Printer Friendly

Bond strength of self-adhesive resin cements to dry and moist dentin.


The self-adhesive resin cements do not require acid conditioning of the tooth structure and application of the bonding agent before cementation. These luting materials simplify the cementation procedures, because they save time and reduce the number of steps for cementation of indirect restorations and posts, when compared to conventional resin cements. (1-3)

The bonding to tooth structures is promoted by specific functional monomers, which differ among different commercial products. According to the manufacturers, the functional monomers are able to bond chemically the calcium from hydroxyapatite, which is one of the bonding mechanisms responsible for the retention of the restoration. (4-6) However, little information is available about these chemical reactions, and the durability of this bonding requires further investigation, since clinicians have switched from conventional resin cement to these new self-adhesive resin cements. (7-9)

The manufacturers' instructions provide information regarding the proper use of these materials; however, some of these are unclear regarding the humidity conditions of mineralized tissues (enamel and dentin) before cementation. The purpose of this in vitro study was to measure the bond strength of pre-polymerized composite discs to underlying dentin, using two self-adhesive resin-based cements under three humidity conditions. In addition, the bond failure site morphology was analyzed and compared among material types and humidity conditions. The research hypothesis tested was that the bond strength would be significantly higher when the resin cement is applied to wet dentin than when it is used on dried surfaces.


Two self-adhesive resin cements were selected:

* RelyX Unicem (3M ESPE, St. Paul, USA) and

* Clearfil SA Cement (Kuraray Noritake Dental Inc., Kurashiki, Japan).

The composition and the batch number are presented in Table 1. One hundred and twenty freshly extracted incisor bovine teeth (stored in a 0.05% thymol [LabSynth, Diadema, Brazil] solution at 5[degrees]C) were used and randomly divided into four groups (n = 10; Institutional Review Board protocol #089/2009). Their buccal surfaces were wet and abraded with 180-grit silicon carbide paper (Carborundum Abrasivos, Vinhedo, Brazil) using a machine (APL-4, Arotec Ind. e Com. Ltda., Cotia, Brazil) to remove the enamel and to expose a flat dentin surface with a remaining dentin thickness ranging from 1.0 to 1.5 mm. Afterwards, the teeth were abraded with 600-grit silicon carbide paper (Carborundum Abrasivos, Vinhedo, Brazil) for 10 s to standardize the smear layer formation. The humidity conditions tested were:

1. Dry: air-dried for 10 s, 70 psi and a distance of 10 mm between the dentin surface and the tip of the air-syringe (Dabi Atlante, Ribeirao Preto, Brazil).

2. Slightly moist: water application with a Micro-brush disposable applicator (Microbrush International, Grafton, USA) on dried dentin, and water excess removed with absorbent paper (Kleenex, Kimberly-Clark, Mogi das Cruzes, Brazil).

3. Moist: the same application of condition 2 without the removal of water.

One hundred and twenty pre-polymerized (B2D shade; Sinfony, 3M ESPE, St. Paul, USA), light cured composite resin discs, 2 mm thick and 10 mm in diameter, were prepared to simulate overlying laboratory-processed composite resin restorations. The surface of each disc to be bonded to the prepared tooth was airborne-particle abraded with 50 [micro]m aluminum oxide (Danville Engineering Inc., San Ramon, USA) for 10 s (air pressure: 0.552 MPa; distance from the tip: 1.5 cm), and silanated using coupling agents (Ceramic Primer, 3M ESPE, St. Paul, USA or Clearfil Ceramic Primer, Kuraray Noritake Dental Inc., Kurashiki, Japan), according to the manufacturer's directions. (10_

All cements were manipulated and applied according to the manufacturers' instructions. The mixed resin cement pastes were applied to the sandblasted and silanated surface of the pre-polymerized composite resin disc, after which the disc was placed on the dentin surface. A 500 g load was applied for 5 min. For light-polymerized groups, the load was removed and the light-activating tip (XL 3000, 3M ESPE, St. Paul, USA) was positioned against the composite resin disc after loading, and the unit was activated for 40 s. To facilitate the specimen-gripping length while bond testing was being performed, a 3-mm-thick block of autopolymerizing composite resin (Concise, 3M of Brazil, Sumare, Brazil) was then added to the untreated, pre-polymerized composite resin surface.

The teeth were stored in distilled, deionized water at 37[degrees]C for 24 h, and were then vertically, serially sectioned into several 1.0-mm-thick slabs using a cutting instrument (Isomet 1000, Buehler Ltd., Lake Bluff, USA). Each slab was further sectioned perpendicularly to produce bonded sticks approximately 1.0 mm2 in cross-section. Each bonded stick was attached to the grips of a microtensile testing device (Cometa, Piracicaba, Brazil) with cyanoacrylate glue (Super Bonder, Henkel/Loctite, Diadema, Brazil), and tested in tension in a universal testing machine (EZ Test, Shimazu, Kyoto, Japan) at a crosshead speed of 0.5 mm/min until failure. After testing, the specimens were removed carefully, and the cross-sectional area at the site of fracture was measured to the nearest 0.01 mm with a digital caliper (727-6/150, Starret Ind. e Com. Ltda., Itu, Brazil). The specimen's cross-sectional area was divided by the peak tensile load at failure to calculate the stress at fracture (MPa). A single failure stress value was then calculated for each tooth by averaging the values of 6 sticks from that tooth. A 3-way analysis of variance (ANOVA) (factors: material, humidity and time) was performed to determine the effect of these major factors on and their interaction with tensile strength. The Tukey-Kramer test was used to detect multiple comparisons among the experimental groups. All statistical testing (SAS Institute Inc., Cary, USA) was performed at a preset alpha of 0.05.

Fractured surfaces of tested specimens were allowed to air-dry (Marconi Equip. Lab., Piracicaba, Brazil) overnight at 37[degrees]C, after which they were sputter-coated with gold (MED 010, Balzers, Balzer, Liechtenstein) and examined by a single individual using a scanning electron microscope (voltage 15 kV; VP 435, Leo, Cambridge, UK). Failure patterns were classified as:

1. cohesive within the resin cement;

2. adhesive along the pre-polymerized composite overlay-resin cement interface;

3. adhesive along the dentin surface;

4. mixed when simultaneously exhibiting the dentin surface and remnants of the resin cement; and

5. cohesive within the dentin.

Representative areas of the failure patterns were photographed at 400x.


The mean bond strength values are presented in Table 2. Three-way ANOVA revealed statistically significant differences only for the factor, "humidity" (p = 0.0475). Conversely, the statistical analysis revealed no significant differences for the "material" (p = 0.3309) and "time" (p = 0.8859) factors. The double interactions between "material and humidity" and "material and time" factors were significant (p = 0.0384 and p = 0.0072, respectively). The triple interaction was not statistically significant (p = 0.5440).

The Tukey-Kramer test revealed significant differences among humidity conditions only for Clearfil SA Cement (p < 0.05). Analysis of data with respect to these differences in the humidity condition showed that the Clearfil SA Cement had a significantly lower bond strength when applied to the dried dentin surface than when applied to moist dentin (p < 0.05). However, the dry and slightly moist conditions did not differ from each other (p > 0.05). The storage time did not influence the bond strength results (p > 0.05).

Figure 1 shows the proportional prevalence (%) of the failure patterns in all experimental groups. Representative images depicting the failure classifications are presented in Figures 2-6. All groups showed cohesive failure within the resin cement (type 1; Figure 2). RelyX Unicem presented a high incidence of adhesive failure along the pre-polymerized composite overlay-resin cement interface (type 2; Figure 3), whereas adhesive failures along the dentin surface (type 3) and mixed fracture (type 4) were observed for Clearfil SA Cement (Figures 4 and 5, respectively) at both evaluation times. Cohesive failures within the dentin (type 5) were observed for both luting materials only after the storage of specimens for 6 months (Figure 6).


The functional monomer of RelyX Unicem is methacrylated phosphoric ester, which reacts chemically with the hydroxyapatite, promoting the bonding to the dental structures and with filler particles that are the basic components of this self-adhesive resin cement. This second acid-base reaction is important in neutralizing the acidic characteristic of the resin cement and reducing the hydrophilicity after mixing of the catalyst and base pastes. (3,11-13) The bond strength of RelyX Unicem to dentin obtained in this study ranged from 15.7 [+ or -] 2.9 MPa to 19.7 [+ or -] 2.8 MPa. These values were higher than those obtained by Piwowarczyk et al. (14) (6.2 MPa), Yang et al. (15) (8.2 MPa), Goracci et al. (16) (6.8 MPa), Holderegger et al. (17) (9.2 MPa), and Egilmez et al. (18) (13 MPa). On the other hand, similar results were found by De Munck et al.,11 Sarr et al., (19) Luhrs et al., (20) Mazzitelli et al., (21) Ebert et al., (22) and Inukai et al. (23)

Although the hydrated dentin substrate can facilitate ionization of the acid monomers, the results of this study suggested that the humidity conditions did not affect the bond strength of RelyX Unicem to dentin, i.e., no significant difference was observed when the self-adhesive was applied to surfaces with different humidity conditions. Conversely, when Guarda et al. (24) did not over-dry the dentin surface before cementation, a higher bond strength was observed for RelyX Unicem. Moreover, Mazzitelli et al. (21) found that RelyX Unicem performed better under simulated pulpar pressure, because the constant intrapulpar water perfusion changes the substrate wetness.

The functional monomer of Clearfil SA Cement is the 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP), which is able to form a strong and stable ionic bond with calcium from hydroxyapaptite. (25) Besides this chemical interaction, (26) Clearfil SA Cement can also provide micromechanical retention, since its monomer is capable of infiltrating the dentinal substrate. (27,28) The wetness of dentin was important for increasing the bond strength of this resin cement. In the presence of water, the acidic monomer of Clearfil SA resin cement was ionized, acid-etched the dentin, and interacted with the dentinal substrate. Thus, the extrinsic dentinal wetness may have optimized these acid-base reactions, allowing for better setting and bonding.

In comparison with RelyX Unicem, few studies have investigated the bond strength of Clearfil SA Cement to dentin. In this study, the bond strength results for Clearfil SA Cement ranged from 12.7 [+ or -] 6.0 MPa in dry dentin to 22.1 [+ or -] 4.6 MPa in moist dentin, which were significantly different. The bond strength results for Clearfil SA Cement from Ebert et al., (22) Inukai et al. (23) and Ilday et al. (29) corroborated our data, while Egilmez et al. (18) showed lower bond strength values than those obtained in this study.

The self-adhesive resin cements (RelyX Unicem and Clearfil SA Cement) tested in this study showed no significant difference between materials in terms of bond strength. Although they present different compositions, these commercial formulations did not influence the bonding to dentin. In addition, the storage in water for 6 months did not alter the bond strength to dentin for any of the resin cements tested, independent of the humidity conditions of dentin. The chemical reaction between 10-MDP and calcium from hydroxyapatite is considerably stable, (25-28) which explains the absence of bond strength reduction for Clearfil SA Cement. The setting reaction of RelyX Unicem increases the pH value, changing the monomer nature from hydrophilic to hydrophobic, and this neutralization reaction is important for the long-term stability of RelyX Unicem cement regarding bond strength to dentin. (3,11-13)

Although no change was observed in bond strength, the failure pattern was modified after storage of the bonded beam specimens for 6 months in water. The specimens stored in water for 6 months induced some cohesive failures within dentin, which did not occur for the specimens stored for 24 hours. The storage of bonded beams instead of restored teeth and without a peripheral composite-enamel bond (30) seemed to accelerate the degradation rate of the exposed dentin, resulting in cohesive failures within dentin during the tensile test.


The storage in water for 6 months does not decrease the bond strength of self-adhesive resin cements to dentin. Conversely, the humidity conditions can change the bond strength to dentin; however, these results are product-dependent.

Declaration of Interests: The authors certify that they have no commercial or associative interest that represents a conflict of interest in connection with the manuscript.

Corresponding Author:

Marcelo Giannini


Submitted: Apr 07, 2013

Accepted for publication: Jun 18, 2013

Last revision: Jul 12, 2013


This study was supported by grants from PIBIC/CNPq (Programa Institucional de Bolsas de Iniciagao Cientifica/Conselho Nacional de Desenvolvimento Cientifico e Tecnologico) and FAPESP (Fundagao de Amparo a Pesquisa do Estado de Sao Paulo), processes nos. 2009/51674-6 and 2010/13599-0, Brazil.


(1.) Radovic I, Monticelli F, Goracci C, Vulicevic ZR, Ferrari M. Self-adhesive resin cements: a literature review. J Adhes Dent. 2008 Aug;10(4):251-8.

(2.) Burgess JO, Ghuman T, Cakir D. Self-adhesive resin cements. J Esthet Restor Dent. 2010 Dec;22(6):412-9.

(3.) Ferracane JL, Stansbury JW, Burke FJ. Self-adhesive resin cements--chemistry, properties and clinical considerations. J Oral Rehabil. 2011Apr;38(4):295-314.

(4.) Aguiar TR, Di Francescantonio M, Ambrosano GMB, Giannini M. Effect of curing mode on bond strength of self-adhesive resin luting cements to dentin. J Biomed Mater Res B Appl Biomater. 2010 Apr;93(1):122-7.

(5.) Pisani-Proenja J, Erhardt MC, Amaral R, Valandro LF, Bottino MA, Del Castillo-Salmeron R. Influence of different surface conditioning protocols on microtensile bond strength of self-adhesive resin cements to dentin. J Prosthet Dent. 2011 Apr;105(4):227-35.

(6.) Vaz RR, Hipolito VD, D'Alpino PH, Goes MF. Bond strength and interfacial micromorphology of etch-and-rinse and self-adhesive resin cements to dentin. J Prosthodont. 2012 Feb;21(2):101-11.

(7.) Benetti P, Fernandes VV, Torres CR, Pagani C. Bonding efficacy of new self-etching, self-adhesive dual-curing resin cements to dental enamel. J Adhes Dent. 2011 Jun;13(3):231-4.

(8.) El-Badrawy W, Hafez RM, El Naga AI, Ahmed DR. Nanoleakage for self-adhesive resin cements used in bonding CAD/CAD ceramic material to dentin. Eur J Dent. 2011 Jul;5(3):281-90.

(9.) Hooshmand T, Mohajerfar M, Keshvad A, Motahhary P. Microleakage and marginal gap of adhesive cements for noble alloy full cast crowns. Oper Dent. 2011 May-Jun;36(3):258-65.

(10.) Soares CJ, Giannini M, Oliveira MT, Paulillo LAMS, Martins LRM. Effect of surface treatments of laboratory-fabricated composites on the microtensile bond strength to a luting resin cement. J Appl Oral Sci. 2004 Mar;12(1):45-50.

(11.) De Munck J, Vargas M, Van Landuyt K, Hikita K, Lambrechts P, Van Meerbeek B. Bonding of an auto-adhesive luting material to enamel and dentin. Dent Mater. 2004 Dec;20(10):963-71.

(12.) Gerth HUB, Dammaschke T, Zuchner H, Schafer E. Chemical analysis and bonding reaction of RelyX Unicem and Bifix composites--a comparative study. Dent Mater. 2006 Oct;22(10):934-41.

(13.) Al-Assaf K, Chakmakchi M, Palaghias G, Karanika-Kouma A, Eliades G. Interfacial characteristics of adhesive luting resins and composites with dentine. Dent Mater. 2007 Jul;23(7):829-39.

(14.) Piwowarczyk A, Bender R, Ottl P, Lauer HC. Long-term bond between dual-polymerizing cementing agents and human hard dental tissue. Dent Mater. 2007 Feb;23(2):211-7.

(15.) Yang B, Ludwig K, Adelung R, Kern M. Micro-tensile bond strength of three luting resins to human regional dentin. Dent Mater. 2006 Jan;22(1):45-56.

(16.) Goracci C, Cury AH, Cantoro A, Papacchini F, Tay FR, Ferrari M. Microtensile bond strength and interfacial properties of self-etching and self-adhesive resin cements used to lute composite onlays under different seating forces. J Adhes Dent. 2006 Oct;8(5):327-35.

(17.) Holderegger C, Sailer I, Schuhmacher C, Schlapfer R, Hammerle C, Fischer J. Shear bond strength of resin cements to human dentin. Dent Mater. 2008 Jul;24(7):944-50.

(18.) Egilmez F, Ergun G, Cekic-Nagas I, Vallittu PK, Lassila LV. Bond strength of self-adhesive resin cements to dentin after antibacterial and chelating solution treatment. Acta Odontol Scand. 2013 Jan;71(1):22-31.

(19.) Sarr M, Mine A, De Munck J, Cardoso MV, Kane AW, Vreven J, et al. Immediate bonding effectiveness of contemporary composite cements to dentin. Clin Oral Investig. 2010 Oct;14(5):569-77.

(20.) Luhrs AK, Guhr S, Gunay H, Geurtsen W. Shear bond strength of self-adhesive resins compared to resin cements with etch and rinse adhesives to enamel and dentin in vitro. Clin Oral Investig. 2010 Apr;14(2):193-9.

(21.) Mazzitelli C, Monticelli F, Osorio R, Casuccia A, Toledano M, Ferrari M. Effect of simulated pulpal pressure on self-adhesive cements bonding to dentin. Dent Mater. 2008 Sep;24(9):1156-63.

(22.) Ebert J, Leyer A, Gunther O, Lohbauer U, Petschelt A, Frankenberger R, et al. Bond strength of adhesive cements to root canal dentin tested with a novel pull-out approach. J Endod. 2011 Nov;37(11):1558-61.

(23.) Inukai T, Abe T, Ito Y, Pilecki P, Wilson RF, Watson TF, et al. Adhesion of indirect MOD resin composite inlays luted with self-adhesive and self-etching resin cements. Oper Dent. 2012 Sep-Oct;37(5):474-84.

(24.) Guarda GB, Gonjalves LS, Correr AB, Moraes RR, Sinhoreti MAC, Correr-Sobrinho L. Luting glass ceramic restorations using a self-adhesive resin cement under different dentin conditions. J Appl Oral Sci. 2010 May-Jun;18(3):244-8.

(25.) Yoshida Y, Nagakane K, Fukuda R, Nakayama Y, Okazaki M, Shintani H, et al. Comparative study on adhesive performance of functional monomers. J Dent Res. 2004 Jun;83(6):454-8.

(26.) Fujita K, Ma S, Aida M, Maeda T, Ikemi T, Hirata M, et al. Effect of reacted acidic monomer with calcium on bonding performance. J Dent Res. 2011 May;90(5):607-12.

(27.) Reis AF, Arrais CAG, Novaes PD, Carvalho RM, De Goes MF, Giannini M. Ultramorphological analysis of resin-dentin interfaces produced with water-based single-step and two-step adhesives: nanoleakage expression. J Biomed Mater Res B Appl Biomater. 2004 Oct;71(1):90-8.

(28.) Reis AF, Giannini M, Pereira PNR. Long-term TEM analysis of the nanoleakage patterns in resin-dentin interfaces produced by different bonding strategies. Dent Mater. 2007 Sep;23(9):1164-72.

(29.) Ilday N, Gungor H, Duymus ZY. Dentine treatment effects on bonding strength of adhesive resin cements. Mater Res Innov. 2011 Jun;15(3):202-7.

(30.) Kasaz AC, Pena CE, Alexandre RS, Viotti RG, Santana VB, Arrais CAG, et al. Effects of a peripheral enamel margin on the long-term bond strength and nanoleakage of composite/dentin interfaces produced by self-adhesive and conventional resin cements. J Adhes Dent. 2012 Jun;14(3): 251-63.

Carolina Bosso Andre [a], Thaiane Rodrigues Aguiar [a], Ana Paula Almeida Ayres [a], Glaucia Maria Bovi Ambrosano [b], Marcelo Giannini [a]

[a] Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.

[b] Department of Social Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.

Table 1-Composition and lot number of the materials
tested in this study.

Resin cement   Composition (lot number)

Clearfil SA    Bis-GMA, TEGDMA, sodium fluoride,
Cement         10-methacryloyloxydecyl dihydrogen phosphate,
               hydrophobic aromatic dimethacrylate, hydrophobic
               aliphatic dimethacrylate, silanated barium glass
               filler, silanated colloidal silica, dl-camphorquinone,
               initiators, accelerators, catalysts, pigments
               (filler = 66 wt%; 45 vol%; avg. 2.5 [miscro]m) (0004AB)

RelyX          Methacrylated phosphoric acid esters, triethylene
Unicem         glycol dimethacrylate, substituted dimethacrylate,
               silanized glass powder, silane treated silica, sodium
               persulfate, substituted pyrimidine, calcium hydroxide
               (filler = 72 wt%; avg. < 9.5 [micro]m) (365945)

Table 2-Mean (standard deviation) bond strength (MPa) of
resin cements to dentin.

Resin cement         Evaluation time

Clearfil SA Cement   24 hours
RelyX Unicem
Clearfil SA Cement   6 months
RelyX Unicem

Resin cement                      Humidity conditions

                     Dry             Slightly moist   Moist
Clearfil SA Cement   12.7 (6.0) B    15.7 (6.3) AB    19.0 (8.4) A
RelyX Unicem         18.9 (5.8) A    19.3 (3.6) A     19.7 (2.8) A
Clearfil SA Cement   14.2 (6.2) B    17.8 (7.0) AB    22.1 (4.6) A
RelyX Unicem         18.3 (6.7) A    15.7 (2.9) A     16.5 (3.6) A

No significant difference (p > 0.05) in bond strength was noted
between resin cements and evaluation times (uppercase letters =
COPYRIGHT 2013 Sociedade Brasileira de Pesquisa Odontologica - SBPQO
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2013 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:Dental Materials
Author:Andre, Carolina Bosso; Aguiar, Thaiane Rodrigues; Ayres, Ana Paula Almeida; Ambrosano, Glaucia Maria
Publication:Brazilian Oral Research
Date:Sep 1, 2013
Previous Article:The academic dimension of university extension programs.
Next Article:Evaluation of the adaptation of zirconia-based fixed partial dentures using micro-CT technology.

Terms of use | Privacy policy | Copyright © 2020 Farlex, Inc. | Feedback | For webmasters