Annals of African Medicine
Home About AAM Editorial board Ahead of print Current Issue Archives Instructions Subscribe Contact us Search Login 


 
Table of Contents
ORIGINAL ARTICLE
Year : 2022  |  Volume : 21  |  Issue : 3  |  Page : 244-249  

An in vitro comparative assessment of manual hand file, rotary protaper ni-ti, erbium:yttrium–aluminum–garnet laser, canal brush, and ultrasound methods for smear layer removal


1 Department of Restorative Dentistry, College of Dentistry in Al-RASS, Qassim University, Buraydah, Saudi Arabia
2 Orthodontic Demonstrator, Department of Orthodontics and Paediatric Dentistry College of Dentistry, Qassim University, Al-Qassim Region, Kingdom of Saudi Arabia
3 Department of Conservative Dentistry and Endodontics, Sardar Patel Post Graduate Institute of Dental and Medical Sciences, Lucknow, Uttar Pradesh, India
4 Department Conservative Dentistry and Endodontics, DY Patil Dental School, Pune, Maharashtra, India
5 Department of Conservative Dentistry and Endodontics, School of Dental Sciences, Karad, Maharashtra, India
6 Department of Paediatric and Preventive Dentistry, Rural Dental College, PMT-PIMS, Ahmednagar, Maharashtra, India
7 Department of Maxillofacial Surgery and Diagnostic Sciences College of Dentistry, Qassim University, Al Qassim Region, Kingdom of Saudi Arabia

Date of Submission19-Dec-2020
Date of Decision24-Apr-2021
Date of Acceptance02-Jun-2021
Date of Web Publication26-Sep-2022

Correspondence Address:
Nandita Bansal
Department Conservative Dentistry and Endodontics, DY Patil Dental School, Lohegaon, Pune, Maharashtra
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/aam.aam_115_20

Rights and Permissions
   Abstract 


Background: Selection of instruments is important to prevent any complications such as ledge formation and instrument breakage. The main drawback linked with instrumentation is smear layer formation. Objectives: This study was done for comparison of manual hand file, rotary ProTaper Ni-Ti, erbium:yttrium–aluminum–garnet (Er:YAG) laser, ultrasound, and CanalBrush (CB) methods for smear layer removal. Methodology: Sixty freshly extracted single-rooted mandibular first premolars extracted for orthodontic treatment purpose were selected and classified into six groups. Group I was negative control in which no final agitation of irrigant was performed. In Group II, solution activation was performed with ProTaper Universal System, in Group III, solution activation was done with canal brush, in Group IV, ultrasound activation was done, in Group V, solution agitation was performed with Er:YAG laser agitation, and in Group VI, canal preparation with hand files was performed. Smear layer score was evaluated after canal preparation with each method. Results: Score 1 was seen in 3 (30%) in Group IV and 6 (60%) in Group V, score 2 was seen in 3 (30%) in Group I, 8 (80%) in Group II, 7 (70%) in Group III, 5 (50%) in Group IV, 3 (30%) in Group V, and 4 (40%) in Group VI. Score 3 was observed in 7 (70%) in Group I, 2 (20%) in Group II, 3 (70%) in Group III, 2 (20%) in Group IV, 1 (10%) in Group V, and 6 (60%) in Group VI. A statistically significant difference was found in smear layer removal score in all groups (P < 0.05) except between Group I versus VI (P > 0.05). Conclusion: Complete removal of the smear layer was not observed in any of the methods used in the study; however, Er: YAG laser was found to be better as compared to other methods.

   Abstract in French 

Résumé
Contexte: La sélection des instruments est importante pour éviter toute complication telle que la formation de rebords et la rupture d'instruments. Les Le principal inconvénient lié à l'instrumentation est la formation d'une couche de frottis. Objectifs: Cette étude a été réalisée pour comparer des limes manuelles, méthodes rotatives ProTaper Ni-Ti, laser erbium:yttrium-aluminium-grenat (Er:YAG), ultrasons et CanalBrush (CB) pour l'élimination des frottis. Méthodologie: Soixante premières prémolaires mandibulaires monoracinaires fraîchement extraites à des fins de traitement orthodontique ont été sélectionnées et classés en six groupes. Le groupe I était un témoin négatif dans lequel aucune agitation finale de l'irrigant n'a été effectuée. Dans le groupe II, l'activation de la solution a été réalisée avec le système universel ProTaper, dans le groupe III, l'activation de la solution a été effectuée avec une brosse canalaire, dans le groupe IV, l'activation par ultrasons a été fait, dans le groupe V, l'agitation de la solution a été effectuée avec une agitation au laser Er:YAG, et dans le groupe VI, la préparation du canal avec des limes manuelles a été effectué. Le score de la couche de frottis a été évalué après la préparation du canal avec chaque méthode. Résultats: le score 1 a été observé chez 3 (30 %) dans le groupe IV et 6 (60 %) dans le groupe V, le score 2 a été observé chez 3 (30 %) dans le groupe I, 8 (80 %) dans le groupe II, 7 (70 %) dans le groupe III, 5 (50 %) dans le groupe IV , 3 (30%) dans le groupe V, et 4 (40 %) dans le groupe VI. Le score 3 a été observé chez 7 (70 %) dans le groupe I, 2 (20 %) dans le groupe II, 3 (70 %) dans le groupe III, 2 (20 %) dans Groupe IV, 1 (10 %) dans le groupe V et 6 (60 %) dans le groupe VI. Une différence statistiquement significative a été trouvée dans le score d'élimination des frottis dans tous les groupes (P < 0,05) sauf entre le groupe I et VI (P > 0,05). Conclusion: L'élimination complète de la frottis n'a été observée dans aucun des méthodes utilisées dans l'étude; cependant, le laser Er:YAG s'est avéré meilleur par rapport aux autres méthodes.
Mots-clés: Brosse canalaire, erbium : laser yttrium-aluminium-grenat, ProTaper, frottis, ultrasons

Keywords: Canal brush, erbium: yttrium–aluminum–garnet laser, ProTaper, smear layer, ultrasound


How to cite this article:
Ismail PM, AlMogbel AM, Priya R, Bansal N, Mattigatti S, Nara A, AlMutairi FJ. An in vitro comparative assessment of manual hand file, rotary protaper ni-ti, erbium:yttrium–aluminum–garnet laser, canal brush, and ultrasound methods for smear layer removal. Ann Afr Med 2022;21:244-9

How to cite this URL:
Ismail PM, AlMogbel AM, Priya R, Bansal N, Mattigatti S, Nara A, AlMutairi FJ. An in vitro comparative assessment of manual hand file, rotary protaper ni-ti, erbium:yttrium–aluminum–garnet laser, canal brush, and ultrasound methods for smear layer removal. Ann Afr Med [serial online] 2022 [cited 2023 Feb 6];21:244-9. Available from: https://www.annalsafrmed.org/text.asp?2022/21/3/244/356821




   Introduction Top


A good endodontically treated tooth demands for proper shaping, cleaning, and obturation of canals. The selection of instruments is of paramount importance to prevent any complications such as ledge formation and instrument breakage.[1] One of the main drawbacks linked with instrumentation is smear layer formation. There have been long discussion and debate among researchers about the usefulness of smear layer.[2] One school of thoughts is that smear layer could inhibit intracanal disinfectants penetration into the dentinal tubules, and improper sealing of obturation materials such as gutta percha.[3] Other say that it may serve as a physical barrier by reducing dentin permeability and delaying medications from accessing infected dentinal tubules. Bacteria which left in dentinal tubules after endodontic therapy may be sealed by the smear layer.[4]

Cleaning and disinfection of root canals are important factors for ensuring successful root canal treatment. Disinfecting agent must dissolve and remove organic and inorganic parts of the dentin.[5] Numerous researches have been conducted so far to assess effectiveness of different instrumentation techniques based on its ability to debride the canals with few advantages and disadvantages of one over another. Manual Ni-Ti instrumentation and rotary endodontics have been used for many years. ProTaper Ni-Ti has reduced the canal preparation time significantly.[6]

Erbium:yttrium–aluminum–garnet (Er:YAG) lasers are of great concern for cleaning and disinfection of root canals. Canal brush is widely used with contra-angle handpiece in rotary motion. Ultrasonics uses an acoustic streaming effect that helps in transportation of irrigants into the apical parts of the root canal with small oscillating files.[7] The present study compared manual hand file, rotary ProTaper Ni-Ti, Er:YAG laser, ultrasound, and canal brush methods for smear layer removal.


   Methodology Top


The study was conducted in the department of conservative dentistry and endodontics and commenced after ethical clearance from the institutional ethical committee. Sixty freshly extracted single-rooted mandibular first premolars extracted for orthodontic treatment purpose were selected for the study.

Teeth were decoronated with a diamond disc and root length of 15 mm was obtained. Working length using #10 K-file was assessed. Biomechanical preparation of the canals was performed with ProTaper Universal System. Following this, specimens were divided into 6 groups of 10 each. Group I was negative control in which no final agitation of irrigant was performed. In Group II, solution activation was performed with ProTaper Universal System, in Group III, solution activation was done with canal brush (Coltene Whaledent, Langenau, Germany), in Group IV, ultrasound activation was done [Figure 1], in Group V solution agitation was performed with Er:YAG laser agitation with a wavelength of 2940 nm [Figure 2], and in Group VI, canal preparation with hand files was performed. Irrigation was done with 3% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraaceticacid (EDTA) throughout the preparation [Figure 3].
Figure 1: (a) ProTaper, (b) CanalBrush and (c) EndoActivator used for the study

Click here to view
Figure 2: Laser technique used for root canal cleaning (a erbium:yttrium–aluminum–garnet Machine, b and c erbium:yttrium–aluminum–garnet laser agitation)

Click here to view
Figure 3: (a) Sodium hypochlorite and (b) Ethylenediaminetetraacetic acid used for the study

Click here to view


Following EDTA agitation, all specimens were irrigated with 1 mL solution of 1% NaOCl for 60 s followed by a final rinse with a 5 mL solution of 0.9% sterile saline solution. With absorbent paper points, the root canals were dried. Specimens were then sectioned into two halves. Specimens were rinsed with a sodium cacodylate-buffered solution and incubated in osmium tetroxide for 1 h and examined under Χ 2000 magnification of scanning electron microscope. A method proposed by Torabinejad et al. for the evaluation of presence or absence of a smear layer in the apical third was adopted in the present study. Score 1 indicated no smear layer, score 2 indicated moderate smear layer, and a score of 3 indicated a heavy smear layer.[8] The results thus received were analyzed using Kruskal– Wallis and Mann–Whitney U-tests.


   Results Top


[Table 1] shows the type of method employed for instrumentation and solution agitation. Each group had 10 specimens. [Table 2] and [Graph 1] show that score 1 was seen in 3 (30%) in Group IV and 6 (60%) in Group V, Score 2 was seen in 3 (30%) in Group I, 8 (80%) in Group II, 7 (70%) in Group III, 5 (50%) in Group IV, 3 (30%) in Group V, and 4 (40%) in Group VI. Score 3 was observed in 7 (70%) in Group I, 2 (20%) in Group II, 3 (70%) in Group III, 2 (20%) in Group IV, 1 (10%) in Group V, and 6 (60%) in Group VI.
Table 1: Distribution of specimens

Click here to view
Table 2: Assessment of smear layer scores

Click here to view



[Table 3] shows a statistically significant difference in smear layer removal score in all groups (P < 0.05) except between Group I versus VI (P > 0.05).
Table 3: Comparisons between groups according to smear layer removal

Click here to view



   Discussion Top


Endodontic treatment comprised cleaning, shaping, disinfection, and obturation of root canals. It is evident that irregularities provide hinderance to complete debridement of root canal by mechanical filing.[9] Copious irrigation during canal cleaning flushes out debris, tissue solvent, and lubricant. It is found that inadequate debridement of the root canal system leads to endodontic flare-up, thus it becomes essential to clean the root canal.[10]

The smear layer is formed on hard surfaces of the teeth upon cutting with rotary or hand instrumentation. Smear layer is made up of dentin, odontoblastic processes, pulp tissues, bacteria, and necrotic tissue.[11] Smear layer formation on walls of root canals after mechanical preparation may be infected and acts as a reservoir of microorganisms. It is suggested that microorganisms left in the smear layer can re-infect the canal.[12] The presence of smear layer can obstruct the penetration of root canal irrigants and intracanal medicaments. Smear layer can enhance the risk of microleakage and bacterial infection. NaOCl and EDTA are the most commonly used methods for the effective removal of this smear layer.[8] Elimination of the smear layer is suggested three-dimensional cleansing of the root canal structure.[13]

Due to antimicrobial influence and tissue dissolving property, NaOCl claims as the gold standard but it has no effect on inorganic components of smear layer. Hence, NaOCl can be used along with EDTA which acts on inorganic debris formed during root canal instrumentation.[14] Earlier researches also established that it is hard to attain total removal of the smear layer using NaOCl needle irrigation. It was also observed that smear removal can be attained better in coronal and middle third in comparision to apical one-third.[13]

Laser method has been suggested as an alternative method to conventional chemomechanical method in endodontic procedure for disinfection and debridement of root canal. Several studies have indicated that laser-activated irrigations prominently improved the outcome of irrigation solutions in eliminating smear layer by assisting the deep penetration of irrigants into dentinal tubules in reaching the apical third of the root canals.[15] Various lasers such as Er:YAG, neodimium:yttrium–aluminum–garnet (Nd:YAG), erbium, chromium:yttrium–scandium–gallium garnet (Er, Cr:YSGG) and carbon dioxide (CO2) have been suggested for removal of debris and smear from the root canals. Lasers can eliminate smear layer by vaporizing tissues in the root canals. It has been suggested that erbium lasers (Er:YAG) can be more effective in removing smear layer from the root canals because of their ablating effect on minerals existing in smear layer and debris.[13]

In 1971, Weichman and Johnson reported the first use of laser in endodontics. Irradiation with laser is comparatively less destructive with lower intensity at an extended time period compared to higher intensities with shorter duration. Lasers can be applied in different endodontic techniques such as cleaning and disinfecting the root canal system, pulp capping/pulpotomy, obturation, apical surgery, and endodontic retreatment. The wavelengths of laser suggested for disinfection and cleaning the root canal procedure are 532 nm for potassium titanyl phosphate (KTP), 635 to 980 nm for diode, 1064 nm for Nd:YAG, 2780 nm for Er, Cr:YSGG, 2940 nm for Er:YAG, and 9600 and 10 600 nm for CO2. The physical effect of lasers in endodontics depends on the absorption of their wavelengths in biological components and chromophores such as water, apatite minerals, and various pigmented substances (microorganisms). Wavelengths of the visible and near-infrared electromagnetic radiation (Nd:YAG, diode, KTP lasers) are poorly absorbed in water and hydroxyapatite and have higher bactericidal properties in dentine. Erbium lasers with higher wavelengths are greatly absorbed in hydroxyapatite and water, they have a shallow outcome on dentine walls, and can be suggested for interruption of intracanal biofilms and elimination of the smear layer.[16]

Antimicrobial action of the Nd:YAG (1064 nm) depends on thermal heating of the bacterial environment and local heating inside bacteria (through chromophores inside bacteria sensitive to the laser light).[16] Erbium lasers (Er:YAG, 2940 nm; Er, Cr:YSGG, 2790 nm) in endodontics are very effective in the elimination of the smear layer from root canal space.[16]

Smear layer formation and debris elimination of various rotary systems may differ because of dissimilarities in kinematics and system design.[13] Syringe irrigation is a typical technique for root canal irrigation, but this method is not competent in the apical third of the root canal. It is problematic to completely eradicate the residual smear layer, predominantly in the apical third of the root due to the smaller size of the apical third compared with the other thirds hampers the circulation and action of the irrigating solutions.[17] The present study compared manual hand file, rotary ProTaper Ni-Ti, Er:YAG laser, ultrasound, and canal brush methods for smear layer removal.

Reddy et al. conducted a study on 50 subjects divided into 2 groups with 25 samples in each group. Group A with manual instruments and Group B with rotary instruments evaluated smear layer and debris removal. The results of the study revealed that both rotary ProTaper NiTi and manual NiTi files did not completely clean root canals. Rotary ProTaper NiTi instruments resulted in more smear and debris as compared to manual NiTi files. Rotary instruments were less time consuming as compared to manual instruments. There was no significant instrument separation found in both the groups.[18]

da Costa Lima et al. assessed fifty distal root canals and divided into five groups as no agitation (control), ProTaper universal file, ultrasound, canal brush, and Nd:YAG laser. They found that ultrasound group (56.6%) had a moderate smear layer (44.4%). Nd:YAG laser group showed no smear layer in 30% of the specimens, moderate smear layer in 70% of specimens. 23.4% in canal brush, 13.4% in ProTaper universal and 86.6% in control groups showed a heavy smear layer on the surfaces of the root canals.[19]

Garip et al.[20] determined the usefulness of the canal brush in eradicating the smear layer remaining on the root canal wall following root canal instrumentation with the ProTaper Universal System. The authors found that irrigation with canal brushing method resulted in clear walls but not significant alone in removing the smear layer.

Wadhwani et al. assessed the capacity of 17% EDTA solution and 19% EDTA gel in smear layer formation and debris removal during root canal procedure with ProTaper and Mtwo NiTi files systems. They concluded that there was no statistically substantial alteration with the use of diverse instruments.[21] Al-Mafrachi et al. evaluated the outcome of Er:Cr:YSGG 2780 nm laser in comparison with Xp-endo Finisher in removal of smear layer during root canal procedure. They observed significantly greater dye penetration in the erbium laser group compared to other groups. There was distinctive removal of smear layer under scanning electron micrographs in erbium laser group. They concluded that laser irradiation is effective in smear removal and in improving the dentin permeability.[15] These findings are in association with our findings.

Aksoy et al. assessed the root canal dentinal wall using scanning electron microscopy (SEM) to verify the presence or absence of smear layer after applying Er:YAG and Er, Cr:YSGG lasers and various NiTi file systems. They concluded that the reciprocating systems created fewer smear layer than rotating instruments. Er,Cr:YSGG and Er:YAG laser stimulations appeared to be more operative than syringe irrigation to eliminate the smear layer. EDTA and laser systems were unsuccessful in the apical third for smear layer removal.[13]

Singh et al. compared the CanalBrush (CB), F-File, and EndoActivator (EA) methods in elimination of smear layer from the root canal system. They concluded that CB eliminates smear layer more proficiently than EndoActivator and F-File in coronal and apical aspect of the root canal. They also observed that CB irrigation method tended to yield cleaner canal walls but was not expressively greater than irrigation alone in eliminating the smear layer from root canal walls.[14] Rödig et al.[22] in their study found no statistically significant differences between canal brush and ultrasound methods.

We observed that maximum removal of smear layer was observed with Er:YAG laser followed by ultrasound, canal brush, ProTaper, hand files, and control.

The shortcoming of the present study is small sample size. Further studies are needed on larger sample size with in vivo evaluation of different methods.


   Conclusion Top


The authors found that Er: YAG laser and canal brush methods are found to be better in removal of smear layer compared to other tested methods.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Wang Z, Shen Y, Haapasalo M. Effect of smear layer against disinfection protocols on Enterococcus faecalis-infected dentin. J Endod 2013;39:1395-400.  Back to cited text no. 1
    
2.
Lui JN, Kuah HG, Chen NN. Effect of EDTA with and without surfactants or ultrasonics on removal of smear layer. J Endod 2007;33:472-5.  Back to cited text no. 2
    
3.
Deplazes P, Peters O, Barbakow F. Comparing apical preparations of root canals shaped by nickel-titanium rotary instruments and nickel-titanium hand instruments. J Endod 2001;27:196-202.  Back to cited text no. 3
    
4.
Garala M, Kuttler S, Hardigan P, Steiner-Carmi R, Dorn S. A comparison of the minimum canal wall thickness remaining following preparation using two nickel-titanium rotary systems. Int Endod J 2003;36:636-42.  Back to cited text no. 4
    
5.
Chan AW, Cheung GS. A comparison of stainless steel and NiTi K files in curved root canals. Int Endod J 1996;29:170-5.  Back to cited text no. 5
    
6.
Hülsmann M, Schade M, Schäfers F. A comparative study of root canal preparation with HERO 642 and Quantec SC rotary Ni-Ti instruments. Int Endod J 2001;34:538-46.  Back to cited text no. 6
    
7.
Levy G, Rizoiu I, Friedman S, Lam H. Pressure waves in root canals induced by Nd: YAG laser. J Endod 1996;22:81-4.  Back to cited text no. 7
    
8.
Torabinejad M, Khademi AA, Babagoli J, Cho Y, Johnson WB, Bozhilov K, et al. Anew solution for the removal of the smear layer. J Endod. 2003;29:170–5.  Back to cited text no. 8
    
9.
Yoo YJ, Shon WJ, Baek SH, Kang MK, Kim HC, Lee W. Effect of 1440-nanometer neodymium: yttrium-aluminum-garnet laser irradiation on pain and neuropeptide reduction: A randomized prospective clinical trial. J Endod 2014;40:28-32.  Back to cited text no. 9
    
10.
Levy G. Cleaning and shaping the root canal with a Nd:YAG laser beam: A comparative study. J Endod 1992;18:123-7.  Back to cited text no. 10
    
11.
Bhagwat S, Heredia A, Mandke L. The smear layer revisited. Indian J Med Res Pharm Sci 2016;3:54-65.  Back to cited text no. 11
    
12.
Violich DR, Chandler NP. The smear layer in endodontics – A review. Int Endod J 2010;43:2-15.  Back to cited text no. 12
    
13.
Aksoy F, Aydin U, Alacam T. Smear layer removal efficiency of Er,Cr; YSGG and Er:YAG lasers in root canals prepared with different NiTi File systems. Ann Med Res 2019;26:1545-50.  Back to cited text no. 13
    
14.
Singh N, Chandra A, Tikku AP, Verma P. A comparative evaluation of different irrigation activation systems on smear layer removal from root canal: An in-vitro scanning electron microscope study. J Conserv Dent 2014;17:159-63.  Back to cited text no. 14
[PUBMED]  [Full text]  
15.
Al-Mafrachi RM, Awazli LG, Al-Maliky MA. Investigation of the effect of Er:Cr:Ysgg laser 2780 nm in comparison with xp-Endo finisher on root canal dentin permeability and smear layer removal: An in vitro study. Dent Health Curr Res 2018;4:1-4.  Back to cited text no. 15
    
16.
Jurič IB, Anić I. The use of lasers in disinfection and cleaning of root canals: A review. Acta Stomatol Croat 2014;48:6-15.  Back to cited text no. 16
    
17.
Kamel WH, Kataia EM. Comparison of the efficacy of smear clear with and without a canal brush in smear layer and debris removal from instrumented root canal using WaveOne versus ProTaper: A scanning electron microscopic study. J Endod 2014;40:446-50.  Back to cited text no. 17
    
18.
Reddy JM, Latha P, Gowda B, Manvikar V, Vijayalaxmi DB, Ponangi KC. Smear layer and debris removal using manual Ni-Ti files compared with rotary Protaper Ni- Ti files – An in-vitro SEM study. J Int Oral Health 2014;6:89-94.  Back to cited text no. 18
    
19.
da Costa Lima GA, Aguiar CM, Câmara AC, Alves LC, Dos Santos FA, do Nascimento AE. Comparison of smear layer removal using the Nd: YAG laser, ultrasound, ProTaper Universal System, and Canal Brush methods: An in vitro study. J Endod 2015;41:400-4.  Back to cited text no. 19
    
20.
Garip Y, Sazak H, Gunday M, Hatipoglu S. Evaluation of smear layer removal after use of a canal brush: An SEM study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;110:e62-6.  Back to cited text no. 20
    
21.
Wadhwani KK, Tikku AP, Chandra A, Shakya VK. A comparative evaluation of smear layer removal using two rotary instrument systems with ethylenediaminetetraacetic acid in different states: A SEM study. Indian J Dent Res 2011;22:10-5.  Back to cited text no. 21
[PUBMED]  [Full text]  
22.
Rödig T, Döllmann S, Konietschke F, Drebenstedt S, Hülsmann M. Effectiveness of different irrigant agitation techniques on debris and smear layer removal in curved root canals: A scanning electron microscopy study. J Endod 2010;36:1983-7.  Back to cited text no. 22
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

Top
 
 
  Search
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  In this article
    Abstract
   Introduction
   Methodology
   Results
   Discussion
   Conclusion
   Introduction
   Methodology
   Results
   Discussion
   Conclusion
    References
    Article Figures
    Article Tables

 Article Access Statistics
    Viewed698    
    Printed26    
    Emailed0    
    PDF Downloaded6    
    Comments [Add]    

Recommend this journal