Factors affecting irrigant extrusion during root canal irrigation: a systematic review

The aim of the present study was to conduct a systematic review and critical analysis of published data on irrigant extrusion to identify factors causing, affecting or predisposing to irrigant extrusion during root canal irrigation of human mature permanent teeth. An electronic search was conducted in Cochrane Library, LILACS, PubMed, SciELO, Scopus and Web of Knowledge using a combination of the terms ‘irrigant’, ‘rinse’, ‘extrusion’, ‘injection’, ‘complication’, ‘accident’, ‘iatrogenic’, ‘root canal’, ‘tooth’ and ‘endodontic’. Additional studies were identified by hand‐searching of six endodontic journals and the relevant chapters of four endodontic textbooks, resulting in a total of 460 titles. No language restriction was imposed. After applying screening and strict eligibility criteria by two independent reviewers, 40 case reports and 10 ex vivo studies were included in the review. A lack of clinical studies focusing on irrigant extrusion during root canal irrigation was evident. The reviewed case reports focused mainly on the clinical manifestations and management of the accidents and did not provide adequate details on the possible factors that may influence irrigant extrusion. The data from the included ex vivo studies were inconclusive due to major methodological limitations, such as not simulating the presence of periapical tissues and not assessing the validity of irrigant detection methods. The extensive variability in the protocols employed hindered quantitative synthesis. The choice of factors investigated in ex vivo studies seems not to have been driven by the available clinical evidence. These issues need to be addressed in future studies.     

Apical extrusion of sodium hypochlorite using different root canal irrigation systems

Introduction

Root canal irrigation carries a risk of extrusion of irrigant into the periapical tissues. The objective of this study was to compare different irrigation systems in matched pairs of teeth prepared to an apical size of 35.06 and 50.06 by measuring the frequency and extent of apical extrusion of sodium hypochlorite (NaOCl) into a simulated periapical environment. The null hypothesis was tested that there is no difference between systems.

Methods

Bilaterally matched pairs (n = 10) of single-canal extracted human anterior teeth were instrumented to an apical size of either 35.06 or 50.06. Teeth were embedded in a gel containing the pH-sensitive dye M-cresol purple that changes from yellow at pH 7.4 to purple at pH 9. Root canals were irrigated with 6% NaOCl (pH 11) by using EndoActivator (EA), EndoVac (EV), Rispi-Sonic/MicroMega 1500 (MM), passive ultrasonic irrigation (PUI), and syringe irrigation with a slot-tipped needle (SN), so that each tooth underwent all irrigation procedures in a randomized crossover design. Apical extrusion was evaluated by image analyses.

Results

The frequency of extrusion was less in teeth with apical preparation size 35.06 (36%) compared with 50.06 (60%) (P = .014) and was dependent on the irrigation system in 35.06 (P = .039) but not 50.06 groups. In the 35.06 group the frequency of extrusion was less for EV than for MM and SN (both P = .029). The extent of extrusion was less for MM compared with PUI (P = .024) and SN (P = .046) in the 35.06 group and greater for SN compared with all other systems in the 50.06 group (P < .05). The null hypothesis was rejected.

Conclusions

The frequency of apical extrusion of NaOCl was dependent on the type of root canal irrigation system and apical preparation size. The extent of extrusion depended on the irrigation system, with syringe and slotted-needle irrigation resulting in the greatest extent of extrusion.     

根尖止点阻止根充材料超充的效果研究

目的:研究根管治疗中制备根尖止点对阻止根管充填材料超充的影响。方法:选取80个单根管上、下颌尖牙,其中40个牙采用逐步后退技术,常规制备根尖止点进行根管预备至根尖孔上1mm,另40个牙亦采用逐步后退技术预备至根尖孔,不进行根尖止点的制备;再将以上各组牙随机平分为两组,分别采用冷牙胶侧方加压和热牙胶垂直加压方法充填根管,观察并记录每组中牙胶超出根尖的牙数,收集每个牙超出的充填材料(牙胶和糊剂)并称量,对实验结果进行统计学分析。结果:制备根尖止点的侧方加压组与不制备根尖止点的侧方加压组之间根充材料超出的量、制备根尖止点的垂直加压组与不制备根尖止点的垂直加压组之间根充材料超出的量均无统计学差异(P>0.05)。结论:通过在初尖锉的基础上扩大3#的方法制备根尖止点并不一定能起到减少根充材料超充的作用。     

Cross-sectional evaluation of the periapical status and quality of root canal treatment in a selected population of urban Turkish adults

AIM: To investigate the prevalence of apical periodontitis and the quality of root canal treatment in an adult Turkish population who visited a university dental clinic. SUMMARY: The periapical status of 8863 teeth belonging to 375 patients was evaluated by two pre-calibrated observers from panoramic radiographs. The presence of apical periodontitis, and the prevalence and quality of root fillings were recorded. The relationship between the radiographic quality of root fillings and apical periodontitis was examined by chi-squared statistical-analysis. Of 8863 teeth, 470 (5.3%) had undergone root canal treatment. Forty-seven per cent of all the subjects had at least one root-filled tooth. Periapical radiolucencies were visible on 4.2% of teeth examined, with 53.5% of root-filled teeth presenting apical periodontitis. Ninety-one per cent of root-filled teeth with periapical pathosis were determined to have inadequate root fillings. A statistically significant correlation was found between the quality of root fillings and the presence of apical periodontitis (P < 0.05). KEY LEARNING POINTS: The radiographic quality of root fillings correlated with periapical radiographic signs of pathosis in a selected population of Turkish adults. There is a need to improve the standards of root canal treatment in the study population.     

Apical extrusion of debris and irrigants using two hand and three engine-driven instrumentation techniques

AIM: To evaluate the weight of debris and irrigant volume extruded apically from extracted teeth in vitro after endodontic instrumentation using the balanced force technique, a hybrid hand instrumentation technique, and three engine-driven techniques utilizing nickel-titanium instruments (ProFile .04, Quantec 2000 and Pow-R). METHODOLOGY: Five groups of 20 extracted human teeth with single canals were instrumented using one or other of five techniques: balanced force, hybrid, Quantec 2000, ProFile .04, or Pow-R. Debris extruded from the apical foramen during instrumentation were collected into preweighed 1.5 mL tubes. Following instrumentation, the volume of extruded irrigant fluid was determined by visual comparison to control centrifuge tubes filled with 0.25 mL increments of distilled water. The weight of dry extruded dentine debris was also established. RESULTS: Overall, the engine-driven techniques extruded less debris than the manual ones. However, there was no statistical difference between the balanced force technique and the engine-driven methods. The volume of irrigant extruded through the apex was directly associated with the weight of extruded debris, except within the ProFile group. The hybrid technique was associated with the greatest extrusion of both debris and irrigant. CONCLUSIONS: Overall, the engine-driven nickel-titanium systems were associated with less apical extrusion.     

Passive ultrasonic irrigation of the root canal: a review of the literature

Ultrasonic irrigation of the root canal can be performed with or without simultaneous ultrasonic instrumentation. When canal shaping is not undertaken the term passive ultrasonic irrigation (PUI) can be used to describe the technique. In this paper the relevant literature on PUI is reviewed from a MEDLINE database search. Passive ultrasonic irrigation can be performed with a small file or smooth wire (size 10-20) oscillating freely in the root canal to induce powerful acoustic microstreaming. PUI can be an important supplement for cleaning the root canal system and, compared with traditional syringe irrigation, it removes more organic tissue, planktonic bacteria and dentine debris from the root canal. PUI is more efficient in cleaning canals than ultrasonic irrigation with simultaneous ultrasonic instrumentation. PUI can be effective in curved canals and a smooth wire can be as effective as a cutting K-file. The taper and the diameter of the root canal were found to be important parameters in determining the efficacies of dentine debris removal. Irrigation with sodium hypochlorite is more effective than with water and ultrasonic irrigation is more effective than sonic irrigation in the removal of dentine debris from the root canal. The role of cavitation during PUI remains inconclusive. No detailed information is available on the influence of the irrigation time, the volume of the irrigant, the penetration depth of the instrument and the shape and material properties of the instrument. The influence of irrigation frequency and intensity on the streaming pattern as well as the complicated interaction of acoustic streaming with the adherent biofilm needs to be clarified to reveal the underlying physical mechanisms of PUI.     

A survey of current trends in root canal treatment: access cavity design and cleaning and shaping practices

The purpose of this study was to evaluate current trends in access cavity design and cleaning and shaping among endodontists. A survey was e‐mailed to active members of the American Association of Endodontists. Data showed that most respondents used traditional (57%) or conservative (43%) access cavities; less than 1% reported using ultraconservative access cavities. A glide path was created by 93% of respondents; NaOCl was used as lubricant by 51% of respondents, while 28% used RC Prep, 9% used liquid EDTA, 7% used Glyde, and 2% did not use any lubricant. Most respondents used NaOCl at 5.25% or higher concentration. Smear layer was removed by 92% of endodontists. Apical gauging was mostly accomplished with hand files. Clinical preferences varied among surveyed endodontists and among different age groups. Currently, very few endodontists use ultraconservative access preparations. There was large variation among the respondents suggesting a possible need for quality guidelines.     

Healing of apical periodontitis after endodontic treatment using three different root canal sealers

Abstract In this study 3 commonly used sealers were evaluated. The materials tested were Proco-Sol, a zinc oxide-eugenol-based sealer, AH26, an epoxy resin, and Klorperka NØ, a resin-gutta-percha-chloroform sealer. The healing of periapical lesions was followed for a period of 3 years. While the response to Kloroperka NØ seemed slightly inferior to the 2 others, no statistically significant differences among the groups could be demonstrated.     

Apical placement of needle tip with an injection-thermoplasticized gutta-percha technique for root canal obturation

Abstract It is recommended that when injection-thermoplasticized gutta-percha is used as the obturation technique, the root canal space should be prepared in such a way that the 23-gauge injection needle tip can be placed at a distance 3 to 5 mm short of the working length. In this study the apical seal and extent of gutta-percha were evaluated when the 23-gauge tip was placed at a distance 4 mm, 6 mm, and 8 mm short of the working length. Ninty-nine human single-rooted mandibular incisors and premolars divided into 3 equal groups were used. Their crowns were separated at the cementoenamel junction and their roots were stored in sodium hypochlorite for 1 week. The roots were then instrumented from size 20 at the working length to size 70:4 mm short of the working length in group A, 6 mm in group B, and 8 mm in group C. Following instrumentation, 3 randomly selected roots of each group were used as control. The remaining 30 roots of each group were covered with aluminium foil and embedded in acrylic blocks. The root canals were then dried, coated with sealer (Roth 811) and obturated by injection of thermoplasticized gutta-percha using the single-phase technique. Vertical condensation followed. The roots were immersed in dye for 3 days and then demineralized, dehydrated and cleared in xylene. Measurements of linear dye penetration for the apical seal and for underextension were done by 2 independent examiners under a stereomicroscope. The results of this study showed no statistically significant difference in leakage between the groups. However, statistically significant differences were found in linear underextension between groups A and C as well as between groups B and C, while no significant difference was found between groups A and B.     

Apical leakage following root canal dressing with calcium hydroxide

Abstract The purpose of this study was to analyse the apical leakage in teeth filled by the lateral condensation technique following medication with calcium hydroxide. One hundred and twenty extracted human teeth were biomechanically prepared by using exclusively reaming motion with files up to #40. Half of the teeth received a calcium hydroxide dressing for 3 days. The medication was removed by irrigation and reaming motion with files #40 up to #70. The teeth were divided in 6 experimental groups, according to the dimension of the utilized instrument. The root canals were filled and posteriorly the teeth were placed into a 2% methylene blue dye solution inside a flask, which was attached to a vacuum pump. Leakage was measured linearly, and the results showed significantly (p<0.01) less leakage in the experimental groups that received calcium hydroxide dressings than in the control groups. The results persisted even after the removal of 300 of dentin from the root canal dentinal walls.     

Lubrication during root canal treatment

Lubrication is involved in all root canal treatment phases, from dental dam placement to canal obturation. Most often associated with instrumentation, lubrication is required to facilitate the mechanical action of hand/rotary files and to help emulsify and suspend the debris produced. Aqueous irrigation solutions such as sodium hypochlorite and ethylenediaminetetraacetic acid (EDTA) should be regarded as lubricants, but paste‐type substances are marketed specifically for this purpose. As more patients demand the retention of challenging teeth with narrow and curved root canals, the importance of lubrication in all aspects of root canal treatment must be acknowledged.