3根型下颌第一恒磨牙远颊根及远舌根根管弯曲度的测量

目的研究3根型下颌第一恒磨牙远颊根及远舌根根管弯曲度的特点。方法从临床采集25颗拔除的3根型下颌第一恒磨牙,开髓揭顶后,将2支8号K锉分别插入远颊根及远舌根根管达根尖孔。RVG（radio visiography）数字成像系统采集牙齿在近远中向和颊舌向的X线数码牙片。将数码牙片导入图像分析软件ImagePro Plus6.0,分别用Schneider法和Weine法测量根管弯曲度及根管入角。结果 Schneider法测得远颊根根管在近远中向弯曲度为9.33°±5.08°,颊舌向为10.06°±5.73°,差异无统计学意义（P〉0.05）;远舌根根管在近远中向弯曲度为11.28°±7.30°,颊舌向为28.34°±13.76°,颊舌向弯曲度显著大于近远中向,差异有统计学意义（P〈0.001）。Weine法测得的各项目均值皆大于Schneider法,而且两者具有高度相关性（Pearson相关系数r=0.972,P=0.000）。远舌根根管在颊舌向根管入角为27.04°±8.85°,明显大于近远中向的13.15°±6.74°,差异有统计学意义（P〈0.001）。结论掌握3根型下颌第一恒磨牙根管弯曲的特点有利于根管预备取得成功。     

根管冠部预处理对后牙弯曲根管弯曲度的影响

目的通过研究后牙弯曲根管,了解根管冠部预处理对根管弯曲度的影响.方法将弯曲度在12°～35°的48个前磨牙和48个第一、二磨牙按照弯曲度不同分别分成两组,一组弯曲度为12°～20°,另一组为21°～35°.用GG钻行根管弯曲部分冠部预处理后,Schneider法测量根管弯曲度,比较相互间有无明显差异.结果前磨牙和磨牙4组标本根管冠部预处理前后的弯曲度相互间均存在显著性差异(P<0.05).前磨牙不同弯曲度的两组标本,冠部预处理前后根管弯曲度的改变相互间无显著差异(P>0.05),而两组磨牙标本相互间存在显著差异(P<0.05);并且,在弯曲度较大的一组(21°～35°),磨牙的弯曲度变化要显著大于前磨牙(P<0.05).结论用GG钻行根管弯曲部分冠部预处理后能显著减小根管弯曲程度,降低根管预备难度,其中磨牙的弯曲度变化较大.     

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。     

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。     

离体下颌前磨牙根管的颊舌向弯曲

目的：确定人下颌第一、二前磨牙的颊舌向根管弯曲程度和情况。方法：离体第一前磨牙69个，第二前磨牙93个，摄近中远中向的X线片，用Photoshop5．0软件分析根管，用Weine氏法测量根管的弯曲度，测量角度大于18度时，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：下颌第一前磨牙根管颊舌向弯曲牙齿的发生率是7.2％（5／69），下颌第二前磨牙根管颊舌向弯曲牙齿的发生率是5．3％（5／93），二者之间无明显的差异（P〉0．05）。结论：下颌前磨牙颊舌向的根管弯曲发生率较低。     

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。     

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.     

3种镍钛机动器械预备磨牙弯曲根管成形能力的比较

目的:比较3种机动镍钛预备系统(Mtwo、ProTaper和Hero642)预备磨牙弯曲根管的根尖偏移和根管弯曲度的变化.方法:采用3种镍钛机动预备系统预备磨牙弯曲根管,拍摄数字化X线片记录预备前、后分别将15#初尖锉和主尖锉置于根管中的根管影像.用Schneider法测量比较根管预备前、后弯曲度的变化,并将根管预备前后器械尖端相应位置描记后,在立体显微镜下借助测距装置测量根尖偏移指数(ATI).所有数据均采用SAS 6.12软件包进行统计学分析.结果:Hero642系统发生器械折断2枚.3种机动镍钛预备系统中,Mtwo系统根管预备的时间最短,预备1个根管仅需26.7s,ProTaper系统和Hero642系统分别需要28.12s和78.98s;经统计学分析,Hero642系统与另2组之间有显著差异(P＜0.01).3种镍钛机动器械预备前、后根管弯曲度的改变均有显著意义.Hero642系统的根尖偏移最大,ProTaper系统的根尖偏移最小.3组标本经方差分析,无显著差异(P＞0.05).结论:Mtwo和ProTaper机动镍钛预备系统用于预备后牙弯曲根管,效率高,成形能力强,是较理想的弯曲细小根管的预备器械.     

第一磨牙冠方预展后根管弯曲度的改变及对初锉选择的影响

目的探讨冠方预展后离体第一磨牙各根管弯曲度的变化及对初锉选择的影响。方法上下颌离体第一磨牙各30颗,共163个根管,平行投照法拍摄X线片,用Schneider法测量根管弯曲度,用GG钻进行冠方预展,比较预展前后根管弯曲度和初锉大小的变化。结果冠方预展后弯曲度比术前减小4.96°±3.85°,差异有统计学意义(P<0.05)。根管原始弯曲度越大,预展后弯曲度的改变也越大。冠方预展后各根管初锉号数比术前增大,平均为0.06±0.05mm。结论冠方预展去除了根管上段的干扰,减小了根管的弯曲度,增大了初锉号数,使根管根尖部的预备变得容易,有效。提倡在根尖部预备之前先行冠方预展。     

壮族人群恒前牙根管弯曲度测定

目的了解壮族人群恒前牙的根管弯曲情况。方法收集新鲜拔除的壮族人群恒前牙245颗,采用间接影像学手段观察其根管类型和弯曲形状,在Schneider法和Sch覿fer法的基础上,结合电子测量尺软件测量分析218颗Ⅰ型根管牙齿的弯曲度、弯曲半径和弯曲长度。结果壮族人群恒前牙以Ⅰ型根管为主,有13颗下颌中切牙和12颗下颌侧切牙为Ⅱ、Ⅲ、Ⅳ型根管。上颌中切牙、侧切牙、尖牙以及下颌中切牙、侧切牙、尖牙Ⅰ型根管近远中向弯曲发生率分别为40%、80%、77%、65%、66%、73%,唇舌（腭）向弯曲发生率分别为62%、69%、70%、62%、41%、61%。弯曲部位多在根尖1/3,多为中度弯曲;上颌尖牙在近远中向上的根管弯曲度最大,下颌尖牙在唇舌（腭）向上的根管弯曲度最大;上颌侧切牙在近远中和唇舌（腭）2个方向上的根管弯曲半径及弯曲长度均较小。结论壮族人群恒前牙根管弯曲情况较复杂,其下颌切牙Ⅱ、Ⅲ、Ⅳ型根管发生率较高。     

镍钛机动根管预备器械对根管弯曲度的影响

目的：评价3种镍钛机动预备系统保持弯曲率的能力及其工作效率,方法：离体下颌磨牙近中弯曲根管64个,随机分为4组：Flexofile,LightSpeed,ProFile,Qantec SC.分别预备到主尖锉30号和40号,对各组器械预备前后的根管弯曲度和预备时间进行测量。结果：Flexofile组的根管弯曲度减少最明显,在颊舌向与另外3组镍钛器械间的差异均有非常显著意义（P＜0．01）,在主尖锉为30号的镍钛组,预备前后的根管弯曲度无统计学差异（P＞0．05）,ProFile和Quantec SC预备都显著缩短操作时间,与Flexofile组间的差异有显著意义（P＜0．01）。结论：镍钛机动预备器械能很好地保持根管的原有弯曲度,节省预备时间。     

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。     

A comparative study of root canal preparation with HERO 642 and Quantec SC rotary Ni-Ti instruments

AIM: The purpose of this study was to compare several parameters of root canal preparation using two different rotary nickel-titanium instruments: HERO 642 (Micro-Mega, Besancon, France) and Quantec SC (Tycom, Irvine, CA, USA). METHODOLOGY: Fifty extracted mandibular molars with root canal curvatures between 20 micro and 40 micro were imbedded into a muffle system. All root canals were prepared to size 45 (Quantec SC), or 40 (HERO 642), respectively. The following parameters were evaluated: straightening of curved root canals, postoperative root canal diameter, safety issues (file fractures, perforations, apical blockages, loss of working length), cleaning ability, and working time. RESULTS: Both Ni-Ti-systems maintained curvature well; the mean degree of straightening was 2.3 degrees for Quantec SC and 1.6 degrees for HERO 642. Most procedural incidents occurred with Quantec SC instruments (five fractures, three apical blockages, eight cases of loss of working length), HERO 642 preparation resulted in three blockages and one perforation. Following preparation with HERO 642, 63% of the root canals showed a round, 24% an oval, and 17% an irregular diameter; Quantec SC preparations resulted in a round diameter in 24% of the cases, oval shape in 29%, and irregular cross-section in 47% of the cases. Mean working time was shorter for HERO 642 (52 s) than for Quantec (117 s). Cleanliness of the root canal walls was investigated under the SEM using a five-score system for debris and smear layer. For debris HERO 642 achieved better results (80% scores 1 and 2) than Quantec SC (76%). The results for smear layer were similar: cleaner root canal walls were found after preparation with HERO 642 (53% scores 1 and 2), followed by Quantec SC (41%). CONCLUSIONS: Both systems respected original root canal curvature well and showed good cleaning ability; Quantec SC showed deficiencies in terms of safety.     

Comparison of root canal preparation with two rotary NiTi instruments: ProFile .04 and GT Rotary

AIM: To compare root canal preparation using ProFile .04 and GT Rotary nickel-titanium instruments (both Dentsply Maillefer, Ballaigues, Switzerland). METHODOLOGY: Fifty extracted mandibular molars with mesial root canal curvatures between 20 and 40 degrees were randomly divided into two groups and embedded in a muffle system. All root canals were prepared to size 45 using ProFile .04 or GT rotary instruments. The following parameters were evaluated: straightening of root canal curvature, postoperative root canal cross-section, cleaning ability, safety issues and working time. RESULTS: Both NiTi systems maintained curvature well; the mean degree of straightening was <1 degrees . The majority of the root canals prepared with ProFile .04 (80.8%) and GT (84.0%) postoperatively showed a round or oval cross-section. For debris, ProFile .04 and GT rotary achieved 67.1% and 71.6% scores of 1 and 2, respectively. Concerning the coronal region statistical analysis showed a better result for GT than for ProFile .04. For the middle and apical thirds of the root canals, results did not differ significantly. None of the two systems completely removed smear layer. Ten procedural incidents occurred with ProFile .04 compared with five with GT. Mean working time was shorter for ProFile .04 (131.8 s) than for GT (143.7 s); the difference was not significant. CONCLUSIONS: Both systems respected original root canal curvature well and were safe to use. Smear layer removal was not satisfactory with either systems.     

Root form and canal anatomy of maxillary first premolars.

The external and internal anatomy of 240 extracted, maxillary first premolars was studied. The external anatomy was studied by measuring each tooth and by observing the direction of the root curvatures from the facial and proximal aspects. The internal anatomy of the pulp cavity was studied by a method of making the teeth translucent. A total of 55.8% of the teeth had a single root, 41.7% had two roots and 2.5% had three roots. Considering all of the first premolars, 17.1% had one canal, 80.4% had two canals and 2.5% had three canals.     

三种器械预备磨牙弯曲根管成形能力的比较

目的　研究手用ProTaper与不锈钢K锉、镍钛合金K锉预备磨牙弯曲根管对根管弯曲度和根尖偏移的影 响。方法　45个弯曲度为20°~40°的磨牙根管,按弯曲度大小排序后分成15个区组,每区组3个根管,再随机分配 至3个不同处理组,每组15个根管。A组采用手用ProTaper系统行冠根向深入法根管预备;B、C组分别采用不锈钢 K锉和镍钛合金K锉行改良逐步后退法预备根管。记录3组根管预备前后根管影像及器械尖端所在位置,测量并 比较3组间根管弯曲度的变化、根尖偏移指数(ATI)和操作时间。结果　A组的根管弯曲度在根管预备前后仅改变 0·28°,明显低于B、C组,ATI亦小于B、C组(P<0·05);B组根管弯曲度的变化和ATI均大于A、C组(P<0·05);A组 的操作时间最短。结论　与不锈钢K锉、镍钛合金K锉比较,采用手用ProTaper预备磨牙弯曲根管成形效果较好, 效率较高。     

Influence of different types of automated devices on the shaping ability of rotary nickel-titanium FlexMaster instruments

AIM: To compare the shaping ability of rotary FlexMaster nickel-titanium instruments in simulated curved canals and in curved canals of extracted teeth when set into permanent rotation with three different torque-limited automated devices. METHODOLOGY: Root canal instrumentation was performed with three different torque-limited automated devices (ENDOadvance, SIRONiTi and Endo IT motor) by FlexMaster nickel-titanium instruments up to size 35. Simulated canals: 28 degree and 35 degree curved canals in resin blocks (n = 20 canals in each group) were prepared. Pre- and post-instrumentation images were recorded and assessment of canal shape was completed with a computer image analysis program. Extracted teeth: A total of 60 curved root canals were divided into three groups, which were balanced with respect to the angle and the radius of canal curvature. Straightening of the canal curvatures was determined with a computer image analysis program. Incidence of canal aberrations, preparation time, changes of working length and instrument failures were recorded both in simulated and real canals. RESULTS: In simulated and real canals, instrumentation with Endo IT was significantly faster than with SIRONiTi (P < 0.05). With respect to canal aberrations in simulated canals, there were no significant differences between the devices (P > 0.05), even though more aberrations were created with ENDOadvance and SIRONiTi. In real canals, the Endo IT motor resulted in significantly less straightening during instrumentation (P < 0.05) than SIRONiTi. A total of three instruments separated (one file in each group) during the enlargement of 35 degree curved simulated canals. All systems maintained working distance well. CONCLUSIONS: All systems respected original root canal curvature well and were safe, indicating that torque-limited rotation handpieces are suitable for preparing curved root canals.     

A comparative study of root canal preparation with NiTi-TEE and K3 rotary Ni-Ti instruments

Aim To evaluate and compare several parameters of curved root canal preparation using two different Ni‐Ti systems: NiTi‐TEE (Sjöding Sendoline, Kista, Sweden) and K3 (Sybron Endo, Orange County, CA, USA). Methodology Fifty extracted mandibular molars with mesial root canal curvatures ranging from 20 to 40° were divided into two groups. In one group, 50 root canals were instrumented using NiTi‐TEE files to an apical size 30; 0.04 taper (the largest available size at the time of this study). In the other group, 50 root canals were prepared with K3 instruments to an apical size 45; 02 taper. Both systems were used in a crowndown manner, with copious NaOCl (3%) irrigation and a chelating agent (Calcinase Slide, lege artis, Dettenhausen, Germany), employing torque‐controlled motors. For assessment of shaping ability, pre‐ and postinstrumentation radiographs and cross‐sectional photographs of canals were taken and changes in canal curvature and root canal diameter documented. Cleaning ability was evaluated by investigating specimens of the apical, medial and coronal third of the root canal wall under a scanning electron microscope using 5‐score indices for debris and smear layer. Procedural errors (instrument separations, perforations, apical blockages, loss of working length) and working time were recorded. Nonparametric anova was used to compare straightening of canal curvatures, canal cross‐sections and canal wall cleanliness (P < 0.05), whereas working time was analysed using the parametric anova (P < 0.05). Results Both Ni‐Ti systems maintained curvature well: the mean degree of straightening was 0.2° for NiTi‐TEE and 0.4° for K3 with no statistical significance between the groups. Post‐instrumentation cross‐sections of the root canals revealed an acceptable contour (round or oval) in 50.6% of cases for the NiTi‐TEE group and in 65.3% of cases for the K3 group. The difference was not significant. The SEM investigation of canal walls showed equally good debris removal for both systems: NiTi‐TEE prepared canal walls in 74.7% of cases with scores I and II; K3 achieved these scores in 78.7% of cases. For smear layer, NiTi‐TEE and K3 only received good scores (I and II) in 38.7% and 40% of canal wall specimens, respectively. For both parameters, no significant differences were found between groups. File fractures did not occur, but loss of working length was observed in one case following the preparation with NiTi‐TEE and in three cases during K3 instrumentation. Mean working time was significantly shorter for NiTi‐TEE (170 s) than for K3 (208 s). Conclusions Both systems maintained original canal curvature well and were safe to use. Whilst debridement of canals was considered satisfactory, both systems failed to remove smear layer sufficiently.     

A comparative study of root canal preparation using Profile .04 and Lightspeed rotary Ni-Ti instruments

AIM: The purpose of this Study was to compare several parameters of root canal preparation using two different rotary nickel-titanium instruments: ProFile .04 (Dentsply/ Maillefer, Ballaigues, Switzerland) and Lightspeed (Lightspeed Technology Inc., San Antonio, TX, USA). METHODOLOGY: Fifty extracted mandibular molars with root canal curvatures between 20 degrees and 40 degrees were divided into two similar groups having equal mean curvatures. The teeth were then embedded into a muffle system as described by Bramante et al. (1987) and modified by Hülsmann et al. (1999b). All root canals were prepared using ProFile .04 or Lightspeed Ni-Ti instruments to size 45 following the manufacturers' instructions. The Lightspeed system was used in a step-back technique: ProFile .04 instruments were used in a crown-down technique. The following parameters were evaluated: straightening of curved root canals (superimposition of pre- and postoperative radiographs), postoperative root canal diameter (superimposition of pre- and postoperative photographs of root canal cross-sections), safety issues (file fractures. perforations, apical blockages, loss of working length) (protocol), cleaning ability (SEM-evaluation of root canal walls using a five-score system for debris and smear layer), and working time (protocol). Statistical analysis was performed using the Wilcoxon test (P < 0.05) for straightening, and Fisher's exact-test (P < 0.05) for comparison of cross-sections, for comparison of contact between pre- and postoperative diameter, root canal cleanliness and working time. RESULTS: Both Ni-Ti systems maintained curvature well; the mean degree of straightening was less than 1 degrees for both ProFile .04 and for Lightspeed with no statistical significance between the groups. Most procedural incidents occurred with Profile .04 instruments (three fractures), Lightspeed preparation was completed without instrument fractures. Loss of working length, perforations or apical blockage did not occur with either instrument. Following preparation with Profile.04. 64.0% of the root canals had a round, 30.7% an oval, and 5.3% an irregular cross-section, Lightspeed preparation resulted in a round cross-section in 41.3% of cases, an oval shape in 45.3% of cases: 13.3% of cases had an irregular cross-section. No significant differences were found between the two systems. Lightspeed instruments enlarged the root canal more uniformly with no specimen showing 50% or more contact between pre- and postoperative diameter. The difference was statistically significant only for the coronal third of the root canals (P = 0.032). Mean working time was significantly shorter for Profile .04 (105 s) than for Lightspeed (140 s) (P = 0.02). For debris removal Lightspeed achieved the best results (68% scores 1 and 2), followed by Profile .04 (48.4%) with no significant differences between the systems. The results for remaining smear layer were similar: the lowest amount of smear layer on the root canal walls was found after preparation with Lightspeed (30.7% scores 1 and 2). followed by Profile.04 (23.1%). In the coronal third of the root canals Lightspeed performed significantly better than Profile .04 (P = 0.029): in the middle and apical third the differences were not significant. CONCLUSIONS: Both systems under investigation respected original root canal curvature and were safe to use. Both systems can be recommended for clinical use.