Matrix Resin Effects on Selected Physicochemical Properties of Amorphous Calcium Phosphate Composites

Abstract

Amorphous calcium phosphate (ACP)-filled bioactive composites show promise in a number of dental applications. This study focused on polymer-filler bonding as a way to improve physicochemical properties of these composites. Photoactivated resins were formulated from ethoxylated bisphenol A dimethacrylate (EBPADMA), triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA) and methacryloxyethyl phthalate (MEP) with four different EBPADMA/TEGDMA mass ratios (1.0, 0.67, 0.5 and 0.25) and a constant HEMA/MEP mass ratio of 2.0. Composites were prepared with the zirconia-ACP (mass fraction 40%). Composites and copolymers were evaluated for their biaxial flexure strength (BFS), degree of vinyl conversion (DC) and water sorption (WS). Composites were also assessed for mineral ion release and polymerization shrinkage (PS). Independent of resin composition, the average BFS was 130±24MPa for both the dry and aqueous-immersed copolymers, but was 70±11MPa for the dry composites and 47±7MPa for the wet composites. The average DC of all of the composites was 84±5% and showed little dependence on resin composition. The WS of both copolymers and composites was 3.2±0.6% with resin composition being a factor in only one formulation EBPADMA/TEGDMA 0.67. Overall ion release was significantly above the theoretical minimum necessary for remineralization. However, Ca ion levels were lower than that observed previously for similar composites based on resins without MEP. This is most likely due to their binding with the carboxylic acid groups of MEP. Since the DC of the copolymers and the PS of the composites both increased with decreasing EBPADMA/TEGDMA ratio in the resin, elevating the EBPADMA/TEGDMA ratio in the resin seems to be an obvious way to improve the PS of composites without adversely affecting the BFS, WS and/or ion release, while only marginally reducing the DC.

Keywords

amorphous calcium phosphate biaxial flexure strength composites degree of vinyl conversion mineral ion release polymerization shrinkage water sorption.

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References

Antonucci, J, M. , Skrtic, D. , Hailer, A.W. and Eanes, E.D. (2001). Bioactive Polymeric Composites Based on Hybrid Amorphous Calcium Phosphate. In: Ottenbrite, R.M. and Kim, S.W. (eds), Polymeric Drugs & Drug Delivery Systems, pp. 301-310, Technomics Publ. Co., Inc., Lancaster .

Skrtic, D. , Antonucci, J.M. , Eanes, E.D. , Eichmiller, F.C. and Schumacher, G.E. (2000). Physicochemical Evaluation of Bioactive Polymeric Composites Based on Hybrid Amorphous Calcium Phosphates , J. Biomed. Mat. Res. (Appl Biomater), 53: 381-391 .

Park, M.S. , Eanes, E.D. , Antonucci, J.M. and Skrtic, D. (1998). Mechanical Properties of Bioactive Amorphous Calcium Phosphate/Methacrylate Composites , Dent. Mater., 14: 137-141 .

Skrtic, D. , Eanes, E.D. and Antonucci, J.M. (1995). Polymeric Calcium Phosphate Composites with Remineralization Potential. In: Gebelein, C.G. and Carraher, C.E. Jr. (eds), Industrial Biotechnological Polymers, pp. 393-408, Technomics Publ. Co., Inc., Lancaster .

Skrtic, D. , Hailer, A.W. , Takagi, S. , Antonucci, J.M. and Eanes, E.D. (1996). Quantitative Assessment of the Efficacy of Amorphous Calcium Phosphate/Methacrylate Composites in Remineralizing Caries-Like Lesions Artificially Produced in Bovine Enamel , J. Dent. Res., 75(9): 1679-1686 .

Skrtic, D. , Antonucci, J.M. , Eanes, E.D. and Eidelman N. (2004). Dental Composites Based on Hybrid and Surface-Modified Amorphous Calcium Phosphates , Biomaterials, 25: 1141-1150 .

Skrtic, D. , Antonucci, J.M. and Eanes, E.D. (2003). Amorphous Calcium Phosphate-Based Bioactive Polymeric Composites for Mineralized Tissue Regeneration , J. Res. Natl. Inst. Stands. Technol., 108: 167-182 .

Skrtic, D. , Antonucci, J.M. , Eanes, E.D. and Brunworth, R.T. (2002). Silica- and Zirconia-Hybridized Amorphous Calcium Phosphate: Effect on Transformation to Hydroxyapatite , J. Biomed. Mater. Res., 59: 597-604 .

Eanes, E.D. , Gillessen, H. and Posner, A.S. (1965). Intermediate States in the Precipitation of Hydroxyapatite , Nature, 208: 365-367 .

10.

Vogel, G.L. , Chow, L.C. and Brown, W.E. (1983). A Microanalytical Procedure for the Determination of Calcium, Phosphate and Fluoride in Enamel Biopsy Samples , Caries. Res., 7: 23-31 .

11.

Murphy, J. and Riley, J.P. (1962). Single Solution Method for the Determination of Phosphate in Natural Waters , Anal. Chim. Acta., 27: 31-36

12.

ASTM F394-78 (re-approved 1991). Standard test method for biaxial strength (modulus of rapture) of ceramic substrates.

13.

Stansbury, J.W. and Dickens, S. (2001). Determination of Double Bond Conversion in Dental Resins by Near Infrared Spectroscopy , Dent. Mater., 17: 71-79 .

14.

Reed, B. , Dickens, B. , Dickens, S. and Parry, E. (1996). Volumetric Contraction Measured by a Computer-Controlled Mercury Dilatometer , J. Dent. Res., 75: 290 .

15.

Morgan, D.R. , Kalachandra, S. , Shobha, H.K. , Gunduz, N. and Stjskal, E.O. (2000). Analysis of a Dimethacrylate Copolymer (Bis-GMA and TEGDMA) Network by DSC and 13C Solution and Solid State NMR Spectroscopy , Biomaterials, 21: 1897-1903 .

16.

Antonucci, J.M. and Stansbury, J.W. (1997). Molecularly Designed Dental Polymers, Desk Reference of Functional Polymer Syntheses and Applications, pp.719-738, American Chemical Society, Washington, DC.

17.

Antonucci, J.M. , Liu, D.W. and Stansbury, J.W. (1993). Synthesis of Hydrophobic Oligomeric Polymers for Dental Applications , J. Dent. Res., 72: 369 .

18.

Skrtic, D. , Antonucci, J.M. and Eanes, E.D. (1996). Improved Properties of Amorphous Calcium Phosphate Fillers in Remineralizing Resin Composites , Dent. Mater., 12: 295-301 .

19.

Skrtic, D. , Antonucci, J.M. and Eanes, E.D. (2001). Effect of the Monomer and Filler System on the Remineralizing Potential Of Bioactive Dental Composites Based on Amorphous Calcium Phosphate , Polym. Adv. Technol., 12: 369-379 .

20.

Braga, R.R. and Ferracane, J.L. (2002). Contraction Stress Related to Degree of Conversion and Reaction Kinetics , J. Dent. Res., 81(2): 114-118 .

21.

Lovell, L.G. , Stansbury, J.W. , Syrpes, D.C. and Bowman, C.N. (1999). Effects of Composition and Reactivity on the Reaction Kinetics of Dimethacryalate/Dimethacryalte Copolymerizations , Macromolecules, 32: 3913-3921 .

22.

Jones, D.W. and Rizkala, A.S. (1996). Characterization of Experimental Composites Biomaterials , J. Biomed. Mater. Res. (Appl. Biomater.), 33: 89-100 .

23.

Liu, G. , Wijn, J.R. , De Groot, K. and Vanblitterswijk, C.A. (1998). Surface-Modification of Nano-Apatite by Grafting Organic Polymer , Biomaterials, 19: 1067-1072 .

24.

Labella, R. , Lambrehts, P. , Van Meerbeek, B. and Vanherle, G. (1999). Polymerization Shrinkage and Elasticity of Flowable Composites and Filled Adhesives , Dent. Mater., 15: 128-137 .

25.

Skrtic, D. and Antonucci, J.M. (2003). Effect of Bifunctional Co-Monomers on Mechanical Strength and Water Sorption of Amorphous Calcium Phosphate- and Silanized Glass-Filled Bis-GMA-Based Composites , Biomaterials, 24: 2881-2888 .

26.

Burrow, M.F. , Inokoshi, S. and Tagami, J. (1999). Water Sorption of Several Bonding Resins , Am. J. Dent., 12(6): 295-298 .

27.

Skrtic, D. and Antonucci, J.M. (2005). In Vitro Cytotoxicity of Amorphous Calcium Phosphate Composites , J. Bioact. Comp. Polym., 20(2): 147 .