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目的 评价不同剂型EDTA对弯曲根管作用的疗效.方法 选择2010年7-12月在中国医科大学口腔医学院综合急诊科就诊的480例急性牙髓炎患者的480颗后牙,包括具有轻度弯曲(simple,S),中度弯曲(medium,M),重度弯曲(difficult,D)3种弯曲根管的上、下颌前磨牙及上、下颌磨牙各40颗,每颗患牙选取1个根管作为研究对象,并将其随机分为试验组和对照组,分别采用凝胶型EDTA和液体EDTA作为根管润滑剂,1%NaClO作为冲洗剂,结合ProTaper冠向深入法预备根管,观察各组根管预备时间以及根管预备后疼痛反应.结果 (1)根管预备时间:上颌前磨牙、磨牙的M、D弯曲根管和下颌前磨牙、磨牙的S弯曲根管试验组和对照组差异有统计学意义(P＜0.05);上颌前磨牙、磨牙的S弯曲根管和下颌前磨牙、磨牙的M、D弯曲根管试验组和对照组差异无统计学意义(P＞0.05).(2)根管预备后疼痛发生情况:上颌磨牙和下颌前磨牙的D弯曲根管以及下颌磨牙的M、D弯曲根管试验组和对照组差异有统计学意义(P＜0.05);上颌前磨牙的S、M、D弯曲根管与上颌磨牙和下颌前磨牙的S、M弯曲根管以及下颌磨牙的S弯曲根管试验组和对照组差异均无统计学意义(P＞0.05).结论 凝胶型EDTA应用于弯曲根管较液体EDTA根管润滑效果好,术后反应轻.     

Sch(a)fer法测量根管弯曲半径准确性的探讨

目的：探讨Schafer法测量根管弯曲半径的准确性。方法：建市弯曲根管长轴的数学模型，将弯曲根管长轴简化为依次由相切的直线l1、圆弧（半径为r、圆心角为θ）、直线l2组成的连线，将Schafer测量法应用于该数学模型，推导Schafer测量法计算公式与模型参数间的数学关系，对Schafer测量法的缺陷进行分析和修正。结果：Schafer法的根管弯曲半径计算公式仅在l2=0的情况下才能成立，l2越长其计算结果越不准确；新的测量方法改用Weine法测量根管弯曲角度，测值代入新的计算公式后能减小l2引起的计算误差。结论：Schafer测量法的准确性依赖于所测弯曲根管的类型。     

两种根管弯曲度测量法间数学关系的推导

目的:研究2种根管弯曲度测量法测值(Schneider法的测值为θS,Weine法的测值为θW)间的数学关系。方法:将弯曲根管长轴简化为依次由相切的线段(长度为l1)、圆弧(半径为r、圆心角为θ)、线段(长度为l2)组成的连线,根据2测量法确定简化弯曲根管长轴测量角时不同的定点、连线方式,推导θS、θW间的函数方程以及与l1、l2、r、θ间的数学关系,分析方程与函数图形的特征。结果:θS与θW间存在以下数学关系:(1)tanθS=(1-cosθW ksinθW)/(sinθW kcosθW),k=l2/r;(2)θW/2≤θS≤θW。k取不同值时函数曲线的形态具有不同的特点。θW在0,π的区间内,θS与θW间呈近似的线性关系;k越大,θS越接近θW,k越小,θS越接近θW/2。结论:Schneider法与Weine法测值间存在着复杂的函数关系,根管根尖部直段的长度(l2)与弯曲段曲率半径(r)之比值是影响2种方法测值间差异的重要因素。     

上颌恒磨牙近中颊根根管弯曲情况的离体研究

目的 分析上颌恒磨牙近中颊根根管分型、弯曲发生情况、弯曲位置、弯曲方向及弯曲程度。方法 收集上颌第一、第二恒磨牙60颗，探查近中颊根管，并于根管内插入006#～015#扩大针，拍摄颊舌向(临床)和近远中向(邻面)X-线片。用Photoshop-6．0软件分析根管弯曲位置、弯曲方向和弯曲角度。结果 ①上颌第一恒磨牙近中颊根MB1根管的发现并探通率为90．6％；MB2根管的发现并探通率为71．8％，近中颊根以2—2型为主(48．27％)；上颌第二恒磨牙近中颊根MB1根管的发现并探通率为89．3％；MB2根管的发现并探通率为60．7％，近中颊根以2—1型为主(48％)。②大多数MB1与MB2根管在两个观察方向均有不同程度的弯曲。第一弯曲多发生于根中1／3及其冠方，临床片所示近颊根管多向远中弯曲，邻面片观察到的根管多向腭侧弯曲。在颊舌向发生的弯曲中，2—1型的MB2根管较MB1根管有更大的弯曲度；而2—2型的MB1与MB2根管弯曲度无显著性差异；2—1型的MB2根管弯曲的发生率与弯曲度均高于2—2型的MB1根管。在近远中向发生的弯曲中，2—1型的MB1根管弯曲度高于2—2型的MB1根管。③第二弯曲多发生于根尖1／3(部分发生于根中1／3)，弯曲度与第一弯曲度无显著性差异。结论 上颌第一、第二恒磨牙近中颊根管多有弯曲，充分了解根管的走向和弯曲度是完善根管治疗的必需。     

不锈钢K锉预备弯曲根管时根管不良形态形成的实验研究

目的:探讨弯曲根管预备时根管不良形态形成的特点与规律。方法:使用手用不锈钢K锉,按逐步后退法预备8个弯曲人工根管,根管预备过程中对根管及根尖孔进行微距摄影,用图像分析软件Image-ProPlus对根管的形态与位置变化进行测量、分析;实验数据采用SPSS10.0统计软件包进行统计学分析,选用配对t检验比较组间差异。结果:根管预备完毕,根管弯曲角度均值从预备前的36.21°(Schneider法)逐渐减小至21.98°,弯曲半径均值从6.28mm增大至11.35mm;根管长轴发生了偏移,与预备前原根管长轴形成2个交点,3个相交区。根管的连续锥度被破坏,并出现一系列预备缺陷。结论:弯曲根管预备时,根管器械在弯曲应力与切削力的共同作用下发生动态的根管偏移,是导致一系列根管不良形态的根本原因。     

离体上颌第二前磨牙根管颊舌向弯曲的发生情况

目的：确定人上颌第二前磨牙的颊舌向根管弯曲程度和情况。方法：收集213个离体的上颌第二前磨牙，拍近远中向的X线片，用Photoshop5．0软件分析根管，Weine氏法测量根管的弯曲度，测量角度大于18度时，则认为根管有明显的弯曲，根管的构型采用Vertucci分类法。结果：单根单根管上颌第二前磨牙的根管弯曲仅有2个，单根双根管牙齿的根管明显弯曲有6个，在28个双根牙中有明显根管弯曲的6个，根管弯曲的牙齿总发生率为6．6％(14/213)。根管弯曲的发生部位多为根尖1/3或附近。结论：上颌第二前磨牙颊舌向根管弯曲的发生率较低。     

Schfer法测量根管弯曲半径准确性的探讨

目的:探讨Schfer法测量根管弯曲半径的准确性。方法:建立弯曲根管长轴的数学模型,将弯曲根管长轴简化为依次由相切的直线l1、圆弧(半径为r、圆心角为θ)、直线l2组成的连线,将Schfer测量法应用于该数学模型,推导Schfer测量法计算公式与模型参数间的数学关系,对Schfer测量法的缺陷进行分析和修正。结果:Schfer法的根管弯曲半径计算公式仅在l2=0的情况下才能成立,l2越长其计算结果越不准确;新的测量方法改用Weine法测量根管弯曲角度,测值代入新的计算公式后能减小l2引起的计算误差。结论:Schfer测量法的准确性依赖于所测弯曲根管的类型。     

下颌第一恒磨牙根管弯曲度的研究

目的：确定下颌第一恒磨牙的根管弯曲程度的情况。方法；收集36个离体的下颌第一恒磨牙，在根管中分别插入15－^#25的根管扩大针，拍摄近远中向（临床）和颊舌向（邻面）的X线片，用Photoshop5.0软件分析根管的弯曲率，根管的构型采用Vertucci分类法。结果：大多数的近中根管在2个观察方向均显示有不同程度的弯曲，弯曲发生处多为根中1／3，近远中向的近中颊要管弯曲度最高（P＜0．05），颊舌向的近中颊，舌根管可在根尖1／3显示第二个弯曲度，弯曲程度均高于同一根管的第一个弯曲度，VertucciⅡ型占近中根的64％。大多数的远中根管无明显的弯曲，且多是单根单根管。结论：下颌第一恒磨牙的近中根管多有不同程度的弯曲，了解根管的弯曲对于成功的牙髓，尖周病治疗是必要的。     

Sch(a)fer法测量根管弯曲半径准确性的探讨

目的:探讨Sch(a)fer法测量根管弯曲半径的准确性.方法:建立弯曲根管长轴的数学模型,将弯曲根管长轴简化为依次由相切的直线l1、圆弧(半径为r、圆心角为θ)、直线l2组成的连线,将Sch(a)fer测量法应用于该数学模型,推导Sch(a)fer测量法计算公式与模型参数间的数学关系,对Sch(a)fer测量法的缺陷进行分析和修正.结果:Sch(a)fer法的根管弯曲半径计算公式仅在l2＝0的情况下才能成立,l2越长其计算结果越不准确;新的测量方法改用Weine法测量根管弯曲角度,测值代入新的计算公式后能减小l2引起的计算误差.结论: Sch(a)fer测量法的准确性依赖于所测弯曲根管的类型.     

关中地区汉族成人前牙根管弯曲度调查

目的：了解关中地区汉族成人前牙根管弯曲情况。方法：采用间接影像学手段，运用改良的Schneider测量方法，利用电子测量尺进行测量，分析根管弯曲情况。结果：前牙多数为Ⅰ型根管，其中上颌尖牙根管弯曲发生率高（68．5％）。各牙位的弯曲发生位置偏根尖1／3处。上颌前牙有个别牙为近远中向S型根管弯曲。上颌尖牙根管弯曲度与年龄有显著相关关系（P=0．03）。结论：前牙根管弯曲情况复杂，上颌尖牙根管弯曲程度重。上颌尖牙根管弯曲度与年龄有显著负相关关系。     

上颌第一前磨牙根管颊舌向弯曲情况的研究

目的研究上颌第一前磨牙根管颊舌向的弯曲情况。方法选择100个上颌第一前磨牙为研究对象,开髓并充分暴露根管口后,将1个K型锉插入根管内直至根尖孔处。利用数字成像系统（RVG）拍摄每个牙的近远中向影像,采用Schneider法测量根管的弯曲角度,计算弯曲半径和弯曲部分长度。结果1）100颗上颌第一前磨牙共有176个根管,88个根管存在颊舌向弯曲,其中53个位于根尖1/3;21个根管存在“S”形弯曲,其第一弯曲多见于根中1/3,第二弯曲均见于根尖1/3处。2）颊腭侧根管弯曲情况无统计学差异（P>0.05）,但“S”形根管第二弯曲的弯曲情况更为复杂。3）弯曲角度与弯曲半径无相关关系（r=0.002,P>0.05）,但与弯曲部分长度呈正相关关系（r=0.489,P<0.01）。结论上颌第一前磨牙根管颊舌向弯曲发生率较高,其中“S”形根管的弯曲情况更为复杂。     

广东青少年上颌第一前磨牙根管弯曲情况的研究

目的探讨广东青少年上颌第一前磨牙的根管弯曲情况,并对比分析男女间的差异。方法选择广东青少年上颌第一前磨牙200颗,其中男女各100颗。开髓并充分暴露根管口后,将一支K型锉插入根管内直至根尖孔处。利用牙科数字成像系统拍摄每颗牙的近远中向及颊舌向影像,采用Schneider法测量根管弯曲角度（CCA）,然后选择弯曲角度大于5°的根管,采用Günday法测量根管进入角度（CAA）、弯曲高度（X）和弯曲距离（Y）,分析男女两组之间的差异及CAA与CCA、X和Y的相互关系。结果59.21%的根管存在颊舌向弯曲,男女分别为49.74%、68.98%;41.05%的根管存在近远中向弯曲,男女分别为36.27%、45.99%;6.84%的根管为S形弯曲,男女分别为4.15%、9.63%。单根管在颊舌向、腭根管在颊舌向和近远中向的弯曲率均为女性高于男性（P＜0.05）。颊根管在颊舌向和近远中向Y值和腭根管颊舌向CCA均为女性大于男性（P＜0.05）;男女弯曲颊、腭根管的CAA与CCA及X呈显著正相关（P＜0.01）,与Y呈显著负相关（P＜0.05）。结论上颌第一前磨牙根管存在颊舌向和近远中向弯曲,其中一些为S形根管。女性根管弯曲率高于男性。     

上颌第一磨牙根管弯曲度的实验研究

目的:分析上颌第一磨牙根管弯曲位置、方向及弯曲度。方法:收集80个上颌第一磨牙,在根管中分别插入15#-20#扩大针,拍摄近远中向和颊舌向X线片,用Photoshop6.0软件测量根管弯曲位置、方向和弯曲度。结果:上颌第一磨牙腭侧根管通畅、较直。远中颊侧根管80%在近远中方向、45%在颊舌方向有>5°的明显弯曲,弯曲位置多位于根中1/3,且近远中向弯曲度明显大于颊舌向(P<0.05)。近中颊根颊侧根管在近远中方向、颊舌方向分别有82.5%、77.5%出现>5°的明显弯曲。两个方向上的弯曲度无明显差异(P>0.05)。35%的标本探通了近颊根舌侧根管,其在近远中向、颊舌向出现明显弯曲的比例达91%和83%。结论:上颌第一磨牙四个根管在近远中向、颊舌方向均有不同程度的弯曲,其第二弯曲出现的情况也各不相同。     

Curved molar root canal preparations using Hero 642 rotary nickel–titanium instruments

AIM: The Bramante method was used to study how the natural curvature of root canals was modified when using the Hero 642 nickel-titanium rotary system. METHODOLOGY: Twenty-four canals were selected in freshly extracted human mandibular molars. Every root canal had an angle of curvature greater than 20 degrees. Roots were embedded in clear casting resin using a plaster mould. Cross-sectional cuts were made in the apical, middle and coronal thirds of each root. A first group (control) of 12 curved root canals was prepared using stainless steel hand instruments and the step-back technique. A second group of 12 curved root canals was instrumented using the Hero sequence according to the manufacturer's instructions. For each sectioning level, the amount of dentine removed, the change of shape factor and the canal centre displacement were calculated with the aid of a digital image analysis system. The results were subjected to the Mann-Whitney U-test. RESULTS: No significant difference occurred in the amount of dentine removed, change of shape factor or canal centre displacement in the coronal and middle thirds of the curved canals. In the apical third, transportation was significantly higher (P=0.0171) with stainless steel hand instruments than with the Hero system. CONCLUSIONS: The original canal shape was maintained better in the apical third of curved canals when using the Hero system in a crown-down technique when compared to a hand preparation technique with stainless steel instruments.     

Quantitative three-dimensional analysis of root canal curvature in maxillary first molars using micro-computed tomography

In endodontic therapy, access and instrumentation are strongly affected by root canal curvature. However, the few studies that have actually measured curvature are mostly from two-dimensional radiographs. The purpose of this study was to measure the three-dimensional (3D) canal curvature in maxillary first molars using micro-computed tomography (microCT) and mathematical modeling. Extracted maxillary first molars (46) were scanned by microCT (502 image slices/tooth, 1024 X 1024 pixels, voxel size of 19.5 x 19.5 x 39.0 microm) and their canals reconstructed by 3D modeling software. The intersection of major and minor axes in the canal space of each image slice were connected to create an imaginary central axis for each canal. The radius of curvature of the tangential circle was measured and inverted as a measure of curvature using custom-made mathematical modeling software. Root canal curvature was greatest in the apical third and least in the middle third for all canals. The greatest curvatures were in the mesiobuccal (MB) canal (0.76 +/- 0.48 mm(-1)) with abrupt curves, and the least curvatures were in the palatal (P) canal (0.38 +/- 0.34 mm(-1)) with a gradual curve. This study has measured the 3D curvature of root canals in maxillary first molars and reinforced the value of microCT with mathematical modeling.     

The effects of hand, sonic and ultrasonic instrumentation on the shape of curved root canals

This study compared the effects of hand, sonic and ultrasonic instrumentation on the shape of curved root canals in 60 extracted human lateral incisors and premolars. Each root of moderate or severe canal curvature was mounted onto a simulated crown and filled with a radiocontrast medium. Enlarged photographic prints obtained from radiographs taken before and after root canal preparation were measured. The results indicated a lower incidence of apical zip and elbow formation in the ultrasonic preparations when compared with those prepared by hand and sonic, irrespective of the canal curvature. A more prominent hour-glass shape was prepared by hand and sonic instruments particularly in severely curved root canals. A distinctive taper was produced by each method of preparation. All three instrumentation techniques showed preferential dentine removal from the convex aspect of the canal in the apical portion and the concave aspect in the middle portion of the root canal.     

3种机用镍钛锉对弯曲根管成形能力的比较

目的:比较Twisted File(TF)、ProTaper和Mtwo这3种机用镍钛锉对弯曲根管的成形效果。方法:树脂模拟弯曲根管,分别用TF锉、ProTaper锉、Mtwo锉进行预备,测量预备前后工作长度、根管中轴线和根管弯曲度的变化量。结果:根备后工作长度丧失量:TF组少于Mtwo组(P<0.05);根管中轴线的变化量:根尖部TF组少于Mtwo和ProTaper组(P<0.05),弯曲部TF组与ProTaper组少于Mtwo组(P<0.05);根管弯曲度改变量:TF组与ProTaper组少于Mtwo组(P<0.05)。结论:TF锉在预备弯曲根管时,能够较好地维持根管原始走向,防止根尖偏移,是较理想的弯曲根管预备器械。     

Root canal configuration of deciduous mandibular first molars--an in vitro study

Root canal morphology of deciduous mandibular first molar was studied using roentgenographic and decalcification and clearing methods. Two groups of 15 teeth were formed. In the roentgenographic group, roots of the teeth were separated from the crown at the level of CEJ. Cut roots of the teeth were radiographed from both mesiodistal and buccolingual directions using separate IOPA films. In the decalcification and clearing group, teeth were decalcified and made transparent. Dye was injected later. The roots of the teeth were examined under 10 times for number, curvature, types and additional features of root canals. Deciduous mandibular first molar showed variability in root canal morphology. Four to five root canals were recorded. Majority of the teeth had 1-1 type of root canal anatomy, but 1-2 type anatomy was also reported. Straight, curved and S-shaped canal curvatures were recorded. Horizontal anastomosis, lateral canals and buccolingually broad root canals were also recorded.     

Extent of microleakage in relation to root canal morphology

The purpose of this study was to study with standardized methods the length and extent of the microleakage developing around the root canal fillings. The preparational errors were evaluated in twenty straight and curved root canal using computer graphic analysis. The step back technique was used for root canal preparation. The shape of the instrumented root canals were analyzed macroradiographically in order to evaluate unwanted procedural root canal deformities. The root canals were obturated with lateral condensation technique using AH-26 sealer and guttapercha points. After the teeth having been made transparent a silver nitrate penetration test was performed in vacuum and both the linear dye penetration and the extent of dye penetration surface area were measured from four directions with computer assisted digitized method. The linear dye penetration values were higher in straight root canals than in curved ones: 2.22 + 1.17 mm and 1.81 + 1.24 mm respectively. The dye penetration surface area was slightly also larger in straight than in curved root canals: 1.3 +/- 0.71 mm2 vs. 1.06 +/- 0.5 mm2. Nevertheless the differences were statistically non significant. In curved root canals the highest dye penetration values were measured at the inner curvature of the canals. This findings was also corroborated by a coincidence test.