4种机用镍钛锉根管预备后形成牙本质微裂的研究

目的 运用micro-CT比较T-Flex、Reciproc Blue (RB)、ProTaper Gold (PTG)和ProTaper Universal(PTU) 4种机用镍钛锉在体外根管预备后牙本质微裂形成方面的差异。方法 选用根管弯曲度不大于10°的新鲜离体双根管前磨牙32颗建立体外根管预备模型。根据所用镍钛系统将其随机分为T-Flex、RB、PTG、PTU组（n=8）。设置micro-CT体素大小为17.18μm,扫描分析预备前后牙根横断面图像（n=56 940）,观察牙本质微裂的存在。各组结果以存在裂纹的断层图像的数量及百分比来表示,McNemar检验用于比较预备前后牙本质裂纹的存在是否有显著差异,显著性水平设定为P<0.05。结果 总体有11.04%的图像显示有牙本质微裂（n=6 288）。T-Flex、 RB、 PTG和PTU组在预备后观察到具有牙本质微裂截面的比例各自为9.82%、 10.79%、 12.27%和11.25%。所有在预备后断层图像上发现的牙本质裂纹在相应的预备前图像中均已存在。使用上述镍钛系统预备前磨牙根管未出现新的微裂纹。结论 未经根管预备的...     

四种机用镍钛系统根管预备后牙本质微裂比较研究

目的    通过比较4种机用镍钛系统体外预备根管后产生牙本质微裂的差异,为临床医生选择根管预备器械和方法提供参考。方法    选取2016年1—10月在中国医科大学附属口腔医院、鞍钢集团总医院口腔科及中国医科大学附属第一医院鞍山医院口腔科门诊拔除的新鲜完整下颌切牙为研究对象,按统一标准选择125颗样本制作研究模型,采用随机号码表法将样本平均分为5组,4个预备组分别应用机用ProTaper Next（N组）、WaveOne Gold（W组）、M3-Pro（M组）、ProTaper Universal（P组）进行根管预备,余下一组作为对照（C组）不进行根管预备。在距根尖3、6、9 mm处水平切割牙根,显微镜下观察记录各截面出现牙本质微裂情况,应用SPSS软件进行卡方检验。结果    未预备的C组没有发现牙本质微裂,P组产生微裂的牙数与N组、W组和M组分别对比均有显著增多,差异有统计学意义（P < 0.05）。所有预备组在距根尖3 mm处产生微裂的牙总数对比距根尖6 mm处和9 mm处有显著增多,差异有统计学意义（P < 0.05）。结论    应用机用镍钛器械进行根管预备可能造成牙本质微裂,在距根尖3 mm处产生的微裂要显著多于距根尖6 mm和9 mm处;相较ProTaper Universal,使用ProTaper Next、WaveOne Gold和M3-Pro可显著降低微裂的发生率。     

镍钛器械对椭圆形根管预备效果的影响

椭圆形根管具有特殊的解剖学形态,使用镍钛器械预备根管时在追求良好的成形能力同时,也会有不良的影响。目前几种常用的镍钛器械中,既有较高牙本质切削效率的优势也有形成牙本质微裂的风险;虽然镍钛器械代代更新,但是目前研究发现无论哪种器械对于椭圆形根管预备均具有一定的缺陷。本文将从镍钛系统对椭圆形根管的成形能力,包括切削能力、保持原有根管形态的能力以及不良影响如推出根尖孔碎屑量、形成牙本质微裂的影响两个大方面进行综述,为选择合适的镍钛器械预备椭圆形根管提供依据。     

3种镍钛器械预备重度弯曲根管后牙本质微裂纹的观察

目的 研究3种镍钛器械预备重度弯曲根管后牙本质微裂的发生情况。方法 收集临床上拔除的近中根牙根弯曲度在25°~40°的磨牙240颗,按弯曲度25°~30°（不包括25°）、30°~35°、35°~40°随机分为A、B、C 3组,每组80个标本,均用K锉预备到15#。将3组随机分为4个亚组,每个亚组20颗,1组为对照组,另外3组为实验组。对照组不进行镍钛预备,将实验组中的牙根分别用WaveOne、ProTaper Next、M3-Pro 3种镍钛器械进行预备,并浸泡于1%亚甲蓝24 h。然后分别取牙根最弯处以及距最弯处上、下2 mm的截断面,在体视显微镜下观察各断面牙本质微裂纹的情况。采用SPSS 20.0软件包对数据进行统计学分析。结果 WaveOne、ProTaper Next、M3-Pro 3组均使牙本质产生微裂,WaveOne组发生比例最高,ProTaper Next组最低,WaveOne组与其他2组的差异有统计学意义（P<0.05）,ProTaper Next组与M3-Pro组无显著差异（P>0.05）。随着牙根弯曲角度的增大,WaveOne、ProTaper Next、M3-Pro 3组牙本质微裂的数量增加,除Waveone组在 A（25°~30°）与C（35°~40°）2组中牙本质微裂发生比例的差异有统计学意义（P<0.05）外,其余均无统计学差异（P>0.05）。结论 ProTaper Next与M3-Pro更有利于中重度弯曲根管的预备。     

不同预备方式预备根管后牙本质裂纹产生状况分析

目的    评价往复运动和旋转运动的镍钛器械预备根管后牙本质裂纹产生的情况。方法    2015年5月于中国医科大学中心实验室选用人的单根管下颌第一前磨牙60颗,随机分为4组（每组15颗）：A组采用手用不锈钢K锉进行根管预备,B组采用机用Protaper进行根管预备,C组采用Reciproc进行根管预备,D组采用单支锉Wave One进行根管预备。将预备完成的离体牙垂直于牙体长轴分别距离根尖3、6、9 mm水平截断,体视显微镜下观察并记录牙本质裂纹产生情况。结果    使用Protaper预备根管产生的牙本质裂纹明显多于使用Reciproc和Wave One组（P < 0.05）,后两组产生裂纹情况差异并无统计学意义（P > 0.05）。结论    旋转运动的镍钛锉比往复运转的镍钛锉产生的牙本质裂纹多,降低牙根的抗折性。     

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。     

ProTaper根管预备器械的研究现状

ProTaper器械是一种新型的镍钛机动根管预备器械，它采用可变多锥度的刃部，凸三角形横截面的设计，使该器械具有更高的切削力、弹性和理想的成形根管能力。同时，ProTaper的器械数量少，操作省时，可以明显提高根管预备效率，尤其适于弯曲根管的预备。     

不同镍钛根管预备系统对牙本质裂纹形成的影响

目的 探讨不同镍钛旋转预备系统ProTaper Universal（PU）、ProTaper Next（PN）和X+File（X+）对牙本质微裂纹形成的影响。方法 将100颗下颌前磨牙随机分为4组（n=25）。组1为对照组（不做根管预备）;组2为PU预备组（SX预备根管口,S1、S2、F1、F2预备直达工作长度）;组3为PN预备组（Protaper Universal SX预备根管口,再用ProTaper Next X1、X2预备直达工作长度）。组4为X+预备组（Protaper Universal SX预备根管口,然后用X+File X1、X2预备直达工作长度）。预备完成后,所有离体牙在距根尖顶点3mm、6mm和9mm处垂直于牙体长轴做横切片,在根管显微镜下观察并记录裂纹形成情况。卡方检验对裂纹形成数目进行统计分析。结果 对照组未产生牙本质裂纹。镍钛旋转系统PU、PN和X+的牙本质裂纹发生率分别为60%,32%和24%（P<0.05）。仅PU组产生完全裂纹,且数目高于另外3组（P<0.05）。在根尖1/3处,PU组的不完全裂纹数高于另外3组（P<0.05）。PN组和X+组的牙本质裂纹发生率无明显差异（P>0.05）。结论 本研究中使用的3种镍钛根管预备系统均产生了牙本质裂纹。其中,X+File与ProTaper Next产生的牙本质裂纹较少,这可能与镍钛金属结构、尖端设计以及中心定位能力有关。     

根管区段预备技术

本文介绍了根管区段预备技术的概念及步骤,并介绍了在各步使用的特定器械。区段技术将根管分为两个区段：冠区（根管弯曲之上的区段）和根尖区（弯曲之下的区段）。不论根管弯曲程度如何．都应先作确定弯曲所在。预备分成4步．第一步：确定弯曲到根尖的距离;第二步：镍钛旋转器械敞开根管冠区;第三步：用逐步后退法扩大根尖区．依次用ISO#20锥度．02．#25.02,#25．04．#25．06镍钛旋转器械;第四步：用#3006或者#35．06镍钛旋转器械完成根尖1／3的成型。     

弯曲根管用镍钛器械预备后根管偏移的研究

目的:研究3种镍钛根管预备器械预备后牙弯曲根管产生根管偏移的情况。方法:选择48个弯曲度>25°的下颌第一、二磨牙近中根包埋于Branmante模型中,分别用机动Hero642、Profile和手用ProTaper、不锈钢K锉进行根管预备。拍摄根管预备前后根尖、根中段横截面的影像,测定根管偏移的量、方向和轴中心率。结果:Hero642和Profile在根尖段和根中段根管的偏移显著小于不锈钢K锉,手用ProTaper仅在根尖段小于不锈钢K锉; 3种镍钛器械的轴中心率均低于不锈钢K锉,而镍钛器械组间无显著性差异;镍钛器械和不锈钢器械在根尖段根管中心偏向近中侧,而在根中段不锈钢K锉和手用ProTaper根管中心多数偏向远中侧,与Hero642和Profile有显著性差异。结论:Hero642、Profile和ProTaper在预备弯曲根管时有较小的偏移及良好的中心定位作用,尤其是Hero642和Profile对根尖和根中段成形能力较佳。     

Rationale for the use of low-torque endodontic motors in root canal instrumentation

Abstract – Fracture of nickel‐titanium rotary files is an iatrogenic error which can seriously jeopardize root canal therapy. If a high‐torque motor is used, the instrument‐specific limit‐torque (fracture limit) is often exceeded, thus increasing the risk of intracanal failure. A possible solution to this problem is to use a low‐torque endodontic motor which operates below these values. If the torque is set just below the limit of elasticity for each instrument, the risk of fracture is likely to be markedly reduced. The purpose of this paper was to discuss mechanical properties of NiTi rotary instruments, the rationale for selecting low torque values, and to use clinically a new endodontic motor (step‐motor) which operates below the limit of elasticity of each rotary file. The step‐motor was found to be helpful in reducing the risk of instrument fracture. Irreversible material damage (plastic deformation) and instrument fracture were rarely seen. Low‐torque instrumentation also increased tactile sense and, consequently, mental awareness of rotary instrumentation.     

Hand and nickel-titanium root canal instrumentation performed by dental students: a micro-computed tomographic study

The aim of this study was to evaluate root canals instrumented by dental students using the modified double-flared technique, nickel-titanium (NiTi) rotary System GT files and NiTi rotary ProTaper files by micro-computed tomography (MCT). A total of 36 root canals from 18 mesial roots of mandibular molar teeth were prepared; 12 canals were prepared with the modified double-flared technique, using K-flexofiles and Gates-Glidden burs; 12 canals were prepared using System GT and 12 using ProTaper rotary files. Each root was scanned using MCT preoperatively and postoperatively. At the coronal and mid-root sections, System GT and ProTaper files produced significantly less enlarged canal cross-sectional area, volume and perimeter than the modified double-flared technique (P < 0.05). In the mid-root sections there was significantly less thinning of the root structure towards the furcation with System GT and ProTaper (P < 0.05). The rotary techniques were both three times faster than the modified double-flared technique (P < 0.05). Qualitative evaluation of the preparations showed that both ProTaper and System GT were able to prepare root canals with little or no procedural error compared with the modified double-flared technique. Under the conditions of this study, inexperienced dental students were able to prepare curved root canals with rotary files with greater preservation of tooth structure, low risk of procedural errors and much quicker than with hand instruments.     

Shape of the root canal after ultrasonic instrumentation with K-Flex files

Abstract This study investigated the feasibility of using K-Flex files with the Cavi-Endo ultrasonic unit. The effectiveness of the K-Flex files in shaping canals was compared with the ultrasonic Cavi-Endo K-files. Simulated curved canals in clear resin blocks were instrumented ultrasonically using the 2 file types. Pre- and postinstrumentation photographs were taken and the following were evaluated: apical and coronal areas, the incidence of the narrowing of the canals coronal to the apical transport (elbows). Displacement amplitude measurements were carried out in order to see any relationship between the incidence of elbows and displacement amplitudes of the files. The results indicated that the K-Flex files were more efficient than the ultrasonic K-files and resulted in less elbow formation. No direct relationship was observed between displacement amplitudes and the incidence of elbow formation. It is suggested that the manufacturers of ultrasonic units consider different file designs.     

A histobacteriological assessment of nonvital teeth after ultrasonic root canal instrumentation

Abstract The purpose of this study was to evaluate and discuss the bactericidal effect of ultrasound when applied in the root canal of teeth with necrotic pulp and periapical lesions. Twenty newly extracted teeth were instrumented with an ultrasonic unit and K-files using 0.5% sodium hypochlorite as irrigating solution. Compacted debris and micro-organisms were frequently observed in the apical region and in dentinal tubules of the root canal wall. Overinstrumentation that sometimes occurred led to contamination of the periapical lesions with micro-organisms and debris from the root canal.     

Comparative debridement study between hand and sonic instrumentation of the root canal

Abstract The cleaning efficiency of hand and sonic instrumentation with MM Sonic 3000 in 60 single-rooted human straight teeth was evaluated using light and scanning electron microscopy. The root canals were instrumented with K-type files and Shaper Sonic files, respectively, and manually irrigated with 1 % sodium hypochlorite. The results showed no statistically significant difference between hand and sonic instrumentation. In both groups a smear layer, untouched predentin and pulp tissue debris were generally observed.     

Inability of laser and rotary instrumentation to eliminate root canal infection

BACKGROUND: The authors evaluated the antibacterial effectiveness of laser instrumentation and rotary instrumentation of anterior, single-rooted teeth infected with Enterococcus faecalis. METHODS: The authors divided 35 infected samples into five groups: Group A: inoculation, laser, 17 percent ethylene-diamine-tetra-acetate (EDTA), 2.5 percent sodium hypochlorite (NaOCl) (n=10); Group B: inoculation, laser, 17 percent EDTA, sterile saline (n = 10); Group C: inoculation, rotary, 17 percent EDTA, 2.5 percent NaOCl (n=10); Group D: inoculation, no instrumentation (positive control) (n=5); Group E: no inoculation, no instrumentation (negative control) (n=5). They sampled and incubated dentin shavings from each canal for bacterial growth. RESULTS: In Group A, eight tubes were positive for bacterial growth. In Group B, 10 tubes were positive for bacterial growth. In Group C, six tube were positive for bacterial growth. In Group D, all of the tubes were positive for bacterial growth. In Group E, no tubes showed bacterial growth. The Fisher exact test showed no significant differences among groups A, E and C. CONCLUSION: Neither the laser nor the rotary instrumentation was able to eliminate endodontic infection. CLINICAL IMPLICATIONS: Although lasers have been presented as high-tech tools for disinfecting root canals, the laser was ineffective in this study.     

Efficacy and safety tests of six automated devices for root canal instrumentation

Abstract it was the purpose of this study to lost the efficacy and safety of automated devices for root canal instrumentation. Instruments tested were Giromatic with (a) barbed broaches and Hedstrom files, and (b) RISPI files; Dynatrak with Unifiles; Canal Finder System with K-files and modified Hedstrom files; Cavi-Endo with K-files and diamond-coated instruments; Endostar 5 with K-files; and MM sonic 3000 with (a) RISPI files, and (b) Sonic Shapers. Transparent plastic models with simulated root canals of various widths and shapes were used. The canals were enlarged by 0.2 mm at their apices and the instrumentation time-was recorded. Complications during instrumentation were also recorded. With regard to efficacy, 3 devices stood out among the instruments tested: Giromatic with RISPI files, the Canal Finder System, and the MM Sonic 3000. With the Canal Finder System and the MM Sonic 3000 the tests were completed without complications. It was concluded that automated devices for endodontic treatment are now available that are both efficient and remarkably safe.     

Efficacy of various concentrations of NaOCl and instrumentation techniques in reducing Enterococcus faecalis within root canals and dentinal tubules

AIM: To evaluate the efficacy of 0.5%, 2.5% and 5.25% sodium hypochlorite (NaOCl) as intracanal irrigants associated with hand and rotary instrumentation techniques against Enterococcus faecalis within root canals and dentinal tubules. METHODOLOGY: A total of 180 extracted human premolar teeth were infected for 21 days with E. faecalis. The specimens were divided into 12 groups, as follows: group 1: 5.25% NaOCl + Hybrid technique (Valdrighi et al. 1998); group 2: 5.25% NaOCl + nickel-titanium (NiTi) rotary technique 4 mm shorter than the apex (by FOP-UNICAMP); group 3: 5, 25% NaOCl + NiTi rotary technique (Hero 642); group 4: 2.5% NaOCl +Hybrid technique; group 5: 2.5% NaOCl + NiTi rotary technique 4 mm shorter than the apex; group 6: 2.5% NaOCl + NiTi rotary technique (Hero 642); group 7: 0.5% NaOCl + Hybrid technique; group 8: 0.5% NaOCl + NiTi rotary technique 4 mm shorter than the apex; group 9: 0.5% NaOCl + NiTi rotary technique (Hero 642); group 10: sterile saline solution + Hybrid technique; group 11: sterile saline solution + NiTi rotary technique 4 mm shorter than the apex; group 12: sterile saline solution + NiTi rotary technique (Hero 642). Canals were sampled before and after preparation. After serial dilution, samples were plated onto brain heart infusion (BHI) agar, and the colony forming units (CFU) that were grown were counted. The teeth were sectioned into three thirds and dentine chips were removed from the canals with conical burs. The samples obtained with each bur were immediately collected into test tubes containing BHI broth, and were incubated at 37 degrees C and plated onto BHI agar. The CFU were counted and analysed. RESULTS: At all depths and thirds of the root canals and for all techniques used, 5.25% NaOCl was shown to be the most effective irrigant solution tested when dentinal tubules were analysed, followed by 2.5% NaOCl. No differences among concentrations in cleaning the canals were found. CONCLUSIONS: Especially at higher concentrations, NaOCl, was able to disinfect the dentinal tubules, independent of the canal preparation technique used.