器械根管预备效果的评价

目的:比较机用ProTaper、MTwo与手用ProTaper根管预备效率和根管壁清洁效果。方法:选择新鲜拔除的下颌第一前磨牙80个,随机分为A、B、C、D 4组,分别采用机用ProTaper、MTwo、手用ProTaper和不锈钢K锉进行根管预备,记录每一根管预备完成总时间;收集根管预备过程中推出根尖孔的碎屑,干燥后称重;采用扫描电镜观察预备后根管壁的清洁效果,并进行碎屑和玷污层评分。结果:B组根管预备时间最少,平均41 s,推出根尖孔的牙本质碎屑量也最少,平均为3.1 mg,与其他各组相比有统计学差异(P<0.05)。D组预备时间最多,平均为204 s,推出根尖孔的碎屑量平均为10.35 mg。A组和C组预备时间分别是68 s,73 s,推出根尖孔的碎屑量各为5.45 mg和5.3 mg。用扫描电镜观察根管壁并对各部位进行碎屑和玷污层的评分,各组冠1/3均比根尖部评分低。在同一部位,B组的评分低于其他3组,D组的评分高于其他3组,差异均有统计学意义(P<0.05)。结论:与ProTaper和传统不锈钢K锉相比,Mtwo器械完成根管预备时间、推出根尖孔的牙本质碎屑量、根管壁清洁度等均优于前两者。     

手用ProTaper对弯曲根管成形能力评价的研究

目的评价手用ProTaper对弯曲根管的成形能力。方法将16个弯曲人工根管随机分为2组,实验组(PT组)使用手用ProTaper按冠根向深入法预备根管,对照组(SS组)用不锈钢K锉按逐步后退法预备根管;根管预备过程中对人工根管进行数码照相,图像分析软件Image-ProPlus对根管的形态与位置变化进行测量、分析。结果PT组预备完毕时根管弯曲角度均值从预备前的36°减小到26°,弯曲半径均值未见增大,根管壁光滑、流畅,未见根管不良形态形成;SS组预备完毕根管弯曲角度均值减小到22°,弯曲半径均值从6mm增大至11mm,根管壁切削不均衡,出现了根管偏移、根尖孔拉开、根管台阶等不良形态。结论手用ProTaper对弯曲根管成形能力优于不锈钢K锉。     

两种镍钛系统预备根管对牙根抗折强度的影响

目的比较ProTaper和K3镍钛预备系统预备根管对牙根抗折载荷的影响。方法 30颗完整的离体单根恒牙根管预备后随机分成三组,两个实验组分别采用ProTaper和K3镍钛预备系统预备根管,对照组采用不锈钢K锉逐步后退法预备根管,三组均采用冷牙胶侧压充填根管。将标本用万能试验机垂直加载直至标本发生纵裂,记录牙根纵裂时的最大抗压载荷和纵裂的类型。结果两个实验组的平均抗压载荷值分别是206.05±73.31N和210.04±64.57N,两个实验组之间无明显统计学差异。对照组平均抗压载荷值(269.10±56.64N)高于两实验组,但差异不具有统计学意义。83.3%的牙根纵裂线发生于颊舌方向。结论相比传统的逐步后退法,ProTaper和K3大锥度镍钛器械预备不会明显降低牙根的最大抗压载荷。以上两种镍钛预备技术对牙根抗压载荷的影响无区别。     

单支锉ProTaper Sx预备乳牙根管根尖推出物量的体外研究

目的:体外比较单支锉ProTaper Sx和不锈钢K锉预备乳牙根管的时间和根尖推出物量.方法:门诊收集离体乳牙,经截冠、分根后,按远中根管、近中根管、前牙根管、腭根管、近颊根管及远颊根管六种根管类型各收集16个,共96个.将每种类型根管随机均匀分配至Sx组(n=48)和K锉组(n=48).分别用ProTaper Sx和不锈钢K锉进行根管预备,各根管均用10 mL 0.2％氯己定溶液冲洗,记录预备时间、测定根尖推出碎屑量和根尖渗出冲洗液量,进行统计学分析.结果:K锉组(328.8s)的预备时间是Sx组(180.9 s)的近1.8倍,差异有统计学意义(P<0.05).两种器械均会造成一定的根尖推出物,但推出物的量不同.Sx组的根尖推出碎屑量和根尖渗出冲洗液量(0.00128±0.00056)g;(0.00614±0.00183)g均低于K锉组(0.00345±0.00124)g;(0.02930±0.01879)g,差异均有统计学意义(P<0.05).结论:与不锈钢K锉相比,单支锉ProTaper Sx预备乳牙根管具有预备时间短、根尖推出物量少的特点.     

三种方法预备C形根管对根管壁切削的比较

目的:评价3种常用根管预备方法预备C形根管时对根管壁薄弱区的切削程度,为临床治疗提供参考.方法:收集临床拔除的具有C形根管的下颌第二恒磨牙60颗,应用改良Bramante技术,于距根尖2、5、8mm处将牙根横断.将样本随机分为3组,使用不同预备器械和方法进行预备.比较预备前后根管横截面形态的数码图像,对3种不同方法的切削程度进行评价.评价指标包括牙本质切削面积、根管壁最小厚度出现部位及最小值变化和根管壁侧穿发生情况.数据进行方差分析.结果:C形根管壁的薄弱区多出现在舌侧,3种预备方法对C形根管壁薄弱区的切削没有显著差异.手用不锈钢器械组中发生3例侧穿.结论:在C形根管预备时应特别注意避免在颊舌侧薄弱区的过度切削,以免发生穿孔.     

ProTaper和ProTaper Universal机用镍钛器械在模拟根管内成形能力的研究

目的：利用树脂模拟根管比较机用ProTaper和ProTaper Universal在弯曲根管内的成形能力。方法：使用机用ProTaper和ProTaper Universal预备两组模拟树脂根管,记录预备时间、树脂切割量、外形改变等,并对预备前后模拟根管形态改变、弯曲内外侧去除树脂量的多少进行分析和比较。结果：两组器械在预备时间上、器械变形方面无显著性差异,但预备后根管中下段均有部分偏移。ProTaper Universal F1、F2在弯曲内侧切割的树脂量多于ProTaper,而F3的树脂切割量少于ProTaper F3。结论：两组器械均能较好地完成根管预备,但是在预备根管中下段时,都会造成一定程度上的偏移。     

ProTaper机用镍钛锉根管预备的临床效果分析

目的 评价ProTaper机用镍钛锉根管预备的临床效果。方法 选择300颗患牙（638个根管）随机分为ProTaper组和K锉组,分别用ProTaper机用镍钛锉和K锉进行根管预备,采用χ2检验比较根管预备后的疼痛反应、根管充填效果及器械分离情况。结果 ProTaper组根管预备后疼痛发生率为6.00%,较K锉组的根管预备后疼痛发生率（26.67%）少（P<0.01）,ProTaper组根管恰填率为93.77%,较K锉组（88.64%）高（P<0.05）,两组间的器械分离则无统计学差异（P＞0.05）。结论 ProTaper机用镍钛锉能有效降低根管预备后疼痛的发生和提高根管充填质量,而且较为安全。     

手用ProTaper镍钛锉在治疗弯曲根管中的应用

目的 探讨手用ProTaper镍钛锉在治疗弯曲根管中的效果。方法 将101例患者的132个弯曲根管随机分为两组,实验组68颗用手用ProTaper镍钛锉,对照组64颗用不锈钢K锉,两组均采用冠根向深入法进行根管预备,比较两组在根管预备时间、根管形态、预备后疼痛以及根充效果的差异。结果 手用ProTaper镍钛锉根管预备形态较好,预备时间减少,预备后疼痛发生率降低,根充恰填率明显增高。两组具有显著性差异(P<0.05)。结论 手用ProTaper镍钛锉组可有效改善弯曲根管治疗效果。     

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。