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Table of Contents   
ORIGINAL ARTICLE  
Year : 2021  |  Volume : 24  |  Issue : 3  |  Page : 236-240
Evaluation of smear layer removal of radicular Dentin in comparison with different irrigation devices: An in vitro study


Department of Conservative Dentistry and Endodontics, Panineeya Institute of Dental Sciences and Research Centre, Hyderabad, Telangana, India

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Date of Submission12-Apr-2019
Date of Decision21-Jul-2019
Date of Acceptance12-Feb-2021
Date of Web Publication08-Dec-2021
 

   Abstract 

Aim: The aim of this study was to evaluate the efficacy of smear layer removal from the root canals using 2 ml of 5.25% sodium hypochlorite passive ultrasonic irrigation, EndoVac, and diode laser during endodontic therapy.
Materials and Methods: Forty single-rooted human teeth were selected. Access cavity preparation was done. Working length was determined. Instrumentation was initiated with ISO hand files number 15 k file, followed by ProTaper rotary files size F3. Two milliliters of 5.25% NaOCl was used as an irrigant after every instrumentation, with a final flush of 17% EDTA, followed by a rinse with 3 ml of distilled water. Teeth samples were divided into four groups – Group I (n = 10) conventional irrigation with 5.25% NaOCl, 17% EDTA for 1 min, Group II (n = 10) instrumented and irrigated with ultrasonic activation for 1 min, Group III (n = 10) instrumented and irrigated with EndoVac for 1 min, Group IV (n = 10) (analyzed with irradiation of 2 W continuous wave of 910 nm diode laser). Teeth samples were then sectioned longitudinally. Scanning electron microscope examination of canals was done for evaluating smear layer at different levels. Statistical data analysis was done by one-way ANOVA test to evaluate the smear layer score at a significance level of P ≤ 0.05.
Results: Group III and Group IV have a minimal amount of smear layer at the apical third when compared to Group I and Group II which was statistically significant with a P < 0.05.
Conclusion: Diode laser and EndoVac performed better in removing the smear layer when compared with 2 ml of 5.25% sodium hypochlorite and ultrasonic irrigation.

Keywords: Diode laser; EndoVac; passive ultrasonic irrigation

How to cite this article:
Karunakar P, Solomon RV, Kumar B S, Mounika G. Evaluation of smear layer removal of radicular Dentin in comparison with different irrigation devices: An in vitro study. J Conserv Dent 2021;24:236-40

How to cite this URL:
Karunakar P, Solomon RV, Kumar B S, Mounika G. Evaluation of smear layer removal of radicular Dentin in comparison with different irrigation devices: An in vitro study. J Conserv Dent [serial online] 2021 [cited 2022 Aug 12];24:236-40. Available from: https://www.jcd.org.in/text.asp?2021/24/3/236/332000



   Introduction Top


Adequate debridement is the main aim of and also a big challenge to endodontic treatment especially in the apical portion of the root canal. The main goal of nonsurgical endodontic treatment is to shape and clean the root canals as thoroughly as possible to eliminate debris and microorganisms and achieve three-dimensional fluid-tight seal.[1]

However, after instrumentation of the root canals, an amorphous, irregular layer is formed on the root canal walls known as the smear layer. This smear layer acts as a physical barrier for the passage of irrigants and intracanal medicaments which ultimately results in compromising the disinfection. Endodontic irrigation is the process of delivery of endodontic irrigants within the root canal system. Irrigation is complementary to instrumentation in facilitating the removal of bacteria, debris and necrotic tissue especially, from areas of the root canal walls that remain unprepared by mechanical instruments.[2],[3]

Effective irrigation depends on various irrigants and irrigation devices and techniques. Traditional needle irrigation has been proved to be insufficient for a complete cleaning of the complex anatomy of the root canal system (especially the lateral canals, isthmuses, and the apical third); therefore, endeavors are being made to develop new irrigants and irrigating devices to improve the root canal disinfection in everyday endodontic practice.[4]

Various irrigation devices, ultrasonics, EndoVac and lasers, in combination or alone, have been evaluated for the removal of the smear layer with varying results. Passive ultrasonic irrigation has been suggested nowadays for the removal of the smear layer. Lasers have also been extensively investigated to remove the smear layer. Lasers such as argon laser, neodymium doped yttrium aluminum garnet, CO2 laser, erbium doped yttrium aluminium garnet and diode laser have all been researched and met with favourable results. In the present decade, the diode laser has been used extensively for the removal of smear layer because of its ease of use, versatility, compactness allowing easy mobility and less cost of the machine as compared to other lasers.[5]

In the present decade, the diode laser has been used for the removal of smear layer because of its ease of use, versatility, compactness allowing easy mobility less cost of the machine as compared to other lasers.

Hence, the present aim of this study is to compare the cleaning efficacy of conventional syringe irrigation, passive ultrasonic irrigation, EndoVac, and laser in removing smear layer from the root canal wall using scanning electron microscope (SEM) image analysis.


   Materials and Methods Top


Forty freshly extracted single-rooted human teeth were selected. All the teeth were radiographed to verify the presence of a single canal, mature apex, and absence of any resorption. Inclusion criteria included single-rooted teeth with straight, patent roots, and fully formed apices, extracted for periodontal or orthodontic reasons. The teeth with caries, cracks, and dilacerations were excluded. The soft tissues were removed from the root surface by a soft brush and teeth were stored in 10% formalin solution.

Teeth were then decoronated using a low-speed diamond disc to obtain a uniform root length of 18 mm. The pulp tissue was extirpated using barbed broach and the working length was established by inserting a number 10 K file into each root canal until it was just visible at the apical foramen and by subtracting 1 mm from this point. Root apices were then closed with sticky wax to simulate the closed-end model. Cleaning and shaping was performed using ProTaper rotary system (Dentsply Maillefer, Ballaigues, Switzerland) and the canal was enlarged up to F3 size.[4]

Irrigation procedure

Irrigation was performed using a 27 gauge side vented needle (Appli-Vac, Vista Dental Products, USA). The needle was placed within 1–2 mm of the working length in each canal. Canals were irrigated with 2 ml of 5.25% NaOCl for 1 min between each instrument change. After instrumentation, canals received a final flush of 5 ml of 17% EDTA. This was followed by a flush of 5 ml of distilled water for 1 min to remove any remnants of irrigating solutions and the canals were dried with sterile paper points (Dentsply).

Grouping of samples

Samples were divided into four groups:

  • Group I (n = 10) conventional irrigation with 5.25% NaOCl, 17% EDTA for 1 min
  • Group II (n = 10) instrumented and irrigated with 5.25% NaOCl, 17% EDTA along with ultrasonic activation for 1 min
  • Group III (n = 10) instrumented and irrigated with 5.25% NaOCl, 17% EDTA along with EndoVac for 1 min
  • Group IV (n = 10) instrumented and irrigated with 5.25% NaOCl, 17% EDTA (analyzed with irradiation of 2W continuous wave of 910 nm diode laser).


Teeth were longitudinally bisected into buccal and lingual parts by wedging process with the help of a chisel.

After the drying process, samples were coated with gold palladium by sputter coater bio-rade, placed into the SEM device) and scanned in three coronal, middle, and apical parts. Finally, photomicrographs were taken in ×2500 magnification, scored them using a score system that had been designed by Rome et al.

  • Score 1: Clean root canal wall with complete absence of smear layer, all dentinal tubules open and clean
  • Score 2: Minimal amount of smear layer; more than 50% of the dentinal tubules open
  • Score 3: Moderate amount of smear layer; <50% of dentinal tubules open
  • Score 4: Heavy smear layer with complete obliteration of dentinal tubules.


Statistical analysis

ANOVA test was used to evaluate the smear layer score P < 0.05 which was considered statistically significant.


   Results Top


Group III and Group IV were efficient in the removal of smear layer from the apical third and statistically significant when compared with Groups I and II with a P < 0.05.



Group 1 has more amount of smear layer scores when compared to the Group 2 Group 3 and Group 4.



Group III and Group IV are statistically significant when compared to Group II and Group I



The mean value score of each group presented in [Table 5]



The Confidence level score and comparisons of smear layer removal effects in each group are presented in [Table 6]



The Confidence level score and comparisons of smear layer removal effects in each group are presented in [Graph 2]



Inter group comparison of mean Smear layer scores at coronal, middle, apical using Mann – Whitney U- test.



Graph 4: Inter group comparison of mean Smear layer scores at coronal, middle, apical using Mann – Whitney U- test


   Discussion Top


One of the prerequisites of successful endodontic treatment is an efficient removal of the smear layer from the dentinal walls. Past studies have shown that current irrigation methods may be effective at cleaning the coronal portions of root canals but much less effective in the apical portions of canals. Therefore, the present study analyzed newer irrigation delivery systems such as EndoVac and diode laser devices for smear layer removal.[6] Apical negative pressure (EndoVac) and diode laser are such promising techniques that claim to improve the irrigant's effectiveness particularly at the apical third of the canal.[6],[21]

Cameron and Mader et al. studied the smear layer as two components being superficial smear layer and debris clogged in the dentinal tubules which extended up to 40 mm into the dentinal tubules.

In the present study, Group I showed the presence of heavy smear layer throughout the length of the canals which is similar to previous studies by Torabinejad et al. and Goldman et al. that showed NaOCl and EDTA would be ineffective in removing the smear layer at the apical third.[7],[8],[9],[10],[11],[12] SEM images of Group I showed the heavy presence of smear layer mainly in the apical portion of root canal and closure of dentinal tubules.

In Group II, the addition of ultrasonics to EDTA helped to increase the smear layer removing efficacy of EDTA by enhancing its penetration into the dentinal tubules mainly present in the coronal and middle regions of the root canals. From the observations of the present study, it was seen that the apical third of the canals was least influenced by ultrasonic irrigation and most of the tubules remained occluded with smear debris. This could be attributed to the fact that the oscillation of the ultrasonic tips is decreased by the constraining narrow walls of the apical most part of the root canal. Because the amplitude of the oscillation is largest at the instrument's tip, any attenuation affects the apical third region most significantly as the diameter of the canal is smallest in this part of the canal system.[5],[7],[8]

In Group III, it presented adequate removal of smear layer removal which was statistically significant when compared with conventional and passive ultrasonic irrigation groups. But in using the EndoVac, blockage of the microcannula is a concern. One of the main purposes of the macrocannula is to remove as much debris as possible before the smaller microcannula is used, thus reducing material that may clog the microcannula which ultimately results in incomplete removal. SEM images of Group III showed the minimal amount of smear layer with the opening of dentinal tubules.[13],[14],[15]

In Group IV, the diode laser with power of 1.5 watts in CW parameter settings used in this study was based on the study by Alfredo et al. who demonstrated that these parameters yielded a temperature rise approximately 10°C, which does not exceed the limit supported by the periapical tissues. SEM images of Group IV showed with the opening of dentinal tubules. Thirty seconds time application was used according to the study by Marchesan et al. The apical third had lesser smear layer scores than the middle and coronal third.[16],[17],[18],[19],[20] This can be attributed to the narrower diameter of the canal in the apical region resulting in a closer approximation of the laser tip to the root canal walls and thus melting and evaporating the smear layer easily. These ultramorphological changes could be attributed to the photothermal, photochemical, photodisruption, photodissociation, photoplasmolysis, and photoacoustic effect of the diode laser.[21],[22],[23] Localized melting, fusion, and constriction of the dentinal tubule openings were found in many samples as similar to findings of Wang et al. The thin flexible fiber of 200 μm tip provides better access to the apex which ultimately results in increased efficacy of smear layer removal at apical third.[24],[25]

Based on statistical analysis, the diode laser and EndoVac irrigation proved to be effective in the apical regions in removing the smear layer removal with a P < 0.05 when compared with conventional irrigants and passive ultrasonic irrigation.


   Conclusion Top


Under the limitations of this study, it can be concluded that advanced irrigation devices such as diode laser and EndoVac are efficient in removing smear layer at apical third, however further in vivo long-term studies are warranted for their success.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

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Czonstkowsky M, Wilson EG, Holstein FA. The smear layer in endodontics. Dent Clin North Am 1990;34:13-25.  Back to cited text no. 1
    
2.
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Mader CL, Baumgartner JC, Peters DD. Scanning electron microscopic investigation of the smeared layer on root canal walls. J Endod 1984;10:477-83.  Back to cited text no. 3
    
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Byström A, Sundqvist G. Bacteriologic evaluation of the efficacy of mechanical root canal instrumentation in endodontic therapy. Scand J Dent Res 1981;89:321-8.  Back to cited text no. 4
    
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Alfredo E, Silva SR, Ozório JE, Sousa-Neto MD, Brugnera-Júnior A, Silva-Sousa YT. Bond strength of AH Plus and epiphany sealers on root dentine irradiated with 980 nm diode laser. Int Endod J 2008;41:733-40.  Back to cited text no. 10
    
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White RR, Goldman M, Lin PS. The influence of the smeared layer upon dentinal tubule penetration by plastic filling materials. J Endod 1984;10:558-62.  Back to cited text no. 11
    
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Niemz MH. Laser Tissue Interactions: Fundamentals and Applications. 3rd ed, Springer News; 2007. p. 80.  Back to cited text no. 12
    
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O'Connell MS, Morgan LA, Beeler WJ, Baumgartner JC. A comparative study of smear layer removal using different salts of EDTA. J Endod 2000;26:739-43.  Back to cited text no. 16
    
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Doğan H, Qalt S. Effects of chelating agents and sodium hypochlorite on mineral content of root dentin. J Endod 2001;27:578-80.  Back to cited text no. 17
    
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Saleh IM, Ruyter IE, Haapasalo M, Ørstavik D. The effects of dentine pretreatment on the adhesion of rootcanal sealers. Int Endod J 2002;35:85966.  Back to cited text no. 18
    
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Teixeira CS, Felippe MC, Felippe WT. The effect of application time of EDTA and NaOCl on intracanal smear layer removal: An SEM analysis. Int Endod J 2005;38:285-90.  Back to cited text no. 19
    
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Ari H, Erdemir A. Effects of endodontic irrigation solutions on mineral content of root canal dentin using ICPAES technique. J Endod 2005;31:1879.  Back to cited text no. 20
    
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Nielsen BA, Craig Baumgartner J. Comparison of the EndoVac system to needle irrigation of root canals. J Endod 2007;33:611-5.  Back to cited text no. 21
    
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Desai P, Himel V. Comparative safety of various intracanal irrigation systems. J Endod 2009;35:545-9.  Back to cited text no. 22
    
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Heilborn C, Reynolds K, Johnson JD, Cohenca N. Cleaning efficacy of an apical negative-pressure irrigation system at different exposure times. Quintessence Int 2010;41:759-67.  Back to cited text no. 23
    
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Abarajithan M, Dham S, Velmurugan N, Albuquerque VD, Ballal S, Senthilkumar H. Comparison of endovac irrigation system with conventional irrigation for removal of intracanal smear layer: An in vitro study. Oral Surg Oral Med Oral Pathol 2011;112:407-411.  Back to cited text no. 24
    
25.
Castagnola R, Lajolo C, Minciacchi I, Cretella G, Foti R, Marigo L, et al. Efficacy of three different irrigation techniques in the removal of smear layer and organic debris from root canal wall: A scanning electron microscope study. G Ital Endod 2014;28:79-86.  Back to cited text no. 25
    

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Correspondence Address:
Dr. Gaini Mounika
Department of Conservative Dentistry and Endodontics, Panineeya Institute of Dental Sciences and Research Centre, Dilsukhnagar, Hyderabad - 500 060, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JCD.JCD_208_19

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