|Year : 2016 | Volume
| Issue : 1 | Page : 24-28
Effect of endoactivator and Er,Cr:YSGG laser irradiation in removing the smear layer after root canal instrumentation: An in vitro study
Koppolu Madhusudhana, Sannapureddy Swapna, Chinni Suneelkumar, Anumula Lavanya, Mandava Deepthi
Department of Conservative Dentistry and Endodontics, Narayana Dental College and Hospital, Nellore, Andhra Pradesh, India
|Date of Web Publication||18-Mar-2016|
Narayana Dental College, Chinthareddypalem, Nellore - 524 002, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Aim: The objective of this study was to assess the effectiveness of smear layer removal with a newer endodontic irrigation device, i.e., endoactivator system and with hard tissue laser, i.e., erbium, chromium:yttrium, scandium, gallium garnet laser (Er,Cr:YSGG).
Materials and Methods: Forty-four mandibular premolars, single-rooted, noncarious teeth were selected. All the canals were prepared by using ProTaper Universal rotary files (Dentsply Maillefer, Ballaigues, Switzerland) and 3% NaOCl. Teeth were then divided into two control groups and two experimental groups. Group A: Negative control group (N = 11)- without any final irrigation, Group B: Positive control group (N = 11)- final rinse with 1 mL smear clear for 1 min using no. 30 gauge needle, Group C: Endoactivator group (N = 11)-1 mL smear clear + endoactivator, Group D: Er,Cr:YSGG laser group (N = 11). Teeth were sectioned and observed for smear layer removal at apical, middle, and coronal thirds under scanning electron microscope (SEM).
Results: Results were interpreted analytically by Kruskal-Wallis test and Wilcoxon signed-ranks test.
Conclusion: The two experimental groups were significantly more efficient in smear layer removal than the control groups. There was no significant difference between the endoactivator and laser groups. All groups showed more efficient smear layer and debris removal coronally than in the middle and apical regions.
Keywords: Endoactivator, erbium, chromium: Yttrium, scandium, gallium garnet laser (Er,Cr:YSGG laser), irrigation, smear clear
|How to cite this article:|
Madhusudhana K, Swapna S, Suneelkumar C, Lavanya A, Deepthi M. Effect of endoactivator and Er,Cr:YSGG laser irradiation in removing the smear layer after root canal instrumentation: An in vitro study. J NTR Univ Health Sci 2016;5:24-8
|How to cite this URL:|
Madhusudhana K, Swapna S, Suneelkumar C, Lavanya A, Deepthi M. Effect of endoactivator and Er,Cr:YSGG laser irradiation in removing the smear layer after root canal instrumentation: An in vitro study. J NTR Univ Health Sci [serial online] 2016 [cited 2020 Mar 29];5:24-8. Available from: http://www.jdrntruhs.org/text.asp?2016/5/1/24/178951
| Introduction|| |
The success of root canal treatment depends on cleaning and shaping, followed by three-dimensional obturation of the root canal system. One of the essential objectives of root canal treatment is to clean the root canals as scrupulously as possible to eliminate tissue debris and microorganisms. Root canal instrumentation techniques produce an irregular, granular, and amorphous layer called the smear layer.  Theoretically, this layer is assumed to harbor bacteria and limit the effective disinfection by prohibiting the seepage of disinfectants, other intracanal medicaments, and root canal sealers into the dentinal tubules. ,
Subsequent removal of smear layer entails the use of irrigating solutions that can dissolve both organic and inorganic components to eliminate microorganisms and augment the chances of three-dimensional sealing of the root canal system.  The usage of 5.25%, 2.5%, or 1% sodium hypochlorite (NaOCl) in different studies proved its antimicrobial effect and tissue dissolution properties. It has no effect on inorganic portion of smear layer. ,, For complete removal of the smear layer, the recommended combination is sodium hypochlorite and a chelating agent. 
Smear Clear (Sybron Endo, Orange, CA) consists of 17% ethylenediaminetetraacetic acid (EDTA), a cationic surfactant, and an anionic surfactant. , It has been noted that smear layer removal is less anticipated in the apical region when compared with the coronal and middle thirds of the root. It is possibly because of the smaller apical canal dimensions hindering irrigant penetration.  Therefore, alternative methods are required to increase irrigant penetration into the apical third of the canal.
Several techniques and devices have been proposed to improve the efficacy of irrigation, including sonic or ultrasonic devices and different types of lasers. Recently, the EndoActivator System (Dentsply Tulsa Dental Specialties, Tulsa, OK) was introduced to improve the irrigation phase. It is a sonically driven canal irrigation system that comprises a portable handpiece and three types of disposable flexible polymer tips of different sizes that do not cut root dentin. Its design allows for the safe activation of various intracanal reagents and could produce vigorous intracanal fluid agitation. ,
Lasers are used to activate the irrigation solution by the transfer of pulsed energy. Erbium, chromium:yttrium, scandium, gallium garnet (Er,Cr:YSGG) laser (Waterlase MD, Biolase, San Clemente, USA) has a 2,790 nm wavelength delivered by using radial firing tips. This wavelength has highest absorption in water and high affinity to hydroxyapatite. 
This study was initiated to evaluate the efficacy of smear layer removal with latest endodontic irrigation device, i.e., endoactivator system and with hard tissue laser, i.e., Er,Cr:YSGG laser.
| Materials and methods|| |
Forty four extracted human single rooted mandibular premolars were selected for this study. Teeth were radiographed from the buccal and mesial aspects to visualize the root canal anatomy and to ensure closed apices. The collected teeth were cleaned and stored in 0.1% thymol solution at room temperature until they were used.
Standardized access cavity preparation was done. The pulp tissues were removed using a barbed broach (Dentsply Maillefer, Switzerland). The working length was measured by reducing 1 mm from length recorded when tips of #15 K-files were visible at the apical foramina. The root canals were prepared with the crown-down technique using ProTaper Universal nickel-titanium rotary instrument (Dentsply Maillefer, Switzerland) up to size F2. After each file, the canal was irrigated with 1 mL of 3% NaOCl for 1 min. Samples were then allocated to two control groups and two experimental groups (N = 11).
Group A: Negative control group - without any final irrigation.
Group B: Positive control group - the canals were irrigated with a final flush of 1 mL smear clear for 1 min using no. 30 gauge needle.
Group C: Endoactivator group - the canals were irrigated with a final flush of 1 mL smear clear. Endoactivator was used to activate the irrigant for 60 s at 10,000 cycles per min with a size 25/.04 polymer tip.
Group D: Laser group - the canals were irrigated with a final flush of 1 mL smear clear.
Irrigant was irradiated with Er,Cr:YSGG laser with radial firing tip. The Waterlase MD laser (Biolase, San Clemente, USA) was used with a panel settings of output power 1.25 W, pulse energy 62.5 mJ/pulse, and pulse frequency 20 Hz. Tip was moved from apical portion to coronal part of canal in a time duration of 20 s.
Longitudinal grooves were made on the buccolingual surfaces of the teeth using a silicon carbide disc without penetrating the canal and then the teeth were split into two halves with a chisel. The samples were then dehydrated and sputter-coated with gold and examined under scanning electron microscope (SEM) with a magnification of 1,000×. Three photomicrographs for each specimen were taken to visualize coronal, middle, and apical portion.
The scoring procedure was carried out by two independent examiners, resulting in a sufficient interobserver reproducibility, by using the criteria reported by Torabinejad et al.,  who measured the presence of smear layer as follows: Score 1 = no smear layer; absence of smear layer on the surface of the root canal; all tubules clean and open. Score 2 = moderate smear layer; no smear layer on the surface of the root canal, but tubules contain debris. Score 3 = heavy smear layer; smear layer covers the root canal surface and the tubules.
The notable differences in the amount of smear layer removal were analyzed by Kruskal-Wallis test and Wilcoxon signed-ranks test. The level of statistical significance was set at P < .05. All statistical analyses were performed by using Statistical Package for the Social Sciences (SPSS) 15.0 software (SPSS-Inc., Chicago, US).
| Results|| |
SEM images of all groups at coronal, middle, and apical thirds were represented in [Figure 1].
|Figure 1: Removal of smear layer of root canal walls in Negative, Positive control groups, EndoActivator and Laser groups. A, B, C represents the smear layer removal at coronal, middle and apical thirds of negative control group respectively; D, E, F represents coronal, middle and apical thirds of positive control group respectively; G, H, I represents coronal, middle and apical thirds of EndoActivator group respectively and J, K, L represents coronal, middle and apical thirds of laser group respectively|
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Mean value of the smear layer of the four groups
[Table 1] presents the mean values of the smear layer of the four groups. The two experimental groups effectively removed the smear layer and were statistically significant when compared to the control groups. There was no statistical significant difference between endoactivator and laser groups. The endoactivator group was significantly better than the positive control group. Thus to summarize, the endoactivator and laser were efficient in smear layer removal. The positive control group was better than the negative control group but less efficient when compared to the endoactivator and laser groups. When the different root canal levels of all the groups were compared, smear layer removal was found to be better at the coronal third than the middle third. It was least at the apical third.
| Discussion|| |
It is a known fact that the smear layer is microcrystalline, and organic particle debris is formed on root canal walls after root canal instrumentation. It obstructs the penetration of disinfectants and sealers into dentinal tubules thus compromising the seal of canal filling.  Several authors have shown that smear layer removal improves the fluid-tight seal of the root canal system whereas other factors such as the obturation technique or the sealer do not produce significant effects.  Currently, the consensus is toward smear layer removal and there are various methods to remove smear layer such as chemical removal, organic acids, mechanical removal (ultrasonic), and lasers. 
Literature has shown that smear layer removal is best accomplished by sodium hypochlorite and EDTA combination. In the present study, the same combination was used to achieve better results.  In all the three groups of the present study, the same irrigants, i.e., NaOCl and smear clear were used. The only difference that was employed in group C and group D was that the activation of irrigant was done with endoactivator in group C and with hard tissue laser in group D. In conventional syringe needle irrigation, irrigating solution was delivered only 1 mm deeper than tip of needle.  The penetration depth of irrigating solution is limited because needle tip is often located in coronal third of narrow canal or at middle third of wide canal.  Moreover, irrigating solution may not be able to penetrate deep into apical part of root canal because of high surface tension. 
Results have shown that smear layer removal was best achieved by the endoactivator group that is significantly better than the positive control group. The findings of this study showed that endoactivator removed smear layer better than laser but there is no statistically significant difference.
Previous studies by Rodig et al. and Caron et al. have shown that endoactivator helps in better smear layer removal than the other irrigation devices. , Peeters et al. proved that laser driven activation with Er,Cr:YSGG laser aids in smear layer removal.  But in the above-mentioned studies, none of the studies have compared the smear layer removal between endoactivator and Er,Cr:YSGG laser. In this study, we have compared effect of endoactivator and Er, Cr:YSGG laser irradiation in removing the smear layer.
The reason for better results in the endoactivator group might be due to hydrodynamic activation. Vigorous intracanal fluid agitation combined with sonic oscillating movements produces ample shear forces to achieve cleaner canals. When the activator tip moves toward length, the reagent is displaced. When the activator is partially withdrawn, there is an effective exchange of solution into the apical one third of the canal. A pumping action synergistically combined with mechanical agitation explains the better results obtained with the endoactivator. Use of the highest vibrational frequency of 10,000 rpm might also have ensured better smear layer removal. 
In the present study, even the laser group also achieved better smear layer removal due to laser-driven irrigation that results in cavitation, formation of large elliptical bubbles, and more homogeneous laser irradiation in which active cutting energy is directed laterally to the root canal walls by radial firing tips. 
Regardless of the irrigation technique, results showed that the coronal and middle thirds were cleaner compared with the apical one third. This may be attributed to the larger diameter in these regions, the major circulating volume of irrigant present in coronal and middle thirds as opposed to the apical third exposing dentin to a higher volume of irrigants, and making smear layer and debris removal easier. ,
| Conclusion|| |
Within the limitations of this study, endoactivator and Er,Cr:YSGG laser activation groups achieved better smear removal. Further studies with larger sample size have to be undertaken before extrapolating the results into clinical scenario.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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