A new non-instrumental technique for cleaning and filling root canals

The aim of this in vitro study was to test the ability of a novel non-instrumental technique to prepare and obturate root canals. Cleaning of the root canal system was achieved with a device which was able to develop, under reduced pressure, controlled cavitation. The same device was used for proper drying and subsequent obturation of the root canal system. A total of 55 freshly extracted molars with 120 canals were treated either by the step-back technique and lateral condensation of gutta-percha and AH26 as a sealer or by the new device. The teeth were then sectioned horizontal to the long axis of the root canal and examined by light microscopy. The cross-sectional area, area with residual pulpal tissue and voids were assessed morphometrically. Overall, the treatment with the new device resulted in similar cleanliness and obturation quality when compared with the control group. Total treatment time using the new non-instrumental technique, however, was less than half of that using hand instrumentation.     

不同根管器械预备弯曲根管的实验研究

目的比较手用不锈钢K锉、手用ProTaper锉、机用ProTaper锉在预备中、重度弯曲根管时的成形能力及其对根尖孔形态特征的影响。方法将40个树脂根管模型分为A、B、C、D组,A、B、C组各12个树脂根管模型,其中每组20°根管和30°根管各6个;D组4个树脂根管模型,均为小于5°根管。分别以手用不锈钢K锉、手用ProTaper锉、机用ProTaper锉预备根管,数码相机摄片,运用专业图像分析软件Auto-CAD比较根管偏移及根尖孔形态。结果B组中轴偏移明显高于A组和C组（P<0.05）,其中C组与A组在个别根管段有显著差异（P<0.05）。预备后根尖孔B组各项值均显著高于其他各组,B3组根管值显著高于B2组（P<0.05）。相同根管弯曲度下C组值高于A组;不同弯曲度下30°根管值高于20°根管值,但均无显著性差异（P>0.05）。结论两种镍钛器械均产生根管偏移,根管弯曲度是偏移产生的主要原因;与不锈钢器械相比,镍钛器械能较好地保持原根管走向及根尖孔形态。     

Effect of a separated instrument on bacterial penetration of obturated root canals

The aim of this study was to determine the effect a separated instrument has on the time required for bacterial penetration of obturated root canals. Twenty-six extracted human mandibular premolars with single canals were used in the study. Group 1 consisted of teeth that contained a separated size 40 Profile rotary file and were obturated with gutta-percha and zinc oxide eugenol sealer to the level of the separated file. Group 2 consisted of teeth that were similarly obturated, but without a separated file. The negative control canals were obturated and had the entire root surface sealed with nail polish. The positive controls were obturated without sealer. Streptococcus sanguis was placed in the access chamber daily, and penetration was determined when turbidity was noted in the culture broth. The results showed no significant difference between the two experimental groups.     

Air pressures developed beyond the apex from drying root canals with pressurized air

Air introduced into tissues during invasive procedures can be harmful. Endodontic treatment is not frequently associated with this phenomenon, but serious results can occur if air forced into tissues impinges on critical anatomical structures and/or carries infection into deeper areas. Extracted teeth were connected to a pressure gauge during and after canal instrumentation and pressures measured. Also, a fresh porcine jaw was instrumented in the presence of a radiopaque tracer during air drying. Significant pressures were detected beyond the apex of the roots, especially with root apical diameters of file sizes larger than 20.     

Effect of a separated rotary instrument on bacterial penetration of obturated root canals

OBJECTIVE: The purpose of this study was to determine the effect of a separated rotary instrument on the time required for bacterial penetration of obturated root canals METHODOLOGY: Twenty-six extracted human mandibular premolars with single canals were used in this study. Group 1 consisted of teeth that contained a separated size 40 K3 rotary file, and were obturated with gutta-percha and AH-26 sealer to the level of the separated file. Group 2 consisted of teeth that were obturated similar to Group 1 but without a separated file. The negative control canals were obturated and had the entire root surface sealed with nail varnish. The positive controls were obturated without sealer. Enterococcus faecalis was placed in the access chamber daily, and penetration was determined when turbidity was noted in the culture broth. RESULTS: The results showed no significant difference between Groups 1 and 2. However, differences between the experimental groups and control groups were statistically significant. CONCLUSION: Under the conditions of the present study, the separated instrument itself does not play a significant role in the sealing ability of the obturation material.     

Comparison of the Canal Master endodontic instrument and K-type files for enlargement of curved root canals

Twenty mandibular molars with 40 mesial curved root canals were instrumented with a circumferential technique using K files and the Canal Master instrumentation technique by junior dental students whose only endodontic experience had been completion of a preclinical endodontic course. Preoperative and postoperative radiographs were taken facially and mesially with instruments in place. The canals were evaluated radiographically for transportation 1 mm and 4 mm from the apex. The mesial roots were cross-sectioned at the same level. The sections were evaluated for roundness of the canal preparation. It was concluded that the Canal Master instrumentation technique transported the root canal less and produced rounder preparations than the K file circumferential technique. There appears to be a greater tendency for breakage with the Canal Master.     

根管弯曲参数对镍钛根管器械应力分布影响的有限元研究

目的：建立模拟机用镍钛根管器械进行根管预备的三维有限元模型,研究根管弯曲参数对镍钛根管器械应力分布产生的影响,探讨有限元分析法研究镍钛根管器械机械性能的可靠性及其临床意义。方法：用Micro-CT扫描并建立ProTaper Universal F2三维有限元模型。用Hyperworks 10.0建立不同弯曲半径（2mm、5mm）、弯曲角度（30°、45°）和弯曲部位（根中、根尖）的八种简化弯曲根管的几何和有限元模型。用ANSYS 12.1研究器械在旋转进入八种弯曲根管底部的应力分布云图及特点,并对三个弯曲参数进行敏感性分析。结果：器械在根管8的应力最大（1426.0Mpa）,在根管1的应力最小（651.2Mpa）。弯曲半径导致器械应力变化权重最大（44.9%）。结论：本研究证实了有限元分析法在研究镍钛根管器械机械性能方面的有用性。根管的弯曲半径是决定器械应力分布最为关键的参数。在临床急弯根管预备中应尽量使用小号器械。     

应用根管显微镜取出根管内金属异物的疗效分析

目的：评价根管显微镜下应用超声技术取出根管内异物的临床效果。方法：选取因根管内异物就诊的患者39例。在根管显微镜下采用超声根管锉、超声工作尖制备距离异物的直线通路,将根管内金属异物取出。结果：39例根管金属异物成功取出33例并完成根管治疗,异物取出率84．61％。结论：应用根管显微镜和超声技术取出根管内金属异物的方法安全有效。     

不同根管充填技术对椭圆形根管充填效果的比较

目的:通过比较3种不同方法充填椭圆形根管后的牙胶充填面积百分数来评价各种充填法的效果。方法:选取人离体单根管前磨牙30个,手用ProTaper预备后随机分为3组,分别用冷牙胶侧方加压法、热塑牙胶注射加压法(ObturaⅢ)和连续波充填法(System B+ObturaⅢ)进行充填,然后分别在距根尖2、5、8 mm处横断,各个横断面在手术显微镜下拍照,再用图像分析软件记录横断面的根管面积和牙胶充填面积,从而计算出牙胶充填面积百分数。结果:在2 mm处,3种充填法的牙胶充填面积百分数无显著性差异(P>0.05);在5 mm处,ObturaⅢ组和SystemB+ObturaⅢ组无显著性差异(P>0.05),但都显著大于冷牙胶侧压组(P<0.05),8 mm与5 mm处结果相同。结论:在5,8 mm水平,ObturaⅢ和SystemB+ObturaⅢ充填法的效果好于冷牙胶侧压法,而在2 mm水平,3种充填法的的效果无明显差别。