下颌切牙唇舌径宽度与单双根管之间关系的CBCT研究

目的:采用CBCT观察下颌恒切牙根管形态,分析下颌切牙唇舌径宽度及近远中宽度与单双根管之间的关系。方法:选取75名进行CBCT扫描的患者,共计282颗下颌切牙,测量其釉质牙骨质界处唇舌径及近远中径宽度,并观察其根管形态。结果:下颌切牙单双根管的唇舌径宽度平均宽度分别为5.62mm、6.35mm,具有显著性差异(P<0.001),与性别差异无关,唇舌径的宽度的最佳界值为6.05 mm。单双根管的近远中径宽度平均宽度分别为4.00mm、4.04mm,无显著性差异(P=0.423)。结论:当唇舌径宽度大于或等于6.05mm时,可以提示下颌切牙双根管的存在的可能,唇舌径宽度的大小能够作为一种下颌切牙根管治疗术前的评估指标。     

锥形束CT与透明牙染色法对下颌恒切牙根管形态的比较研究

目的:采用锥形束CT(cone-beam CT,CBCT)与透明牙染色法观察下颌恒切牙根管形态,比较2种方法对根管形态研究结果的一致性.方法:选取根尖发育完全、牙根完整、未进行过牙髓治疗的离体下颌恒切牙61颗,进行CBCT扫描.并用透明牙染色法对根管系统进行染色,比较2种方法对下颌恒切牙根管数目、根管Vertucci分型的一致性,分析2种方法对根管分支结构检出率之间的差异.采用SPSS 17.0软件包对数据进行统计学分析.结果:CBCT法和透明牙法对单、双根管的一致性检验的Kappa值为0.847 (P＜0.001),2种方法对Vertucci根管分型一致性检验的Kappa值为0.861 (P＜0.001);2种方法根管分支结构的检出率分别为8.19％、22.95％,差异具有显著性(P=0.025),透明牙染色法的根管分支结构检出率显著高于CBCT.结论:CBCT能准确反映离体下颌恒切牙的根管类型,但对根管分支结构的诊断不如透明牙染色法,CBCT是一种较准确的诊断根管形态的方法.     

多角度投照技术在上颌第一恒磨牙近颊根管识别中作用的研究

目的 探讨X线不同投照角度对上颌第一恒磨牙近中颊根双根管的识别作用。方法 选取临床拔除的上颌第一恒磨牙40个,在无诊断丝和存在诊断丝情况下分别进行X线投照,从0°到30°每间隔5°拍摄1张,每个牙齿拍摄14张X线片。将离体牙制成透明牙标本以提供金标准确定近颊根根管数目。结果 40个上颌第一恒磨牙MB2的发现率为67.50%;诊断丝投照对根管识别的正确率高于无诊断丝投照;诊断丝近中水平偏移15°与无诊断丝近中水平偏移20°投照具有最好的双根管检出率。结论 利用诊断丝及偏移角度X线投照能提高上颌第一恒磨牙近中颊根双根管的检出率。     

牙科数字成像系统、锥形束CT及透明牙对离体第一恒磨牙根管系统诊断价值的对比性研究

目的 对比分析牙科数字成像系统（RVG）、锥形束CT（CBCT)及透明牙3种检查方法在诊断离体第一磨牙根管系统的价值,分析第一磨牙根管影像解剖学与根管解剖学的对应关系,为第一磨牙根管治疗提供影像解剖依据。方法 拍摄269颗离体第一磨牙颊舌向、近远中向RVG和CBCT后,再制作根管染色透明牙,应用RVG、CBCT和透明牙对各牙根中上2/3、根尖1/3区根管系统和管间交通支进行分类统计,以评估CBCT在根管诊断中的应用价值。结果 CBCT对第一磨牙主根管中上2/3区的显示率达96.55%;CBCT、透明牙对第一磨牙根尖1/3区根管系统的显示差异有统计学意义（P<0.05）。上、下颌第一磨牙近中根变异较大,双或多根管与管间交通支发生率均较高。结论CBCT与透明牙在显示第一磨牙主根管系统（牙根中上2/3区）方面基本等效;在根尖1/3区透明牙对细小分歧根管的显示明显优于CBCT;RVG对多根管牙根、根尖细小分歧根管的显示明显受限;上、下颌第一磨牙近中根双或多根管与管间交通支发生率均较高。CBCT对牙根、根管的显示具有清晰直观、准确快捷的优点,是目前无创诊断根管疾病最可靠方法。     

青少年下颌第一恒磨牙牙根及根管的锥形束 CT 研究

目的:应用锥形束CT(CBCT)分析青少年下颌第一恒磨牙牙根及根管形态。方法:收集2012-07~12拍摄CBCT的183例12~16岁青少年患者的366颗下颌第一恒磨牙的锥形束CT影像资料,记录患者年龄、性别、观察牙位及牙根数目、根管数目及根管形态,利用SPSS 19.0软件统计分析下颌第一恒磨牙牙根及根管数目的性别差异和左右侧差异。结果:纳入研究的366颗下颌第一恒磨牙中,近中单根者365颗,远中单根者282颗(77.05%),双根者83颗(22.68%),1颗牙为C形根。近中单根双根管者356颗(97.27%),单根一根管者9颗(2.46%);远中单根一根管者229颗(62.57%),单根双根管者53颗(14.48%),双根各一根管者83颗(22.68%);C形根3根管者1颗(0.27%)。牙根及根管数目在男女之间与左右侧之间差异均无统计学意义。结论:下颌第一恒磨牙以双根居多,牙根变异主要发生在远中根,远中舌根的发生率较高;性别间与左右侧牙之间无明显差异。     

CBCT根管形态三维容积重建可视化技术的研究

目的:探讨基于CBCT图像的根管形态三维容积重建可视化技术。方法:32颗牙根完整、根尖孔发育完成,未行牙髓治疗的离体下颌恒切牙以及8例牙隐裂患者进行CBCT高清模式扫描图像进行根管形态容积重建(volume rendering, VR)。在进行容积重建前,对选取的下颌恒切牙根管形态通过轴位图像和多平面重建(multiple planar reconstruction, MPR)评估确定其根管形态。将CBCT轴位图像以DICOM格式输入第三方软件Simplant进行根管形态容积三维重建并进行根管数目评估。结果:离体和在体条件下Simplant重建图像根管数目显示准确率分别为96.9%和93.4%,Fisher确切概率法检验显示与MPR法不具有显著性差异。结论:CBCT三维容积重建可视化技术可以直观准确的显示双根管下颌恒切牙。     

下颌恒切牙根管形态的影像学研究

目的：探讨下颌恒切牙根管解剖形态的影像学特征，为临床采用X线片评估该牙根管系统提供依据。方法：中国人下颌恒切牙300个，采用传统X线胶片和数字化X线片从唇舌向和近中远中向投照牙片，两名牙体牙髓专科医师同时观察牙片，判读根管数目、根管类型、根管钙化程度，并根据根管直径推测根管横切面形状。结果：下颌恒切牙有1个根管（67．89％）和2个根管（32．11％），唇舌向X线片双根管检出率（3．34％）明显低于近中远中向（32．11％）（P〈0．05）。根管类型按Vertucci分类，Ⅰ型67．9％，Ⅱ型11．4％，Ⅲ型18．1％，Ⅳ型0．7％，Ⅴ型1．0％，Ⅵ型1．0％。根管钙化率：1级为89．67％，2级为7．33％，3级为3．0％。根管横切面形状扁长形以根中1／3最高，达85．6％。结论：下颌恒切牙根管解剖形态复杂，临床上唇舌向X线片可能掩盖部分根管解剖信息。     

偏位投照与锥形束CT在寻找遗漏根管中的准确性比较

目的:分析比较偏位投照与锥形束CT(CBCT)在根管治疗中发现遗漏根管的应用。方法:对200例患牙常规拍摄术前正位根尖片和CBCT,术中插诊断丝拍摄20°～30°偏位投照根尖片,完善根管治疗。比较偏位投照与CBCT发现的遗漏根管数,采用SPSS 19.0软件包对数据进行统计学分析。结果:200例患牙中,偏位投照发现8例患牙有遗漏根管,前牙及前磨牙3例,磨牙5例。而CBCT扫描显示有15例,其中,前牙及前磨牙4例,磨牙11例。CBCT发现数量大于偏位投照,但差异无显著性(P>0.05)。结论:偏位投照与CBCT有利于发现遗漏根管,帮助临床完善根管治疗。     

不同年龄段双根管下颌侧切牙舌根管开口位置及分叉角度的锥形束CT研究

目的    通过锥形束CT（cone beam CT,CBCT）对下颌侧切牙双根管发生率及双根管牙的舌根管开口位置和双根管间分叉角度进行研究,为临床中对双根管下颌侧切牙的治疗提供理论依据。方法    于2019年10月至2020年5月在西部战区总医院口腔科因种植、正畸、牙髓病等原因拍摄的CBCT影像学资料中随机抽取300例符合纳入标准的患者CBCT资料,对其中符合纳入标准的586颗下颌侧切牙的影像进行分析,筛选出其中的双根管牙,将它们按患者年龄分组,记录舌根管开口处的位置及根管分叉角度,并进行分析。结果    纳入研究的586颗下颌侧切牙中有95颗为双根管,双根管发生率为16.2%;在低年龄组（≤ 30岁）、中年龄组（> 30 ~ 60岁）及高年龄组（> 60岁）,双根管下颌侧切牙的舌根管开口处距切端距离分别为（12.48 ± 1.43）、（11.18 ± 1.21）、（9.81 ± 0.86）mm,组间差异有统计学意义（P < 0.05）;而根管分叉角度在各年龄段的差异无统计学意义（P > 0.05）。下颌侧切牙舌根管开口处至切端距离和根管分叉角度在左右侧之间均具有对称性（r值分别为0.626和0.603,均P < 0.001）。结论    下颌侧切牙双根管发生率较高,并且随着年龄的增加,舌根管开口处至切端的距离在逐渐减小;同时两侧的双根管发生率、舌根管开口处至切端距离以及根管分叉角度均有较高的对称性。     

离体上颌第一前磨牙根管颊舌向弯曲的研究

目的确定人上颌第一前磨牙的颊舌向根管弯曲程度和情况.方法收集115颗离体的上颌第一前磨牙,拍近远中向的X线片, 用Photoshop5.0软件分析根管,用Weine氏法测量根管的弯曲度,测量的角度大于18°时,则认为根管存在明显的弯曲,根管的构型采用Vertucci分类法.结果 20%的上颌第一前磨牙在颊舌向存在明显的根管弯曲,单根管的牙齿无明显的颊舌向根管弯曲,大多数的颊舌向根管弯曲发生于双根双管的牙齿,37%的双根牙齿有根管弯曲,根管弯曲的发生部位多为牙根的偏根尖部分.结论上颌第一前磨牙的颊舌向根管弯曲发生率为20%,多在根尖1/3出现1个弯曲.     

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.     

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。     

5种着色氧化锆陶瓷的细胞毒性评价

目的：对掺杂5种微量着色剂的氧化锆陶瓷的生物安全性进行初步评价.方法：采用四氮唑盐比色法（MTT）细胞毒性评价方法,用5种着色氧化锆陶瓷材料的浸提液体外培养L929小鼠成纤维细胞2 d、4 d、7 d,于倒置相差显微镜下观察细胞形态;用MTT检测各实验组和对照组的吸光度值（OD值）,计算各组细胞的相对增殖率,并按照6级毒性分类法对各实验组进行评级.结果：培养期细胞贴壁生长,细胞形态正常.随着培养天数增加细胞大量增殖,各实验组的毒性评级为0-1级.结论：添加5种微量着色剂的氧化锆陶瓷无细胞毒性,具备体内应用的生物安全基础.