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 Table of Contents  
Year : 2020  |  Volume : 17  |  Issue : 3  |  Page : 125-130

Microbial reduction after using different root canal irrigation–activation techniques

1 Department of Endodontics, Faculty of Dentistry, Tanta University, Tanta, Egypt
2 Department of Microbiology and Immunology, Faculty of Medicine, Tanta University, Tanta, Egypt

Date of Submission11-Feb-2020
Date of Acceptance19-Apr-2020
Date of Web Publication30-Oct-2020

Correspondence Address:
Ayah A Shehab Aldean
Department of Endodontics, Faculty of Dentistry, Tanta University, Tanta
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/tdj.tdj_7_20

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The aim was to clinically evaluate the microbial reduction after using different irrigation–activation techniques including needle irrigation, passive ultrasonic irrigation (PUI) and EndoVac.
Materials and Methods
Twenty-four patients with single rooted, single-canal teeth with primary endodontic infection were selected for this study then randomly assigned into three groups according to the final irrigation–activation method. Group 1 (control group) needle irrigation, group 2 (PUI irrigation) and group 3 (EndoVac irrigation). The first microbial sample (S1) was taken after access cavity preparation under complete aseptic condition then the second microbial sample (S2) after chemomechanical preparation using ProTaper Universal rotary system up to F3 or F4 or F5 according to canal size. Finally, the third microbial sample (S3) was taken after irrigation–activation, the three samples were cultured on blood agar aerobic and anaerobic, incubated for 24–48 h at 37°C, the growing colonies were counted and recorded as colony forming units.
PUI group showed the highest microbial reduction, while the needle group showed the lowest microbial reduction with statistically significant difference with both PUI group and EndoVac group. While no statistically significant difference was recorded between PUI and EndoVac groups.
Irrigation–activation increases the efficacy of irrigation concerning the microbial reduction and PUI is the most recommended method of activation.

Keywords: colony forming units, EndoVac, microbial reduction, needle irrigation, passive ultrasonic irrigation

How to cite this article:
Shehab Aldean AA, Darrag AM, Shaheen NA, Ezzat MM. Microbial reduction after using different root canal irrigation–activation techniques. Tanta Dent J 2020;17:125-30

How to cite this URL:
Shehab Aldean AA, Darrag AM, Shaheen NA, Ezzat MM. Microbial reduction after using different root canal irrigation–activation techniques. Tanta Dent J [serial online] 2020 [cited 2020 Nov 27];17:125-30. Available from: http://www.tmj.eg.net/text.asp?2020/17/3/125/299635

  Introduction Top

Endodontic infections are complex diseases associated with apical tissue inflammation that is determined by microbial, immunological, and environmental factors[1],[2]. It is polymicrobial in nature and includes the emergence of microbial colonization in form of biofilms. Biofilms were deeply seated in areas that are difficult to reach by mechanical instrumentation which in turn enhanced microbial resistance, virulence, antibiotic resistance and colonization potential [3],[4],[5].

Reducing the numbers of root canal microorganisms has many measures including the use of various instrumentation techniques, irrigation regimens, and in some cases intracanal medications. Consequently, the endodontic treatment should depend on a broad spectrum antimicrobial strategy to deal with such infections[6],[7].

The complex anatomy of the root canal system permits microorganisms to survive and decreases the efficacy of chemomechanical preparation of the root canal in reduction of endodontic infection. So, the irrigation techniques must ensure that irrigant solution reach effectively to such areas of root canals[8],[9].

The conventional endodontic irrigation syringe and needle which involves dispensing of an irrigant into a canal through needles/cannulas of variable gauges, either passively or with agitation that is achieved by moving the needle up and down the canal space. It has been advocated as an efficient method of irrigant delivery because it is very easy to manipulate, and there is good control of needle depth and volume of irrigant delivered[10]. However, its safety has been questioned because of the positive pressure used to introduce the irrigant into the canal, which could extrude the solution to the periapical area, resulting in severe tissue damage and postoperative pain[11].

Passive ultrasonic irrigation (PUI) enhance removal of the biofilms when combined with sodium hypochlorite (NaOCl) as this permits heating of the irrigating solution that increase its antibacterial effect, eliminates dentin debris and the smear layer which are areas of microbial stagnation, thereby achieving greater cleaning effect[12],[13].

EndoVac is an apical negative pressure (ANP) irrigation system, which is used to irrigate and remove debris at the apex without forcing irrigant solution into the periapical area. It is more efficient in apical debridement when compared with standard irrigation techniques. It has been shown to improve the antimicrobial efficacy of irrigants. In addition, EndoVac irrigation can result in a significant reduction of postoperative pain in patients[14],[15].

  Materials and Methods Top

Study setting

Twenty-four patients requiring routine endodontic therapy, selected from the outpatients who present to clinic of Endodontic Department, Faculty of Dentistry, Tanta University.

Ethical consideration

The purpose of the present study was explained to the patients and informed consents were obtained according to the guidelines on human research adopted by the Research Ethics Committee at Faculty of Dentistry, Tanta University.

Inclusion criteria

Patients with single rooted, single-canal teeth with primary endodontic infection, diagnosed with pulp necrosis and/or symptomatic or asymptomatic apical periodontitis as confirmed radiographically and by negative response to sensibility tests.

Exclusion criteria

Fractured or badly decayed teeth that could not be isolated with a rubber dam were excluded from this study, in addition to single rooted teeth with multiple canals or previous root canal treatment.

All the steps of dental intervention were performed under completely aseptic conditions. The tooth was completely isolated using a rubber dam (Midwest Dental, Wichita Falls, Texas, USA). OpalDam (Ultradent, South Jordan, Utah, USA) was applied to flow, surrounding the cervix of the isolated tooth then cured for 10 s using light cure (Woodpecker Medical Instrument Co., Guangxi, China) to prevent any possible leakage of saliva. The operative field was disinfected using swabs moistened with 3% hydrogen peroxide (Ahram, Giza, Egypt) until no further bubbling occurred, then followed by a 2.5% NaOCl (Prime Dental, Bhiwandi, Maharashtra, India) rinse for 1 min[16],[17].

The access cavity was prepared using long shank rose head bur size 2 and Endo Z bur (Komet; Brasseler, Lemgo, Germany) attached to high speed contra angle hand piece (NSK, Tokyo, Japan) The access cavity preparation was performed without using water spray but under manual irrigation with sterile normal saline (FIPCO, Borg el arab, Egypt) and with high suction[18].

Working length was determined with the aid of apex locator (Meta System Co. Ltd, Seongnam-si, Korea) and then confirmed by digital radiograph (New Life Radiology sr.I, Grugliasco TO, ITALY) using initial apical file (MANI Inc., Utsunomiya, Japan) sizes 15, 20, or 25 according to each canal size.

The first microbial sampling (S1) was taken from the root canal after access cavity preparation[19]. Canal was irrigated using 1 ml sterile saline solution and the sample was taken using successive sterile paper points (MetaBiomed, Cheongju, Korea) that were introduced into the full length of the canal and kept in place for 60 s until absorb all the fluid inside the canal[20]. The paper point sample was immediately transferred into tube containing 1 ml sterile saline as a transport medium[21] and the maximum time between sample collection and microbiological laboratory processing was 2 h[22], at Microbiology and Immunology Department, Faculty of Medicine, Tanta University.

Root canal instrumentation was completed at the same appointment in all cases using ProTaper Universal rotary system (DentsplyMaillefer, Ballaigues, Switzerland) up to master apical file corresponding to F3, F4, and F5 according to each canal size[23]. After complete chemomechanical preparation, the second microbial sample (S2) was taken and managed as S1.

Group assignment

The 24 patients were randomly assigned into three groups (n = 8 each) according to the final irrigation–activation method with 5 ml of 2.5% NaOCl solution as follow:

  1. Group 1 (control group): conventional needle (Endoneedle, Elsodent, France) and syringe irrigation.
  2. Group 2: PUI with #10 endosonic file (Aceton Group, Paris, France).
  3. Group 3: EndoVac (Discus Dental, Culver City, GA, California, USA)

After final irrigation–activation in each group the third microbial sample (S3) was taken.

All microbial samples (S1, S2, S3) were managed with a sterile double ended calibrated loop 1–10 μl (Deltalab, Barcelona, Spain), aseptically streak the blood agar (Oxoid, London, UK) plates which were incubated aerobically and anaerobically at 37°C for 24–48 h[24]. Then, the colonies that developed on each plate were counted and multiplied to give the number of colony forming units (CFUs)/ml of each specimen[16],[20].

Statistical analysis

Data of samples S1, S2, and S3 were collected and tabulated S2 and S3 counts were expressed as percentage of microbial reduction regarding to S1 and S2 counts. The mean and SD of CFU in each group were calculated and statistically analyzed using one-way analysis of variance with SPSS software version 20 (SPSS Inc., Chicago, Illinois, USA) whenever a statistically significant results were recorded (P ≤ 0.05) among the tested groups, Tukey's pairwise multiple comparison test was performed among the three groups and paired t-test performed among the three samples in the same group.

  Results Top

Regarding the microbial reduction after irrigation–activation represented in percentage of microbial reduction of S3 to S2, Tukey's pairwise comparison test was performed. It revealed statistically significant difference for aerobic and anaerobic count (P ≤ 0.001) between group 1 and group 2, group 1 and group 3, while there was no statistical significant difference between group 2 and group 3 P values of 0.194, 0.177 for aerobic and anaerobic, respectively [Table 1].
Table 1: The means and SD of the percentage of reduction of number of aerobic and anaerobic colony forming unit/ml between the three samples

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Regarding total microbial reduction in one visit recorded in relation between S3 and S1, Tukey's pairwise comparison test was performed. It revealed statistically significant difference for aerobic and anaerobic count between group 1 and group 2, group I and group 3, while the statistical significant difference between group 2 and group 3 recorded for aerobic only P value of 0.001 and nonsignificant for anaerobic P value of 0.632 [Table 2].
Table 2: The means and SD of the number of colony forming unit/ml for S1, S2, and S3 the three groups in aerobic and anaerobic culture

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Statistical analysis using one-way analysis of variance revealed statistical significant difference between the three samples in the same group. Therefore, paired t-test was performed and revealed statistical significant difference between each two samples in the same group.

  Discussion Top

Microorganisms and their toxic by-products are the predominant causative agents in pulpal and periapical diseases. The main objectives of root canal treatment are disinfection and prevention of microbial re-infection of the root canal system[18]. Because of the anatomical complexity of root canal systems and the limitations of currently available mechanical shaping devices and procedures, there are some parts of the canal walls remain unprepared after root canal instrumentation[25].

Hence, chemomechanical debridement of infected root canals plays an essential role in root canal disinfection accompanied with different techniques of irrigation agitation[21].

Mechanical irrigation agitation has been found to increase the efficacy of irrigation solutions. Therefore, machine assisted irrigation techniques including PUI and EndoVac negative pressure irrigation were used in this study in comparison to the traditional syringe and needle method[26].

Total count of cultivable bacteria was detected through culturing method, using non-selective blood agar media which promotes total growth of microorganisms, that incubated aerobically and anaerobically to get separate counts of CFUs of aerobic and anaerobic microorganisms[20],[27]. Therefore, culturing method was used in this study.

Root canal preparation is considered as the most important phase of endodontic treatment with regard to bacterial elimination. Rotary multi-instrument systems, which consist of a series of nickel-titanium (Ni-Ti) instruments used in continuous rotation motion showed highly significant bacterial reduction in clinical studies[28],[29]. Therefore, ProTaper universal rotary Ni-Ti system was used for root canal preparation in this study.

Regarding irrigation agitation techniques, the present study revealed that PUI is more effective than needle and syringe irrigation with significant difference while no statistical significant difference when comparing to EndoVac irrigation. This may be attributed to that during ultrasonic irrigant activation, the file oscillation allows the irrigant to flow into the irregularities of the canal, accessing areas that were not touched by the instruments and providing better cleanliness of the root canal system. The cavitation effect produced by PUI resulting in temporary weakening of the cell membrane, making the bacteria more permeable to NaOCl[30]. Moreover, the increase in the irrigant temperature improve the effectiveness of NaOCl on tissue dissolution[31].

In addition, ultrasound causes de-agglomeration of bacterial biofilms via the acoustic streaming action. De-agglomeration of biofilms within a root canal might render the resultant planktonic bacteria more susceptible to the bactericidal activity of NaOCl[30].

The high microbial count found in control group may be due to several disadvantages of needle irrigation as the irrigant solution reach only 1–2 mm beyond the needle tip, inability to reach the whole canal space specially apical third due to vapor lock effect[32].

The nonsignificant difference between PUI and EndoVac irrigation may be explained by the EndoVac ability to make irrigant solution reach the working length mainly due to the design of the microcannula, which eliminates the apical vapor lock and its ability to allow apical exchange of irrigants, improving the cleaning performance[27].

These results are in agreement with Nakamuraet al.[25] that reported ultrasonic activation was more effective than a needle activated irrigation protocol for reducing the number of bacteria evaluated clinically. Moreover, These results were also supported by Spoletiet al.[33] that found there are more number of surviving bacterial colonies in group in which ultrasonic was not used. Also Carveret al.[34] noted that the use of ultrasonic irrigation following hand/rotary instrumentation in vivo produced a significantly greater reduction in CFU counts in infected necrotic human molars[34].

The result of this study are also in agreement with Townsend and Maki[35], they found that ultrasonic irrigation was significantly more effective in removing intracanal bacteria than both needle irrigation and EndoVac. Also Hockettet al.[36] concluded that ANP delivery of irrigants with the EndoVac had the potential to achieve better microbial control than positive pressure needle irrigation.

Furthermore, the result of this study is in agreement with Cohencaet al.[27], who demonstrated better disinfection of root canals when using contemporary irrigation delivery systems. While no significant difference was found between ANP 'EndoVac' and PUI in bacterial reduction, they were both statistically better than traditional needle irrigation.

In contrary, The result of this study were in disagreement with Beuset al.[37] that compared the results of a nonactivated needle irrigation protocol with a PUI protocol in rendering canals bacteria free; they found that there is no statistical difference between needle and PUI groups and this may be due to absence of standardization before microbiological sample in both groups, samples were taken directly after PUI activation, while in needle activation, a hand file equal in apical size to the master apical file was inserted into the canal, reamed against the canal walls to remove any debris, bacteria from the dentin walls of the canal and then the sample was taken.

Furthermore, these results were in disagreement with Paivaet al.[38], they reported that PUI approach did not succeed to significantly enhance disinfection beyond that achieved by chemomechanical preparation. This may be explained by the different methodology as it did not have control group and used PCR method which detect viable and nonviable bacteria.

Comparing the samples in the same group, S2 (the second microbial sample after chemomechanical preparation) has reduced the microbial count when compared with S1 which is considered as 100%, The microbial reduction is accomplished by mechanical preparation which remove the infected dentin along the root canal, combined with the use of irrigant solution[39],[40]. In addition, NaOCl that is able to dissolve organic tissue remnants and flush out debris from the prepared root canals and exhibit powerful antimicrobial activity[41]. While S3 the third microbial sample after irrigation–activation methods which have great role on microbial reduction.

Results of the present study revealed that chemomechanical preparation has great role in microbial reduction, despite the detection of positive cultures which may be due to the complexity root canal systems[42]. so it is better to use adjunctive method of irrigation agitation to increase the microbial reduction[43],[44].

When comparing the percentage of reduction S3 to S2 in each group that represent microbial reduction of irrigation–activation, there is statistically significant difference revealing the role of irrigation–activation on microbial reduction as mentioned before.

  Conclusion Top

Within the limitations of this study, it was concluded that:

  1. Root canal instrumentation and irrigation–activation have major role in microbial reduction.
  2. None of the tested irrigation–activation techniques completely eliminated the organisms.
  3. Both PUI and EndoVac irrigation has the ability to disrupt the microbial communities within the canal as effectively

Further, in-vivo studies should be directed toward evaluation of the clinical signs and symptoms accompanied with microbial reduction before and after chemomechanical preparation with different irrigation protocol, irrigation–activation and application of intracanal medication.

Furthermore, in-vitro studies should evaluate the effect of treatment modalities on polymicrobial biofilm instead of planktonic bacteria.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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  [Table 1], [Table 2]


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