Bonding Nano-filled Resinmodified. Dentin Using Different Selfetch

Transcription

1 Ó Operative Dentistry, 2011, 36-4, Bonding Nano-filled Resinmodified Glass Ionomer to Dentin Using Different Selfetch Adhesives F El-Askary M Nassif Clinical Relevance A sandwich technique restoration using nano-filled RMGI/resin composite can be achieved in one clinical bonding step using the self-etch adhesives. SUMMARY Objective: To investigate the shear bond strength of the nano-filled resin-modified glass ionomer (RMGI) to dentin using different selfetch adhesives. Materials and Methods: Two resin-based restorative materials, a nano-filled RMGI (Ketac Nano-100, 3M ESPE) and a restorative composite (Grandio, VOCO) were bonded to bovine dentin using four self-etch adhesives (Futurabond M, VOCO; Adper Easy Bond, 3M ESPE; G Bond, GC Corp; and One Coat, Coltène). One hundred bovine anterior teeth were used in this study. Subsequent to labial enamel removal, Farid S. El-Askary, BDS, MSc, PhD, associate professor, Ain Shams University, Operative Dentistry Department, Faculty of Dentistry, Cairo, Egypt *Mohammed S. Nassif, BDS, MSc, PhD, lecturer, Ain Shams University, Dental Biomaterials Department, Faculty of Dentistry, Cairo, Egypt *Corresponding author: Ain Shams University, Dental Biomaterials Department, Faculty of Dentistry, 2 Mamoun Street, Abbasia Square Cairo, Egypt; moh2006mat@yahoo.com DOI: / L each adhesive was applied according to manufacturer instructions. Fifty teeth were restored with the nano-filled RMGI and the other 50 were restored with the resin composite. Cylinders of 332 mm from the two restorative materials were bonded to dentin, and the specimens were stored in distilled water for 24 hours. Shear bond strength testing was performed in a universal testing machine at a crosshead speed of 0.5 mm/min. Two randomly selected specimens from each group were chosen for evaluation by scanning electron microscopy (SEM). Failure modes were evaluated using the stereomicroscope. All data for shear bond strength in MPa were expressed as mean 6 standard deviation (SD). Statistical analysis was carried out using SAS program (SAS, 1988). Results: Two-way analysis of variance revealed that the adhesives, the restorative materials, and their interactions (adhesives and restorative materials) had a significant effect on the shear bond strength to bovine dentin. Conclusions: Self-etch adhesives used in this study can adequately bond the nano-filled RMGI to dentin.

2 414 Operative Dentistry INTRODUCTION Nano-filled resin-modified glass ionomer (nano-filled RMGI) is a newly introduced version of resinmodified glass ionomer cement (RMGIC). It is a new technical development that combines the benefits of a resin-modified light-cure glass ionomer with bonded nano-filler technology. Its chemistry is based on the methacrylate modified polyalkenoic acid, which was first employed in Vitrebond liner/base material (Ketac Nano-100, technical product profile, 3M ESPE). The use of nano primer is recommended by the manufacturer to bond the nano-filled RMGI to hard tooth surfaces. Nano primer is a one-component, acidic primer that does not need a preconditioning step. However, it is not clear how the nano primer can react with the smear layer covered dentin; the use of the nano-filled RMGI without the prior application of the nano primer should not be performed. 1 One of the indications of nano-filled RMGI is as a base material under restorative resin composite restorations, the so-called sandwich technique. This technique first requires the application of the nano primer to bond the nano-filled RMGI and then application of either etch-and-rinse or self-etch adhesives to bond the overlying resin composite. These double treatments of the tooth structure will increase not only the application procedure s steps but also, consequently, the restorative procedure s time. The trend today is to reduce application steps, so one-step self-etch adhesives were introduced. 2 Self-etch adhesives are user-friendly and lessen clinical application time. The elimination of the rinsing step makes such adhesives less technique sensitive and reduces the risk of making errors during application. 3-5 Although a study by Wang and others 6 showed that the use of the etch-and-rinse single-bottle adhesive did not improve the bond strength of RMGI to dentin, it was reported that the use of different self-etch adhesives improved the bond strength of RMGI to dentin. 7,8 This approach will facilitate the application of both RMGI and composite using a one-step bonding procedure, thus reducing application time. Today, different self-etch adhesives are available with different chemical formulations. Some adhesives contain polyalkenoic acid copolymers in their chemical compositions, while others do not. The question is, can different self-etch adhesives bond the nano-filled RMGI to dentin with the same efficiency? The purpose of this study was to investigate the effect of different self-etch adhesives with different chemical formulations on the shear bond strength of a nano-filled RMGI to dentin. The null hypothesis tested was that the use of the self-etch adhesives had no effect on the shear bond strength of nano-filled RMGI to dentin. MATERIALS AND METHODS In addition to the nano primer, four different selfetch adhesives were used; three were one-step selfetch adhesives and the fourth was a two-step selfetch adhesive. These adhesives were chosen according to their chemical formulations. Two different restorative materials were used: a nano-filled RMGI and a nano-hybrid resin composite. Compositions and manufacturers of adhesives and restorative materials used in this investigation are presented in Table 1. One hundred bovine anterior teeth were collected and used in the present study. The teeth were thoroughly cleaned and stored in 0.1% thymol solution for not more than 1 month. Subsequent to root removal, the pulp tissue was removed and the pulp chamber was blocked with sterile cotton. The labial enamel was wet ground on a laboratory trimmer to expose approximately 10 mm of flat dentin surface. The teeth were fixed from their labial side on the base of a rectangular mold with doublesided adhesive tape. Auto-cured acrylic resin was poured, and the mold was immersed in tap water to reduce the temperature rise during polymerization of the acrylic resin. After resin polymerization, the dentin surfaces were wet ground over 600 grit SiC paper for 60 seconds to create a standardized smear layer. The specimens were then ultrasonically cleaned in distilled water for 5 minutes prior to the bonding procedure to remove any remaining silicon carbide dust particles. The teeth were divided into two main groups (50 each) according to the restorative material used, either the nano-filled RMGI or the resin composite. Each main group was then divided into five subgroups (10 each) according to the self-etch adhesive used. The nano primer and the self-etch adhesives were applied according to manufacturer instructions. Experimental grouping and bonding procedures are summarized in Table 2. Before light curing each adhesive, a polyethylene tube (3 mm internal diameter and 2 mm in height) was positioned over the dentin surface. The adhesives were light cured using a halogen light curing unit (Hilux, Benlioglu; Ankara, Turkey) with an output of 600 mw/cm 2. The light intensity was checked periodically using a radiometer (Demetron-

3 El-Askary & Nassif: Nano Ionomer-SE Adhesives 415 Table 1: Materials, Compositions and Manufacturers Materials Compositions Manufacturers Nano primer HEMA 35%-45%, water 40%-50%, Vitremere copolymer 10%-15%, photoinitiator 3M ESPE, Dental Products, Seefeld, Germany Ketac Nano-100 (nano-filled RMGI) Silane treated glass 40%-50%, silane treated Zirconia oxide silica 20%-30%, polyethylene glycol dimethacrylate 5%- 15%, silane treated silica 5%-15%, HEMA 1-10%, glass powder,5%, Bis- GMA,5%, TEGDMA,1% 3M ESPE, Dental Products, Seefeld, Germany Futurabond M (one-step self-etching adhesive) UDMA, HEMA, phosphoric acid methacrylate, ethanol, water, catalysts (CQ/amine), silica nano particles VOCO GmbH, Cuxhaven, Germany. Adper Easy Bond (one-step self-etching adhesive) 2-hydroxyethyl methacrylate (HEMA), Bis-GMA, methacrylated phosphoric esters, 1,6 hexanediol dimethacrylate methacrylate functionalized polyalkenoic acid (Vitrebond copolymer), finely dispersed bonded silica filler with 7 nm primary particle size, ethanol, water, CQ, stabilizers 3M ESPE, Dental Products, Seefeld, Germany G-Bond (one-step self-etching adhesive) 4-MET, UDMA, TEGDMA, acetone, water, fumed silica fillers, photoinitiator GC Corporation,Tokyo, Japan One Coat (two-step self-etching adhesive) Primer 1: water, acrylamidosulfonic acid methacrylates, polyalkenoate methacrylized Coltène-Whaledent AG, Altstätten/Switzerland Bond 2: methacrylates, polyalkenoate methacrylized Grandio (nano-hybrid resin composite) 87% weight inorganic filler in a methacrylate matrix (Bis-GMA, TEGDMA) VOCO GmbH, Cuxhaven, Germany Abbreviations: Bis-GMA, bisphenol A diglycidyl methacrylate; CQ, camphorquinone; 4-MET, 4-methacryloyloxyethyl trimellitic acid; HEMA, 2-hydroxyethyl methacrylate; TEGDMA, triethylene glycol dimethacrylate; UDMA, urethane dimethacrylate. 100, Demetron Research Corp, Danbury, CT, USA). The tube was filled with either the nano-filled RMGI or the resin composite, a polyester strip was applied and pressed gently, and the material was light cured according to manufacturer instructions using the halogen light curing unit. The teeth and their attached material cylinders were stored in distilled water at 378C for 24 hours. After 24 hours, each specimen was mounted to the universal testing machine (LR5K series, Lloyd Instrument, Fareham, UK). A metallic chisel-bladed instrument was positioned as accurately as possible to the restoration/dentin interface. The test was run at a crosshead speed of 0.5 mm/min until failure. The load recorded in Newtons was divided over the calculated surface area, and the shear bond strength was retrieved in MPa. Group 6 was not tested because all specimens of this group were spontaneously dissociated from the dentin surface during the 24-hour storage period, and their shear bond strength was expressed as MPa for statistical analysis. Specimens from each group were evaluated under a stereomicroscope (S2-PT Olympus, Tokyo, Japan)

4 416 Operative Dentistry Table 2: Experimental Groups and Application Procedures in This Study Groups Descriptions Application Procedures 1 Nano primer þ nano-filled RMGI Nano primer was applied on dentin surfaces for 15 seconds, air-dried using gentle compressed air for 10 seconds, and light cured using a halogen light curing unit for 10 seconds. Nano-filled RMGI was dispensed over a pad with the aid of the Clicker Dispenser, mixed using metallic spatula for 20 seconds, was applied and was light cured for 20 seconds. 2 Futurabond M þ nano-filled RMGI Futurabond M was applied for 20 seconds, gently air-dried for 5 seconds, and light cured for 20 seconds. Nano-filled RMGI was applied as group 1. 3 Adper Easy Bond þ nano-filled RMGI Adper Easy Bond was applied for 20 seconds, gently air-dried for 5 seconds, and light cured for 10 seconds. Nano-filled RMGI was applied as in group 1. 4 One Coat þ nano-filled RMGI One Coat Primer 1 (yellow) was applied to dentin, rubbed in for 20 seconds, and gently air-dried for 2 seconds. One Coat Bond 2 (black) was applied to dentin, rubbed in for 20 seconds, and gently air-dried for 2 seconds and light-cured for 20 seconds. RMGI was applied as in group 1. 5 G Bond þ nano-filled RMGI G Bond was applied for 10 seconds, air-dried using full-pressure compressed air for 5 seconds, and light cured for 10 seconds. RMGI was applied as in group 1. 6 Nano primer þ resin composite Nano primer was applied as in group 1 and composite material was applied and light cured for 40 seconds using a halogen light curing unit. 7 Futurabond M þ resin composite Futurabond M was applied as in group 2. Composite material was applied as in group 6. 8 Adper Easy Bond þ resin composite Adper Easy Bond was applied as in group 3. Composite material was applied as in group 6. 9 One Coat þ resin Composite One Coat Primer 1 and the One Coat Bond 2 were applied as in group 4. Composite material was applied as in group G Bond þ resin composite G Bond was applied as in group 5. Composite material was applied as in group 6. at 403 magnification. The dentin side was evaluated, and the fracture pattern was analyzed as adhesive, mixed, or cohesive either in the restorative materials or in dentin. Two specimens were randomly chosen from each subgroup for scanning electron microscope (SEM) evaluation. Dentin blocks of approximately mm, completely including the bonded area, were obtained, ultrasonically cleaned for 5 minutes, and dehydrated in ascending concentrations of ethanol, 50%, 70%, and 90% for 20 minutes each and in 100% ethanol for 1 hour. The specimens were left to dry on absorbent paper in a closed container overnight. The specimens were fixed on a specimen holder using double-faced stickers and sputter coated (BAL- TEC, SCD 005,, Cologne, Germany). Dentin sides of the fracture specimens of the nano-filled RMGI and resin composite were evaluated at 253 and using SEM (Philips XL series, XL30, Eindhoven, The Netherlands) operated at 20 Kv. All data for shear bond strength in MPa were expressed as mean 6 standard deviation (SD). Statistical analysis was carried out using SAS program (SAS, 1988, STAT/ User s Guide, Release 6.03 ed., Cary NC, USA). Twoway analysis of variance (ANOVA) was run to test the effects of the restorative materials, adhesives, and their interaction on shear bond strength. Oneway ANOVA (SAS) followed by the Duncan multiple range test were used to test the effects of adhesives within each restorative material. Student t-test (procedure TTEST of SAS) was run to compare the effect of restorative materials on shear bond strength within each adhesive.

5 El-Askary & Nassif: Nano Ionomer-SE Adhesives 417 Table 3: Mean a 6 SD of the Shear Bond Strength of Nano-filled RMGI and Resin Composite Using Different Self-etch Adhesives Table 4: Two-way Analysis of Variance for the Effect of Adhesives, Restorative Materials, and Their Interaction on the Shear Bond Strength Nano-filled RMGI Resin Composite p Mean 6 SD dt Mean 6 SD dt Nano primer b c Futurabond M b ab Adper Easy Bond a a One Coat a ab G Bond a b Abbreviations: dt, Duncan multiple range test for the effect of the different adhesives; p, probability for the effect of the restorative materials; SD, standard deviation. a Means with the same letter within each column are not significantly different at p¼0.05. RESULTS The shear bond strength data for each restorative material and self-etch adhesive are presented in Table 3. Two-way ANOVA (Table 4) revealed that both materials and adhesives have a significant effect of the shear bond strength to dentin. The interactions between the two independent variables (materials and adhesives) also have a significant effect on shear bond strength. One-way ANOVA followed by the Duncan multiple range test (Table 3) showed that three of the selfetch adhesives used (Adper Easy Bond, One Coat, and G Bond) significantly improve the shear bond strength of nano-filled RMGI compared with the nano primer. No statistically significant difference was shown in the shear bond strength between the Futurabond M and the nano-filled RMGI. Nano primer was not able to bond composite to dentin (Group 6), with all specimens failing before testing, and the shear bond strength was expressed as MPa, showing a statistically significant difference with all self-etch adhesives used. No statistically significant difference was recorded between the self-etch adhesives when composite was bonded to dentin, except between Adper Easy Bond and G Bond, where Adper Easy Bond shows a significantly higher shear bond strength. Student t-test showed that nano primer records statistically significant higher shear bond strength when used with nano-filled RMGI than when used Source SS df MS F Sig Adhesives Restorative materials Adhesives * restorative materials Error Total Abbreviations: df, degrees of freedom; MS, mean square; Sig, significance (probability level); SS, sum of squares. with composite. All self-etch adhesives show statistically significant higher shear bond strength with composite than with nano-filled RMGI except the One Coat adhesive, which shows no statistically significant difference between nano-filled RMGI and resin composite. The Failure Mode Analysis Failure mode analysis (Table 5) showed that the mixed type of failure is the predominant failure type in all evaluated groups except for Group 6, in which all specimens failed adhesively between the nano primer and resin composite. SEM microphotographs of the different failure modes are presented in Figures 1 through 3. DISCUSSION Direct posterior restorations are commonly used in daily dental practice because of their good esthetics and low cost. 9 The success of composite restorations, especially in deep interproximal cavities, depends on several clinical factors, among them the proper isolation as well as the optimum solvent evaporation and adequate light curing of the adhesive resin. These factors render the composite restoration a technique sensitive to most general dental practitioners. 17 The sandwich technique was developed to overcome such difficulties in the bonding of resin composite to dentin. 9 It was reported that the clinical durability of the glass ionomer (GI) is, to some extent, more predictable than the resin composite, through its chemical bonding to dentin. 3 This technique is based on the application of either

6 418 Operative Dentistry Table 5: Failure Mode Analysis Adhesive Failure Mixed Failure Cohesive Failure in Restoration Cohesive Failure in Dentin Total Group Group Group Group Group Group Group Group Group Group Total conventional GI or RMGI under composite restoration to overcome the technique sensitivity of composite restoration. 18 With the increased interest in using nano materials in dentistry, a nano-filled RMGI is now available for dental practitioners. 19 The use of the nano primer is a mandatory step to bond nano-filled RMGI to enamel and dentin. 1 Double bonding procedures to tooth substrates should be performed in the nanofilled RMGI/composite sandwich technique. These double bonding procedures are required to bond both the nano-filled RMGI and resin composite separately to tooth substrates. This will increase the clinical bonding steps and, consequently, the application time of the sandwich technique using the nanofilled RMGI/composite combinations. Contemporary adhesives can be classified into three main categories: etch-and-rinse, self-etch, and glass ionomers. 4 Self-etch adhesives were introduced as alternatives to the etch-and-rinse types. According to their clinical application steps, self-etch adhesives are either two-step or one-step. 3 With the elimination of the rinsing step in the self-etch adhesives, the clinical application time was reduced. 4 The chemical compositions of adhesives should aim to fulfill the requirements of the adhesive systems meeting our clinical needs. To some extent, all contemporary adhesives contain similar components. 20 However, additional elements may be present in some adhesives and not included in the chemical composition of others. In this study, the choice of adhesives was based on the presence or lack of ingredients such as methacrylized polyalkenoate or the presence of acidic monomer that contains carboxylic groups. Besnault and others 7 report the improvement in the shear bond strength of the RMGI to dentin using different self-etch adhesives. In their study, they used the RMGI, which did not include the Vitremere copolymer in its composition. Accordingly, the present study aimed to evaluate if nano-filled RMGI, which does contain Vitrebond copolymer, can be bonded to dentin using the four different self-etch adhesives containing or not containing the polyalkenoic acid copolymer in their chemical compositions. Further, this study was aimed to evaluate the self-etch adhesive or adhesives that can bond both with the nano-filled RMGI and composite in a single bonding step to reduce clinical application steps and, consequently, application time in the sandwich technique. In the present study, self-etch adhesives have a significant effect on the shear bond strength of the nano-filled RMGI to dentin, so the null hypothesis must be rejected. Three of the self-etch adhesives used in this study improve the shear bond strength of the nano-filled RMGI to dentin; however, the Futurabond M does not improve bond strength and shows similar bond strength with the nano primer. Two of the self-etch adhesives Adper Easy Bond and One Coat that improve the bond strength of the nano-filled RMGI contain methacrylized polyalkenoate in their chemical compositions and the other one (G Bond) contains acidic monomer 4-MET containing two carboxylic groups. Futurabond M contains neither a methacrylized polyalkenoate nor an acidic monomer such as 4-MET in its chemical composition. Therefore, the presence or absence of the polyalkenoate copolymer or the carboxylic group affects the bond strength of the nano-filled RMGI to dentin. This could be the reason that Futurabond M did not improve the bond strength of the nano-filled RMGI over the nano primer. One of the advantages of the glass ionomer cements is their self-adhesive capacity to tooth tissue. 21,22 Unfortunately, this property was not supported in a previous study that evaluated bonding effectiveness of the nano-filled RMGI. 1 For

7 El-Askary & Nassif: Nano Ionomer-SE Adhesives 419 Figure 1. SEM photomicrographs of groups 1-5 (dentin side). (A): Predominant adhesive failure with remnant of nano-filled RMGI at the periphery of the bonded area is shown. (B): Complete cohesive failure in the nano-filled RMGI. (C, D, and E): Mixed failure, remnants of nano-filled RMGI still attached to the dentin surface. A, adhesive; RMGI, nano-filled RMGI. (Original magnification 253) this reason, the manufacture recommends the use of the nano primer to bond the nano-filled RMGI to tooth structure. Nano primer is an acidic primer with a ph of 3 (Ketac Nano-100, technical product profile, 3M ESPE). This high ph value does not allow the nano primer to remove or dissolve completely the smear layer (Figures 1A and 3A). In the SEM photomicrograph of the fractured surface of the nano-filled RMGI bonded with nano primer, the presence of the smear plugs occluding the dentinal tubules was shown. This observation was in agreement with Coutinho and others 1 and Korkmaz and others 19 who reported no evidence of demineralization or hybrid layer formation and the absence of cement extensions inside the dentinal tubules. The high incidence of the mixed failure type or even the presence of some specimens that failed cohesively with the nano-filled RMGI (Table 5, Figure 1) could be attributed to the presence of voids (Figure 3B), which might be due to air entrapment within the material during mixing. In the present study, nano primer failed to bond resin composite to dentin, and all specimens failed prematurely during their storage period. This might be attributed to the absence of the intermediate adhesive layer following the application of the nano primer. 19 One-step self-etch adhesives did not meet the clinical predictions in terms of their bond durability, as high incidence of failure during their clinical service was reported. 3 One-step self-adhesives could bond resin composite to dentin, statistically, with the same results as the etch-and-rinse adhesives. 23 The different self-etch adhesives used in this study bonded the resin composite to dentin with the same efficiency. However, G bond showed the lowest shear bond strength results among all adhesives used. It was reported that when the application of the G bond was doubled, the bond strength was improved, which could lead to an explanation that the short time recommended by the manufacturer could not be enough for the chemical bonding mechanism to take place. 24 The shear bond strength of the resin composite to dentin was statistically higher than the bond strength of the nano-filled RMGI, except for the One Coat self-etch adhesive. Although, bond strength of RMGI using One Coat was still lower than the One Coat/resin composite bond, the difference was not statistically significant. One Coat is a two-step self-etch adhesive: the One Coat self-etch primer is applied first, followed by the application of the One Coat Bond 2. The bond (One Coat Bond 2) of the One Coat self-etch adhesive does not contain solvent in its chemical composition (One Coat, technical product profile, Coltène). This hydropho-

8 420 Operative Dentistry Figure 2. SEM photomicrographs of groups 6-10 (dentin side). (A, B, and E): Predominate adhesive failure. (C and D): Mixed failure with remnants of resin composite still attached to the dentin surface. A, adhesive; C, resin composite. (Original magnification 253) bic, nonsolvated layer might be the cause in bonding the RMGI and composite with the same efficiency. This is an explanation that needs further investigation. From the results of this study, it would appear that when completing an interproximal open sandwich procedure, the bonding step for both the RMGI and composite can be accomplished simultaneously with a single, self-etching bonding agent. In this technique, the use of nano primer may not be necessary, which may make the application of the nano primer prior to the nano-filled RMGI dependent on the clinical condition. CONCLUSIONS Under the limitations of this study, it can be concluded that: 1) The self-etch adhesives used in this study appear to adequately bond nano-filled RMGI (Ketac Nano-100) to bovine dentin. Figure 3. Representative SEM microphotographs of groups 1, 2, and 5 (dentin side). (A): SEM microphotograph of group 1 shows the presence of smear plugs occluding the dentinal tubules, and apparently detected grinding grooves. (B): SEM microphotograph of group 2, the presence of voids in the nano-filled RMGI, which might be due to air entrapment during the mixing procedure. Adhesive failed at the bottom of the hybrid layer. (C): SEM microphotograph of group 5 shows the presence of both nano-filled RMGI ruminants and adhesive still attached to the dentin surface. Failure occured between the nano-filled RMGI and the adhesive and also within the nano-filled RMGIC material itself. A, adhesive; HL, hybrid layer; RMGI, nano-filled RMGI; SP, smear plug; V, voids. (Original magnifications 15003)

9 El-Askary & Nassif: Nano Ionomer-SE Adhesives 421 2) Absence of a polyalkenoic acid copolymer or an acidic monomer containing a carboxylic group in the adhesive negatively affects the shear bond strength of the nano-filled RMGI. 3) Nano primer appears to be unable to bond Grandio composite to bovine dentin. Acknowledgements The authors would like to thank Dr. E. Eid, Middle East Dental Company, Cairo, Egypt, for supplying the Ketac N-100 and Easy bond, VOCO Company (VOCO GmbH. Cuxhaven, Germany) for supplying Futurabond M and Grandio restorative resin composite, and GC Europe, N.V., B 3001 Leuven, Belgium, for supplying the G Bond used in this study. (Accepted 25 January 2011) REFERENCES 1. Coutinho E, Cardoso M, De Munck J, Neves A, Van Landuyt K, Poitevin A, Peumans M, Lambrechts P & van Meerbeek B (2009) Bonding effectiveness and interfacial characterization of a nano-filled resin-modified glassionomer Dental Materials 25(11) Van Landuyt K, Peumans M, De Munck J, Lambrechts P & Van Meerbeek B (2006) Extension of a one-step selfetch adhesive into a multi-step adhesive. Dental Materials 22(6) Peumans M, Kanumilli P, De Munck J, Van Landuyt K, Lambrechts P & Van Meerbeek B (2005) Clinical effectiveness of contemporary adhesives: A systematic review of current clinical trials. Dental Materials 21(9) De Munck J, Van Landuyt K, Peumans M, Poitevin A, Lambrechts P, Braem M & van Meerbeek B (2005) A critical review for the durability of adhesion to tooth tissues: Methods and results Journal of Dental Research 84(2) Van Meerbeek B, De Munck J, Yoshida Y, Inoue S, Vargas M, Vijay P, Van Landuyt K, Lambrechts P & Vanherle G (2003) Buonocore memorial lecture. Adhesion to enamel and dentin: Current status and future challenges. Operative Dentistry 28(3) Wang L, Sakai V, Kawai E, Buzalaf M & Atta M (2006) Effect of adhesive systems associated with resin-modified glass ionomer cements Journal of Oral Rehabilitation 33(2) Besnault C, Attal JP, Ruse D & Degrange M (2004) Selfetching adhesives improve the shear bond strength of the resin modified glass ionomer cement to dentin. Journal of Adhesive Dentistry 6(1) Pereira P, Yamada T, Inokoshi S, Burrow M, Sano H & Tagami J (1998) Adhesion of resin modified glass ionomer cements using resin bonding systems. Journal of Dentistry 26(5) Koubi S, Raskin A, Dejou J, About I, Tassery H, Camps J & Proust P (2010) Effect of dual cure composite as dentin substitute on the marginal integrity of Class II opensandwich restorations. Operative Dentistry 35(2) Charton C, Falk V, Marchal PY & Colon P (2007) Influence of Tg, viscosity and chemical structure of monomers on shrinkage stress in light-cured dimethacrylate-based dental resins Dental Materials 23(11) Shortall AC, Palin WM & Burtscher P (2008) Refractive index mismatch and monomer reactivity influence composite curing depth Journal of Dental Research 87(1) Attar N, Turgut M & Güngör H (2004) The effect of flowable resin composites as gingival increments on the microleakage of posterior resin composites Operative Dentistry 29(2) Rode KM, Kawano Y & Turbino M (2007) Evaluation of curing light distance on resin composite microhardness and polymerization Operative Dentistry 32(6) Uhl A, Sigush BW & Jandt K (2004) Second generation LEDs for the polymerization of biomaterials Dental Materials 20(1) Eiriksson S, Pereira P, Swift E, Heymann H & Sigurdsson A (2004) Effects of blood contamination on resin-resin bond strength Dental Materials 20(2) Hitmi L, Attal JP & Degrange M (1999) Influence of time point of salivary contamination on dentin shear bond strength of 3 dentin adhesive systems Journal of Adhesive Dentistry 1(3) Giachetti L, Scaminaci Russo D, Bertini F, Pierleoni F & Nieri M (2007) Effect of operator skill in relation to microleakage of total-etch and self-etch bonding systems Journal of Dentistry 35(4) Besnault C & Attal J (2003) Simulated oral environment and microleakage of Class II resin-based composite and sandwich restorations American Journal of Dentistry 16(3) Korkmaz Y, Gurgan S, Firat E & Nathanson D (2010) Shear bond strength of three different nano-restorative materials to dentin Operative Dentistry 35(1) Van Landuyt K, Snauwaert J, Munck J, Peumans M, Yoshida Y, Poitevin A, Coutinho E, Suzuki K, Lambrechts P & van Meerbeek B (2007) Systematic review of the chemical composition of contemporary dental adhesives Biomaterials 28(26) Franklin T & Pashley D (2002) Dental adhesives of the future Journal of Adhesive Dentistry 4(2) Martin T (2003) Milestones in adhesion: Glass ionomer cements Journal of Adhesive Dentistry 5(4) Margvelashvili M, Goracci C, Beloica M, Papacchini F & Ferrari M (2010) In vitro evaluation of bonding effectiveness to dentin of all-in-one adhesives Journal of Dentistry 38(2) Elkassas D, Taher H, Elsahn N, Hafez R & El-Badrawy W (2009) Effect of the number of applications of acetonebased adhesives on microtensile bond strength and the hybrid layer Operative Dentistry 34(6)