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Year : 2022  |  Volume : 11  |  Issue : 1  |  Page : 17-22

An in vitro evaluation of smear layer removal with non-activated self adjusting file, xp-endo finisher and rotary canal brush: A scanning electron microscopic study

1 Department of Conservative Dentistry and Endodontics, KVG Dental College and Hospital, Sullia, Karnataka, India
2 Department of Conservative Dentistry and Endodontics, G.Pulla Reddy Dental College and Hospital, Kurnool, Andhra Pradesh, India
3 Conservative Dentistry and Endodontics, Consultant Endodontist, Bengaluru, Karnataka, India

Date of Submission27-Jun-2021
Date of Decision19-Oct-2021
Date of Acceptance03-Nov-2021
Date of Web Publication23-May-2022

Correspondence Address:
Dr. Krishnaveni M Marella
Department of Conservative Dentistry and Endodontics, KVG Dental College and Hospital, Sullia - 574 239, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jdrntruhs.jdrntruhs_86_21

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Background: Endodontic success involves removal of necrotic vital tissue and microorganisms from the root canal. Irrigation is an essential part of canal debridement, because it allows cleaning beyond what might be achieved by instrumentation alone.
Aim: The aim of this in vitro study is to compare the smear layer removal efficacy of different final irrigation agitation devices.
Materials and Methods: A total of 60 extracted single-rooted human premolar tooth were taken and decoronated. All the specimens were cleaned and shaped using ProTaper universal rotary files system and intermittent irrigation was done using 2 ml of 3% NaOCl and randomly divided into four groups, based on irrigant agitation device. Group 1 = conventional needle, Group 2 = Rotary canal brush, Group 3 = Non-activated Self adjusting file, and Group 4 = Xp-endo finisher. Final irrigant used is 17% Ethylene Diamine Tetra Acetic acid (EDTA) smear clear. All the specimens were finally flushed with distilled water and dried with paper points, then they were split longitudinally into halves and examined under scanning electron microscope. Data were analyzed using SPSS version 23, P value of <0.05 was considered statistically significant.
Results: Non-activated self adjusting file (SAF) and Xp-endo finisher showed significantly cleaner walls with removal of smear layer followed by canal brush. There was no significant statistical difference (P < 0.05) between non-activated SAF and Xp-endo finisher.
Conclusion: Xp-endo finisher shows superior results compared with other agitation methods.

Keywords: Smear clear, smear layer, sodium hypochlorite

How to cite this article:
Marella KM, Sampathi NR, Pavani LN, Manduru CS, Moosani GK. An in vitro evaluation of smear layer removal with non-activated self adjusting file, xp-endo finisher and rotary canal brush: A scanning electron microscopic study. J NTR Univ Health Sci 2022;11:17-22

How to cite this URL:
Marella KM, Sampathi NR, Pavani LN, Manduru CS, Moosani GK. An in vitro evaluation of smear layer removal with non-activated self adjusting file, xp-endo finisher and rotary canal brush: A scanning electron microscopic study. J NTR Univ Health Sci [serial online] 2022 [cited 2023 Feb 4];11:17-22. Available from: https://www.jdrntruhs.org/text.asp?2022/11/1/17/345811

  Introduction Top

The ultimate goal of endodontic therapy should be to return the involved teeth to a state of health and function.[1] Instrumentation of the root canal system during endodontic therapy is recognized as being one of the most important stages in root canal treatment. Success of endodontic treatment is directly influenced by proper debridement of root canal and biomechanical preparation.[2]

After instrumentation of infected root canals, dentin debris and smear layer are formed on root canal walls.[3] The investigator to describe the smear layer on instrumented root canals were McComb and Smith (1975).[4] Endodontic success requires removal of smear layer because it contains bacteria, their by-products, and necrotic tissue. Presence of these limits the optimum penetration of disinfecting agents, acts as a barrier between filling materials and the canal wall, and therefore compromise the formation of a satisfactory seal.[4]

Sodium hypochlorite (NaOCl) in 1 – 5.25% concentration is an irrigant solution used widely in root canal treatment because of its bactericidal properties and ability to dissolve organic tissues.[5] But NaOCl has not been shown to be effective in removing smear layer.[6]

Different chelating agents have been used for the removal of the smear layer. EDTA in combination with sodium hypochlorite is commonly used for the effective removal of the smear layer from the root canal system.[7]

Recently, liquid EDTA has been introduced, smear clear 17% EDTA solution from Sybron endo (Orange, CA, USA) containing cetrimide (a quaternary ammonium compound), and an additional surfactant which increases the efficacy in removal of smear layer in root canal.[8]

To attain maximum efficacy of irrigants, an effective irrigation delivery system is required which will delivery it with adequate flow and volume to the working length to be effective in debriding the complete canal system.[9] Different irrigation agitation systems has been introduced to improve the effective delivery of irrigant before obturation.[10]

Canal brush (Coltene Whaledent, Langenau, Germany) is an endodontic microbrush commercially available. Weise et al. showed that the use of the small and flexible canal brush with an irrigant removed debris effectively from simulated canal extensions and irregularities.[11]

A new instrument for irrigant agitation, the XP-endo Finisher (XPF; FKG Dentaire SA, La Chaux-de-Fonds, Switzerland), has been recently introduced as an adjunctive approach to improve the effectiveness of irrigation in endodontics. XPF is an ISO 25/.00 instrument produced using a special type of alloy, the NiTi Max Wire (Martensite-Austenite Electropolish-FleX, FKG). It is used at 800 rpm with irrigating solutions after root canal preparation to size #25 or larger.[12],[13]

The Self adjusting file (SAF) is a hollow file designed, such that it adapts itself to the canal shape after inserting into root canal. The SAF is operated with vibrating handpieces with 3000 to 5000 vibrations per minute and an amplitude of 0.4 mm. The hollow tube design allows for continuous irrigation. A special irrigation device (VATEA, ReDent-Nova) is connected by a silicon tube to the irrigation hub on the file and provides continuous flow of the irrigant of choice at a low pressure and at flow rates of 1 to 10 mL/min.[14],[15]

In this study, the vibration mechanism was switched off and used only for irrigation purpose termed as non-activated SAF. There are limited published data to compare new and emerging devices and methods for disinfection of root canal system. Therefore, this study was planned to evaluate and compare the efficacy of smear clear when combined or agitated with non-activated SAF, XP-endo Finisher, and canal brush in removal of smear layer and debris, a scanning electron microscopic study.

  Materials and Methods Top

A total of 60 freshly extracted human mandibular premolars were collected. Approval form institutional ethics committee was taken on 12-08-2015. Inclusion criteria includes mandibular premolars which were extracted for periodontal or orthodontic purposes having single straight canals with one root and one canal, mature apices, with a curvature of 0–10°, exclusion criteria includes fractured teeth, carious teeth, teeth with internal/external resorption, hypoplastic teeth, and teeth with open apices. All the specimens were cleaned of tissue fragments and any visible debris using ultrasonic scaler (Satelec, Switzerland) and were stored in purified filtered water until use. Teeth were decoronated by using diamond disc, establishing a standardized root length of 16 mm to standardize canal instrumentation. Working length was recorded when the tip of the k file at the apical foramen and working length was obtained by deducting 1 mm from the recorded length. All the specimens were cleaned and shaped with Rotary NiTi instruments (ProTaper universal) upto F4 and intermittent irrigation of canal done using 2 ml of 3% NaOCl between each file use. All the specimens were then randomly divided into four groups with 15 samples each and treated as follows.

Group I: Conventional needle irrigation (n = 15) 5 ml of 17% EDTA is used as a final irrigant using 30-guage needle followed by 5 ml 3% of NaOCl to remove EDTA remnants.

Group II: Canal brush (Coltene whale Dent) (n = 15) canals were filled with 5 ml of 17% EDTA (Smear Clear) and all samples were agitated using a medium-sized canal brush operated on a contra angle handpiece at 600 rpm for 1 min followed by 5 ml 3% of NaOCl.

Group III: Non-activated SAF (n = 15) In this study, vibrational mechanism was turned off, and the system was used only for irrigation with a VATEA peristaltic pump. After instrumentation, 5 ml of 17% EDTA is used followed by a final flush with 5 ml 3% of NaOCl.

Group IV: XP-endo Finisher (n = 15) The canals were filled with 5 ml of 17% EDTA (Smear Clear) and all samples were agitated with XP-endo Finisher file operated on a contra angle handpiece at 800 rpm for 1 min in slow and gentle motion followed by 5 ml of 3% NaOCl.

After the completion of procedure, the specimens were flushed with 5 ml of distal water to rinse off the residual irrigants and dried with paper points. All samples from the four groups were split longitudinally by creating grooves on the buccal and lingual side without entering the lumen using a diamond disc and the chisel was used to split the samples into halves. These samples were dipped in 2% of glutaraldehyde, dehydrated by immersed in ethanol. Then, the specimens were mounted on the brass stubs for gold sputtering.[16],[17] These samples were examined under scanning electron microscope for smear layer at 1000×. Photographs were taken from the coronal third (10 mm from apex), middle third (6 mm from apex), and apical third (2 mm from apex). Photographs were blindly evaluated using Schafer and Lohmann criteria.

The cleanliness of each canal was evaluated by means of a numeric evaluation scale as follows:

  1. Smear layer score (dentin particles, remnants of vital or necrotic pulp tissue, bacterial components, and retained irrigant):

    a. Score 1: No smear layer, orifices of the dentinal tubules patent

    b. Score 2: Small amount of smear layer, some open dentinal tubules

    c. Score 3: Homogeneous smear layer along almost the entire canal wall, with only very few open dentinal tubules

    d. Score 4: The entire root canal wall covered with a homogeneous smear layer, with no open dentinal tubules

    e. Score 5: A thick homogenous smear layer covering the entire canal wall

Statistical analysis

All the data were analyzed using SPSS version 23. Kruskal–Wallis test and Mann–Whitney U test were done for intergroup comparison of smear layer. Friedman test and Wilcoxon sign rank test done for interlocation comparison in various groups. A P value of <0.05 was considered statistically significant.

  Results Top

After instrumentation, canal walls exhibited varying amounts of remaining smear layer along the entire length. The mean and standard deviations for smear layer scores are presented in [Table 1].
Table 1: Mean and Standard Deviation (SD) of Smear Layer Score at Various Locations in Various Groups

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Group I showed the presence of heavy smear layer throughout the entire length of the root canals. The mean score for all the experimental groups at each third of the canal were less than those of the control group. Minimum mean score were observed at group IV at coronal portion. There was significant difference between groups at all three locations on overall assessment (P < 0.001).

Intergroup comparison shows that control group had highest score when compared with all groups at all three locations (P < 0.001). Group II showed significantly higher smear layer scores at coronal level compared with group III followed by group IV. On intergroup comparison, group IV showed lower mean scores but no statistical significant difference observed between group III and group IV as shown in [Table 2]. Coronal third showed minimum scores while apical third had maximum scores. Scores at coronal and middle third were significantly lower compared with apical level (P < 0.001) as shown in [Table 3].
Table 2: Inter Location Comparison in Various Groups (Wilcoxon Sign Rank Test)

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Table 3: Intergroup Comparison of Smear Layer Score

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  Discussion Top

The removal of vital necrotic tissue and microorganisms from the root canal system is important for endodontic success. Success of endodontic treatment can bring about by thorough chemo mechanical debridement.[18] Published literature claims that NiTi rotary instruments generates smear layer that cover root canal surface and block dentinal tubules.[19]

Effective irrigant delivery and agitation are prerequisites to promote root canal disinfection, debris removal, and smear layer removal from in accessible areas and to improve successful endodontic treatment. Therefore, this study evaluates the efficacy of irrigation activation devices like canal brush, non-activated SAF, and XP-endo Finisher in smear layer removal.

Zehnder[20] described ideal properties of different endodontic irrigants, but none of them exhibit all properties. Till date, sodium hypochlorite (NaOCl) is gold standard, which has a broad anti bacterial spectrum. Drawbacks of this sodium hypochlorite is unable to remove the smear layer. Different chelating agents are available in market, 17% liquid EDTA (Sybron Endo, Orange, CA) smear clear was chosen in this study as an irrigant.[21] Smear clear is 17% liquid EDTA containing cetrimide, a quaternary ammonium compound and an additional proprietary surfactant (polyoxyethylene-iso-octylcyclohexyl ether). Abou-Rass and Patonai confirmed that reduction of surface tension of endodontic solutions improved their flow into narrow root canals.[22],[23] In this study, all the root canals were prepared with rotary file upto size 40, which was in agreement with the study conducted by Usman et al.[24]

In this study, mean score was maximum in Group I at all three locations [Table 1]. Conventional group showed presence of heavy smear layer in the root canal wall and very few dentinal tubules were open [Figure 1]. Conventional handheld syringe needle irrigation is relatively weak and penetration depth of irrigating solution are therefore limited.[25]
Figure 1: Shows SEM images of coronal third of Group I, II, III, IV

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Canal brush (Group 2) showed lower mean smear layer score at coronal and middle third compared with conventional irrigation (Group 1). Group 2 showed a statistical significant difference in the coronal and middle third. The superior results of Group 2 compared with Group 1 is in accordance with the previous studies done by Garip et al. and Narmatha et al.[26]

Group IV showed lower smear layer score and cleaner walls at coronal and middle third as in agreement with the previous studies.[27],[28] Xp-endo Finisher shows cleaner walls with removal of smear layer in coronal part followed by middle part compared with canal brush and non-activated SAF illustrated in [Figure 1] and [Figure 2]. Removal of smear layer scores at all three regions is described as follows: coronal, middle, followed by apical. Apical level is narrower than the middle and coronal level. So, less amount of irrigation can be delivered to this area.[29]
Figure 2: Shows SEM images of middle third of Group I, II, III, IV

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Intergroup comparisons revealed that control group had significantly higher scores when compared with other study groups at three regions and over all comparisons. Canal brush removes more smear layer compared with conventional needle irrigation. It might be because of up and down motion and activation of irrigant with canal brush for 30 s in a slow speed handpiece. Similar findings were reported by Garip et al.[29] and NarmathaVJ et al.[26] concluding that irrigating with canal brush produce cleaner canal walls.

XP-endo Finisher shows minimum mean score as in agreement with the study conducted by Mohanad Ghazi Azzawi. The efficiency of the XP-endo Finisher file might be due to expansion capacity given by its small core size. The file shows good flexibility and ability to contact all areas of the canal walls. It also has shape memory effect.[28]

At apical level, non-activated SAF and Xp-endo finisher produce less smear layer scores compared with canal brush and conventional irrigation system as shown in [Figure 3]. But statistically, significant difference was found between the Xp-endo Finisher and non-activated SAF. No studies were there comparing these irrigation devices, hence further studies were needed.
Figure 3: Shows SEM images of apical third of Group I, II, III, IV

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At the middle and coronal third, Xp-endo finisher produces less smear layer scores compared with non-activated SAF but no significant difference between group III and IV. However, further studies are needed in depth comparison to find out efficacy of XP-endo Finisher file and non-activated SAF in smear layer.

  Conclusion Top

Within the limitations of present study, it was concluded that Group IV (Xp endo Finisher) showed the cleaner walls in removing smear layer over root canal at coronal and middle third. On pair wise comparison there was no significant difference in smear layer removing capability between Xp endo finisher and Non activated SAF.

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Conflicts of interest

There are no conflicts of interest.

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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2], [Table 3]


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