Illuminating the Role of Agglomerates on Critical Physicochemical Properties of Amorphous Calcium Phosphate Composites
Justin N. O'Donnell, Joseph M. Antonucci, Drago Skrtic
Amorphous calcium phosphate (ACP) composites show promise in a number of anti-cariogenic applications. The objectives of this study are to compare the water sorption (WS), mechanical strength and ion release of polymeric composites formulated with either as-made or milled ACP after 1, 2 and 3 mo of aqueous exposure. The photo-curable resin comprised an ethoxylated bisphenol A dimethacrylate (62.8 mass %), triethylene glycol dimethacrylate (23.2 mass %), 2-hydroxyethyl methacrylate (10.4 mass %) and methacryloxyethyl phthalate (2.6 mass %). Composites were prepared with either as-made (median diameter, dm = 70.88 ?m) Zr-ACP or milled Zr-ACP (dm = 3.10 ?m) as the filler phase at 40 mass %. The unfilled resins (copolymers) and composites were evaluated for WS (gravimetrically) after water vapor exposure. Composites were immersed in saline (pH = 7.40; 23 oC) and assessed for Ca and PO4 release as well as for their biaxial flexure strength (BFS) both dry and after aqueous immersion.The mean WS (mass %) peaked at 3 mo with as-made ACP composite (2.73 0.09) > milled ACP composite (1.63 0.24) = copolymer (1.47 0.11). In both the dry state and after 1 mo immersion, the BFS (in MPa) of milled ACP composites approached the BFS of the copolymers (96 32), and was significantly higher than the BFS of as-made ACP composites. BFS of both composite types declined with water aging. However, at 3 mo the BFS of milled ACP composites still remained higher than the BFS of as-made ACP composites [(55 10) vs. (43 11)]. The maximum Ca and PO4 (in mmol/L) released from the as-made and milled ACP composites were [Ca=(0.97 0.16), PO4=(0.39 0.07)] and [Ca=(0.59 0.08), PO4=(0.22 0.03)], respectively. Despite moderately reduced ion release, milled ACP composites are superior to the as-made ACP composites due to significantly lower WS and higher BFS after prolonged aqueous exposure.
, Antonucci, J.
and Skrtic, D.
Illuminating the Role of Agglomerates on Critical Physicochemical Properties of Amorphous Calcium Phosphate Composites, Journal of Composite Materials, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852734
(Accessed May 29, 2023)