Sasafuchi et al.

Int Chin J Dent 2003; 3: 7-12.

Effect of chemical irrigants and medicaments for endodontic treatment
on dentin bonding
Yasutaka Sasafuchi, DDS, PhD, Toru Nikaido, DDS, PhD, and Junji Tagami, DDS,PhD
Cariology and Operative Dentistry, Department of Restorative Sciences,Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
Purpose: To evaluate the bond strengths of two different types of resin luting cements to dentin treatedwith chemical irrigants and medicaments for root canal treatment.
Materials and Methods: The bovine incisors were ground with silicon carbide paper to expose a dentin.
Dentin surface was treated with either 3% hydrogen peroxide (H2O2), 5% sodium hypochlorite (NaOCl),the combination of H2O2 and NaOCl (H2O2/NaOCl), formocresol (FC), or calcium hydroxide (Ca(OH)2) for
60 s, then rinsed and air dried. Dentin without any treatment was used as the control group. The area forbonding was then demarcated with a vinyl tape (4 mm-in-diameter hole), and bonded using one of tworesin cement, Super-Bond C&B or Panavia F according to the manufactures’ instructions. After storage inwater for 1 day, tensile bond strengths were measured using a universal testing machine.
Results: For Super-Bond C&B, statistically lower early bond strengths were obtained in the experimentalgroup compared with the control. In the case of Panavia F, the early bond strengths decreased significantlyin H2O2, H2O2/NaOCl, and Ca(OH)2, while no influence of NaOCl and FC on early bond strengths wasobserved. However, the visual inspection showed a large increase of adhesive failures between the resinand dentin occurred with the experimental groups, which was marked for both resin cements.
Conclusion: The early bond strengths of resin cements to dentin were adversely influenced by the chemicalirrigants and medicaments for root canal treatment. (Int Chin J Dent 2003; 3: 7-12.)
Clinical Significance: The medicaments for endodontic treatment are the clinical factors influencing dentin
bonding of the resin cements.
Key Words: chemical irrigant, dentin bonding, medicament for endodontic treatment, resin cement.

Introduction
The conventional belief that all endodontically treated teeth are weaker or more brittle than vital teeth,1
has lead to the philosophy encouraging aggressive reinforcement of remaining tooth structure. Until
recently, nonvital teeth were usually treated with a crown, core, and/or dowel.2 This often leads to goodremaining tooth structure being sacrificed for the preparation of a traditional cast restoration.
The function of a conventional coronoradicular post is to provide retention for a core. Post retention

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Int Chin J Dent 2003; 3: 7-12.

using conventional luting cements (zinc phosphate, polycarboxylate, and glass ionomer cements) isbelieved to be a major factor in restoration survival. However, overpreparation of the post space and large
diameter posts decrease the resistance against root fracture and increase the risk of apical pathoses.3 A
significant increase in dowel retention using adhesive resin cements was demonstrated compared withconventional cements.4 Therefore, the use of adhesive resin cement can compensate for the reduction of
overpreparation for the post and dowel.5 Endodontic therapy has become a routine procedure for treating
and retaining nonvital teeth. Endodontic treatment consists of removing all contents of the root canalsystem before and during shaping. Successful cleaning entails the use of instruments to mechanicallyremove dentin, irrigants to flush loosened debris away, and chemicals to dissolve contaminants frominaccessible regions.6 H2O2 and NaOCl have been commonly used as chemically active irrigants.7 For root
canals that require more than one visit to complete, there are sufficient remaining bacteria within the root
canal system to grow and reinfect the root canal space between appointments. Placement of intracanal
medicaments, such as FC and Ca(OH)2, has become a popular method of preventing bacterial regrowth.8
However, there are limited information about the effect of chemical irrigants and medicaments for root
canal treatment on dentin bonding.9,10 The purpose of this study was to evaluate the early bond strengths oftwo different types of resin luting cements to dentin treated with chemical irrigants and medicaments forroot canal treatment.

Materials and Methods
Freshly extracted bovine incisors, stored frozen, were used in this study. The labial surfaces of theincisors were ground with 600-grit silicon carbide paper under a stream of running water to expose a flat
surface in superficial dentin. Then these incisors were divided into two groups. A dentin surface without
any treatments was used as the control group. For the experimental group, the dentin surface was treatedwith either 3% H2O2, 5% NaOCl, the combination of H2O2 and NaOCl (H2O2/NaOCl), FC, or Ca(OH)2 for
60 s, then rinsed with water for 10 s and air dried. The bonding area was demarcated with a vinyl tape (4mm diameter hole), and then one of two resin cements, Super-Bond C&B (Sun Medical, Moriyama, Japan)
or Panavia F (Kuraray Medical, Tokyo, Japan), was applied to the dentin surface according to themanufactures’ instructions (Table 1). In the Super-Bond C&B group, dentin was treated with 10% citricacid-3% ferric chloride for 5 s, rinsed with water for 10 s then air-dried. The mixture of monomers,catalyst, and PMMA powder were applied to the dentin surface using brush-on technique.

A resincomposite rod, used for the tensile bond test, was cemented immediately to the dentin surface (Fig. 1). Inthe Panavia F group, the dentin surface was conditioned with a mixture of ED primer A and B for 60 s.
The mixture of Paste A and Paste Universal was applied to the dentin surface. A resin composite rod wasplaced on the conditioned dentin surface, and light-cured for 20 s each from three directions (Optilux, Kerr,Orange, CA, USA). Thirty minutes after specimen preparation, they were stored in water at 37˚C in for
one day. Following this, tensile bond test was performed at a crosshead speed of 2 mm/minute using auniversal testing machine (Autograph AG-500B, Shimadzu, Kyoto, Japan). The failure mode of specimens

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was examined visually after completion of the tensile test. Ten specimens were measured for each test
group. The data were statistically analyzed using analysis of variance (ANOVA) and Fisher’s PLSD test at
the 5% level.
Table 1. Manufacturers' instructions for the rein cements evaluated.
Cement/Components

Chemical composition

Directions

Etchant

10% Citric acid, 3% Ferric chloride

5 s apply, rinse, gentle dry

Adhesive

4-META, MMA, TBB, PMMAMix, brush-on techniqueSuper-Bond C&B

Panavia F
ED Primer A

MDP, HEMA, Chemical initiator, Water, 5-NMSAED Primer B

5-NMSA, Chemical initiator, Water

Paste A

Silanated silica, Microfiller, MDP, Dimethacrylates,

Mix, 60 s apply, dry

Photo/chemical initiator
Paste Universal

Silanated barium glass, Surface treated NaF,Dimethacrylates, Chemical initiator

Mix, 20 s light-cured

4-META; 4-methacryloxyethyl trimellitate anhydride, MMA; methyl methacrylate, TBB; tri-n-butyl borane, PMMA;
poly(methyl methacrylate), MDP; 10-methacryloyloxydecyl dihydrogen phosphate, HEMA; 2-hydroxyethyl methacrylate,5-NMSA; N-methacryloyl 5-aminosalicylic acid.

Composite resin rod
Vinyl masking tape (Ø 4 mm)
Resin cement
Bovine toothFig. 1.

Specimen assembly for the tensile test.

Results
The tensile bond strengths of the two bonding systems to dentin are summarized in Table 2. Statisticallylower bond strengths were obtained in the experimental groups compared with the control groups forSuper-Bond C&B (p<0.05). However, this was not the case for Panavia F. The bond strengths decreasedsignificantly in H2O2, H2O2/NaOCl and Ca(OH)2 (p<0.05), while no influence of NaOCl and FC on bondstrengths was observed.
Visual inspection showed mixed failure of adhesive failures between the resin and dentin, and cohesive9Sasafuchi et al.

Int Chin J Dent 2003; 3: 7-12.

failure within the bonding resin occurred predominantly for all materials in the control groups. However, alarge increase of adhesive failures between the resin and dentin occurred with the groups treated withchemical solutions. This was marked for both resin cements.
Table 2. Tensile bond strengths to endodontically treated teeth.
Control

H 2O 2NaOCl

H2O2/NaOCl

FCCa(OH)2Super-Bond

16.0 (5.8)

4.9 (1.3)*

5.8 (1.3)*

7.1 (1.7)*

13.8 (3.8)*

8.2 (2.3)*

Panavia10.9 (3.5)

3.8 (2.4)*

10.3 (3.1)

5.9 (2.5)*

8.9 (1.8)

7.5 (1.7)*

N=10, Mean (S.D.). Data indicated with an asterisk are significantly different from the control (p<0.05).

Discussion
Adhesion of resin cement to dentin occurs as a result of hybrid layer formation which is as the same asresin composite.11 Two different types of resin cements were used in this study. Super-Bond C&B iscomposed of 10-3 solution and 4-META/MMA-TBB resin with PMMA powder. The ferric chloride in the10-3 solution is believed to act as a stabilizer of collagen during the demineralization process. The4-META monomer promotes the penetration of monomers into demineralized tooth structure.12 Panavia F
is composed of ED primer and the dual-cured resin cement. ED primer functions as a self-etching primerand also as a co-activator for interfacial polymerization of the resin cement. An adhesion promoting
methacrylate, MDP, is an important ingredient of the cement.
For Super-Bond C&B, the tensile bond strengths to dentin statistically decreased, when the dentin
surfaces were treated with the chemical irrigants and also the medicaments. For Panavia F, the bondstrengths also significantly decreased after the treatment with chemical irrigants and medicaments on dentin
surface except for the case of NaOCl and FC. From the visual inspections of the fracture modes, mixed
failure of adhesive failures between the resin cement and dentin, and cohesive failure within the resin
cement occurred predominantly in the control groups, whereas adhesive failures between the resin anddentin increased with the chemically-treated groups. The tendencies of the fracture modes were similar inboth Super-Bond C&B and Panavia F.
Nikaido et al. reported the chemical irrigation in the root canal of bovine incisors with hydrogen
peroxide and sodium hypochlorite adversely affected on early bond strengths of several dentin bonding
systems to coronal superficial dentin.13 However, Clearfil Liner Bond II self-etching bonding system washardly affected by the chemical irrigants used. The result of the current study is the same tendency of theprevious one. However, the chemical irrigants and the medicaments were applied on the superficial
coronal dentin directly before bonding in this study. Therefore, influence of such treatments on dentin
bonding must be severer than the previous study. Generally, NaOCl is believed to damage the organic

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Int Chin J Dent 2003; 3: 7-12.

components of dentin, mainly the collagen. This may influence the penetration of monomers into thedemineralized dentin structure. In addition, NaOCl breaks down to sodium chloride and oxygen. H2O2
also breaks down to water and oxygen. The liberation of oxygen takes place by the chemical reaction of
H2O2 with NaOCl. Oxygen from such chemicals causes strong inhibition of the interfacial polymerizationof resin bonding materials.14 On the other hand, NaOCl has been used to obtain adhesion between dentin
mineral and dentin adhesives.15,16 Acceptable adhesion to phosphoric acid-NaOCl treated dentin wasobtained, when the NaOCl treated teeth were rinsed thoroughly to remove any residual NaOCl.17
Soeno et al. reported soaking of dentin surface in FC for 2 days decreased the bond strengths of several
resin cements.18 Since the soaking period of FC on dentin surface was only 1 minute for each specimen inthis study, therefore, the influence of FC on the bond strength is relatively mild in this study. However, thebond strength of Super-Bond C&B significantly decreased with the FC treatment. One of the ingredients in
FC is formaldehyde, which is generally known to fix collagen. FC applied on the dentin surface probably
modifies the smear layer and the underlying dentin, which would change permeability of monomers intodentin and affect the bond strength.
Ca(OH)2 also affected the bond strength of each resin cement to dentin. Ca(OH)2 indicates high pH
value around 10 to prevent the bacterial regrowth. When Ca(OH)2 was applied, a powder of Ca(OH)2 ismixed with saline to prepare a paste, and then placed on the dentin surface with an injection. The high pH
value of Ca(OH)2 may influence the denature of dentin collagen. Also, the Ca(OH)2 would contaminate thedentin surface after the treatment since Ca(OH)2 is a powder, which is not easy to be rinsed off completely.
When an adhesive system is applied to nonvital tooth, the influence of endodontic treatment and also theregions, such as coronal dentin, pulpal floor dentin and root dentin, should be considered. For a direct
restoration, Yoshiyama et al. reported that the self-etching primer systems produced good adhesion tocoronal, cervical and mid-root dentin, but bonding to apical root dentin was poor.19 Akagawa et al.
reported that the self-etching bonding system, Clearfil Liner Bond 2V, provided good bonding to pulpal
floor dentin as well as to superficial and deep coronal dentin.20

However, there have been limited

information about the regional bond strengths of resin cement for nonvital tooth.9,10 Further studies should
be required to know dentin bonding performance of resin cement for nonvital tooth restorations.

Conclusion
The medicaments for endodontic treatment are the clinical factors influencing dentin bonding of the resin
cements. We need to focus in these results in order to obtain a successful adhesive restoration.

References
1. Gutmann JL. The dentin-root complex: Anatomic and biologic considerations in restoring endodontically treated teeth. JProsthet Dent 1992; 67: 458-67.
2. Wagnild GW, Muller KI. Restoration of the endodontically treated tooth. Pathways of the pulp. 7th ed. St. Louis: Mosby;
1994. p. 691-717.

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3. Assif D, Gorfil C. Biomechanical considerations in restoring endodontically treated teeth. J Prosthet Dent 1994; 71:565-7.
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1999; 81:135-41.
5. Nissan J, Dmitry Y, Assif D. The use of reinforced composite resin cement as compensation for reduced post length. JProsthet Dent 2001; 86: 304-8.
6. West JD, Roane JB. Cleaning and shaping the root canal sysytem. Pathways of the pulp. 7th ed. St. Louis: Mosby;
1994. p. 203-57.
7. Chow TW. Mechanical effectiveness of root canal irrigation. J Endod 1983; 9: 475-9.
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Pathways of the pulp. 7th ed. St Louis: Mosby; 1998. p. 20-49.
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Prosthet Dent 2002; 87: 431-7.
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Dent Mater 1998; 14: 312-20.
11. Nakabayashi N. Resin reinforced dentine due to infiltration of monomers into dentine at the adhesive interface. J JpnDent Mater 1982; 5: 54-64.
12. Nakabayashi N, Kojima K, Masuhara E. The promotion adhesion by infiltration of monomers into tooth substrates. J
Biomed Mater Res 1982; 16: 265-73.
13. Nikaido T, Takano Y, Sasafuchi Y, Burrow MF, Tagami J. Bond strengths to endodontically-treated teeth. Am J Dent
1999; 12: 177-80.
14. Nikaido T, Nakabayashi N. Relationship between polymerization and adhesion to teeth. Adhes Dent 1998; 6: 229-34.
15. Hosoda H, Sugizaki J, Nakajima M, Shono T, Tagami J. A study on the mechanism of bonding between resin anddentin. Part 1. Bonding to dentin treated with sodium hypochlorite. Jpn J Conserv Dent 1993; 36: 1054-8.
16. Vargas MA, Cobb DS, Armstrong SR. Resin-dentin shear bond strength and interfacial ultrastructure with and without ahybrid layer. Oper Dent 1997; 22: 159-66.
17. Inai N, Kanemura N, Tagami J, Watanabe LG, Marshall SJ, Marshall GW. Adhesion between collagen depleted dentinand dentin adhesive. Am J Dent 1998; 11: 123-7.
18. Soeno K, Taira Y, Atsuta M. Influence of formaline cresol on bond strength of adhesive luting agents to dentin. J Oral
Rehabil 2000; 27: 623-8.
19. Yoshiyama M, Carvalho RM, Sano H, Horner JA, Brewer PD, Pashley DH. Regional bond strengths of resins to humanroot dentin. J Dent 1996; 24: 435-42.
20. Akagawa H, Nikaido T, Tagami J. Bonding of resin composite to pulpal chamber floor. Am J Dent (in press).

Reprint request to:Dr. Yasutaka Sasafuchi
Cariology and Operative Dentistry, Department of Restorative Sciences
Graduate School, Tokyo Medical and Dental University
1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
FAX: +81-3-5803-0195 E-mail: sasafuchi.ope@tmd.ac.jp
Received on September 4, 2002. Revised on November 29, 2002. Accepted on December 22, 2002.
Copyright ©2003 by the Editorial Council of the International Chinese Journal of Dentistry.

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