Influence of drying time and temperature on bond strength of contemporary adhesives to dentine

journal of dentistry 37 (2009) 315–320

available at www.sciencedirect.com

journal homepage: www.intl.elsevierhealth.com/journals/jden

Influence of drying time and temperature on bond strength of contemporary adhesives to dentine Fernanda C.P. Garcia a,*, Ju´lio C.F. Almeida b, Raquel Osorio c, Ricardo M. Carvalho d, Manuel Toledano c a

Faculty of Ceilaˆndia, University of Brasilia-UnB, Ceilaˆndia-DF, Brazil Division of Dentistry, University Hospital of Brası´lia, University of Brasilia-UnB, Brası´lia-DF, Brazil c Department of Dental Materials, School of Dentistry, University of Granada, Granada, Spain d Department of Operative Dentistry, UFL, College of Dentistry, Gainesville, Flo´rida, USA b

article info

abstract

Article history:

Objectives: To evaluate the bond strength (mTBS) of self-etching adhesives in different

Received 5 November 2008

solvent evaporation conditions.

Received in revised form

Methods: Flat dentine surfaces from extracted human third molars were bonded with: (1) 2

18 December 2008

two-steps self-etching adhesives (Clearfil SE Bond—CSEB); (Protect Bond—PB) and (2) 2 one-

Accepted 19 December 2008

step self-etch systems (Adper Prompt L Pop—ADPLP); (Xeno III—XIII). Bonded dentine surfaces were air-dried for 5 s, 20 s, 30 s or 40 s at either 21 8C or 38 8C. Composite buildups were constructed incrementally. After storage in water for 24 h at 37 8C, the specimens

Keywords:

were prepared for microtensile bond strength testing. Data were analyzed by two-way

Bond strength

ANOVA and Student–Newman–Keuls at a = 0.05.

Self-etching adhesives

Results: CSEB and PB performed better at warm temperature with only 20 s of air-blowing.

Drying time

The bond strength increased when XIII was performed at warm temperature at 40 s airblowing. Extended air-blowing not affect the performance of ADPLP, except at 30 s airblowing time at warm temperature. Conclusions: The use of a warm air-dry stream seems to be a clinical tool to improve the bond strength to self-etching adhesives. # 2009 Elsevier Ltd. All rights reserved.

1.

Introduction

Hybridization of dentine with resin by monomer interdiffusion has been demonstrated as the fundamental mechanism in achieving effective dentine bonding.1 This process is modified with the use of modern systems that contain hydrophilic functional groups, the so-called self-etch adhesives.2 They are currently offered in both two-step and onestep versions, following the trend of simplification of bonding steps. Although simplified systems comply with clinical desire for speed of use they do not guarantee equal or improved bonding effectiveness.3–5 Major characteristics of self-etch

systems include hydrophilicity and a relative high concentration of solvent in solution.6 A general consensus exists that solvents have to be evaporated from resin-infiltrated dentine matrix, as remaining solvent can lead to poor properties of the resulting polymer,7–10 have an adverse effect on the polymerization of adhesives6,8,11,12 and consequent quality and durability of the bonds.14–16 Residual solvent can be clinically avoided by allowing an evaporation time between application and curing of the adhesive. The drying time allowed to evaporate solvent can have a significant effect on bond strength.13,17–19 This potential effect seems to depend upon the type of solvent,

* Corresponding author. Tel.: +55 61 3877 4735. E-mail address: [email protected] (Fernanda C.P. Garcia). 0300-5712/$ – see front matter # 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.jdent.2008.12.007

316

journal of dentistry 37 (2009) 315–320

tooth-syringe distance, air-blowing step and the temperature used to evaporate it from the surface.12,13,19–24 Thus, the purpose of this study was to evaluate the effect of different solvent evaporation conditions on the mTBS of four self-etch adhesives to dentine. The null hypothesis tested was that mTBS was not affect by both duration and air-temperature of the drying step for solvent evaporation.

2.

Materials and methods

For this experiment, 64 extracted intact human third molars stored in tap water with a few crystals of thymol at 4 8C were used within 1 month of extraction. Teeth were collected under a protocol approved by the Ethics Committee Board of Bauru School of Dentistry, University of Sa˜o Paulo. Two 2-step self-etch and two 1-step self-etch adhesives were utilized (Table 1).

2.1.

Bonding procedures

Flat dentine surfaces were created on mid-coronal dentine using a slow-speed diamond saw (Isomet, Buehler Ltd., Lake Bluff, IL, USA). The surfaces were polished with wet 500-grit silicon carbide paper to create smear-layer-covered dentine for bonding. The samples were divided into two experimental groups (Table 1). The exposed dentine was rinsed with water and blotted dry with a cotton pellet, leaving a moist surface according to the manufacturer’s directions. All the bonding procedures were carried at a room temperature (23 8C) and

60% relative humidity. In order to evaluate the effects of airdrying time and air-temperature, the teeth of the first group were gently air-dried over 5 s followed by extended periods up to 20 s, 30 s or 40 s with air-temperature maintained at 21 8C. The air-stream was generated by air syringe. The distance that air tips was 2 cm far away from the samples. The temperature degree and constancy of that temperature throughout the blowing time was verified using a digital thermostat. Manufacturers usually recommend 5 s air-drying at 21 8C. The teeth of the second group were treated the same way, except that air-temperature was delivered at 38 8C. For this group, warm air was generated by a specific tooth dryer hand piece (A-dec, Newberg, OR, USA). In brief, the device utilizes pressure to force dry air to pass through a tube into two distinct swirling air streams. The pressure against the swirling system agitates air molecules to generate heat that warms the air that is flown out gently from the tip orifice. The air-temperature at the tip orifice is very high and gradually cools away from the tip. Previous calibration procedures determined that the temperature of the air could be maintained constant at 38 8C at a distance of 2 cm from the tip, at a constant pressure (60 psi). Three teeth were randomly assigned per adhesive and drying combination (temperature  time). Resin build-up ‘‘crowns’’ (Clearfil AP-X, Kuraray Med. Inc., Tokyo, Japan) were handily constructed on the bonded surfaces in increments of 1 mm to a height of 5 mm. Each layer was light cured with a power density of 500 mW/ cm2 (Spectrum 800, Dentsply/De Trey, Milford, USA) for 40 s. The bonded teeth were stored in distilled water at 37 8C for 24 h before being tested.

Table 1 – Chemical formulations of the adhesives applied and manufactures directions. Adhesive systems/batch number Clearfil SE Bond (Kuraray Co. Ltd., Osaka, Japan) (41151)

Protect Bond (Kuraray Co. Ltd., Osaka, Japan) (000001)

Composition Primer: 10-methacryloyloxydecyl dihydrogen phosphate (MDP), 2-hydroxyethyl methacrylate) (HEMA), hydrophilic dimethacrylate, D,L-camphorquinone (CQ), N,N-diethanol-p-toluidine (DET), water, ethanol. Bond: MDP, HEMA, bis-GMA, hydrophobic dimethacrylate, CQ, DET, silanated colloidal silica Primer: methacryloyloxydodecylpyridinium bromide (MDPB), MDP, HEMA, water, photoinitiator. Bond: MDP, HEMA, bis-GMA, hydrophobic dimethacrylate, CQ, DET, silanated colloidal silica.

Adper Prompt-L-Pop (3M ESPE, Seefeld, Germany) (166123)

Red blister: methacrylated phosphoric esters, bis-GMA, Initiators based on camphorquinone, stabilizers. Yellow blister: water, HEMA, polyalkenoic acid, stabilizers.

Xeno III (Dentsply DeTrey, Konstanz, Germany) (0212000852)

Liquid A: HEMA, butylated hydroxy toluene (BHT), highly dispersed silicon dioxide, water and ethanol. Liquid B: (with the highest viscosity): phosphoric acid modified methacrylate resin, mono fluoro phosphazene modified methacrylate resin, UDMA, BHT, camphorquinone (CQ), ethyl-4-dimethylaminobenzoate.

Manufacturers directions a b d g h j a b d g h j c h e i* j f b i* j

a: apply primer; b: leaved undisturbed for 20 s; c: apply active one coat of adhesive for 15 s; d: air-drying was at 5 s, 20 s, 30 s or 40 s at 21 8C or 38 8C*; e: apply passively second coat of adhesive; f: mixture liquid A + B in equal amounts for 5 s and apply generous coats; g: apply bond; h: uniformly bond coat using gently air-dry; i: uniformly bond coat using gently air-dry*; j: light cure for 10 s (500 mW/cm2). *according manufacturers directions.

317

journal of dentistry 37 (2009) 315–320

2.2.

Microtensile bond strength testing

The bonded teeth were longitudinally sectioned in both ‘‘x’’ and ‘‘y’’ directions across the bonded interface using an Isomet saw (Buehler Ltd., Lake Bluff, IL, USA) with crosssectional area of approximately 1 mm2, to obtain an average of 20–25 beams per tooth.22 Each beam was attached to a modified Bencor Multi-T testing apparatus (Danville Engineering Co., Danville, CA, USA) with a cyanoacrylate resin (Zapit Dental Venture of America Inc., Corona, USA) and tested in tension in a universal testing machine (Instron Corporation, Canton, MA, USA) operating at a crosshead speed of 1 mm/ min.22 After testing, the cross-sectional area at the site of fracture was measured with a digital caliper (Stainless, Precision, SA, Barcelona) to permit calculation of bond strengths in megapascal (MPa).

2.3.

Statistical analysis

A two-way analysis of variance ANOVA was used to detect any statistical differences. The Student–Newman–Keuls test was used to analyze differences between the drying time vs. airtemperature. Significance level was set at a = 0.05.

3.

Results

Statistical analysis revealed that there were statistically significant differences and there was interaction between factors drying time and air-temperature for the adhesives tested ( p < 0.05, Table 2). For shorter drying time (5 s), there seems to be less influence of the air-temperature, conversely, when specimens were dried for longer time, there was a tendency that bond strengths were higher at the higher temperature. The bond strength was increased to CSEB and PB when the solvent evaporating step was performed with a warm air-

stream at 20 s of drying time. The application of extended airblowing time to ADPLP not affected the bond strength, however the application of warm temperature significantly favored its performance when 30 s drying time was used. For XIII, the bond strength increased when the air-blowing time was 40 s performed with warm air-dry stream. Overall, the mTBS for adhesive systems were lower when the air-temperature was 21 8C.

4.

Discussion

Nowadays, self-etching systems have been proposed as suitable agents for dentine bonding and appears to be a promising approach for reducing technique sensitivity in dentine bonding. The all-in-one adhesives have reduced the number of steps involved and there are two types of these systems, the two-bottle and one-bottle adhesives. CSE and PB are two-bottle, two-step self-etch adhesives. XIII falls in category of two-bottles while ADPLP is one-bottle system. These systems are generally formulated with hydrophilic and hydrophobic monomers dissolved in solvents such ethanol, acetone and water, or in solvent mixtures.25 The high concentrations of solvent present in some of these systems may compromise polymerization in case of deficient evaporation of the solvents.12 The effects of air-drying on removal of organic solvent and water from adhesive resin has only been investigated recently with self-etch adhesives19,26 and with prepared experimental resin blends.27 Little is known about how much of the solvent is kept within interfacial bond. Such solvent surplus may directly affect the bond integrity, provide pathways for nanoleakage and affect polymerization of the infiltrated monomers.10,14,27,28 The resultant interfacial structures also become more hydrophilic and, thus more prone to hydrolytic degradation.3,6 For that reason, it is essential to remove as much solvent as possible from the surface prior to

Table 2 – Average (S.D.) of bond strength (MPa) for each adhesive according duration and air-temperature of the drying step. Adhesive systems

Air-blowing time (s)

Air-temperature 21 8C

**

CSEB

5* 20 30 40

54.4 (17.4) N = 10A 54.5(10.7) N = 11A 51.8(15.5) N = 12A 37.5(9.9) N = 24B

NS S NS S

51.8(15.1) N = 12B 67.6(16.13) N = 12A 61.5(14.2) N = 12AB 64.6(13.9) N = 10AB

PB

5* 20 30 40

39.7(12.3) 29.3(10.0) 35.3(13.1) 44.1(11.3)

NS S S S

40.2(8.4) N = 12B 50.4(9.7) N = 12A 53.9(7.9) N = 10A 54.6(12.0) N = 12A

ADPLP

5* 20 30 40

28.2(8.1) N = 12A 29.6(14.5) N = 8A 19.0(8.4) N = 9 A 30.9(9.9) N = 10A

NS NS S NS

25.3(13.2) N = 9A 29.0(12.8) N = 10A 30.4(9.8) N = 9A 33.4(8.0) N = 12A

XIII

5* 20 30 40

32.9(17.1) N = 18B 51.8(11.0) N = 10A 18.6(7.9) N = 14C 32.3(16.6) N = 12B

NS NS S S

37.6(14.6) N = 10B 40.3(14.1) N = 9B 38.3(9.9) N = 10B 64.9(14.9) N = 9A

N = 12)AB N = 12B N = 13AB N = 11A

N = number of specimens. Same capital letters indicates no statistically differences for each column ( p > 0.05). Signficance for each line.

**

Air-temperature 388C

318

journal of dentistry 37 (2009) 315–320

cure. Therefore, an adhesive whose bond strength is not heavily reliant on the technique sensitivity related to its application may perform better in clinical situation.19 Since the introduction of self-etching systems, a gently airdry was generally required for removing excess solvent from solution. It is commonly recommended by the manufacturers that gently air-dry should be performed in order to achieve higher bond strength values.19 Thus, this study assessed the influence of the duration and air-temperature of the drying step on solvent evaporation of simplified adhesives on the dentine bond strength. The results showed that both drying time and air-temperature had a significant effect on mTBS. Thus, this requires rejection of the anticipated null hypotheses. Besides the importance of the application method in the resultant bond strength of adhesives, the great variability between the performances of different self-etch adhesives can in part be ascribed to the use of different functional monomers with different properties, regarding acidity, hydrolytic stability and chemical interaction capacity.29,30 As a fact, main variances among the adhesives may be determinant of the extent of water-solvent evaporation of the tested products. These are relative concentration of water/HEMA, presence of photoinitiator compounds in the primer and presence of ethanol.12 In general, prolonged air-drying resulted in higher bond strengths. A possible explanation for the reduced bond strength observed with shorter drying times is that residual solvents such water and ethanol may act as inhibitors to monomer penetration and polymerization.8,11,20,23 It has been demonstrated that the relationship between solvent concentration in the adhesive and degree of cure is not direct.31 That means that, depending on the solvent, the degree of cure is not the highest at the lowest concentration in the adhesive resin mixture, indicating that some residual solvent is required for improved conversion. This is particularly true for ethanolcontaining adhesives, such as the ones evaluated in this study. This ideal amount of solvent is suggested to be rather low (ca. less than 10%) and was achieved by purposely incorporating the desired amount of solvent in the adhesive, and not calculated as a residue from the evaporation. If one assumes that residual solvent in the mixture impairing the cure caused the reduced bond strength observed in this study, then it has to be considered that the residual amount was probably higher than the ideal for optimizing the cure. A recent study demonstrated that the addition of 30% ethanol in experimental adhesive resin blends was responsible for the highest degree of conversion. In the same study, the addition of 50% ethanol resulted in compromised cure of the resin blends.32 Conversely, excessive air-drying also resulted in reduced bond strength for PB and XIII, which may indicate that the solvent was then evaporated beyond the ideal, residual concentration that could optimize the cure. On the other hand, excessive airdrying may cause excessive air thinning of the adhesive, and this might partially negate its effectiveness. Additionally, it is possible that remaining adhesive becomes saturated with the oxygen that could in turn inhibit its polymerization.20 Thus, excessive air-drying might lead to an extremely thin adhesive layer, than is not preferred, as it could act less as ‘‘stress breaker’’ at the adhesive interface.33 From the bond strength perspective, temperature increase during air-drying seemed to have a dominant effect on the

outcomes. The increase in air-temperature from 21 8C to 38 8C resulted in significant increases in bond strength for most of the adhesives. This support the concept that using warm air will facilitate and expedite solvent evaporation and the benefits of that can be achieved with a shorter evaporation time. The materials investigated in this study presented different behavior regarding the effects of time and temperature of the air-drying procedure (Table 2). The explanation for these findings must be found in the complex mixture of both hydrophobic and hydrophilic components, dissolved in organic solvents. In particular, the high concentrations of water have raised questions about potentially harmful effects on polymerization given incomplete water removal is realistic.11 This also applies for the high concentrations of solvent that may cause incomplete resin polymerization in case of incomplete evaporation.12 As a fact, more recently, complex process of phase separation have been shown to occur in one-component HEMA-free one-step self-etch adhesives.26 On the other hands, very strong air-drying the phase-separated adhesive might be a clinical technique for removing substantial interfacial water, thereby improving bonding effectiveness.26 ADPLP represents a category of strong one-step self-etch adhesive (pH  1),34 with morphological aspect of dentineadhesive interfaces similar to that produced by etch- and rinse adhesives.3 According to ours findings, ADPLP did not show significant differences in mTBS under different solvent evaporation conditions, since that there was not an influence of drying time on bond strength. This is corroborated with the recent finding that there was no difference for mTBS between the gently and strong air-blowed samples for this adhesive.19 There is an important difference in the manufacturer’s recommendations with respect to how this adhesive is applied on tooth substrate. ADPLP was continuously agitated during application in this study. Agitation of adhesive probably carries in fresh acidic monomers to effectuate a more aggressive demineralization of the basal part of etched dentine.35 Therefore, the continuous agitation of adhesive placed on the dentine surface could enhance the solvent evaporation; improving monomer diffusion.31 It is speculated when agitation of adhesive is used, water is evaporated more quickly, leading a diffusion of the amphiphilic monomer into collagen mesh. However, the bond strength at 30 s air-blowing at low temperature was lower compared to the air-warm temperature. XIII represents a category of strong one-step self-etch adhesive (pH 1).34 Despite the similarity of the acidity with ADPLP, XIII application protocol is different. The mixture is applied and left undisturbed on tooth surface. A difference between XIII and the other adhesives used in this study was that it contains ethanol as a solvent. In this study, this means that air-drying duration and warm temperature significantly influences the evaporation of primer components. This finding is corroborated by recent study in which its adhesive shows the highest extent of evaporation after extend period of air-blowing at warm temperature.12 This helps to explain why the extended drying time would facilitate the residual water evaporation; improving polymerization due to less solvent interference during cure and which improve bond strength.12

journal of dentistry 37 (2009) 315–320

CSEB and PB are a category of a mild two-step self-etch adhesives (pH  2).34 Regarding CSEB and PB, the manufacturer did not specify the air-drying time for the primer. As the solvent of the primer is water, a relatively longer air-drying time seemed necessary to evaporate enough solvent and increase bond strength. As a fact, 20 s seemed to be sufficient to get maximum bonding performance for these systems at 38 8C. This means that duration and air-temperature significantly influences the evaporation of its primers components. Our finding is corroborated by another study in that the prolonged air-drying time resulted in enhanced evaporation of primer components for CSEB and consequently higher mTBS was observed when the primer components were sufficiently evaporated.10,36 Maybe this noticeable stability is related to the composition of these adhesives.37 The functional monomer 10-methacryloyloxydecyl dihydrogen phosphate (MDP) appeared not only to interact most intensively with hydroxyapatite within a clinical reasonable time, but also to have the hydrolytically most stable bond with calcium.4 This chemical bond at the interface may contribute to the stability of the adhesive bond and probably explain these results.

7.

8.

9.

10.

11. 12.

13.

14.

5.

Conclusion

The anticipated null hypothesis was partially rejected. The data suggests that the duration and air-temperature of drying step affected the bond strength of the adhesives tested. In general, temperature increase was dominant towards the effect of the drying step for improved bonding efficacy of selfetching systems.

15.

16.

17.

18.

Acknowledgement This study was partially supported by grants CNPq 300481/95-0 e 474226/03-4; Kuraray, Japan; 01/0610-1 from FAPESP, Brazil to FCPM and #MAT 2008-0234/MAT FROM CICYT FEDER.

references

19.

20.

21. 1. Nakabayshi N, Pashley DH. Hybridization of dental hard tissues. Tokyo, Japan: Quintessence; 1998. 2. Hashimoto M, Ohno H, Sano H, Tay FR, Kaga M, Kudou Y, et al. Micromorphological changes in resin-dentine bonds after 1 year of water storage. Journal of Biomedical Material Research Applied Biomaterial 2002;63:306–11. 3. Van Meerbeek B, De Munck J, Yoshida Y, Inoue S, Vargas M, Vijay P, et al. Adhesion to enamel and dentine: current status and future challenges. Operative Dentistry 2003;28:215–35. 4. Yoshida Y, Nagakane K, Fukuda R, Nakayama Y, Okazaki M, Shintani H, et al. Comparative study on adhesive performance of functional monomers. Journal of Dental Research 2004;83:454–8. 5. Peumans M, Kanumilli P, De Munck J, Van Landuyt K, Lambrechts P, Van Meerbeek B. Clinical effectiveness of contemporary adhesives: a systematic review of current clinical trials. Dental Materials 2005;21:864–81. 6. Tay FR, King NM, Chan KM, Pashley DH. How can nanoleakage occur in self-etching adhesive systems that

22.

23.

24.

25.

26.

319

desmineralize and infiltrate simultaneously? Journal Adhesive Dentistry 2002;4:255–9. Hotta M, Kondoh K, Kamemizu H. Effect of primers on bonding agent polymerization. Journal of Oral Rehabilitation 1998;25:792–9. Paul SJ, Leach M, Rueggeberg FA, Pashley DH. Effect of water content on the physical properties of model dentine primer and bonding resins. Journal of Dentistry 1999;27:209–14. Carrilho MR, Carvalho RM, Tay FR, Pashley DH. Effects of storage media on mechanical properties of adhesive systems. American Journal of Dentistry 2004;17:104–8. Ikeda T, De Munck J, Shirai K, Hikita K, Inoue S, Sano H, et al. Effect of evaporation of primer components on ultimate tensile strengths of primer-adhesive mixture. Dental Materials 2005;21:1051–8. Jacobsen T, So¨derholm KJ. Some effects of water on dentine bonding. Dental Materials 1995;11:132–6. Nunes TG, Garcia FCP, Osorio R, Carvalho RM, Toledano M. Polymerization Efficacy of Simplified Adhesive Systems studied by NMR and MRI techniques. Dental Materials 2006;22:963–72. Cardoso PC, Loguercio AD, Vieira LC, Baratieri LN, Reis A. Effect of prolonged application times on resin-dentine bond strengths. Journal Adhesive Dentistry 2005;7:143–9. Wang Y, Spencer P. Hybridization efficiency of the adhesive/ dentine interface with wet bonding. Journal of Dental Research 2003;82:141–5. Hashimoto M, de Munck J, Ito S, Ohno H, Sano H, Kaga M, et al. In vitro effect of nanoleakage expression on resindentine bond strengths analyzed by microtensile bond test, SEM/EDX and TEM. Biomaterials 2004;25:5565–74. Hashimoto M, Tay FR, Svizero NR, de Gee AJ, Feilzer AJ, Sano H, et al. The effect of common errors on sealing ability of total-etch adhesives. Dental Materials 2006;22:560–8. Sano H, Kanemura N, Burrow MF, Inai N, Yamada T, Tagami J. Effect of operator variability on dentine adhesion: students vs. dentists. Dental Materials Journal 1998;17:51–8. Dickens SH, Cho BH. Interpretation of bond failure through conversion and residual solvent measurements and Weibull analyses of flexural and microtensile bond strengths of bonding agents. Dental Materials 2005;21:354–64. Spreafico D, Stefano S, Dario M, Dino R, Massimo G, Toru T, et al. The effect of the air-blowing step on the technique sensitivity of four different adhesive systems. Journal of Dentistry 2006;34:237–44. Miyazaki M, Platt JA, Onose H, Moore BK. Influence of dentine primer application methods on dentine bond strength. Operative Dentistry 1996;21:167–72. Kanca III J. Effect of primer dwell time on dentine bond strength. General Dentistry 1998;46:608–12. Pashley DH, Carvalho RM, Sano H, Nakagima M, Yoshiama M, Shono Y, et al. The microtensile bond test: a review. Journal Adhesive Dentistry 1999;1:299–309. Miyazaki M, Hirohata N, Takagaki K, Onose H, Moore BK. Influence of self-etching primer drying time on enamel bond strength of resin composites. Journal of Dentistry 1999;27:203–7. Balkenhol M, Huang J, Wo¨stmann B, Hannig M. Influence of solvent type in experimental dentine primer on the marginal adaptation of Class V restorations. Journal of Dentistry 2007;35(4):836–44. Nunes MF, Swift EJ, Perdiga˜o J. Effects of adhesive composition on microtensile bond strength to human dentine. American Journal of Dentistry 2001;14:340–3. Van Landuyt KL, De Munck J, Snauwaert J, Coutinho E, Poitevin A, Yoshida Y, et al. Monomer-solvent phase separation in one-step self-etch adhesives. Journal of Dental Research 2005;84:183–8.

320

journal of dentistry 37 (2009) 315–320

´ iu CKY, Pashley EL, Hiraishi N, King NM, Goracci C, Ferrari 27. Y M, et al. Solvent and water retention in dental adhesive blends after evaporation. Biomaterials 2005;26:6863–72. 28. Shono Y, Terashita M, Shimada J, Kozono Y, Carvalho RM, Russel CM, et al. Durability of resin–dentine bonds. Journal Adhesive Dentistry 1999;1:211–8. 29. Van Meerbeek B, Van Landuyt K, De Munck J, Hashimoto M, Peumans M, Lambrechts P, et al. Technique sensitivity of contemporary adhesives. Dental Materials Journal 2005;24: 1–13. 30. Reis A, Louguercio AD, Azevedo CLN, Carvalho RM, Singer JM, Grande RHM. Moisture spectrum of demineralized dentine for adhesive systems with different solvent bases. Journal Adhesive Dentistry 2003;5:183–92. 31. Jacobsen T, So¨derholm KJ. Effect of primer solvent, primer agitation, and dentine dryness on shear bond strength to dentine. American Journal of Dentistry 1998;11: 225–8. 32. Cadenaro M, Breschi L, Antoniolli F, Navarra CO, Mazzoni A, Tay FR, et al. Degree of conversion of resin blends in relation to ethanol content and hydrophilicity. Dental Materials 2008;24:1194–200.

33. Van Meerbeek B, Vargas M, Inoue S, Yoshida Y, Peumans M, Lambrechts P, et al. Adhesive and cements to promote preservation dentistry. Operative Dentistry 2001;6:119–44. 34. Inoue S, Van Meerbeek B, Vargas M, Yoshida Y, Lambrechts P, Vanherle G. Adhesion mechanism of self-etching adhesives. In: Tagami J, Toledano M, Prati C, editors. Proceedings of conference on: Advanced Adhesive Dentistry. Third International Kuraray Symposium. Cirimido, Italy: Grafiche Erredue; 2000. p. 131–48. 35. Carvalho RM, Chersoni S, Frankenberger R, Pashley DH, Prati C, Tay FR. A challenge to the conventional wisdom that simultaneous etching and resin infiltration always occurs in self-etch adhesives. Biomaterials 2005;26:1035–42. 36. Klein-Ju´nior CA, Zander-Grande C, Amaral R, Stanislawczuk R, Garcia EJ, Baumhardt-Neto R, et al. Evaporating solvents with a warm air-stream: effects on adhesive layer properties and resin–dentine bond strengths. Journal of Dentistry 2008;36:618–25. 37. Holmes RG, Rueggeberg FA, Callan RS, Caughman F, Chan DC, Pashley DH, et al. Effect of solvent type and content on monomer conversion of a model resin system as a thin film. Dental Materials 2007;23:1506–12.