Journal of Restorative Dentistry

: 2016  |  Volume : 4  |  Issue : 2  |  Page : 53--58

Adhesion to pulp chamber dentin: Effect of different endodontic irrigants

Rajni Nagpal1, Payal Singh1, Shipra Singh1, Naveen Manuja2, Rahul Gupta1, Pallavi Sharma1,  
1 Department of Conservative Dentistry and Endodontics, Kothiwal Dental College and Research Centre, Moradabad, Uttar Pradesh, India
2 Department of Pediatric Dentistry, Kothiwal Dental College and Research Centre, Moradabad, Uttar Pradesh, India

Correspondence Address:
Dr. Rajni Nagpal
Department of Conservative Dentistry and Endodontics, Kothiwal Dental College and Research Centre, Moradabad, Uttar Pradesh


Aim: To evaluate the effect of different endodontic irrigation regimens on the sealing ability of resin composite restorations placed within the pulp chamber using contemporary simplified adhesives. Materials and Methods: Seventy-five extracted human molars were divided into six groups. After de-roofing the pulp chamber and extirpating the pulp, pulp chambers were bonded with either G-Bond after irrigation with saline (Group 1); ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) (Group 2), and NaOCl + QMix (Group 3) or bonded with OptiBond adhesive after irrigation with saline (Group 4), EDTA and NaOCl (Group 5), and NaOCl + QMix (Group 6). All the samples were restored with composite. Ten samples per group were assessed for dye penetration. Fifteen samples were assessed under scanning electron microscope. Data were statistically analyzed using Mann–Whitney and Kruskal–Wallis tests at a significance level of P < 0.05. Results: Both EDTA + NaOCl or NaOCl + QMix pretreatment of pulp chamber dentin significantly reduced microleakage scores in adhesive OptiBond, but did not affect the microleakage of G-Bond. Conclusions: EDTA + NaOCl or NaOCl + QMix irrigation of the pulp chamber was not deleterious to the bonding of any of the adhesives tested.

How to cite this article:
Nagpal R, Singh P, Singh S, Manuja N, Gupta R, Sharma P. Adhesion to pulp chamber dentin: Effect of different endodontic irrigants.J Res Dent 2016;4:53-58

How to cite this URL:
Nagpal R, Singh P, Singh S, Manuja N, Gupta R, Sharma P. Adhesion to pulp chamber dentin: Effect of different endodontic irrigants. J Res Dent [serial online] 2016 [cited 2020 Aug 8 ];4:53-58
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Apart from various factors involved in the root canal treatment, which can affect endodontic success, coronal seal plays an equally important role.[1],[2] Torabinejad et al. emphasized the importance of coronal seal and demonstrated that root canal fillings exposed to saliva may become contaminated regardless of the materials and obturation techniques used.[3] On the other hand, even in poorly filled root canals, a favorable endodontic treatment outcome may be achieved when the quality of the coronal restoration is adequate. Previously, leakage through obturated root canals was considered a more important factor in endodontic failure, but recently, the concept of establishing an effective coronal seal soon after the completion of endodontic treatment has gained significance.[4],[5],[6] This is particularly important in multi-rooted teeth where accessory canals may be present.

Various esthetic restorative materials are being increasingly utilized for postendodontic restorations.[7] Restoring an endodontically treated tooth with adhesive restoration reinforces the weakened tooth structure.[8],[9] However, bonding to pulp chamber dentin is more complicated and less predictable than bonding to coronal dentin not only due to structural differences between pulp chamber and coronal dentin, but also because of the use of various irrigants/medicaments and temporary filling materials used during endodontic treatment, which can affect the success of the final adhesive restoration.[10],[11]

As mechanical instrumentation alone does not result in a bacteria-free root canal system, due to the anatomic complexities, use of irrigants is essential to further reduce bacteria and eliminate organic tissue remnants. Sodium hypochlorite (NaOCl) with its antibacterial and tissue-dissolving effects is the most popular endodontic irrigant. Ethylenediaminetetraacetic acid (EDTA) has been advocated as an adjunctive irrigating solution because it can chelate and remove the inorganic portion of smear layer. Besides this, EDTA also has the ability to detach biofilms adhering to root canal walls.[12] Complete removal of the smear layer requires the use of chelating agents followed by tissue solvents because no single solution is capable of providing both effects alone. Accordingly, alternating the use of EDTA and NaOCl solutions has been advocated as an effective irrigation regimen to remove organic and inorganic remnants.

Recently, QMix, a novel irrigant for smear layer removal with added antimicrobial agents, has been developed; QMix™ 2 in one solution contains a mixture of biguanide antimicrobial agents, a polyaminocarboxylic acid calcium-chelating agent, and a surfactant, and has been found to be effective against bacterial biofilms.[13]

Till date, none of the current adhesive materials have proved to provide a hermetic seal. There is scarcity of data evaluating the bonding of self-etch adhesives to pulp chamber in endodontically treated teeth, which is the deepest possible coronal dentin. How these irrigants would affect subsequent bonding procedures for composite restorations is still unclear and controversially discussed in literature.[11],[14],[15],[16]

Therefore, the aim of this study was to evaluate the effect of various endodontic irrigation regimens on the sealing ability of composite restorations placed in pulp chamber using two different all-in-one self-etch adhesives. The null hypothesis tested was that there is no difference in the sealing ability of adhesives bonded to pulp chamber dentin after different irrigation regimens.

 Materials and Methods

The study was performed in 75 permanent extracted human molars. Teeth were cleaned and stored in 0.5% chloramine T Trihydrate (Sigma-Aldrich) and used within 6 months of extraction. Teeth with any caries, cracks, abrasions, attrition, and restorations were excluded from the study. Roof of the pulp chamber was exposed using a carborundum disc horizontally 1.5 mm coronal to the cementoenamel junction and roots were sectioned 2 mm apical to the bifurcation. Pulp tissue was removed carefully with the help of an excavator. Canal orifices were widened with Gates Glidden (Gates drills, Mani, Inc., Tochigi, Japan) drill number 2-3. Root ends were sealed with the intermediate restorative material (IRM; Dentsply Caulk, Milford, DE, USA).

Teeth were randomly divided into six groups (n = 12) according to two different all-in-one self-etch adhesives: G-Bond (G C America) and Optibond All-In-One (Kerr Dental, Orange CA) and three irrigation regimens used: Normal saline; 17% EDTA (Smear Clear, Kerr, Sybron Endo, Glendora, USA) and 1% NaOCl; or 1% NaOCl and QMix.

Group 1 (G-Bond): Pulp chambers were continuously irrigated with normal saline solution for 1 minGroup 2 (G-Bond - EDTA + NaOCl): Pulp chambers were continuously irrigated with 1 ml of 17% EDTA for 1 min followed by 1% NaOCl for 1 minGroup 3 (G-Bond – NaOCl + QMix): Pulp chambers were continuously irrigated with 1% NaOCl for 1 min, rinsed with normal saline followed by QMix irrigation for 1 minGroup 4 (OptiBond All-In-One): Pulp chambers were continuously irrigated with normal saline solution for 1 minGroup 5 (OptiBond All-In-One - EDTA + NaOCl): Pulp chambers were continuously irrigated with 1 ml of 17% EDTA for 1 min followed with 1% NaOCl for 1 minGroup 6 (OptiBond All-In-One - NaOCl + QMix): Pulp chambers were continuously irrigated with 1% NaOCl for 1 min, rinsed with normal saline followed by QMix irrigation for 1 min.

After each irrigation regimen, the final flush was done with distilled water for 60 s. Pulp chambers in Groups 1, 2, and 3 were bonded with G-Bond and Groups 4, 5, and 6 were bonded with OptiBond All-In-One adhesive according to manufacturer's directions. All the samples were restored with composite resin Filtek Z350 (3M, ESPE, St. Paul, USA) and were light cured at 500 mw/cm 2 by Spectrum 800 (Dentsply, Caulk, Milford, USA) for 20 s.

Dye penetration

Ten samples per group were subjected to dye penetration analysis. Specimens were coated with two layers of nail polish leaving 1 mm window around restoration margin and were immersed in 2% methylene blue for 2 days. They were washed under running water and air dried at room temperature for 24 h. All teeth were then sectioned for evaluation under a stereomicroscope (Olympus, Tokyo, Japan) at magnification ×10 and were scored [Table 1].{Table 1}

Scanning electron microscopy

Two restored samples per group were used for analysis of resin–dentin interface under scanning electron microscope. They were sectioned in a buccolingual direction from the center of the restoration. Sectioned surfaces were ground on wet 210 grit SiC paper. Acid-base treatment was done in sectioned teeth sections that were decalcified in 6N HCl for 30 s, rinsed in distilled water, and de-proteinized by 10 min immersion in 1% NaOCl, then rinsed in distilled water. In addition, three samples were prepared for evaluation of surface morphology of pulp chamber floor dentin after different irrigation regimens without composite restoration. All the samples were dehydrated in ascending ethanol concentration (50%, 75%, and 95% for 20 min each and 100% for 1 h), then transferred to a critical point dryer for 30 min. The specimens were then gold sputter coated, and the surfaces were examined under scanning electron microscope (LEO430, England).

Statistical analysis

The data was statistically analyzed by Kruskal–Wallis and Mann–Whitney U-tests using SPSS Base 16.0 software (Statistical Package, SPSS Inc., Chicago, IL, USA) at a significance level of P < 0.05.


Dye penetration scores and statistical analysis results are depicted in [Table 2] and [Table 3]. Both the adhesives depicted microleakage when bonded to pulp chamber dentin. EDTA and NaOCl or QMix pretreatment of pulp chamber dentin significantly reduced microleakage scores in OptiBond adhesive (Group 4 and 5 and Group 4 and 6, P < 0.05), but did not affect the microleakage of G-Bond (Groups 1 and 2 and Groups 1 and 3, P > 0.05).

Scanning electron microscope

Scanning electron microscopic findings are summarized in [Figure 1], [Figure 2], [Figure 3]. Observations of resin–dentin interface [Figure 1]a, [Figure 1]b, [Figure 1]c and [Figure 2]b, [Figure 2]c revealed slight interfacial gap in all the groups except for Group 4 where a large gap could be seen at the resin–dentin interface [Figure 2]a. On the other hand, in Group 5 (OptiBond after EDTA + NaOCl irrigation), a good interfacial seal was evident [Figure 2]b. Evaluation of surface morphology of pulp chamber floor dentin [Figure 3]a, [Figure 3]b, [Figure 3]c after different irrigation regimens revealed more number of open dentinal tubules after EDTA + NaOCl or NaOCl + QMix irrigation.{Figure 1}{Figure 2}{Figure 3}


After endodontic treatment, quality of the coronal restoration is important to periapical health as none of the present-day obturating materials hermetically seal the root canal space.[17] Therefore, the current trend is to place adhesive composite resin restorations immediately at the conclusion of endodontic treatment.[18],[19] However, irrigants used during biomechanical preparation may potentially affect the sealing ability of postendodontic composite restorations. Recently, all-in-one self-etch adhesives have gained popularity due to their simpler clinical application. It is important to determine their sealing potential to pulp chamber dentin, so as to improve endodontic success through coronal leakage prevention.[20],[21]

In the current study, microleakage was observed with both the self-etch adhesives. This could be attributed to the more complex structure of pulp chamber dentin (irregular secondary dentin, collagen-rich predentin, many accessory canals, and sclerotic dentin), which makes bonding less predictable.[22],[23],[24] Moreover, pulp chamber dentin contains a higher number of tubules with larger tubule diameters and small amount of intertubular dentin.[25] In addition, box shape of the pulp chamber results in high C-factor, which may also affect the microleakage of the adhesive resins because of polymerization shrinkage stress.

In the present study, no significant difference was observed in the mean microleakage score of G-Bond and OptiBond All-In-One adhesives. G-Bond is 2-hydroxyethyl methacrylate (HEMA) free adhesive whereas OptiBond All-In-One is HEMA-containing adhesive.[26],[27],[28],[29] The hydrophilic monomer, HEMA, in various concentrations is frequently added to one-step self-etch adhesives because of its positive influence on adhesion to dentin, the miscibility of hydrophilic and hydrophobic components in the adhesive blend, and prevention of phase separation. However, the role of HEMA in improving the bonding performance of adhesives is still controversial. Felizardo et al.[27] concluded that the influence of HEMA on bond strength to dentin was material-dependent.

In the current study, irrigation of the pulp chamber dentin with EDTA and NaOCl had no significant effect on the microleakage of self-etch adhesive G-Bond whereas it significantly reduced the microleakage of the self-etch adhesive OptiBond All-In-One. Contrary to our study, various studies have reported that NaOCl irrigation reduces bond strength of adhesives to dentin due to its oxidizing effect and subsequent interference with resin polymerization.[11],[15],[16] Most of these studies have used a higher concentration of NaOCl and longer application time. However, in the current study, the sequential use of 1% NaOCl (1 min) and 17% EDTA could account for the different results. Seventeen percent of EDTA significantly inhibits endogenous MMP activity of human dentin within 1–2 min.[30] This might minimize hybrid layer degradation after resin-bonding procedures in the root canal space. EDTA decalcifies peritubular dentin in the early stage of irrigation. The use of a proteolytic agent such as NaOCl removes dentin organic components and changes its chemical composition so that it becomes similar to etched enamel.[31] De-proteinization minimizes the technique sensitivity, producing a more durable adhesion to dentin substrate through its hydroxyapatite component.[32],[33],[34] NaOCl treatment of demineralized dentin results in a substrate-rich in hydroxyapatite crystals and may result in a more stable interface over time as it is essentially made of minerals.[35],[36]

Various authors have evaluated the effect of EDTA preconditioning on the bonding of mild and ultra-mild self-etch adhesives to dentin.[37],[38],[39] Both G-Bond and OptiBond All-In-One are mild and ultra-mild all-in-one self-etch adhesives, respectively. Therefore, dentin conditioning with EDTA proved to be beneficial for OptiBond All-In-One. EDTA acts as a mild chelating agent removing hydroxyapatite selectively. Because most of the intrafibrillar minerals remain, the structural support by the minerals is preserved, and resin infiltration is facilitated. Torii et al. also reported that EDTA conditioning was effective in improving dentin bonding for all-in-one adhesives.[40] Soares et al. also depicted increased bond strength of self-etch adhesive systems used with EDTA preconditioning.[41]

Similarly, NaOCl and QMix irrigation significantly reduced microleakage scores in the self-etch adhesive OptiBond All-In-One. QMix contains EDTA and chlorhexidine and a detergent. The incorporated detergent in the QMix formula decreased the surface tension leading to more effective debris removal and better penetration. Stojicic et al.[42] investigated the effectiveness of smear layer by QMix using scanning electron microscopy. QMix removed the smear layer equally as well as EDTA. They concluded that the ability to remove the smear layer by QMix was comparable to that of EDTA. Along with the enhanced effect of EDTA on bonding, CHX has also been found to have a positive effect on bonding of simplified adhesives.[43] Erdemir et al. also reported that endodontic irrigation with a CHX solution significantly increased bond strength to root dentin, which can be due to adsorption of CHX by dentin favoring the resin infiltration into dentinal tubules.[44] Similar to our study, Elnaghy confirmed that the use of QMix, 17% EDTA/2% CHX, and 17% EDTA irrigant regimens significantly enhanced the interfacial bond strength of fiber post and resin cement to root dentin.[45]

Further studies are required to evaluate the effect of time, concentration, and sequence of endodontic irrigation on the bonding of other contemporary adhesive systems to pulp chamber dentin.


Both G-Bond and OptiBond depicted microleakage when bonded to pulp chamber dentin. NaOCl and EDTA or QMiX pretreatment of pulp chamber dentin significantly reduced microleakage scores in adhesive OptiBond. Any of the irrigation regimens did not negatively affect the sealing ability of both the one-step self-etch adhesives tested.

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Conflicts of interest

There are no conflicts of interest.


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