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Year : 2012  |  Volume : 15  |  Issue : 3  |  Page : 261-264
An in vitro comparison of penetration depth of two root canal sealers: An SEM study

Department of Conservative Dentistry and Endodontics, Mamata Dental College, Khammam, Andhra Pradesh, India

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Date of Submission17-Sep-2011
Date of Decision14-Nov-2011
Date of Acceptance17-Feb-2012
Date of Web Publication3-Jul-2012


Aim: The aim of this study was to examine in vitro penetration depth of two resin-based sealers (AH plus and Resino Seal) and Zinc Oxide Eugenol sealer into the dentinal tubules after removing smear layer by passive ultrasonic irrigation.
Materials and Methods: Thirty freshly extracted maxillary central incisors were used. The teeth were decoronated, working length established and prepared upto size 40 file. Each root was subjected to passive ultrasonic irrigation with 2.5% sodium hypochlorite. Three different sealers and gutta-percha were used for obturation. Roots were sectioned using hard tissue microtome. These sections were gold sputtered and examined under scanning electron microscope.
Results: Statistical analyses of the data were performed using Kruskal-Wallis and Mann-Whitney tests. Statistically significant difference was found between AH Plus sealer and Resino Seal sealer and Zinc Oxide Eugenol sealer.
Conclusion: The results showed that AH Plus had maximum penetration depth into dentinal tubules.

Keywords: Sealer penetration; AH plus sealer; Irrigation; Smear layer; sealing ability

How to cite this article:
Singh CV, Rao S A, Chandrashekar V. An in vitro comparison of penetration depth of two root canal sealers: An SEM study. J Conserv Dent 2012;15:261-4

How to cite this URL:
Singh CV, Rao S A, Chandrashekar V. An in vitro comparison of penetration depth of two root canal sealers: An SEM study. J Conserv Dent [serial online] 2012 [cited 2022 Nov 29];15:261-4. Available from:

   Introduction Top

Smear layer removal would influence the penetration of root canal sealers into dentinal tubules, which might be important from the clinical aspect. [1] Filling the root canal system with a sealer that penetrates and remains inside the dentinal tubules may influence the quality of treatment and reduces the microleakage. [2]

Sealers containing antibacterial active ingredients, which kill bacteria might be more effective through closer contact with isolated bacteria by penetration into dentinal tubules. [3]

Passive ultrasonic irrigation can be an important supplement for cleaning root canal system. [4] When it is done with a small file or a smooth wire (size 10-20) oscillating freely in the root canal can induce powerful acoustic microstreaming.­ [5] It removes more organic tissue, planktonic bacteria, and dentin debris from the root canal. [6]

Chemical adhesion between dentin and sealer (with exception of glass ionomer sealers) cannot be achieved. [7] Therefore, it has been suggested that sealer plugs inside the dentinal tubules provide a mechanical interlocking, improving the retention of filling material by root canal walls. [8],[9] The fact that sealer penetration into dentinal tubules increases the interface between filling material and dentin tubules might influence the sealing ability of obturation. [10]

   Materials and Methods Top

Thirty freshly extracted human maxillary central incisors were used in the study. Care was taken to select the teeth that were at least 20 mm long without caries, root fissures, and fractures. All teeth were stored in 10% ethyl alcohol solution until the sample was completed. Organic debris from the external surface of the roots was removed by submerging the teeth in 1% NaOCl solution for 4 days before initiation of the experiment. The crowns of all teeth were cut at cementoenamel junction using slow speed cutting airotor equipped with a diamond-impregnated disk under water coolant with copious water. After the removal of the pulp tissue by a barbed broach (Dentsply Maillefer, Tulsa, OK, USA), a number 10 K file (Dentsply Maillefer) was inserted into each root canal until it could be seen through the apical foramen.

The working length was established by reducing their length by 0.5 mm. All the roots were instrumented using K file (Dentsply Maillefer). The root canals were cleaned and shaped up to number 40 file till the working length and flared using a step back preparation technique. Saline was used for irrigation prior to insertion of each instrument. Each root was subjected to passive ultrasonic irrigation by placing no. 20 size instrument for 15 s along with 2.5% sodium hypochlorite to remove the smear layer. All the samples were randomly divided into 3 groups of 10 each.

Group A

AH plus (Dentsply Maillefer) as sealer.

Group B

Resino Seal (Amrith Chemicals and Mineral Agency, Punjab, India) as sealer.

Group C

Zinc Oxide Eugenol (Vishal Dentocare, Ahmedabad, Gujarat, India) as sealer.

The master apical cone 40 size was inserted into the root canal. The sealers were applied into the root canals with a manually operated Lentulo spiral (Prime Dental Products, Mumbai, Maharashtra, India) and obturated with gutta-percha by lateral condensation technique. The access cavities were sealed with IRM (Dentsply International, Caulk Division, Milford, DE, USA) and radiographs were taken to observe whether a void was present in the obturation of the root canal. After this process they were stored for 48 h at 37°C and 100% humidity to allow sealer to set.

These roots were mounted in blocks of acrylic resin and were sectioned using hard tissue microtome (LEICA SP 1600. Leica Biosystems, Nussloch, GmbH, Heidelberger.). These sections were sputtered coated with gold-palladium, then examined under scanning electron microscope (SEM).

Statistical analyses of the data were performed using Kruskal-Wallis and Mann-Whitney U test. Kruskal-Wallis was done for the penetration depths of each sealer groups and Mann-Whitney U test was done for the comparison between the groups.

   Results Top

All the experimented samples of Group A (AH Plus), Group B (Resino Seal), and Group C (Zinc Oxide Eugenol) where the smear layer had been removed through Passive Ultrasonic Irrigation and subjected to SEM evaluation exhibited penetration of the dentinal tubules by 3 sealers, to varying depths.

Statistically significant difference was found between AH Plus sealer and Resino Seal sealer and Zinc Oxide Eugenol sealer. [Table 1]
Table 1 : Mean penetration depth of the sealersGroup

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   Discussion Top

For success of endodontic treatment the sealer in root canal should attain maximum penetration depth into the dentinal tubules, that increases the interface between sealer and dentinal tubules, which influences the sealing ability of obturation especially in the apical one-third. A smear layer that is formed after instrumentation obstructs the penetration of sealers into the dentinal tubules. [11]

Jhamb et al. compared the microleakage of Acroseal and Ketac-Endo with and without smear layer. The smear layer was removed using 17% EDTA (Ethylene Diamine Tetraacetic Acid) and 17% EGTA (Ethylene Glycol Tetraacetic Acid, and the smear layer was retained in samples using 5% sodium hypochlorite. When microleakages between 5% sodium hypochlorite, 17% EDTA, and 17% EGTA were compared, the microleakage in the former were found to be the highest. The reason might be that 5% sodium hypochlorite does not remove the smear layer but only flushes out the organic debris. The sealing ability of groups using Ketac-Endo was higher than Acroseal because Ketac-Endo is a technique-sensitive material. [12]

Chadha et al. evaluated the depth of penetration of 3 resin-based root canal sealers into the dentinal tubules at the cervical, middle, and apical third of the root canal. Results showed that the penetration depth of EndoREZ and Epiphany into the dentinal tubules is significantly greater than that of AH Plus. The difference in penetration in cervical, middle, and apical third could be due to the presence of significantly higher density of dentinal tubules with greater diameter at the cervical and middle third, when compared with the apical third. When Epiphany and EndoREZ were compared, lesser amount of penetration was seen with Epiphany and this could be due to the difference in viscosity of the sealers. [13]

Bortolini et al. evaluated in vitro intratubular penetration and permeability of endodontic sealers on teeth contaminated with Enterococcus faecalis. Sealers used were AH Plus, Endo CPM-sealer, and EndoRez sealers. He concluded that EndoRez sealer showed better sealing ability of the root canal system, good penetration in dental tubules, and did not permit the permeation of E. faecalis during the experimental period. AH Plus did not present the best result for intratubular penetration, but it was able to prevent the permeation of E. faecalis. [14]

Acoustic streaming is the rapid movement of the fluid in a circular or a vortex-like motion around a vibrating file. Walmsley et al. [15] (1987) defined acoustic microstreaming as the streaming that occurs near small obstacles placed within a sound field, near small sound sources, which arises from the frictional forces between a boundary and a medium carrying vibrations of circular frequency. This could be beneficial in transporting chelating agent and removing smear layer in apical root canal. [16] The smaller the size of file higher is the acoustic streaming.

Passive ultrasonic irrigation was first described by Weller et al. It relies on the transmission of acoustic energy from an oscillating file or smooth wire by means of ultrasonic waves and can induce acoustic streaming [17] and cavitation of the irrigant. The cleaning efficacy of passive ultrasonic irrigation implies the effective removal of dentin debris, microorganisms (planktonic or in biofilm), and organic tissue from root canal. [18]

Cavitation is the fluid mechanical context, which can be described as the impulsive formation of the cavities in the liquid through tensile forces induced by high-speed flows or flow gradients. These bubbles expand and then rapidly collapse producing a force of energy leading to intense sound and damage. Acoustic cavitation can be defined as creation of new bubbles or the expansion, contraction of the pre-existing bubbles in a liquid the process being coupled to acoustic energy ().

According to Roy et al. [19] 1994 two types of cavitation could occur during passive ultrasonic irrigation of the root canals, stable cavitation, and transient cavitation. Stable cavitation could be defined as linear pulsation of gas-filled bodies in a low amplitude ultrasound field. Transient cavitation occurs when vapor bubbles undergo highly energetic pulsations. Transient cavitation only occurs when the file can vibrate freely in the canal.

In the present study, the apical enlargement was done till 40 number to facilitate better removal of smear layer, as study conducted previously stated there was a tendency that ultrasonic irrigation was more effective in removing artificially placed dentin debris from stimulated canal extensions from canal with greater tapers. [20]

The purpose of using a resin-based sealer in root canal is to attain maximum penetration depth into dentinal tubules that increases the interface between resin-based sealer and dentinal tubules, which influences the sealing ability of obturation. The use of resin with greater potential for tubule penetration could be a productive approach to increasing strength and fracture toughness of root dentine. To create a stronger bond, more predictable tubule penetration by thorough removal of smear layer, optimization of resin flow and penetration, and modification of tubule wall to enhance bonding may also result in improved fracture resistance. [21]

It is clear that epoxy resin is capable of strong binding to the tubule wall such that fracture occurs through adjacent intertubular dentine. Thus, the potential for reinforcing dentine is already apparent. Sealer is needed to bond core material to root dentine, the physical properties of sealer should also be similar to those of root dentine.

This study showed that AH Plus sealer had maximum penetration depth into dentinal tubules, that is, 26 μm (mean 24 ± 0.15) as compared with Resino Seal sealer 22 μm (mean 20.2 ± 0.17) and Zinc Oxide Eugenol sealer 4 μm (mean 3 ± 0.50). Structure and coherence of the sealers' matrix into the dentinal tubules might be crucial factor determining the penetration depth of the smear layer-free root canals. [22] Root canal filling materials should have low surface activity or an adequate surface active reagent to penetrate dentinal tubules. The fact that sealer penetration into dentinal tubules increases the interface between the filling material and dentin might influence the sealing ability of obturation and also reinforces the tooth.

   References Top

1.Oksan T, Sen BH, Aktener BO, Tezel H. The penetration of root canal sealers into dentinal tubules An SEM study. Int Endod J 1993;26:301-5.  Back to cited text no. 1
2.Sen BH, Piskin B, Baran N. The effect of tubular penetration of root canal sealers on dye microleakage. Int Endod J 1996;29:23-8.  Back to cited text no. 2
3.Heling I, Chandler NP. The antimicrobial effect within dentinal tubules of four root canal sealers. J Endod 1996;22:257-9.  Back to cited text no. 3
4.Cameron JA. The use of ultrasound in the cleaning of root canals. J Endod 1982;8:472-4.  Back to cited text no. 4
5.Jensen SA, Walker TL, Hutter JW, Nicoll BK. Comparison of the cleaning efficacy of passive sonic activation and passive ultrasonic activation after hand instrumentation in molar root canals. J Endod 1999;25:735-8.  Back to cited text no. 5
6.Cameron JA. The use of ultrasonics in the removal of the smear layer. J Endod 1983;9:289-92.  Back to cited text no. 6
7.Saunders WP, Saunders EM. The effect of smear layer upon coronal leakage of G.P. root fillings. J Endod 1992;25:246-9.  Back to cited text no. 7
8.White RR, Goldman M, Lin PS. The influence of smeared layer upon dentinal tubule penetration by plastic filling materials. J Endod 1984;10:558-2.  Back to cited text no. 8
9.Kennedy WA, Walker WA, Gough RW. Smear layer removal effects on apical leakage. J Endod 1986;12:21-7.  Back to cited text no. 9
10.White RR, Goldman M, Lin PS. The influence of smeared layer upon dentinal tubule penetration by endodontic filling materials. J Endod 1987;13:369-4.  Back to cited text no. 10
11.Cymerman JJ, Jerome LA, Moodnik M. A scanning electron microscope study comparing the efficacy of hand instrumentation with ultrasonic instrumentation of root canal. J Endod 1983;9:327-31.  Back to cited text no. 11
12.Jhamb S, Nikhil V, Singh V. An in vitro study to determine the sealing ability of sealers with and without smear layer removal. J Conserv Dent 2009;12:150-3.  Back to cited text no. 12
[PUBMED]  Medknow Journal  
13.Chadha R, Taneja S, Kumar M, Gupta S. An in vitro comparative evaluation of depth of tubular penetration of three resin based root canal sealers. J Conserv Dent 2012;15:18-21.  Back to cited text no. 13
[PUBMED]  Medknow Journal  
14.Bortolini MC, dos Santos SS, Habitante SM, Rodrigues JR, Vance R, Jorge AO. Endodontic sealers: Intratubular penetration and permeability to Enterococcus faecalis. Indian J Dent Res 2010;21:40-3.  Back to cited text no. 14
[PUBMED]  Medknow Journal  
15.Walmsley AD, Walton RE. Cleaning of oval canals using ultrasonic or sonic instrumentation. J Endod 1993;19:453-7.  Back to cited text no. 15
16.Ahmad M, Roy RA, Kamarudin AG, Safar M. The vibratory pattern of ultrasonic files driven piezoelectrically. Int Endod J 1993;26:120-4.  Back to cited text no. 16
17.Ahmad M, Ford TR, Crum LA. Ultrasonic debridement of root canals Acoustic streaming and its possible role. J Endod 1987;13:490-9.  Back to cited text no. 17
18.Ahmad M, Ford TR, Crum LA. Investigate the oscillatory pattern of ultrasonic file driven by a piezoelectric transducer. J Endod 1999;12:10.  Back to cited text no. 18
19.Roy RA, Ahmad M, Crum LA. Physical mechanisms governing the hydrodynamic response of an oscillating ultrasonic file. Int Endod J 1994;27:197-07.  Back to cited text no. 19
20.van der Sluis LW, Wu MK, Wesselink PR. The efficacy of ultrasonic irrigation to remove artificially placed dentine debris from human root canals prepared using instruments of varying taper. Int Endod J 2005;38:764-8.  Back to cited text no. 20
21.Jainaen A, Palamara JE, Messer HH. The effect of resin-based sealers on fracture properties of dentine. Int Endod J 2009;42:136-43.  Back to cited text no. 21
22.Kokkas AB, Asterios Ch. Boutsioukis, Vassiliadis LP, Starvrianos CK. Effect of smear layer on the penetration depth of three different root canal sealers. J Endod 2004;30:100-3.  Back to cited text no. 22

Correspondence Address:
S Anitha Rao
Sr. Lecturer, Department of Conservative Dentistry and Endodontics, Mamata Dental College, Khammam, Andhra Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0972-0707.97954

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