Bacteriologic status of the root canal after sonic, ultrasonic and hand instrumentation

Abstract The purpose of this study was to assess the bacteriologic status of the root canal after sonic, ultrasonic and hand instrumentation. Root canal infection was induced in 50 single-rooted teeth in young dogs by removing the pulp and filling the canals with dental plaque. After 7 clays the root canals were instrumented under aseptic conditions with conventional hand instruments, a sonic vibratory device or an ultrasonic device. Sterile saline or 2.5% sodium hypochlorite was used as irrigating solution. Following instrumentation a sterile paper point was sealed into the root canals. After 7 d the root canals were reopened under aseptic conditions and the paper points were incubated for the demonstration of bacteria, using pre-reduced thioglycolate culture medium and anaerobic chambers. The results obtained with the different instrumentation techniques and irrigating solutions were compared by means of the Chi-square test. The results indicated that the sonic and ultrasonic devices were not more effective in the elimination of bacteria from the root canal than conventional hand instrumentation. Irrigation with sodium hypochlorite appeared to be more effective than saline in producing bacteria-free root canals; however, this difference was not statistically significant. Thus, it appeared that more than one appointment and the supporting action of an antibacterial medicament between appointments would be necessary to achieve bacteria-free root canals in infected teeth in a predictable manner.     

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.     

声波器械在根管治疗术中的应用

声波根管预备作为一种治疗手段用于牙髓病、根尖周病的治疗取得了一定的疗效。本文对声波器械的技术特点作一综述，包括声波器械的工作原理、切削能力、根管成形能力、去除玷污层的能力和杀菌能力等方面。     

Variations in stroke rate and loading using hand sonic or ultrasonic instrumentation

Abstract An in vitro model system was developed to investigate the stroke rate and loading during hand, sonic, or ultrasonic instrumentation. The model system consisted of a mandibular molar tooth attached to a strain gauge and interface to a computer. Ten clinicians instrumented the distal canal of lower molar teeth. Stroke rates used and loads applied were measured using different sized files with the three different preparation techniques. There was no significant difference in stroke rates between different file sizes (p>0.05) within the same generator, however, stroke rate for hand was significantly slower than for sonic or ultrasonic (p<0.01). Loading of the canal wall rose with increase in file size which was significant for hand (p<0.01) and sonic (p<0.05) but not ultrasonic (p>0.05). There was a tendency for loading to be higher with hand instrumentation, this however was not significant (p>0.05).     

声波器械去除根管玷污层能力的比较研究

目的:比较声波、超声波和手用器械去除根管玷污层能力。方法:收集离体单根管的前磨牙40个,随机分为4组,分别由声波器械、超声波器械、手用器械以及声波和手用器械联合行根管预备,应用扫描电镜进行观察,采用Wilcoxon秩和检验进行统计学分析,根据根管表面的玷污层的量和牙本质碎屑比较声波器械去除根管玷污层的能力。结果:根尖1/3部分,在去除玷污层方面,声波器械组、超声波器械组以及声波器械和手用器械联合组,与手用器械组之间有显著性差异(P<0.05);在去除牙本质碎屑方面,超声波器械组与手用器械组之间亦有显著性差异(P<0.05),声波器械组以及声波器械和手用器械联合组与手用器械组之间有非常显著性差异(P<0.01)。声波器械组以及声波器械和手用器械联合组,与超声波器械组在去除玷污层和牙本质碎屑方面无显著性差异(P>0.05)。根中1/3和根上1/3部分,各组间比较均无显著性差异(P>0.05)。结论:根尖1/3根管预备,声波器械去除玷污层和牙本质碎屑的能力优于手用器械,尤其是去除牙本质碎屑的能力更强;与超声波器械近似。     

Scanning electron microscope study on the efficacy of root canal wall debridement of hand versus Lightspeed instrumentation

AIM: The aim of this in vitro study was to compare the efficacy of root canal wall debridement following hand versus LightSpeed instrumentation. METHODOLOGY: Twenty recently extracted single-rooted teeth were paired and randomly placed into two treatment groups of 10 teeth each. In group 1, a step-back instrumentation without initial coronal flaring with stainless steel Hedstroem files was used; group 2 was instrumented with Ni-Ti LightSpeed instruments. Both groups had the same irrigation regimen: 2.5% NaOCl and a 15% EDTA solution. The teeth were then decoronated and each root split longitudinally into two halves to be examined using the scanning electron microscope (SEM). The presence of superficial debris and smear layer was evaluated by a standardized grading system, and the resulting scores submitted to nonparametric statistics. RESULTS: Under the conditions of this study, the removal of superficial debris was generally excellent with both canal preparation techniques. Both techniques resulted in variable presence of residual smear layer, with a canal wall covered by smear layer as the predominant characteristic. Generally, the amount of smear layer was greater in the apical than in the middle third of the root, however, this difference was statistically significant (P < 0.005) only in hand-instrumented teeth. The use of LightSpeed instruments was associated with significantly more (P < 0.05) smear layer presence in the middle region of the root when compared with hand instrumentation. In addition, less smear layer was present in the apical region following LightSpeed instrumentation than stainless steel hand files, but this difference was not statistically significant. Differences in debridement between the two halves of the same root were more evident with LightSpeed than manual instrumentation, however, there was no statistical significance. CONCLUSIONS: It may be inferred that the choice between hand and LightSpeed instrumentation should be based on factors other than the amount of root canal debridement, which does not vary significantly according to the instruments used.     

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.     

Efficacy of automated versus hand instrumentation during root canal retreatment: an ex vivo study

Aim To compare automated and manual instrumentation techniques for removing filling material from root canal walls during root canal retreatment. Methodology One hundred extracted human single‐rooted teeth were root filled and stored. Specimens were divided into two groups: group A, Endofill plus gutta‐percha; group B, Sealer 26 plus gutta‐percha. The filling material was removed using the following techniques: group I – Gates–Glidden and K‐type files; group II – ProFile; group III – ProTaper; group IV – K3; group V– Micro Mega Hero 642. The remaining filling debris on the root canal walls were assessed radiographically, images were digitized and analysed using Image ProPlus software. The roots were split for evaluation in a stereomicroscope by epiluminescence and photomicrographs were taken for further analysis. The area covered with filling debris was analysed by means of Student's t‐test to compare the evaluation methods. The student's t‐test was also used to compare the removal of filling materials. An anova test was applied to compare the different techniques (P < 0.05). Results A significant difference occurred between radiographic and photomicrographic evaluation methods (P < 0.05). No significant difference was observed between the filling materials on terms of their removal (P > 0.05). Manual instrumentation left more filling debris on the root canal walls when compared to K3 (P < 0.05) and ProTaper (P < 0.01). Conclusions A photomicrographic method by epiluminescence was more effective than the radiographic method to evaluate filling debris. There was no significant difference between the filling materials in terms of their removal. K3 and ProTaper were more efficient than manual instrumentation.     

Endodontic hand instruments: cutting efficiency, instrumentation of curved canals, bending and torsional properties

Abstract In an assessment of the usefulness of different root canal instruments, two aspects are of particular interest for the endodontist: the cutting efficiency of the instruments and their ability id enlarge curved canals without undesirable changes of the canal shape such as the formation of zips and elbows. This review paper is based on own investigations on the cutting efficiency and instrumentation of curved canals. Additionally, two parameters which are described in ISO 3630-1, resistance to bending and resistance to fracture, are discussed. With regard to cutting efficiency in rotary motion, flexible stainless steel reamers and K-files clearly display the best results and are superior to conventional stainless steel as well as titanium-based reamers and K-files. Regarding cutting efficiency in linear motion, stainless steel Hedström files made by certain manufacturers are significantly superior to stainless steel and titanium-based Hedström files of other brands. Flexible stainless steel instruments with modified noncutting lips clearly produce the best canal shape in curved canals. With only rare exceptions, all the instruments tested fulfilled the requirements of the ISO standard concerning resistance to fracture and resistance to bending.     

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.     

不同器械根管预备效果的实验研究

目的：比较临床常用扩锉器械的根管清理效果。方法：将60个离体牙随机分为6组，分别为空白对照组、K型钻组、K型钻和锉组、K型钻和H型锉组、K型锉组和超声扩锉组，采用逐步后退法预备根管。扫描电镜观察根管内壁。结果：根管壁碎屑面积比较，K型锉组＞K型钻组＞K型钻和锉组＞空白对照组＞K型钻和H型锉组＞超声扩锉组，且前3组与其余各组之间具有显著性差异（P＜0．05），而后3者之间无显著性差异（P＞0．05）。结论：超声扩锉与K型钻和H型锉效果最好；K型钻与K型锉交替使用次之；单纯扩或锉不能有效进行根管清理。建议临床采用K型钻和H型锉交替预备根管。     

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目的：评价声波根管器械联合ProTaper锉治疗残髓炎的临床疗效。方法选择2011年2月至2012年2月在南平市妇幼保健院牙体牙髓科门诊就诊的残髓炎患者78例（共78颗患牙）,随机分为试验组（41例）和对照组37例。试验组采用声波根管器械联合ProTaper锉进行根管预备,对照组采用单纯的ProTaper锉进行根管预备。两组患者根管预备完成后均用氢氧化钙封药1周,然后行根管充填。比较两组患者根管预备后24 h、根管充填1周后的术后反应及1年后的疗效。结果试验组患者根管预备后24 h、根管充填1周后的疼痛反应均较对照组轻;试验组1年后的疗效亦优于对照组。结论声波根管器械联合ProTaper锉治疗残髓炎,可减少预备后的疼痛反应,同时提高根管充填的质量,保证根管治疗的成功率,值得临床推广应用。     

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.     

声波、超声波、手用根管器械预备弯曲根管的效果比较

目的：比较声波、超声波和手用根管器械预备弯曲根管的效果。方法：采用3种根管器械预备树脂块模拟根管并进行比较。结果：30个树脂块模拟根管预备效果显示：声波、超声波和手用器械根管预备效果无显著性差异。结论：声波根管器械具有临床应用价值。     

Comparative study of six rotary nickel-titanium systems and hand instrumentation for root canal preparation

Aim To compare ex vivo various parameters of root canal preparation using a manual technique and six different rotary nickel–titanium (Ni–Ti) instruments (FlexMaster, System GT, HERO 642, K3, ProTaper, and RaCe). Methodology A total of 147 extracted mandibular molars were devided into seven groups (n = 21) with equal mean mesio‐buccal root canal curvatures (up to 70°), and embedded in a muffle system. All root canals were prepared to size 30 using a crown‐down preparation technique for the rotary nickel–titanium instruments and a standardized preparation (using reamers and Hedströem files) for the manual technique. Length modifications and straightening were determined by standardized radiography and a computer‐aided difference measurement for every instrument system. Post‐operative cross‐sections were evaluated by light‐microscopic investigation and photographic documentation. Procedural errors, working time and time for instrumentation were recorded. The data were analysed statistically using the Kruskal–Wallis test and the Mann–Whitney U‐test. Results No significant differences were detected between the rotary Ni–Ti instruments for alteration of working length. All Ni–Ti systems maintained the original curvature well, with minor mean degrees of straightening ranging from 0.45° (System GT) to 1.17° (ProTaper). ProTaper had the lowest numbers of irregular post‐operative root canal diameters; the results were comparable between the other systems. Instrument fractures occurred with ProTaper in three root canals, whilst preparation with System GT, HERO 642, K3 and the manual technique resulted in one fracture each. Ni–Ti instruments prepared canals more rapidly than the manual technique. The shortest time for instrumentation was achieved with System GT (11.7 s). Conclusions Under the conditions of this ex vivo study all Ni–Ti systems maintained the canal curvature, were associated with few instrument fractures and were more rapid than a standardized manual technique. ProTaper instruments created more regular canal diameters.     

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.     

Teaching rotary root canal instrumentation using a Peyton teaching approach

Introduction

The aim of the study was two evaluate the effectiveness of a Peyton teaching approach for rotary root canal instrumentation, in comparison to the traditional “see one–do one” method.

Material and Methods

Forty undergraduate students were randomly divided into two groups (n = 20). Students of the first group (G1) were taught how to use rotary instrumentation using a modified Peyton method, whilst the second group (G2) watched a teaching video (30 min) on the same subject. Both groups instrumented a plastic block and subsequently both mesial canals of an extracted lower molar. The quality of the root canal instrumentation was analysed by 2 blinded observers on video recordings and x-rays.

Results

Interobserver correlation was 0.917 (p < .0005; Pearson) for the assessment of the video recordings; students of G1 received significantly more total points (83.55 ± 6.82 points) compared to G2 (69.76 ± 13.82) (p = .001; t-test), the gender had no significant effect on the overall results (p = .444; two-way ANOVA). Significant differences were detected for the categories “initial scouting,” “coronal enlargement,” “glide path preparation,” “preparation using X2 file,” “preparation using X3 file” (p < .05; t-test) as well as for the subcategories “sequence of rinse, recapitulation, rinse” (p = .001; t-test) and “recapitulation” (p < .002; t-test). No differences between groups were observed for the radiographic evaluation with respect to working length and canal straightening.

Conclusion

Teaching rotary instrumentation by using the Peyton approach resulted in improved performance of undergraduate students assessed with a checklist-based process analysis. Enhanced implementation of rotary instrumentation could result in better long-term results of students' root canal treatment.     

根管机械预备与牙本质微裂

根管机械预备是根管治疗术的关键步骤,在清除感染源和根管成形的同时,为化学冲洗和根管充填创造空间.但有学者认为镍钛器械会在机械预备过程中引起牙本质微裂,继而引发微渗漏、牙根纵裂,对根管治疗的预后产生不利影响.文章就根管机械预备过程中形成牙本质微裂的原因、预防及争议做一介绍.     

预备弯曲根管时根管偏移的实验研究

目的：定量研究弯曲根管预备过程中根管的偏移。方法：使用不锈钢K锉按常规法预备8个弯曲人工根管，根管预备过程中对根管、根尖孔进行微距摄影，用图像分析软件Image—Pro Plus对根管的形态和位置变化进行测量、分析。结果：根管预备时随着锉号的递增，弯曲根管逐渐被拉直，表现为根管弯曲角度逐渐减小，弯曲半径、根管轮廓面积逐渐增大，根管口、根尖孔被拉开，根管壁出现3个过度切削区。结论：预备弯曲根管时，根管不同部位的偏移方向、偏移距离并不相同，掌握弯曲根管的解剖形态以及根管器械的力学性能，有助于准确估计根管偏移的大小和方向。