1 Principal and HOD, Department of Conservative Dentistry and Endodontic, C.K.S Theja institute of dental

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1 ORIGINAL ART TICLE AODMR A Comparative Evaluation of Smear Layer removal between GaAlAs Diode Laser and : an In-Vitro Scanning Electron Microscopic Study a Short Study Datta Prasad S 1, Anusha S 2, Sunil Kumar C 3 1 Principal and HOD, Department of Conservative Dentistry and Endodontic, C.K.S Theja institute of dental sciences and research, Tirupati; 2 Post Graduate Student, Department of Conservative Dentistry and Endodontic, C.K.S Theja institute of dental sciences and research, Tirupati; 3 Professor, Department of Conservative Dentistry and Endodontic, C.K.S Theja institute of dental sciences and research, Tirupati. Address for Correspondence: Dr. Anusha S, Post Graduate Student, Department of Conservative Dentistry and Endodontic, C.K.S Theja institute of dental sciences and research, Tirupati, India. ABSTRACT: Aim: To evaluate the efficacy of GaAlAs diode laser and 17%EDTA solution on smear layer removal. Materials and Methods: Twenty seven freshly extracted single rooted mandibular premolars were collected, stored in distilled water, all roots were standardized to 14mm length and instrumented up to F3 protaper. Irrigation was done with 3% sodium hypochlorite solution in all experimental groups while irrigated only with sterile deionized water in control group and were divided into two experimental groups: Group1: GaAlAs diode Laser, Group 2: 17% EDTA, and Group 3: Deionized water. Later, all specimens weree split longitudinally in Bucco-Lingual direction, marked at 4, 8, 12 mm length using vernier calipers from root apices and were dehydrated in seriess of ethanol, mounted on metallic stubs, sputtered with gold, examined and photographed using Scanning electron microscope and smearlayer removal was evaluated. Results: GaAlAs diode laser shows better results at apical third, while at middle third and coronal third 17%EDTA solution is better in smearlayer removal. Conclusion: Based on this study, it can be concluded that combined use of irrigant and irrigant activation method improves the efficacy of smearlayer removal especially at narrow complex areas like apical third of root canal. Keywords: 17% Ethylene diamine tetraacetic acid solution, GaAlAs diode Laser, Sodium hypochlorite, Smear layer, Scanning electron microscope (SEM). INTRODUCTION Biomechanical preparation, type of irrigant used, irrigation method and obturation, plays vital role in the success of root canal treatment. The purpose of irrigation and biomechnical preparation is to disinfect root canal system prior to obturation. Whenever a cavity is prepared, a layer of sludge material is always formed over dentine, this superficial layer is called as smear layer, this was first elucidated by BOYED and KNIGHT in Mc Comb and Smith in 1975 for the first time observed a layer on the walls of instrumented root canals and reported that it was similar in appearance to smear layer, formed on cut enamel. Instrumentation produces 1-5μm thick smear layer on dentinal surface 1, consisting of 7 organic and inorganic component, such as vital or necrotic pulp tissue, microorganisms, saliva, blood cells and dentinal debris. 2 Bacteria harbor themselves deep into dentinal tubules and may survive for longer period and may cause reinfection later and for this reason, smear layer has to be removed from root canal walls for better treatment. 3 Among many endodontic irrigants NaOCl is one of the efficient irrigants that removes only organic part of the smear layer. Hence NaOCl is used along with EDTA solution to remove both organic and inorganic portion of smear layer. For better results in clinical conditions it is good to leave 17% EDTA solution inside the prepared root canal for 15 minutes. 4 But exposure of EDTA for longer duration might

2 result in excessive removal of peritubular and intra tubular dentine. Many studies have shown that even combined use of NaOCl and EDTA cannot remove smear layer completely mainly at apical third and narrower parts of root canal 5. Many irrigant activation techniques like, sonic and ultrasonic devices have been proposed to overcome this problem but with conflicting results. Activation of irrigating solutions coming into existence and beginning to display signs of future potential. Diode lasers are gaining importance in dentistry as they are more compact and economical than other type of lasers. Usage of Diode Laser provide certain advantages such as smear layer removal, reduction of bacteria and hence results in reduced apical leakage 5. Hence the purpose of this study is to assess the effectiveness of diode laser for smear layer removal in coronal, middle and apical thirds of root canal when compared to 17% EDTA solution Materials and Methods Preparation of teeth specimens: Twenty seven Mandibular premolars with single root and single root canal were selected for this study. Teeth with caries and any restorations were excluded. Fully developed teeth with intact root apices were selected using periapical radiographs. Any calculi and debris deposits present over selected teeth were removed using curettes and further disinfected using Sodium hypochlorite solution for 30 minutes and autoclaved and stored in deionized water until they were used. All the selected teeth were decoronated to standardized length of roots to 14mm. Working length was determined by reducing 1mm from anatomical length.10k file was inserted into canal orifice until its tip became just visible through apical foramen. All root canals were instrumented with protaper Ni-Ti rotary instruments up to F3 protaper size to provide good volume of irrigant to flow up to the working length and to allow the tip of irrigant activation devices to reach up to 8 appropriate working length. Biomechanical preparation of all the samples of experimental groups were done using 3% Sodium hypochlorite solution while only deionized water was used in control group. All prepared root canals were rinsed finally with distilled water to remove any residual irrigants if present after biomechanical preparation and then dried with absorbent paper points. After preparation, all specimens were enclosed with sticky wax at their apical tips to create closed end canal model and divided as following groups: 1. GaAlAs Diode laser; 2.17% EDTA solution; 3.De-ionized water (control) Group 1 : GaAlAs Diode laser GaAlAs diode laser device of 2.5 W power was used in pulsed mode in this experiment. Sodium hypochlorite solution was placed inside the canals, Fiber optic tip was passed upto established working length and then lased for 10 secs. It is most important to note that the laser tip should be in continuous movement inside the root canal and should not left still inside the root canal,as it may cause raise in temperature of root surface. The fiber tip was kept moving inward and outward the root canal in a continuous circular motion for about ten cycles (Figure 1). Between each inward and outward cyclic movement fresh irrigant was flushed into the root canal to reduce thermal stress. At last all root canals were rinsed with distilled water to remove any remnants of irrigant if present. Figure 1: Diode Laser (Group I) Group 2: 17% Ethylenediamine tetraaceticacid solution: Continuous copious irrigation was done with 17 % Ethylenediamine tetraacetic acid solution in the root canal for 50 seconds and followed by irrigating with 3%NaOCl solution and

3 Prasad DS et al: A Comparative Evaluation of Smear Layer removal between GaAlAs Diode Laser and again root canal was irrigated with 17%EDTA solution for 50secs (Figure 2), final flushing was done with distilled water to remove any remnants of irrigant present if any. Figure 2: (Group II) Group 3: (De-ionized ionized water) Here no any specific irrigation protocol is followed to remove smear layer. Only instrumentation done under distilled water, to assess the maximum smear layer that can be formed after instrumentation.(figure.(figure 3) Figure 4: Tooth splitting with colored Gutta percha cone inside the canal Figure 5: Sputtering all teeth specimens with gold Figure 3: Deionized water (Group III) Preparation of tooth samples for scanning electron microscopic (SEM) analysis All the prepared samples were then dried dr with absorbent paper points. Colored Gutta percha points were placed inside the root canal and then two longitudinal grooves were made on buccal and lingual surfaces of root canal using a diamond disc. Make sure that diamond disc should not penetrate into the root canal. Colored Guttapercha cone was used to ensure that there is no intrusion of disc into canals. Roots were then split into two halves using chisel.the half which is most visible up to the apex was selectedd for SEM analysis. All the roots were then marked at three levels 4mm, 8mm,12mm from the root apex using vernier calipers to define apical, middle mi and coronal thirds.(figure 4) These specimens were then dehydrated in ascending series of ethanol and mountedd on metallic stubs, sputtered with gold (Figure 5), examined and photographed using a scanning electron microscope(carl e(carl Zeiss SEM EVO MA15). (Figure 6) 9 Figure 6: Examined and photographed under Scanning electron microscope The amount of smear layer was assessed and recorded in accordance with the criteria proposed by Sadr-Lahijani Lahijani et al6 (Figure 7) Score 1- Dentinal tubules completely open. Score 2- >50% dentinal tubules open. Score 3- <50% dentinal tubules open. Score 4- Nearly all of the dentinal tubules covered with smear layer. All the tooth specimens were scored independently by two blinded evaluators. STATISTICAL ANALYSIS The scoring procedure was implemented by two examiners who performed the blinded evaluations independently. The reliability of the intra-examiner examiner and inter-examiner inter results was verified by using the kappa test. Data was analyzed using SPSS software, by nonnon parametric Kruskal-Wallis Wallis test.

4 Prasad DS et al: A Comparative Evaluation of Smear Layer removal between GaAlAs Diode Laser and Score 1 Score 2 Score 3 Score 4 Figure 7: Figures representing scores according to Sadr-Lahijani et al Criteria Apical third Middle third Coronal third Diode Laser group 17% EDTA group group Figure 8: SEM (scanning electron microscope) figures at canal thirds of all groups RESULTS Scanning electron microscopic figures at canal thirds of all groups were given below (Figure 8). 10 Inter group comparison: According to the present study, at apical third diode laser with NaOCl shows significantly best results in smear layer removal followed by 17% EDTA solution(graph: 1). While at middle third

5 (Graph: 2) and coronal third (Graph: 3) 17% EDTA is shows significantly best in smear layer removal than diode laser with 3%NaOCl. Intergroup comparison (comparison between the groups Intra group comparison: Within diode laser group (Graph: 4) apical third shows highest smear layer removal than the other two thirds of root canal. However, No significant Graph 1 :Apical third Contr ol Laser Laser apex Graph 2: Middle third Graph 3 : Coronal third Laser EDTA 9.06 EDT A 7.83 EDTA difference between coronal and middle third was observed. Within 17% Ethylene diamine tetraacetic acid solution group (Graph: 5), best smear layer removal at coronal third followed by middle third was observed while least smear layer removal at apical third was observed. Mean ranks Intra group comparison (Comparison within the group) Graph 4 :Diode Laser Graph 5 : 17%EDTA apex middle LASER coronal apex middle coronal DISCUSSION The removal of any vital and necrotic pulp tissue, microbes and their toxins along with smear layer is essential for endodontic success. Studies have shown that currently used method of especially rotary instrumentation technique produces a smear layer that covers root canal

6 walls and block opening of dentinal tubules. Therefore, this study evaluated the efficacy of diode laser on removal of smear layer and 17% EDTA Solution as it is one of the acceptable method that removes the smear layer. Scanning electron microscope is one of the best techniques used to assess the removal of smear layer. 6 According to results of present study the efficacy of Diode laser in smear layer removal is more than 17% EDTA solution at apical third. As canal is narrower in the apical third, the laser tip will be closer to canal wall and it will be easy for thawing and evaporating. While at middle third and at coronal third 17% EDTA showed better smear layer removal than Diode Laser. Diode laser offers benefits like thermal disinfection and biosimulation. These effects are dependent on penetration of laser energy through dentine. Deeper penetration ensures that microorganisms distant from root canal space also could be destroyed which acts as an adjunct to antimicrobial effects of irrigants. Also diode laser can instigate agitation, cavitation and shock waves in irrigant solution. 7 Mohamed Helmy et al by his electron microscopic study, determined the effect of diode laser and some irrigants (H2O2, and NaOCl) on surface morphology of root canal wall and concluded that scanning electron microscope showed a smoother dentine surface with the removal of smearlayer and debris when treated with laser irradiation compared to irrigation with NaOCl and H2 O2. This improves adaptability of sealer to root canal wall. Thus, the diode laser has great potential in future for root canal disinfection. 8 Xiangjun Guo et.al, conducted studies on smear layer removal comparing EDTA and NaOCl. The results showed that without any activation, combination of NaOCl and EDTA solution used as irrigant during root canal preparation was efficient in smear layer removal but complete removal of smear layer is not possible especially at narrowest portion 12 like that of apical thirds of root canal because of the reasons given as follows: 1.The decreased diameter at apical third of root canal results in reduced availability of volume of irrigant present at apical third of root canal, also decreases the back flow of irrigant. 2.The other reason is that number of tubules present at apical third is very less compared to the tubules at middle and coronal thirds and 3.As the mineralization increases with the age, diameter of root canal especially at apical third get further decreases and also number of dentinal tubules also get reduced. 9 The Presence of apical vapor lock effect adversely affect debridement efficacy especially for conventional irrigation method with syringe needle. This might be the reason for inefficient removal of smear layer at apical third of root canal as there is no irrigant agitation / activation technique to distort apical vapor lock effect. According to present study root canal prepared by mechanical preparation along with diode laser provide complete disinfection of root canal. However, further in vivo studies are required to compare diode laser. CONCLUSION Based on this study, it can be concluded that irrigant activation methods can be used as an adjunct in biomechanical preparation as they improves the efficacy of smearlayer removal especially at narrow complex areas like at apical thirds of root canal. Hence according to this present study, it can be suggested that, GaAlAs diode laser along with 17% EDTA solution can show best results in smear layer removal. REFERENCES 1.Wesselink PR, Turkun M. The smear layer: a phenomenon in root canal therapy. International endodontic journal 1995;28(3): Arslan H, Ayranci BL, Karatas E, Topcuoqlu HS, Yavuz MS, Kesim B. Effect of agitation of EDTA with 808-nm diode laser on removal

7 of smear layer. Journal of endodontics 2013; 39(12): Violich DR, Chandler NP. Smear layer in endodontics - a review. International Endodontic journal 2010; 43: Kovac J, Kovac D, Review of effect of irrigating solutions in endodontic therapy. BratisiLekListy 2011;112(7): Wang X, Sun Y, Kimura Y, Kinochita JI, Ishizaki NT, Matsumoto K. Effects of Diode laser irradiation on smear layer removal from root canal walls and apical leakage after obturation. Journal of Photomedicine and laser surgery 2005;23(6): Ahuja P, Nandini S, Ballal S, Velmurgan N. Effectiveness of Four Different Final Irrigation Activation Techniques on Smear Layer Removal in Curved Root Canals-A Scanning Electron Microscopy Study. J Dent (Tehran) 2014;11(1): Lagemann M, George R, Chai L, Walsh LJ.Activation of EDTA by a 940nm diode laser for enhanced removal of smear layer. Aust Endod Journal 2014;40(2): EI- Batanouny HM, EI-Khodery EMA, Zaky AA. Electron microscopic study on the effect of diode laser and some irrigants on root canal dentinal wall. Cario Dental Journal 2008;24(3): Guo X, Miao H, Lei Li, Zhang S, Zhou D, Yan Lu, Wu L. Efficacy of four different irrigation techniques combined with 60 o C 3% sodium hypochloirite and 17% EDTA in smear layer removal. Bio Med Central Oral health 2014;14(1): Tay FR, Gu LS, Schoeffel GJ, Wimmer C, Susin L, Zhang K, Arun SN, Kim J, Looney SW, Pashley DH. Effect of vapor lock on root canal debridement by using a side-vented needle for positive-pressure irrigant delivery. J Endod 2010; 36(4): How to cite this article: Prasad DS, Anusha S, Kumar SC. A Comparative Evaluation of Smear Layer removal between GaAlAs Diode Laser and : an In-Vitro Scanning Electron Microscopic Study a Short Study. Arch of Dent and Med Res 2017;3(1):