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Biomaterials & Bioengineering

Changes in Resin-infiltrated Dentin Stiffness after Water Storage

S. Chiaraputt1, S. Mai2, B.P. Huffman3, R. Kapur3, K.A. Agee3, C.K.Y. Yiu4, D.C.N. Chan5, C. Harnirattisai6, D.D. Arola7, F.A. Rueggeberg5, D.H. Pashley3 and F.R. Tay3,*

1 Faculty of Dentistry, Srinakharinwirot University, Thailand;
2 Guanghua School of Stomatology & Institute of Stomatological Research, Sun Yatsen University, Guangzhou, China;
3 Department of Oral Biology and
5 Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, GA 30912-1129, USA;
4 Pediatric Dentistry and Orthodontics, University of Hong Kong, Hong Kong SAR, China;
6 Department of Operative Dentistry, Faculty of Dentistry, Mahidol University, Thailand; and
7 Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, MD, USA

Correspondence: * corresponding author, ftay{at}mail.mcg.edu


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS & METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Plasticization of polymers by water sorption lowers their mechanical properties in a manner that is predictable by the polarity of their component resins. This study tested the hypothesis that when adhesive resins were used to create resin-infiltrated dentin, the reductions in their flexural moduli after water storage would be lowered proportional to their hydrophilic characteristics. Three increasingly hydrophilic resin blends were used to fabricate polymer beams and macro-hybrid layer models of resin-infiltrated dentin for testing with a miniature three-point flexure device, before and after 1–4 weeks of water storage. Flexural modulus reductions in macro-hybrid layers were related to, and more extensive than, reductions in the corresponding polymer beams. Macro-hybrid layers that were more hydrophilic exhibited higher percent reductions in flexural modulus, with the rate of reduction proportional to the Hoy’s solubility parameters for total intermolecular attraction forces ({delta}t) and polar forces ({delta}p) of the macro-hybrid layers.

Key Words: water • hydrophilicity • solubility parameter • macro-hybrid layer • flexural modulus


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS & METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
As contemporary dentin adhesive resins are rendered more hydrophilic, they become more prone to water sorption (Unemori et al., 2003; Malacarne et al., 2006; Yiu et al., 2006). Increase in water sorption expedites the plasticization of these polymer matrices, undermines their thermomechanical and hydrolytic stability, and contributes to the reduction of service lives of resin-dentin bonds (Tanaka et al., 1999; Ferracane, 2006). Thus, an experimental ethanol wet-bonding technique was recently introduced for coaxing comparatively hydrophobic resins to acid-etched dentin (Nishitani et al., 2006; Pashley et al., 2007; Sadek et al., 2007). When the composition and fractional contributions of the resinous components are known, solubility parameter theory has been shown to be a reliable predictor of water sorption behavior and water-induced deterioration of mechanical properties in neat resin mixtures with increasingly hydrophilic characteristics (Yiu et al., 2004; Ito et al., 2005; Nishitani et al., 2007). These findings serve as models for predicting the long-term performance of adhesive layers that couple resin composites to the underlying resin-infiltrated dentin. However, the direct relationship between resin hydrophilicity and water-induced changes in the mechanical properties of resin-infiltrated dentin is less well-characterized (Sano et al., 1995).

Nanoindentation of resin-dentin interfaces provides valuable information on the mechanical properties of separate interfacial components, such as hybrid layers and resin tags (Van Meerbeek et al., 1993; Schulze et al., 2005), but not on the bulk mechanical properties of resin-infiltrated dentin that contains these two interfacial components. A macro-hybrid layer model, created from 200-µm-thick disks of mid-coronal dentin, has been developed for the quantification of matrix shrinkage and resin uptake during solvent evaporation and resin infiltration (Agee et al., 2006; Becker et al., 2007; Pashley et al., 2007). It is anticipated that flexural testing of "idealized" macro-hybrid layers prepared from optimally resin-infiltrated demineralized dentin should provide information that serves as a predictor of how resin hydrophilicity affects water-induced changes in the flexural modulus of resin-infiltrated dentin. Thus, the objectives of this study were to test the null hypotheses that: (1) there is no correlation between changes in flexural modulus of polymer beams and macro-hybrid layers prepared from these resins after water storage; and (2) resin hydrophilicity has no effect on the changes in flexural modulus of macro-hybrid layers after water storage.


   MATERIALS & METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS & METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Model Resin Blends
Three unfilled light-curable resin blends (Resins A–C) with known compositions and concentrations were formulated and ranked in an increasing order of hydrophilicity based on their solubility parameters (TableGo). These model resins represent experimental non-solvated versions of dentin adhesives (Pashley et al., 2007). Resin A is similar to the comparatively hydrophobic bonding resin components in three-step etch-and-rinse adhesives. The ethanol-solvated version of Resin A has also been used as the primer component in the experimental ethanol wet-bonding technique. Resin B is relatively hydrophilic and is representative of the major composition of two-step etch-and-rinse adhesives. Resin C contains a bifunctional methacrylate derivative of phosphoric acid and, being very hydrophilic, is similar to one-step self-etch adhesives. The Hoy’s component solubility parameters for dispersion forces ({delta}d), polar forces ({delta}p), and hydrogen bonding ({delta}h), and the solubility parameter for total intermolecular attraction forces ({delta}t) of each resin blend were calculated by summing the molar attraction constants of its chemical components (Computer Chemistry Consultancy, Singen-Friedingen, Germany).


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  		Table. Composition of Experimental Dental Adhesive Neat Resin Blends with Increasing Hydrophilicity, Their Hoy’s Solubility Parameters after Polymerization, Degrees of Conversion, and Flexural Properties Determined under 24-hour Dry Conditions are Presented in the Upper Part of the Table. Macro-hybrid Layers of Demineralized Dentin Infiltrated with These Resins, Their Hoy’s Solubility Parameters after Resin Polymerization, and Their 24-hour Dry Flexural Modulus before Water Storage are Shown in the Bottom Part of the Table.
 
Curing Properties
The curing characteristics of the model resin blends were assessed by Fourier transform infrared spectroscopy (FTIR) according to the methods described by Daronch et al.(2006) (Appendix), to ensure that changes in flexural modulus after water storage were not caused by a lower extent of cure due to the inclusion of hydrophilic and ionic resin monomers. Percent monomer conversion was determined by comparison of changes in the ratios of aliphatic (1638 cm–1)-to-aromatic (1608 cm–1) C=C absorption peaks in the uncured and cured states. We obtained conversion rate by calculating the derivative of real-time conversion from the conversion-time curve.

Polymer Beams and Macro-hybrid Layers
Twenty-four 7 (length) x 3 (width) x 0.3 (depth) mm polymer beams and 15 macro-hybrid layers of the same dimensions were prepared from each resin blend (Appendix). Human third molars used to prepare the macro-hybrid layers were collected after the individuals’ informed consent was received under a protocol approved by the MCG Human Assurance Committee. Each macro-hybrid layer was derived from the center of a mid-coronal dentin disk to ensure that dentinal tubules were oriented parallel to the plane of maximum stress during three-point flexure (Arola and Reprogel, 2006). Prior to resin infiltration, the dentin was completely demineralized in 0.5 M EDTA containing protease inhibitors to prevent collagen degradation (Pashley et al., 2004). Since macro-hybrid layers were much thicker than authentic hybrid layers created during clinical bonding, a prolonged ethanol wet-bonding protocol was used to optimize resin infiltration (Sadek et al., 2008). Sectioning/polishing after resin polymerization was performed with a non-aqueous silicone fluid (DC200 Fluid-10 centiStokes, Dow-Corning Corp., Midland, MI, USA) as the coolant/lubricant, to prevent water sorption by hydrophilic resin components prior to mechanical testing (Hosaka et al., 2007). Specimens were stored in air for 24 hrs before being tested. The Hoy’s solubility parameters for the macro-hybrid layers (TableGo) were estimated by assuming 70% resin and 30% collagen peptide content (Pashley, unpublished observations), with a fractional contribution algorithm (Agee et al., 2006) based on the amino acid composition of dentin collagen (Miller et al., 1998).

Three-point Flexure
Flexural testing was performed with a miniature three-point flexure device (Fig. 1AGo). We first determined the flexural properties of the 3 neat resins (N = 12) by centrally loading the polymer beams to fracture using a universal tesing machine (Vitrodyne V100, Liveco Inc., Burlington, VT, USA) at a crosshead speed of 1 mm/min. Stress-strain curves were prepared from the load-displacement data (Appendix), from which the flexural modulus, flexural strength, and energy at rupture were determined by means of a statistics/curve-fitting software (Prism 5, GraphPad, San Diego, CA, USA). We examined both polymer beams and macro-hybrid layers (N = 12) after 1–4 weeks’ water storage by loading them to 2% strain (Appendix) in de-ionized water (Fig. 1BGo), to obtain the respective flexural moduli before and after different water storage periods.


Figure 1
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  		Figure 1. Three-point flexure. A schematic showing the miniature three-point flexure device consisting of a supporting base with a 5-mm span and a loading piston milled from aluminum blocks. The diameter for both supports and the loading piston was 1 mm. The supporting base was fixed with cyanoacrylate glue to a glass Petri dish, which in turn was attached to a metal fixture. This design enabled testing to be performed in either air or a liquid medium. Both polymer beams and macro-hybrid layers were prepared to 0.30 ± 0.01 mm thick, to establish a span-to-depth ratio of approximately 16:1, to minimize shear and local deformation effects during three-point flexure (Mujika, 2007). (B) A schematic depicting three-point flexure of the polymer beams and macro-hybrid layers to 2% strain in water during the repeated flexure part of the experiment. These schematics are not drawn to scale.

 
Statistical Analyses
All data were examined for normality and homoscedasticity before the use of parametric statistical methods. Flexural properties of polymer beams determined under dry conditions were analyzed by one-way ANOVA and Tukey’s multiple comparison tests. The flexural modulus of each polymer beam and macro-hybrid layer group obtained after different periods of water storage were separately analyzed with one-way repeated-measures ANOVA and Tukey’s tests. The data were further normalized as percent changes of the respective baseline modulus. Correlation between the percent changes in flexural modulus of the polymer beams and macro-hybrid layers during the 4 wks of water storage was performed by Pearson’s product-moment analysis. The percent change data for the 3 macro-hybrid layer groups were further analyzed with non-linear regression to determine if the results could be represented by a global model, from which the half-lives (i.e., rate of reduction) of the maximum expected changes in the flexural modulus of the macro-hybrid layers were determined. We then used regression analyses to examine the relationship between these half-lives and their Hoy’s solubility parameters. For all analyses, statistical significance was pre-set at {alpha} = 0.05.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS & METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Resin C, the most hydrophilic resin blend, exhibited the highest degree of conversion (Fig. 2AGo; TableGo), although it took slightly longer to polymerize kinetically (Fig. 2BGo). Thus, its lower flexural properties (p < 0.05; TableGo) were not caused by a lower extent of cure. All polymer beams revealed plastic deformation beyond 2% strain (Fig. 2CGo). Before water storage, macro-hybrid layers that were loaded beyond 2% strain exhibited residual strains after being unloaded (Fig. 2DGo). Thus, flexure of both polymer beams and macro-hybrid layers in the subsequent water storage experiments was conducted at 2% strain.


Figure 2
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  		Figure 2. Degree of conversion and stress-strain curves. Superimposition of FTIR results on the degree of conversion, and (B) conversion rate of the 3 experimental neat resin blends with increasing hydrophilic characteristics. Results represent the mean of 5 readings for each resin blend. (C) Representative stress-strain curves of the 3 polymerized neat resin beams that were stressed to failure under dry condition. (D) A representative stress-strain curve of a macro-hybrid layer fabricated with Resin A that was stressed to 3% strain under dry conditions before being unloaded. Plastic deformation resulted in the exhibition of a residual strain after unloading. Similar results were observed for the other two resin blends (not shown). Thus, subsequent experiments on repeated flexure of the macro-hybrid layers after water storage were conducted at 2% strain.

 
The baseline flexural moduli of macro-hybrid layers are included in the TableGo. There were no significant changes in the flexural modulus of polymer beams and macro-hybrid layers of Resins A and B after the 3rd wk of water storage, and of Resin C after the 2nd wk of water storage (Fig. 3AGo). The normalized percent reductions in flexural modulus of macro-hybrid layers were all higher than those of the respective neat resins, with a significant positive correlation between the two groups of results (p < 0.001). The percent reductions in flexural modulus of the 3 macro-hybrid layers were consistent with the global model of one-phase exponential association (Fig. 3BGo). Linear regression of the half-lives for percent reduction in flexural modulus and the solubility parameters of the macro-hybrid layers revealed significant negative correlations between half-lives and {delta}p [p = 0.042] and {delta}t [p = 0.019] (Fig. 3CGo).


Figure 3
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  		Figure 3. Regressions and correlations. (A) Pearson’s correlation between the mean percent decrease in flexural modulus of the polymer beams (N = 12; horizontal standard deviations) and that of the macro-hybrid layers (N = 12; vertical standard deviations) after 1–4 wks of water storage. Dotted lines: 95% confidence intervals. Reductions in the flexural modulus of the macro-hybrid layers after water storage tend to reflect the neat resins from which they were prepared, with the reductions being more extensive in the resin-infiltrated dentin than in the polymerized resins. (B) The percent decreases in flexural modulus of the macro-hybrid layers after 4 wks of water storage were consistent with a one-phase exponential association model: Y = Ymax*[1–exp(-KX)], where Ymax represents the maximum anticipated percent reduction in flexural modulus for a particular macro-hybrid layer, and K is a rate constant. The half-lives [ln(2)/K] shown along the X axis represent the times required for the flexural modulus of these macro-hybrid layers to drop to half of their maximum anticipated percent changes in flexural modulus. (C) Linear regression analyses of the half-lives of macro-hybrid layers vs. their Hoy’s solubility parameters for polar forces ({delta}p) and total intermolecular attraction forces ({delta}t). As adhesive resin blends are rendered increasingly hydrophilic, the percent reductions in the stiffness of the corresponding resin-dentin interfaces become more extensive after water storage. The rate of reduction in the flexural modulus also significantly increases in a manner that is proportional to the overall hydrophilicity of the respective resin-dentin interfaces and, specifically, to the polarity of these interfaces.

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS & METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
The use of a macro-hybrid layer model is not as unrealistic as it may seem, since clinicians are routinely faced with the challenge of bonding to caries-affected dentin with several-hundred-micrometer-thick zones of partially demineralized dentin (Wang et al., 2007). The correlation between the percent changes in flexural modulus of polymer beams and macro-hybrid layers after water storage requires rejection of the first null hypothesis. Although reduction in mechanical properties of resin-infiltrated demineralized collagen matrices reflects those of the resin blends that were used to infiltrate these matrices, the reductions were more extensive in the former. This phenomenon may be explained by the presence of two parallel water transport processes–diffusion through the polymer matrix, and through a network of micro-channels along the polymer-fiber interface (Tsenoglou et al., 2006). The latter process is responsible for rapid conveying of water molecules to the interior of a fiber-polymer composite. Water sorption is more detrimental to the mechanical properties of a fiber-polymer composite than to those of a neat unfilled polymer (Lassila et al., 2002), since water not only interacts physically (i.e., plasticization) and chemically (i.e., hydrolysis) with the polymer matrix, but also damages the boundary interface by forming microcracks that act as nanoscopic water reservoirs.

The half-lives of the percent reduction in the flexural modulus of macro-hybrid layers were inversely related to the total cohesive energy derived from intermolecular attraction forces ({delta}t) in the respective resin polymers, and, specifically, to the energy derived from polar attraction forces ({delta}p). Thus, the second null hypothesis—that resin hydrophilicity has no effect on the changes in flexural modulus of macro-hybrid layers after water storage—has to be rejected. It is prudent to point out that the results from this study were generated under two opposing "idealized" and "taxing" conditions that were far removed from clinical practice. On the one hand, a prolonged resin infiltration protocol approximating those used in soft-tissue resin embedding was used to create "idealized" macro-hybrid layers. Optimal resin infiltration within these macro-hybrid layers was confirmed in a pilot study with silver nitrate challenge and transmission electron microscopy. Protease inhibitors were also included in the demineralizing fluid. These precautionary measures were incorporated into the experimental design to avoid introducing parameters such as differential resin diffusivity and degradation of incompletely infiltrated collagen matrices, which might complicate the interpretation of the results. In contrast, the macro-hybrid layers were challenged by having all their external surfaces exposed to water. Under such a taxing condition, expedited water sorption should result in a more rapid decline in their flexural moduli. For macro-hybrid layers fabricated with Resin A, the least hydrophilic resin blend, the mean flexural modulus was reduced by 28% after the first wk and by 41% after the fourth wk of water storage. For Resin C, the most hydrophilic resin blend, the drop in modulus was 62% after the first wk and 66% after the fourth wk. Clinically, resin-infiltrated dentin is covered by the overlying adhesive layer and resin composite, and by the underlying mineralized dentin, which would greatly limit the rate and extent of water sorption. Only when gaps are present along the bonded interface should such rapid declines in the stiffness of resin-infiltrated dentin be expected. Thus, the numerical data of this study should not be literally translated to a clinical setting. Rather, the philosophic connotation of our in vitro modeling is that the advantages offered by increasingly hydrophilic adhesive systems will ultimately be compromised by both the greater extent and the more rapid rate of decline in the mechanical properties of resin-dentin interfaces created with these resins.

A uni-axial flexure test was adopted for the testing of both polymer beams and macro-hybrid layers in lieu of the piston-on-well type of bi-axial flexure design used previously (Ito et al., 2005) for the testing of polymer beams. This is due to the frequent cracking of circular macro-hybrid layers when 6-mm-diameter specimens were tested under biaxial loading. This rendered the use of this less-flexible design unrealistic for repeated flexure evaluations of macro-hybrid layers. Likewise, preparation of 9-mm-diameter circular macro-hybrid layers also met with difficulties, since enamel was frequently encountered along the circumference of a dentin disk. The miniature three-point flexure test was designed with the intention of testing smaller dentin beams that contain a more homogeneous orientation of the dentinal tubules. It was modified by reducing the original 25-mm span length in the ISO 4049 standard for three-point flexure to a shorter span length of 5 mm, to permit creation of 7-mm-long beams of human coronal dentin. This reduction in span length also eliminated the need for the use of overlapping irradiation, which creates residual stresses when a long resin beam is polymerized sequentially at different locations (Palin et al., 2005). Since our flexural moduli are similar to published values, the shortened span length, adjusted to a specimen thickness of 0.32 mm, seemed to give accurate results.

The stress-strain curves of polymer beams and macro-hybrid layers appeared to be characteristic of materials exhibiting viscoelastic/viscoplastic behavior. Considering that the elastic modulus of resin-infiltrated dentin (1.8–3.4 GPa) is much lower than that of mineralized dentin (ca. 14–19 GPa) (Van Meerbeek et al., 1993; Schulze et al., 2005), these biologic composites are unlikely to fail by crack initiation and propagation under the load range experienced during masticatory function. However, since the elastic moduli of resin-infiltrated dentin continue to drop via slow water sorption during intra-oral function, it is likely that these structures will develop time-dependent, high creep strains that eventually result in failure of the resin-dentin interfaces. This hypothesis is supported by the results of a recent microscopic moiré interferometry study (Wood et al., 2008) that demonstrated relatively large microstrains (ca. 6000 µ{varepsilon}) across resin-dentin interfaces when they were subjected to clinically relevant stresses. Since the microscopic nature of these interfaces precludes measurement of changes in their mechanical properties during cyclic fatigue, further studies of the time-dependent properties of resin-dentin interfaces, such as creep, stress relaxation, and dynamic (sinusoidal) loading, should be performed with the macro-hybrid layer model.


   ACKNOWLEDGMENTS
 
The authors thank Bisco Inc. for preparing the 3 experimental resin blends used in this study and Michelle Barnes for secretarial support. This work was supported by the MCG Dental Research Center and by NIDCR Grant DE04911 (P.I. David Pashley).


   FOOTNOTES
 
A supplemental appendix to this article is published electronically only at http://jdr.iadrjournals.org/cgi/content/full/87/7/655/DC1.

Received for publication December 29, 2007. Revision received February 27, 2008. Accepted for publication March 17, 2008.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS & METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  • Agee KA, Becker TD, Joyce AJ, Rueggeberg FA, Borke JL, Waller JL, et al. (2006). Net expansion of dried demineralized dentin matrix produced by monomer/alcohol saturation and solvent evaporation. J Biomed Mater Res A 79:349–358.[Medline] [Order article via Infotrieve]
  • Arola DD, Reprogel RK (2006). Tubule orientation and the fatigue strength of human dentin. Biomaterials 27:2131–2140.
  • Becker TD, Agee KA, Joyce AP, Rueggeberg FA, Borke JL, Waller JL, et al. (2007). Infiltration/evaporation-induced shrinkage of demineralized dentin by solvated model adhesives. J Biomed Mater Res B Appl Biomater 80:156–165.[Medline] [Order article via Infotrieve]
  • Daronch M, Rueggeberg FA, De Goes MF, Giudici R (2006). Polymerization kinetics of pre-heated composite. J Dent Res 85:38–43.
  • Ferracane JL (2006). Hygroscopic and hydrolytic effects in dental polymer networks. Dent Mater 22:211–222.[Medline] [Order article via Infotrieve]
  • Hosaka K, Tagami J, Nishitani Y, Yoshiyama M, Carrilho M, Tay FR, et al. (2007). Effect of wet vs. dry testing on the mechanical properties of hydrophilic self-etching primer polymers. Eur J Oral Sci 115:239–245.[Medline] [Order article via Infotrieve]
  • Ito S, Hashimoto M, Wadgaonkar B, Svizero N, Carvalho RM, Yiu C, et al. (2005). Effects of resin hydrophilicity on water sorption and changes in modulus of elasticity. Biomaterials 26:6449–6459.[CrossRef][Medline] [Order article via Infotrieve]
  • Lassila LVJ, Nohrström T, Vallittu PK (2002). The influence of short-term water storage on the flexural properties of unidirectional glass fiber-reinforced composites. Biomaterials 23:2221–2229.
  • Malacarne J, Carvalho RM, de Goes MF, Svizero N, Pashley DH, Tay FR, et al. (2006). Water sorption/solubility of dental adhesive resins. Dent Mater 22:973–980.[CrossRef][Medline] [Order article via Infotrieve]
  • Miller RG, Bowles CQ, Chappelow CC, Eick JD (1998). Application of solubility parameter theory to dentin-bonding systems and adhesive strength correlations. J Biomed Mater Res 41:237–243.[CrossRef][Medline] [Order article via Infotrieve]
  • Mujika F (2007). On the effect of shear and local deformation in three-point bending tests. Polym Test 26:869–877.
  • Nishitani Y, Yoshiyama M, Donnelly AM, Agee KA, Sword J, Tay FR, et al. (2006). Effects of resin hydrophilicity on dentin bond strength. J Dent Res 85:1016–1021.
  • Nishitani Y, Yoshiyama M, Hosaka K, Tagami J, Donnelly A, Carrilho M, et al. (2007). Use of Hoy’s solubility parameters to predict water sorption/solubility of experimental primers and adhesives. Eur J Oral Sci 115:81–86.[Medline] [Order article via Infotrieve]
  • Palin WM, Fleming GJ, Marquis PM (2005). The reliability of standardized flexure strength testing procedures for a light-activated resin-based composite. Dent Mater 21:911–919.[Medline] [Order article via Infotrieve]
  • Pashley DH, Tay FR, Yiu C, Hashimoto M, Breschi L, Carvalho RM, et al. (2004). Collagen degradation by host-derived enzymes during aging. J Dent Res 83:216–221.
  • Pashley DH, Tay FR, Carvalho RM, Rueggeberg FA, Agee KA, Carrilho M, et al. (2007). From dry bonding to water-wet bonding to ethanol-wet bonding. A review of the interactions between dentin matrix and solvated resins using a macromodel of the hybrid layer. Am J Dent 20:7–20.[Medline] [Order article via Infotrieve]
  • Sadek FT, Pashley DH, Ferrari M, Tay FR (2007). Tubular occlusion optimizes bonding of hydrophobic resins to dentin. J Dent Res 86:524–528.
  • Sadek FT, Pashley DH, Nishitani Y, Carrilho MR, Donnelly A, Ferrari M, et al. (2008). Application of hydrophobic resin adhesives to acid-etched dentin with an alternative wet bonding technique. J Biomed Mater Res A 84:19–29.[Medline] [Order article via Infotrieve]
  • Sano H, Takatsu T, Ciucchi B, Russell CM, Pashley DH (1995). Tensile properties of resin-infiltrated demineralized human dentin. J Dent Res 74:1093–1102.
  • Schulze KA, Oliveira SA, Wilson RS, Gansky SA, Marshall GW, Marshall SJ (2005). Effect of hydration variability on hybrid layer properties of a self-etching versus an acid-etching system. Biomaterials 26:1011–1018.
  • Tanaka J, Ishikawa K, Yatani H, Yamashita A, Suzuki K (1999). Correlation of dentin bond durability with water absorption of bonding layer. Dent Mater J 18:11–18.[Medline] [Order article via Infotrieve]
  • Tsenoglou CJ, Pavlidou S, Papaspyrides CD (2006). Evaluation of interfacial relaxation due to water sorption in fiber-polymer composites. Compos Sci Technol 66:2855–2864.
  • Unemori M, Matsuya Y, Matsuya S, Akashi A, Akamine A (2003). Water sorption of poly(methyl methacrylate) containing 4-methacryloxyethyl trimellitic anhydride. Biomaterials 24:1381–1387.
  • Van Meerbeek B, Willems G, Celis JP, Roos JR, Braem M, Lambrechts P, et al. (1993). Assessment by nano-indentation of hardness and elasticity of the resin-dentin bonding area. J Dent Res 72:1434–1442.
  • Wang Y, Spencer P, Walker MP (2007). Chemical profile of adhesive/caries-affected dentin interfaces using Raman microspectroscopy. J Biomed Mater Res A 81:279–286.[Medline] [Order article via Infotrieve]
  • Wood JD, Sobolewski P, Thakur V, Arola D, Nazari A, Tay FR, et al. (2008). Measurement of microstrains across loaded resin-dentin interfaces using microscopic moiré interferometry. Dent Mater 24:859–866.[Medline] [Order article via Infotrieve]
  • Yiu CK, King NM, Pashley DH, Suh BI, Carvalho RM, Carrilho MR, et al. (2004). Effect of resin hydrophilicity and water storage on resin strength. Biomaterials 25:5789–5796.
  • Yiu CK, King NM, Carrilho MR, Sauro S, Rueggeberg FA, Prati C, et al. (2006). Effect of resin hydrophilicity and temperature on water sorption of dental adhesive resins. Biomaterials 27:1695–1703.

Journal of Dental Research, Vol. 87, No. 7, 655-660 (2008)
DOI: 10.1177/154405910808700704
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