|Year : 2022 | Volume
| Issue : 1 | Page : 196-202
Machine-Assisted irrigation systems for smear layer removal in root canal treatment: A systematic review
Kajol Relan, Manoj Chandak, Pooja Chandak, Akshay Jaiswal
Department of Conservative Dentistry and Endodontics, Sharad Pawar Dental College and Hospital, DMIMSDU, Wardha, Maharashtra, India
|Date of Submission||07-Dec-2021|
|Date of Decision||10-Jan-2022|
|Date of Acceptance||19-Feb-2022|
|Date of Web Publication||25-Jul-2022|
Dr. Kajol Relan
Department of Conservative Dentistry and Endodontics, Sharad Pawar Dental College and Hospital, DMIMSDU, Sawangi, Wardha, Maharashtra
Source of Support: None, Conflict of Interest: None
Objectives: The objective was to evaluate the efficacy of three machine-assisted irrigation systems in smear layer removal from apical one-third of the root canal system. Data Source: A comprehensive search of last 10 years was performed in the following systematic electronic database: PubMed/Medline and Scopus. Data Selection: We included in-vitro studies that compared Endoactivator, Endovac, and Passive ultrasonic irrigation system's clinical success of smear layer removal in apical one-third of the root canal systems. Data Synthesis: A total of 72 nonduplicated studies were retrieved in the systematic search. Seven studies included in the study assessed the success rate of smear layer removal in the apical third of the root canal system of three irrigation systems through scanning electron microscopic evaluation. These studies were classified as low risk of bias. The studies evaluating the scanning electronic microscopy of smear layer removal in the apical one-third of the root canal comparing the Endoactivator and Passive ultrasonic irrigation showed no statistical difference (P < 0.05). The studies evaluating the scanning electronic microscopy of smear layer removal in the apical one-third of the root canal comparing the Endoactivator and Endovac showed statistical difference (P > 0.05). Conclusion: Based on the findings, Endovac irrigation system was found to be effective in smear layer removal from apical one-third of the root canal system. Further in-vivo studies and clinical trials are required for more conclusive results.
Keywords: Apical one-third of the root, Endoactivator, Endovac, irrigation of the root canal, passive ultrasonic irrigation, smear layer removal
|How to cite this article:|
Relan K, Chandak M, Chandak P, Jaiswal A. Machine-Assisted irrigation systems for smear layer removal in root canal treatment: A systematic review. J Datta Meghe Inst Med Sci Univ 2022;17:196-202
|How to cite this URL:|
Relan K, Chandak M, Chandak P, Jaiswal A. Machine-Assisted irrigation systems for smear layer removal in root canal treatment: A systematic review. J Datta Meghe Inst Med Sci Univ [serial online] 2022 [cited 2022 Aug 18];17:196-202. Available from: http://www.journaldmims.com/text.asp?2022/17/1/196/352244
| Introduction|| |
Mechanical and chemical cleaning of the root canal is the main apprehension of the endodontic treatment. The main reason is to thoroughly eliminate micro-organisms and their substrates from the canal. Ramifications, isthmuses, and canal irregularities get accumulated with hard tissue debris. It also contains smear layer which is an irregular surface layer. It is amorphous and it covers the root canal walls. This is due to instrumentation of canal walls. This layer involves inorganic and organic components. Inorganic include dentin debris. Organic part includes microbes, fragments of odontoblastic processes, and pulpal remnants. There are two layers in smear layer. The outer layer is 1–2 μm thick. The inner layer spreads 40 μm in depth. It sticks lightly to the dentinal tubules. Debris and smear layer is considered as undesirable consequence of shaping procedure. This disrupts with adaptation of root canal filling materials. Adaptation to “hard-to-reach areas” is also prevented. A good biomechanical preparation results in successful root canal treatment. Despite the instruments and method used for biomechanical preparation, some parts of the root canal remains as it is. Byström et al. established that mechanical instrumentation alone is inefficient. Meticulous irrigation with disinfectants is necessary for proper disinfection of the root canal. Use of NaOCl followed by ethylenediaminetetraacetic acid (EDTA) helps soften the organic tissues. This also helps in demineralizing the smear layer. Several systems are available for irrigation of the root canal.[l], They are basically either manual or machine assisted. Accumulated hard tissue debris cannot be effectively removed from complexities by manual irrigation., Hence for effective irrigation, greater amount of solution along with frequent exchange of solution is recommended.,, To increase the efficacy of disinfection process, removal of debris is necessary. Irrigating solution is considered effective to eliminate organic tissue. Smear layer should be removed. It should kill microbes. This is possible if it is carried to apical region of the root canal system. The most commonly used machine-assisted irrigation systems include ultrasonic, sonic, and apical negative pressure systems.
The widely cited system in current literature is irrigation using ultrasonic tips. The principle behind this technique is that the energy released from the instrument, due to acoustic streaming and cavitation, enhances the property of the irrigating solution., Efficacy of occurrence of this phenomenon depends on free available space within the root canal. It also depends on the power and intensity of the system. It also depends on the absence of interference on the tip. Ultrasonic irrigation activation has more efficacy in the cervical part. Its efficacy is less in the apical part. This is due to anatomic features of the root canal. Ultrasonics works with a frequency of 25,000–30,000 Hz.
It has been reported that apical negative pressure system provides better disinfection. It provides better cleanliness. It provides less apical extrusion of irrigants., It is possible to deliver large amount of irrigant in apical region using negative pressure irrigation. It also provides better debridement in apical root canal. This is because of its ability to dislodge the vapor lock.
The principle behind sonic irrigation is same as ultrasonic. It is acoustic energy transmission to the irrigation solution. This increases velocity of movement of irrigant. Hence, there is improvement in the distribution of irrigant into the root canal. The flexible polymer tips are used in sonic activation with Endoactivator. It prevents cutting of root canal during accidental contact. Endoactivator works with a frequency of 190 Hz–6000 Hz.,
Many in vitro studies were carried out to evaluate the effectiveness of the irrigation systems in smear layer removal in apical third of the root canal system.
Therefore, aim of this systematic review is to critically analyze the published data and compare the effectiveness of Patient Under Investigation (PUI), Endoactivator and Endovac in cleaning and disinfecting at the apical third of the root canal system.
| Methodology|| |
Two independent researchers conducted searches in PubMed/Medline through the year 2010 to identify studies published in English. The keywords used were “smear layer removal,” “Endoactivator,” “Endovac,” “Passive Ultrasonic Irrigation” and “apical one third of the root canal system.” The search details were ([([smear layer removal] AND [Endoactivator]) OR [Endovac]] OR [Passive ultrasonic irrigation]) AND (apical one third of the root canal system).
Using PRISMA guidelines statement, this systematic review was conducted. Reviewing all the abstracts and all texts, the studies are carefully chosen according to the inclusion and exclusion criteria and are reported below. None of the manuscript author was contacted during this process. Disagreements between authors were evaluated, and the studies were eliminated through discussion among researchers until a consensus was reached. Flowchart for this systematic review is shown in [Figure 1].
The inclusion criteria for this review included studies published in English with restrictions on year of publication, that is last 10 years, and studies which evaluated apical cleaning efficacy of ultrasonic irrigation, sonic irrigation, and Endovac system of root canal using sodium hypochlorite in adult patients with fully formed permanent teeth undergoing endodontic treatment. The types of studies were in vitro and ex vivo studies using human cells, prospective studies, and retrospective studies.
Studies that resulted in cytotoxicity of irrigant, apical extrusion of the debris, inadvertent dentin removal, and in vivo studies were excluded. In addition, studies with nonstandardized root canal preparation within and between Endoactivator, Endovac, and PUI and/or did not use the same volume, composition, concentration, and contact time of irrigant solutions for the PUI, Endoactivator, and Endovac groups were also excluded. Reviews, opinion articles, case reports, serial cases, and studies that did not perform the chemo mechanical step were excluded.
| Quality Assessment for Risk of Bias and Data Extraction|| |
In second step, full text of the chosen articles was read out for data extraction and quality assessment was done as per Office of Health Assessment and Translation (OHAT) tool by two independent reviewers. In the cases of difference between reviewers, the third senior reviewer clarified the discrepancy. In the beginning, 72 articles were selected which included irrigation efficacy of all the irrigation systems in the entire root canal. Ten studies which included apical extrusion of the debris, inadvertent dentin removal, and in vivo studies were excluded. Also, three full-text articles based on quantitative analysis were excluded. Hence, only seven articles were selected [Figure 1]. Title, abstract, and a scientific context based on irrigation efficacy of systems in the apical third were included. Intrusion, statistical analysis, and evaluation period were also used and main results were extracted from each experimental study.
In this study, after quality assessment for risk of bias was done by three independent reviews and by OHAT tool, it was found that all studies included low risk of bias. Quality assessment for risk of bias for in vitro studies were done by OHAT tool as shown in [Table 1].
| Criteria for Selection of The Studies|| |
First, studies were selected by analysis of the titles. If the title indicated inclusion, the abstract was evaluated carefully and articles considered eligible for review (or in case of doubt) were selected for reading. Due to the lack of randomized clinical trials and prospective and retrospective studies, this review included in vitro studies and ex vivo studies using human root canals. For this reason, the patient -intervention -comparison- outcome system was adapted: Population (studies that evaluated human root canals), Intervention (evaluation of cleaning efficacy of three irrigation systems in apical third of root canal), Comparison (comparison of the three irrigation systems), and Outcomes (machine assisted irrigation systems are more efficient in irrigation of root canals).
| Results|| |
The preliminary screening of the retrieved studies was conducted using titles and abstracts. The authors independently evaluated the studies and discussed the results until a decision was reached by consensus. Among the 100 studies, 50 duplicates were discarded, obtaining a total of 50 articles. Those 50 articles were screened and 30 articles were excluded as they were review articles. Of the 20 full text articles, 10 articles were excluded after reading the title and abstract because did not exactly match with the subject to be reviewed; despite coinciding with the subject. Of the remaining 10 articles, 7 studies had qualitative synthesis and therefore included in the systematic review. One ex-vivo study, six in vitro studies included in the study. [Figure 1] summarizes the details and results of the search strategy. [Table 2] presents the reported efficacy of three irrigating devices for smear layer removal in apical third of root canal.
|Table 2: Qualitative analysis and characteristics of the included studies|
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Tamara Costa Lopes Schiavotelo et al. study, included 44 maxillary molars. These molars were instrumented and randomly divided into three groups comparing nonactivated irrigation, Passive ultrasonic irrigation and Endoactivator. No statistical significant difference in smear layer removal was found between the irrigation techniques in apical third of the canal (P = 0.061).
Priyatam Karade et al. study, included 40 single-rooted premolars. The samples were instrumented and divided into five groups depending upon the irrigation system used; Needle and syringe, Endoactivator, Passive ultrasonic irrigation, and Endovac irrigation system. The results showed that Endovac group presented with cleaner canals in 60% and 80% cases in the apical third of the canal and differed significantly from the other groups (P = 0.011 and P = 0.001, respectively).
Sanghamitra Suman et al. study, included 40 mandibular premolars. The samples were instrumented and divided into four groups; needle and syringe, Endoactivator, Endovac and laser (Er: YAG) according the final irrigation. Endovac system (3.49 ± 0.67) proved to be effective than Endoactivator (4.01 ± 0.48) in removing debris from the apical third of the canal.
Varun Raj Kumar et al. study included 40 single-rooted premolars. The samples were instrumented and divided into the groups; needle and syringe irrigation, Max I probe needles, Endoactivator and Endovac according to the irrigation system used for final irrigation. Endoactivator (0.8 ± 0.42) and Endovac (0.4 ± 0.52) proved to be efficient in removing smear layer from apical third of the canal.
Xiangjun Guo et al. study, included 50 single-rooted teeth. The samples were instrumented and divided into five groups; needle and syringe, passive ultrasonic irrigation, navitip fx group, Endoactivator group. Endoactivator group showed effective irrigation in the apical third of the canal compared to other groups.
Manuele Mancini et al. study, included 65 single-rooted premolars. The samples were instrumented and divided into five groups. Two control groups, Endoactivator, Passive ultrasonic irrigation, Endovac groups. The efficacy of the systems were as Endovac > Endoactivator > Passive ultrasonic irrigation in smear layer removal in apical third of the root canal.
Luciana Magrin Blank-Goncalves et al. study, included 62 mandibular molars. The samples were instrumented and divided into three groups; needle and syringe, passive ultrasonic irrigation and Endoactivator systems. Endoactivator and ultrasonic irrigation were proved to efficacious than conventional needle and syringe. However there was no significant difference seen between Endoactivator and ultrasonic group (P = 0.0007).
| Discussion|| |
Root canal shaping is done to attain tapering funnel shaped canal. This shaping is from coronal opening to the apex. Combined use of mechanical instrumentation and irrigation is necessary. Along with this use of several irrigating solutions in an appropriate sequence is essential. This will help achieve proper canal disinfection. Irrigating solutions capable of removing organic and inorganic tissue efficiently remove smear layer. For increasing flow and circulation of irrigant inside root canal, different delivery systems are proposed. Irrigant volume is a major factor in removal of smear layer. Vibrations generated by ultrasonic, sonic, and endovac systems produce acceptable cleaning. This study aims at analyzing various irrigation systems for their effectiveness in smear layer elimination from root canal walls from apex.
Luciana Magrin Blank-Goncalves et al. in 2011 analyzed qualitatively, smear layer removal in apical third of curved roots. They compared Endoactivator and Passive ultrasonic irrigation and the control group with no irrigation. They analyzed the smear layer according to the scoring system as score 0-no smear layer, score 1-moderate smear layer, score 2-heavy smear layer, smear layer covers the root canal surface and tubules. They found that EA and PUI both equally produced cleaner canals in the apical third with a score 0. The control group was with the score 2. Conventional group was with the score 1. There were no noteworthy changes in cleaning efficacy of EA and PUI in apical third of the root canals.
Manuele Mancini et al. in 2013 compared the smear layer removal and canal cleanliness of Sonic, Endovac and Ultrasonic irrigation (PUI). They evaluated the cleaning efficacy at 1, 3, 5, 8 mm from the apex with a 5 score index system coded by Hulsmann et al. The scoring goes as score 1-no smear layer (dentinal tubules open), score 2-small amount of smear layer, score 3-homogenous smear layer covering the root canal wall, score 4-complete root canal wall covered with homogenous smear layer, score 5-heavy non homogenous smear layer covering complete root canal walls. At 1 mm from apex the root canal wall was covered with heavy debris in control group whereas the mean score reduced significantly up to 20% in endovac group. At 3 mm from the apex the mean score reduced 34% in Endoactivator and 24% in Endovac group. At 5 mm from the apex the mean score reduced 40% in Endovac, 40% in endoactivator and 20% in PUI. At 8 mm from apex all the systems were efficient in improving root canal cleanliness. He found that Ultrasonics showed poor results in apical third of the root canal. Endovac produced highest degree of cleanliness at 1, 3, 5, and 8 mm from the apex. EA system showed similar results at 3, 5, and 8 mm from apex. This is because microcannula in endovac reaches working length that ensures irrigation in apical third. EA tip is positioned 2 mm from the apex. Therefore efficacy of Endoactivator is increased 3 mm from the apex. Hence Endovac produced cleaner canal in the apical third than Endoactivator and PUI.
Xiangjun Guo et al. in 2014 stated that 60°C 3% NaOCl and 17% EDTA combination used along with Navitip fx or Endoactivator or PUI were effective in elimination of smear layer in the root canal. The smear layer removal was scored according to following criteria: 1: smear layer was completely absent; 2: smear layer covered <25% of the canal wall and dentinal tubules; 3: smear layer evident in 25%-50% of the canal surface and tubules; 4: smear layer evident in 50%–75% of canal surface and tubules; 5: smear layer covering 75%–100% of canal surface and tubules. The author in this study stated that Endoactivator has more efficacy in removal of smear layer than PUI. This is attributed to polymer based tip of the Endoactivator that has smooth surface so it does not cut the root dentin. Endoactivator tip diameter increases with consecutive enlargement of the root canal. It uses sonic frequency that ensures better smear layer removal. On the contrary, with the use of Ultrasonic tip, care is to be taken not to touch the tip to the root canal walls. This is because it causes inadvertent removal of root dentin. It is hard to keep the tips from not touching the walls. Hence the study concluded that Endoactivator performed better than Passive Ultrasonic irrigation in removal of smear layer in apical third of the root canal. Yet no irrigation system has efficacy in total removal of smear layer in apical third of root canal.
Varun raj et al. in 2015 compared Max I probe, Endoactivator and Endovac in cleaning efficacy at apical third of the root canal. The scoring criteria was score 0-no smear layer (more than 80% of the tubules open), score1-Minor smear layer (more than 50% of the tubules open), score 2 – Heavy smear layer (More than 30% of the tubules open), score 3 – Maximum obliteration of tubules. In conventional syringe and needle irrigation the score was 2 and 3. In Max I probe needle irrigation the score was 2 and 3. In Endoactivator group the score was 1. In Endovac group the score was 0 and 1 with maximum samples showing score 0. Hence endovac proved better in apical cleaning of the root canal system. This was attributed to negative pressure created by endovac removes the smear layer efficiently at 1 mm from working length in apical third of the root canal system. It showed least amount of debris at all levels.
Sanghamitra Suman et al. in 2017 compared Er: YAG laser, Endovac, and Endoactivator for smear layer removal in the root canal. The 5 score index system coded by Hulsmann et al. was used. The mean score at apical third was highest for control group that was 5. This was followed by laser that was 4.47 followed by Endoactivator having 4.01. The least mean score was for Endovac with 3.49. Endovac was found to be better in cleaning of smear layer in apical third of the root canal than all the other irrigation devices. That was due to negative pressure generated in the apical third of the canal. This resulted in more irrigant volume distributed at apical third. This also reduces risk of debris extrusion beyond apex. The principle of mechanism of Endoactivator is hydrodynamic agitation of the irrigant. In spite of this mechanism, it cannot overcome the vapor lock effect. Hence efficacy of Endoactivator is less as compared to Endovac.
Priyatam Karade et al. in 2017 compared Endoactivator, Endovac, Passive ultrasonic irrigation, and conventional needle and syringe irrigation for smear layer removal in the root canal. The 5 score index system coded by Hulsmann et al. was used. Also the score A and B were used which depicted Clean and almost clean canals. The score C and D depicted canals covered with smear layer. In syringe and needle irrigation, 100% of the samples showed score C and D in the apical third. In Endoactivator group 100% of the samples showed scores C and D in apical third however 90% and 80% of the samples showed scores A and B in coronal and middle third respectively. In PUI group 100% of the samples showed scores C and D in the apical third whereas 100% and 90% samples showed scores A and B in coronal and middle third respectively. In Endovac group 60% of cases showed score A and B and 40% of the cases showed scores C and D in apical third. 100% and 90% cases showed scores A and B in coronal and middle third of the canal respectively. In Passive ultrasonic irrigation (PUI) showed effective smear layer removal in coronal and middle third. This was because PUI produced acoustic streaming and cavitation. Endoactivator removed smear layer effectively because of its sonic frequency. Also it has flexible polymer tips. This will prevent unnecessary cutting of the sound dentin and tips are placed 2 mm from the apex. Efficiency of endovac group is mainly because of apical negative pressure approach. Irrigant is drawn towards the apex down the canal walls that creates stormy force at the tip of microcannula. To surpass the vapor lock effect, the microcannula opening vacate debris from canal systems. This results in effective apical third irrigation of the canal. Hence Endovac was effective in smear layer removal in the apical third of the root canal than Endoactivator and PUI.
Tamara Costa Lopes Schiavotelo et al. in 2017 performed the study on smear layer removal effectiveness of Endoactivator and PUI systems in curved canals. The 5 score index system coded by Hulsmann et al. was used. The mean value for nonactivated irrigation system was 3.80 followed by PUI that was 3.83 and with Endoactivator was 3.00 at the apical third of the canal. He evaluated that EA showed better removal of smear layer from root canal walls in cervical and middle third of the roots than passive ultrasonic irrigation. Superiority of EA in middle third is due to flexibility of tip. Also it can easily follow canal curvature whereas rigid ultrasonic tip cannot. However, no noteworthy difference was found in efficacy of smear layer removal by EA and PUI in apical third of the root canal.
Mechanical and chemical cleaning of the root canal is the main apprehension of the endodontic treatment. The main reason is to thoroughly eliminate micro-organisms and their substrates from the canal. In this systematic review four in vitro studies showed that Endovac showed better results in smear layer removal in apical one third of the root canal system than Endoactivator and PUI. One in vitro studies compared all the three irrigation systems and showed that Endoactivator performed better in the cervical and middle third than PUI. However both Endoactivator and PUI showed same results in the apical third of the root canal. One in vitro study stated that Endoactivator provided better cleaning in apical third of curved root canals than PUI.
Double blinded investigators were assigned to review the studies included and their outcomes and the reviews are depicted in [Table 3].
| Conclusion|| |
This systematic review highlighted the need for randomized clinical trials comparing the Endovac, Endoactivator, and PUI modalities. As all the studies had similar method of analysis, reviewing all the studies, it can be concluded that Endovac is effective in smear layer removal in the apical third of the root canal system.
The authors would like to thank Dr. Pradnya Nikhade for her valuable support and guidance.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]