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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 33  |  Issue : 2  |  Page : 92-96

Sealer penetration in the dentinal tubules: A confocal laser scanning microscopy study


1 Department of Conservative Dentistry and Endodontics, Swami Devi Dyal Hospital and Dental College, Panchkula, Haryana, India
2 Department of Periodontics, Swami Devi Dyal Hospital and Dental College, Panchkula, Haryana, India

Date of Submission16-Jan-2021
Date of Decision02-Apr-2021
Date of Acceptance15-Apr-2021
Date of Web Publication11-Jun-2021

Correspondence Address:
Dr. Sanjana Khullar
159 A/D Gandhi Nagar, Jammu, Jammu and Kashmir
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/endo.endo_24_21

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  Abstract 


Context: The penetration of sealer into dentinal tubules is considered to be a desirable feature as sealers prevent the colonization of residual bacteria into the dentinal tubules because of their antibacterial properties.
Aims: This study aims to compare the depth of penetration of ADSEAL, Sealapex, and BioRoot RCS into the dentinal tubules in the apical area using confocal laser scanning microscope (CLSM).
Settings and Design: Quality improvement projects.
Materials and Method: After decoronating 120 extracted single rooted teeth, preparation was done using ProTaper universal rotary files until F3. Then, the samples were divided into four groups (n = 40) and obturated by the following endodontic sealers: Group A-ADSEAL, Group B-Sealapex and Group C-BioRoot RCS along with F3 gutta-percha cone. Before root canal filling, the sealers were mixed with 0.1% Rhodamine B dye. All the samples were sectioned at 3 mm and 5 mm from apex and visualized under CLSM.
Statistical Analysis Used: Data were analyzed using two-way ANOVA and Tukey post hoc tests.
Results: BioRoot RCS has shown significantly higher depth of penetration than resin based sealer and calcium hydroxide based sealer (α < 0.05).
Conclusion: At all root regions, BioRoot RCS exhibited more tubular penetration whereas ADSEAL exhibited less penetration.

Keywords: Bioceramic sealers, confocal laser scanning microscopy, penetration depth


How to cite this article:
Khullar S, Aggarwal A, Chhina H, Kaur T, Sharma M, Bala D. Sealer penetration in the dentinal tubules: A confocal laser scanning microscopy study. Endodontology 2021;33:92-6

How to cite this URL:
Khullar S, Aggarwal A, Chhina H, Kaur T, Sharma M, Bala D. Sealer penetration in the dentinal tubules: A confocal laser scanning microscopy study. Endodontology [serial online] 2021 [cited 2021 Oct 18];33:92-6. Available from: https://www.endodontologyonweb.org/text.asp?2021/33/2/92/318142




  Introduction Top


The goal of root canal obturation is to obtain a three-dimensional seal of the root canal system.[1] Accomplishment of an ideal root canal treatment is attributed to various essential factors such as proper instrumentation, biomechanical preparation, obturation, and post endodontic restoration.[2]

The access to areas such as isthmuses, ramifications, deltas, accessory, and lateral canals is difficult and residual bacteria are most often located there, due to the communication of accessory canals with the periodontal membrane, a potential periodontic-endodontic pathway for bacterial penetration to and from the periodontium can be created.[3] Therefore the penetration of sealer into these areas might have a role in the eradication of bacteria from the dentin tubules.[4] The analysis of the dentin/sealer interface can be done using confocal laser scanning microscope (CLSM). In comparison to conventional scanning electron microscope, CLSM provides the advantage of detailed information about the presence and distribution of sealers inside dentinal tubules at a relatively low magnification through the use of fluorescent Rhodamine-marked sealers.[5]

The ability of sealer penetration into dentinal tubules is the determining factors for the selection of root canal filling materials. Thus, the aim of this study was to assess the depth of penetration of epoxy resin-based sealers-ADSEAL (Meta Biomed Co, Cheongju, Korea), calcium hydroxide based sealer-Sealapex (Sybron Endo, Sybron Endo Specialities, Glendona, CA, USA) and bioceramic sealer-BioRoot RCS (Septodont, Saint-Maur-des Fosses, France) at the apical portion of the root canal.


  Materials and Method Top


Preparation of samples

A total of 120 recently extracted human single-rooted teeth without caries and with well-developed roots and closed apices were selected. Multi rooted teeth, teeth with curved roots, teeth with root resorption, fracture lines, endodontic filling, instrumented canals, and calcified canals were excluded from the study. All the selected teeth were cleaned, polished with pumice and stored in distilled water. The crowns were decoronated close to the cementoenamel junction with a diamond disc mounted in straight hand piece under constant water cooling. The apical patency was maintained by no. 10 k hand file (Mani Inc., Tochigi, Japan). The working length was established by subtracting 1 mm from the total root length (root length mean 12.00 ± 0.2 mm). The root canals were prepared with crown down technique, using ProTaper Universal system (Dentsply-Maillefer, Ballaigues, Switzerland) incrementally up to size F3 (30, 0/6) to working length. The root canals were irrigated with 2 ml 3% sodium hypochlorite at the change of each instrument. Final irrigation was performed by 2 ml 17% Ethylenediaminetetraacetic acid for 3 min and 2 ml 3% sodium hypochlorite for 1 min followed by a final rinse of 2 ml normal saline. After completion of the biomechanical preparation of root canals, the samples were dried and randomly divided into three experimental groups of n = 40 according to the sealer placed.

  • GROUP A-ADSEAL
  • GROUP B-Sealapex
  • GROUP C-BioRoot RCS.


The sealers were manipulated according to the manufacturer's instructions. To allow analysis under the confocal microscope, each sealer was labeled with Rhodamine B dye to an approximate concentration of 0.1%. The sealer was placed with size 30 lentulo spiral in the canals keeping it 1 mm short of the working length and size F3 master gutta-percha cone was coated with sealer and placed in the canal up to the working length. The root canals were obturated with the lateral compaction technique using an endodontic finger spreader and accessory gutta-percha cones with a. 02 taper until the entire length of the root canal was filled. Excess gutta-percha was removed using a heated plugger and vertical compaction was performed 1 mm below the orifice level and then the teeth were sealed with temporary cement barrier and stored in incubator in 37°C at 100% humidity for 1 week. Each specimen was sectioned perpendicular to its long axis with diamond disc at slow speed under constant water cooling to avoid friction. Roots were sectioned at 3 mm and 5 mm from apex and two slices were obtained of two mm thickness. The coronal facing surface of each section was polished for 10 s on each side with abrasive sandpaper. The polished sections were imaged using a confocal laser scanning microscopy.

Penetration depth measurement

The samples were then mounted then mounted onto glass slides and examined with Nikon A1R inverted confocal microscope (Nikon Corp, Japan). The respective wavelength for Rhodamine B dye was 561 nm. Photos of each section were evaluated with NIS-Elements Br 3.0 imaging software (Nikon, Tokyo, Japan). The digital images were imported into ImageJ program (ImageJ software NIH) to measure the total dentinal tubule penetration, using a calibrated measuring tool. The maximum depth of sealer penetration was measured directly in micrometers (μm), from the canal wall to the deepest point at which the sealer was visualized. The depth of sealer penetration was measured and recorded at four standardized points (mesial, distal, buccal, and lingual) on each section. The measured readings were averaged to obtain a single mean value for each section and tabulated.

Statistical analysis

The depth of sealer penetration in the apical area for three different sealers was analyzed at 3 mm and 5 mm level. The three groups were compared by ANOVA followed by post hoc multiple comparisons test (Tukey honestly significant difference). All the statistical tests were two-sided and were performed at a significance level of α = 0.05. Statistical analysis was conducted using IBM SPSS Software (version 22.0). (IBM SPSS Inc., Chicago, IL, USA). With the significance level established at 5% (P < 0.05).


  Results Top


A significant difference was observed between ADSEAL and Sealapex at the 3 and 5 mm levels (P < 0.05), a significant difference was found between ADSEAL and BioRoot RCS at the 3 and 5 mm levels (P < 0.05). No statistical significance in the depth of sealer penetration was found between Sealapex and BioRoot RCS at 3 mm level (P > 0.05) but a significant difference was observed at 5 mm level (P < 0.05), with BioRoot RCS showing greater dentinal tubule penetration [Table 1]. The overall penetration of the sealers was deeper at 5 mm level as compared to the 3 mm level [Figure 1].
Table 1: The mean±standard deviation of the deepest tubular penetration of ADSEAL, Sealapex, and BioRoot rich communication services at 3 mm and 5 mm from the apex

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Figure 1: Confocal laser scanning microscopic images; Group A – ADSEAL at 3 mm (a), 5 mm (d); Group B- Sealapex at 3 mm (b), 5 mm (e); Group C- BioRoot RCS at 3 mm (c), 5 mm (f)

Click here to view



  Discussion Top


The complete sealing and filling of the cleaned and shaped root canal system are important steps that can affect the long-term success of root canal treatment.

Inadequate obturation could result in re-entry and re-growth of microorganisms in the root canal system causing irritation to the periapical tissues and compromising the treatment success.[1] A hermetic seal reduces coronal leakage and bacterial contamination, prevents apical periodontitis, and entombs the remaining irritants in the root canal. Gutta-percha is considered as gold standard filling material, despite of its many desirable properties, it solely fails to provide an effective three-dimensional seal, to overcome this insufficiency endodontic sealers are used along with a core filling material to attain an impervious seal. Sealer fills the residual spaces and creates a union between the core material and the canal wall.[6] Various root canal sealers used in endodontic practice are categorized according to their main chemical constituents: Zinc oxide eugenol, calcium hydroxide, glass ionomer, silicone, resin, and bioceramic-based sealers.[7] Epoxy-resin based root canal sealers especially AH Plus is one of the most frequently used because of its good physiochemical properties and adaptability to the root canal walls. However, it has been demonstrated that it displays higher cytotoxic effects than bioceramic sealers.[6],[8] Bioceramic sealers have excellent biocompatibility due to their similarity with biological materials, like hydroxyapatite. BioRoot RCS (Septodont, Saint-Maur-des Fosses, France) is a powder/liquid hydraulic tricalcium silicate based cement, it is composed of tricalcium silicate, zirconium oxide, and calcium chloride. When comes in contact with the physiologic solution, these sealers release calcium and forms an interfacial calcium phosphate (apatite) layer, thus developing a chemical bond with the dentinal walls. It has a lower cytotoxicity than other conventional root canal sealers, may induce hard tissue deposition and has antimicrobial activity.[9]

The ideal outcome in root canal obturation is to have high volume of gutta-percha and minimal volume of sealer within the root canal space and enhanced penetration into the canal irregularities and dentinal tubules.[10] The removal of the smear layer of the root canal walls is considered to be fundamental to allow sealer penetration into dentinal tubules irrespective of the root canal sealer used.[11],[12] Bacteria may penetrate into dentinal tubules up to 100–1,000 μm. Sealer penetration into the dentinal tubule would serve as a reasonable blocking agent that may prevent bacterial repopulation and can maintain their bactericidal action, which is favorable for healing periapical lesions and preventing reinfection.[10],[13]

Using CLSM technology, the present study shows better intratubular penetration for BioRoot RCS at 3 mm and a similarity in penetration of Sealapex at 3 mm from the apex. This finding is in accordance with the study of Ordinola-Zapata et al.[10] This study demonstrated that the maximum and the mean depth penetrations were significantly lower with ADSEAL at 3 mm and 5 mm from the apex as compared with BioRoot RCS and Sealapex. These results show that a calcium silicate-based sealer can penetrate dentinal tubules better. Similar results were found in a study by Cruz et al.[14] and Uzunoglu-Özyürek et al.[4] which showed that the penetrability of BioRoot RCS were superior as compared with epoxy resin-based sealer. On the other hand, Viapiana et al.[15] reported that AH Plus penetrated deeper compared with BioRoot RCS. This inconsistency among studies could be because of the different methodologies used.

The deepest tubular penetration was observed at 5 mm from the apex than at 3 mm level of the root canal for all the tested sealers. These findings are similar to those reported by Camilleri.[16] and McMichael et al.[17] this may be because the number and diameter of dentinal tubules decrease apically in the root canal. To achieve tubule penetration, the particle size of the material must be smaller than the tubule diameter; it can be assumed that because the particles for bioceramic sealer are <1 mm in diameter, they will be well suited for tubule penetration. In the current study, the lesser penetration at 3 mm can be attributed to smaller tubules nearer the apex. The small particle size, hydrophilicity, and low contact angle of bioceramic sealer explains why it penetrated the deepest at this level.[17]

The physical properties of root canal sealers could have an impact on the quality of the final root filling and the healing of periapical lesions. The flowing ability of root canal sealers results in better penetration leading to mechanical interlocking between the sealer and dentin. Epoxy resin-based sealers have a neutral or acidic pH, whereas calcium silicate-based sealers have a basic pH. This parameter might also affect the penetration characteristics of the sealers, leading BioRoot RCS to have a higher penetration depth.[4]

In clinical situations, bioceramic sealer absorbs water from dentinal tubules in the canal walls to expand laterally and adopt the canal shape. As water absorption induces expansion of the material, it improves the seal between the material and dentin.[18] BioRoot RCS has gained popularity, as it shows fewer toxic effects and induces osteogenic growth factor secretion and its particles create mineral plugs through interactions with dentinal fluids. Bioceramic materials have the ability of biomineralization; this process is important for entombing intratubular bacteria and minimizing leakage. The development of a “mineral infiltration zone” in the material in contact with the tissues indicates the formation of tag-like microstructures.[19]

According to the present study BioRoot RCS showed maximum sealer penetration at 3 mm and 5 mm level followed by Sealapex. The least sealer penetration was observed with ADSEAL. This study did not examine the interface between the gutta-percha and dentin wall. The incidence of voids in root canal filling material can result in the proliferation of residual microorganisms and it may jeopardize the treatment outcomes. Further studies are necessary to analyze the interfacial adaptation of these sealers to root canal walls and the long-term results of these materials.


  Conclusion Top


The results of the present study conclude that the depth of penetration of root canal sealers into dentinal tubules using the lateral compaction technique is influenced by the type of sealer and by the root canal level, with penetration decreasing apically. Within the limitations of our study, BioRoot RCS has shown higher dentinal tubule penetration ability to ADSEAL and Sealapex in the apical area, while the overall penetration of the sealers was deeper at 5mm level as compared to the 3mm level.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Ahuja L, Jasuja P, Verma KG, Juneja S, Mathur A, Walia R, et al. A comparative evaluation of sealing ability of new MTA based sealers with conventional resin based sealer: An in vitro study. J Clin Diagn Res 2016;10:ZC76-9.  Back to cited text no. 1
    
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Tyagi S, Tyagi P, Mishra P. Evolution of root canal sealers: An insight story. Eur J Gen Dent 2013;2:199-218.  Back to cited text no. 2
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Nikhil V, Singh R. Confocal laser scanning microscopic investigation of ultrasonic, sonic, and rotary sealer placement techniques. J Conserv Dent 2013;16:294-9.  Back to cited text no. 3
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4.
Uzunoglu-Özyürek E, Erdoğan Ö, Aktemur Türker S. Effect of calcium hydroxide dressing on the dentinal tubule penetration of 2 different root canal sealers: A confocal laser scanning microscopic study. J Endod 2018;44:1018-23.  Back to cited text no. 4
    
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Marciano M, Ordinola-Zapata R, Cavenago BC, Perochena AD, Bramante CM, Moraes IG, et al. The use of confocal laser scanning microscopy in endodontic research: Sealer/dentin interfaces. Microscopy: Science, technology, applications and education. Formatex Microsc Series 2010;3:566-70.  Back to cited text no. 5
    
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Chandra SS, Shankar P, Indira R. Depth of penetration of four resin sealers into radicular dentinal tubules: A confocal microscopic study. J Endod 2012;38:1412-6.  Back to cited text no. 6
    
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Lankar A, Mian RI, Mirza AJ, Siddiqui AA, Alam MK. A comparative evaluation of apical sealability of various root canal sealers used in endodontics. Int Med J 2018;25:39-41.  Back to cited text no. 7
    
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Akcay M, Arslan H, Durmus N, Mese M, Capar ID. Dentinal tubule penetration of AH Plus, iRoot SP, MTA fillapex, and guttaflow bioseal root canal sealers after different final irrigation procedures: A confocal microscopic study. Lasers Surg Med 2016;48:70-6.  Back to cited text no. 8
    
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Siboni F, Taddei P, Zamparini, F, Prati C, Gandolfi MG. Properties of bioroot RCS, a tricalcium silicate endodontic sealer modified with povidone and polycarboxylate. Int Endod J 2017;50:e120-36.  Back to cited text no. 9
    
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Ordinola-Zapata R, Bramante CM, Graeff MS, del Carpio Perochena A, Vivan RR, Camargo EJ, et al. Depth and percentage of penetration of endodontic sealers into dentinal tubules after root canal obturation using a lateral compaction technique: A confocal laser scanning microscopy study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:450-7.  Back to cited text no. 10
    
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Kokkas AB, Boutsioukis ACh, Vassiliadis LP, Stavrianos CK. The influence of the smear layer on dentinal tubule penetration depth by three different root canal sealers: An in vitro study. J Endod 2004;30:100-2.  Back to cited text no. 11
    
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Weis MV, Parashos P, Messer HH. Effect of obturation technique on sealer cement thickness and dentinal tubule penetration. Int Endod J 2004;37:653-63.  Back to cited text no. 12
    
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El Hachem R, Khalil I, Le Brun G, Pellen F, Le Jeune B, Daou M, et al. Dentinal tubule penetration of AH Plus, BC Sealer and a novel tricalcium silicate sealer: A confocal laser scanning microscopy study. Clin Oral Investig 2019;23:1871-6.  Back to cited text no. 13
    
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Viapiana R, Moinzadeh AT, Camilleri L, Wesselink PR, Tanomaru Filho M, Camilleri J. Porosity and sealing ability of root fillings with gutta-percha and BioRoot RCS or AH Plus sealers. Evaluation by three ex vivo methods. Int Endod J 2016;49:774-82.  Back to cited text no. 15
    
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Alsubait S, Albader S, Alajlan N, Alkhunaini N, Niazy A, Almahdy A. Comparison of the antibacterial activity of calcium silicate- and epoxy resin-based endodontic sealers against Enterococcus faecalis biofilms: A confocal laser-scanning microscopy analysis. Odontology 2019;107:513-20.  Back to cited text no. 19
    


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