Canal markings produced by endosonic instruments.

It has been recognised that ultrasonic files leave a diagonal pattern within the canal following endosonic instrumentation. There is confusion on the causative factor on the production of these marks. Furthermore there is little information about the marks produced by sonic files. An in vitro system consisting of highly polished dentin discs demonstrated that the ultrasonic K-file made a diagonal pattern that was an imprint of the cutting edges of the file. The sonic files produced different markings which were the result of their longitudinal and transverse motion. Root canals of extracted teeth were prepared with these instruments and similar grooves were observed. The ultrasonic K-file had diagonal grooves in the coronal and middle third of the root canal but longitudinal marks in the apical third. The rispisonic and shaper files produced debris even in the presence of NaOCl. This debris was formed into discrete parallel bands. Both longitudinal and transverse grooves were present and the canal had many other scratches similar to those seen with the dentin discs. There were differences between the marks produced by either ultrasonic or sonic endosonic instruments but it is unknown whether this influences the long term prognosis of the root canal therapy.     

Canal markings produced by endosonic instruments

Abstract It has been recognised that ultrasonic files leave a diagonal pattern within the canal following endosonic instrumentation. There is confusion on the causative factor on the production of these marks. Furthermore there is little information about the marks produced by sonic files. An in vitro system consisting of highly polished dentin discs demonstrated that the ultrasonic K-file made a diagonal pattern that was an imprint of the cutting edges of the file. The sonic files produced different markings which were the result of their longitudinal and transverse motion. Root canals of extracted teeth were prepared with these instruments and similar grooves were observed. The ultrasonic K-file had diagonal grooves in the coronal and middle third of the root canal but longitudinal marks in the apical third. The rispisonic and shaper files produced debris even in the presence of NaOCl. This debris was formed into discrete parallel bands. Both longitudinal and transverse grooves were present and the canal had many other scratches similar to those seen with the dentin discs. There were differences between the marks produced by either ultrasonic or sonic endosonic instruments but it is unknown whether this influences the long term prognosis of the root canal therapy.     

Endosonic endodontics: the ultrasonic synergistic system

A biotechnological approach using ultrasound has led to the development of a method of root canal therapy in which effective debridement, shaping, irrigation and disinfection of the root canal are easily and quickly completed. This is achieved by a handpiece and a file both energized by ultrasound. A flow-through component enables an irrigation solution to pass along the file into the canal system. The ultrasonically energized file activates the irrigant facilitating solvent, cleansing and disinfecting actions within the root canal system. The energized file is able to debride the canal wall with great facility in an extremely rapid and simple fashion. Progress in metallurgical bonding has enabled a diamond coated file to be developed which gives efficient and rapid preparation of the root canal. Use of this combination of ultrasound, flow-through irrigation and diamond-coated files enables the dentist to perform endodontic treatment expeditiously while adhering to biologic principles.     

Bacteriologic evaluation of ultrasonic root canal instrumentation

The antibacterial effect of ultrasonic instrumentation in the treatment of infected root canals was clinically evaluated. Sodium hypochlorite solution (0.5%) was used as an irrigant, but no antibacterial intracanal dressing was used between the appointments. The ultrasonic technique eliminated the bacteria from the canals more efficiently than hand instrumentation alone. Even though ultrasonication definitely improves the procedure of root canal disinfection, the use of an antibacterial dressing between appointments is necessary to achieve as complete a reduction in bacterial levels as possible.     

A survey of interfacial forces used during endosonic instrumentation of root canals

AIM: The aim of this in-vitro study was to measure interfacial forces acting between root canal dentine and ultrasonic files during endosonic instrumentation. METHODOLOGY: Single-rooted teeth were mounted on a cantilevered aluminium beam to which two pairs of single element strain gauges were joined in a half-bridge configuration mounted at right angles to each other. The strain gauges were connected to an analogue-to-digital converter fitted in a microcomputer via a conditioning amplifier. This enabled strains to be recorded as a function of interfacial forces over a period of time. Twenty operators instrumented root canals using sizes 15, 20 and 25 ultrasonically energized K-type files. The lateral forces generated were calculated. RESULTS: The mean interfacial forces used varied widely between operators and files, ranging from 18 g to 149 g, but there was a consistency in the relative magnitude for each operator. The average force used by the operators increased with file size; the differences between file sizes were significant (P < 0.05). CONCLUSIONS: The range of forces measured is broader than previously reported and may have a bearing on possible uncontrolled dentine removal, even during ultrasonically activated irrigation.     

口康含漱液用于超声根管预备抗菌效果的研究

目的探讨口康与超声联合应用杀灭感染根管内厌氧菌的效果。方法将60例慢性根尖周炎患者共60个患牙随机分为3组,每组各20个患牙,A组常规法手持器械根管预备和常规针筒式根管冲洗,B、C组均用超声法进行根管预备并分别以生理盐水、口康作为超声冲洗液,根管预备前后分别取样进行厌氧培养。结果B组厌氧菌减少程度明显大于A组(P<0.05);C组厌氧菌减少程度明显大于B组(P<0.01),显著大于A组(P<0.001)。结论超声在根管杀菌方面有独特的优势,口康可有效杀灭感染根管内厌氧菌,是一种较理想的根管超声冲洗液。     

中药制剂用于超声根管预备的初步研究

目的评价中药制剂洁尔阴与超声波联合应用杀灭感染根管内厌氧菌的效果。方法将临床诊断为慢性根尖周炎的60例患者的60颗患牙随机分为3组（每组20颗牙）,第1组为传统手持器械对照组,第2组为超声生理盐水对照组,第3组为超声洁尔阴实验组。根管清理前后分别取样进行厌氧培养。结果传统手持器械组与超声生理盐水组之间差异有显著性（P<0.05）;超声洁尔阴组与超声生理盐水组之间差异有极显著性（P<0.01）。结论超声波在根管杀菌方面有独特的优势,中药洁尔阴可有效地杀灭感染根管内的厌氧菌,是符合生物学原则、较理想的超声根管冲洗液。     

口泰用于根管超声冲洗抗菌效果的研究

目的 :研究口泰与超声波联合应用杀灭感染根管内厌氧菌的效果。方法 :将 6 0例慢性根尖周炎患者共 6 0颗患牙随机分为 3组 ,每组各 2 0颗患牙 ,第 1组常规法手持器械根管预备及常规针筒式根管冲洗 ,第 2、3组均用超声法进行根管预备并分别以生理盐水、口泰作为超声冲洗液 ,根管预备前后分别取样进行厌氧培养。结果 :第 2组厌氧菌减少程度明显大于第 1组 (P <0 .0 5 ) ;第 3组厌氧菌减少程度明显大于第 2组 (P <0 .0 1) ,显著大于第 1组(P <0 .0 0 1)。结论 :超声波在根管杀菌方面有独特的优势 ,口泰可有效杀灭感染根管内厌氧菌 ,是一种较理想的根管超声冲洗液     

The efficacy of step-down procedures during endosonic instrumentation

The step-back method of root canal preparation may not be suitable for endosonic files as they may be prevented from working efficiently within the apical region. This study determined the debris present in the apical portion of the canal after using three different endosonic instruments and compared the step-back versus the step-down technique; the latter involves initial preparation of the upper regions of the root canal which may reduce file constraint. Thirty-six teeth were prepared by either the step-back or step-down method using endosonic generators (magnetostrictive, piexoelectric, and sonic). Preparation times were standardized so that files were used for the same period. From scanning electron micrographs, debris removal was scored on a four-point scale by four clinicians. A log linear analysis showed that there was significantly less debris present with the step-down method using piezoelectric and sonic devices. More debris was present when files driven by a magnetostrictive instrument were used with the step-back method. This study showed that the step-down method may be useful when using certain types of endosonic generators.     

Endodontics: Part 7. Preparing the root canal

Research into root canal preparation has led to significant changes in instrumentation techniques. Hand files should be manipulated by the balanced-force technique. Recent designs of endodontic instruments have variable tapers giving improved shaping ability. Nickel-titanium rotary instruments will rapidly and safely open the main root canals creating deep space to permit full permeation of irrigant solutions. Practitioners considering changing their endodontic technique are advised to attend hands-on practical courses to gain competence before using these in clinical practice.     

Another look at root canal instrumentation.

Several aspects of root canal instrumentation need additional research. Various factors must be considered in an analysis of instrumentation of the root canal system: the dentin that is cut; the technique used to cut it; the design of the instruments; the material and manufacturing process used to make the instruments; the irrigant used during the procedure; and the anatomic configuration of the root canal system. An analysis of these factors clearly indicates that existing root canal instruments and techniques are less than ideal and, in fact, do not accomplish what is expected of them. Root canals must be properly, but, at the same time, destructive and unnecessary removal of dentin should be kept to a minimum. The Flex-R and Canal Master instruments were developed to address some of the shortcomings of existing instruments and techniques. More scientifically based research is needed to fully evaluate these new instruments and techniques and to develop future instruments.     

Ultrasound in dentistry. Part 2--Periodontology and endodontics.

Ultrasound in the kHz frequency range is used widely in clinical dentistry. The most common uses are in the fields of periodontology and endodontics. The ultrasonic scaler works by the vibratory chipping action of the oscillating tip and is assisted by the presence of cavitational activity in the associated cooling water. When assessing clinical studies it is often difficult to interpret results from different workers due to the lack of standardization of the ultrasonic scaler. Operators should be aware of the oscillatory pattern of different instruments. Endosonics utilizes an ultrasonically oscillating endodontic file to clean and shape the root canal prior to obturation. The cleaning ability of such files is assisted by the occurrence of acoustic microstreaming forces. The endosonic file is prone to constraint when it contacts the canal wall which alters its oscillatory pattern. Clinical techniques should be modified to reduce this problem.     

Quantification of mechanical versus ultrasonic technique in root canal preparation

The previous investigations of the cutting efficacy of the paracanal dentine with different endodontic instruments have not quantified the amount of the tissue removed. The purpose of this study was to compare the effectiveness of various mechanical canal instrumentations with ultrasonic technique by measuring the weight loss of the root dentine. The investigation concerned 60 single-canal roots of freshly extracted human teeth. Each canal was primarily prepared with Beutel rock reamers, size 3, with penetration to the apex. After desiccation in the thermostat at 60 degrees C for 65 hours, roots were weighed using an electronic scale (Mettler, AE-163, West Germany) with a precision of 10(-4) grams. Samples were devided into six groups according to the endodontic instrument: (1)K-tupbe reamers, (2)K-files, (3) Hedstroem files, (4) giromatic cleansers, (5) giromatic files, (6) ultrasonic files. After having been prepared the root canal was thoroughly irrigated with 4 ml saline, redesiccated and reweighed. Ultrasonic instrumentation was the most effective in removing the root canal dentine compared with all mechanical techniques (t-test; p less than 0.005). The smallest amount of root canal dentine was removed by giro-files. This was statistically significant compared with K-files, giro-files and ultrasonic files. There was no significant difference among the other mechanical instruments used in this study.     

Efficacy of smear layer removal at the root tip by using ethylenediaminetetraacetic acid and erbium, chromium: yttrium, scandium, gallium garnet laser

Introduction

The purpose of this study was to compare the efficacy of laser-driven irrigation in removing the smear layer and debriding the apical region of the root canal (the root tip) with that of ultrasonic irrigation.

Methods

Forty extracted human teeth with straight single roots were randomized into 4 groups (n = 10). The specimens were shaped by using hand instruments up to a size 30/.02 file (Control, Laser 1, and Laser 2 groups) or a size 20/.02 file (Laser 3 group). During instrumentation, each canal was irrigated with 3% NaOCl and 17% ethylenediaminetetraacetic acid alternately between the use of successive files. The 4 groups of 10 teeth were processed as follows. In the Control group, teeth were irrigated with 17% ethylenediaminetetraacetic acid, and the irrigant was activated with an ultrasonic device for 60 seconds. In the Laser 1 and Laser 3 groups, the irrigant was activated with the laser for 60 seconds. In the Laser 2 group, the irrigant was activated with the laser for 30 seconds.

Results

There were significant differences between the smear layer and debris scores for the Laser 1 group and those for the Control (P < .001), Laser 2 (P = .002), and Laser 3 groups (P = .012 and P = .013, respectively). Completely clean root canals were found in the Laser 1 group.

Conclusions

Use of a laser with a plain fiber tip, which produces cavitation in the irrigant, has potential as an improved alternative method for removing of the smear layer from the apical region of a straight root canal.     

Measurements of temperature generated by ultrasonic file in vitro

The temperature rise of the irrigant in the root canal during free vibration of the ultrasonic file was studied in vitro in 10 human teeth. The mean temperature rise was found to be 0.6 degrees C. The minimal temperature increase may not significantly contribute to the effectiveness of ultrasonic root canal instrumentation.     

Comparison of the quality of obturation following endosonic versus hand instrumentation

This study was undertaken to compare the quality of root canal obturation following preparation by endosonic or hand instrumentation. Forty single-canal, extracted lower premolar teeth were selected. One group of 20 teeth was prepared using a standard step-back technique, the other 20 teeth were prepared with an ultrasonic machine. The groups were subdivided, with two operators preparing 10 teeth of each group. The teeth were obturated by a third operator using cold laterally condensed gutta percha. The root apices were then immersed in methylene blue dye for 48 h and the teeth sectioned longitudinally. Image analysis recorded the amount of sealer and void within the obturated canal. The linear distance of dye penetration was measured to provide an indication of apical seal. Examination of the root canal shape resulting from the different preparation techniques used was also undertaken. No significant difference was noted in the percentage of sealer and void present in the root canals obturated after endosonic or hand instrumentation. There was a slightly greater although not significant increase in the degree of linear penetration of dye in canals prepared endosonically. The endosonic technique used in this study appeared to produce a canal preparation of slightly less continuous taper than that obtained with hand preparation.     

Effectiveness of oxidative potential water as a root canal irrigant

AIM: The aim of this study was to evaluate the effectiveness of oxidative potential water (OPW) as an irrigant, based on its ability to remove the smear layer and/or debris from instrumented root canals. METHODOLOGY: One hundred and twenty root canals from extracted human maxillary incisors were instrumented using a conventional step-back technique with irrigation from sodium hypochlorite (NaOCl) or oxidative potential water (OPW). After instrumentation, the canals were irrigated by syringe or ultrasound using 15% EDTA or OPW as an irrigant. The volume of each irrigant used for syringe irrigation was 10, 20, and 30 mL, respectively, whilst the duration for ultrasonic irrigation was 1, 3, and 5 min, respectively. After irrigation, each root was split longitudinally in two with cutting pliers, and the specimens were prepared for SEM observation. The presence of debris and smear layer on each canal wall was assessed using a three-point scale for each parameter. RESULTS: Smear layer was effectively removed with EDTA both introduced via syringe and via ultrasonic irrigation. A similar effect was observed with OPW via syringe irrigation following instrumentation with 5% NaOCl. The canal walls in any of these cases showed open and patent dentinal tubules following smear layer removal. Some specimens irrigated with EDTA exhibited the effect of demineralization on the dentine resulting in funnelling of tubule orifices. Syringe irrigation was more effective in smear layer removal, except for ultrasonic irrigation with 15% EDTA, whilst ultrasonic irrigation was more effective in debris removal including the use of OPW as irrigant following instrumentation with 5% NaOCl. Neither syringe nor ultrasonic irrigation with OPW following instrumentation with OPW removed smear layer or debris effectively. CONCLUSIONS: The most effective irrigation technique for smear removal was 15% EDTA irrigation by means of syringe following instrumentation with 5% NaOCl solution. However, the most effective irrigation technique for debris removal was ultrasonic irrigation regardless of irrigant used. OPW irrigation by means of syringe following instrumentation with 5% NaOCl showed a similar effect to that of 15% EDTA irrigation for removal of smear layer and debris.     

钙化根管的根管显微镜治疗

目的:探讨应用根管显微镜治疗钙化根管的方法,并对其疗效进行评价.方法:因根管钙化进行根管治疗的患牙33个,在根管显微镜引导下,将超声预备、手动NiTi器械预备以及EDTA化学预备相结合进行治疗,记录预备时间,术后1周进行根管充填,半年后复查并进行疗效评价.结果:根管显微镜下钙化根管的治疗成功率为88.9%,平均每根根管耗时25.8 min.结论:在根管显微镜引导下,将超声预备、手动NiTi器械预备以及EDTA化学预备相结合可提高钙化根管治疗的成功率.     

Measurements of temperature generated by ultrasonic file in vitro

Abstract The temperature rise of the irrigant in the root canal during free vibration of the ultrasonic file was studied in vitro in 10 human teeth. The mean temperature rise was found to be 0.6°C. The minimal temperature increase may not significantly contribute to the effectiveness of ultrasonic root canal instrumentation.     

In-vitro measurement of apieally extruded irrigant in primary molars

This study investigated the weights of irrigant extruded apically through extracted primary molar teeth. The aim was to compare the weight of canal irrigant (isotonic sodium chloride solution) extruded through the root canal using either a syringe fitted with a 27-gauge needle or an endosonic unit. Root canals were divided randomly into five groups of 15 discrete canals. The area of each apical foramen was recorded prior to the use of the irrigant. For each irrigation technique the maximum depth of penetration of the needle tip/file was either 2–3 mm or 6–7 mm from the apical foramen. In four groups the crowns of the teeth were in a mandibular position, in the fifth group the teeth were inverted to simulate maxillary teeth. The results showed that irrigant was extruded using both methods. There was significantly less extrusion of irrigant when the endosonic unit was used (P < 0.01). There was no statistically significant relationship between foramen area and amount of extruded irrigant (P > 0.05). There was no significant extrusion of irrigant in teeth with closed apices when either of the two methods was used (P>0.05).