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Adhesion of Amorphous Calcium Phosphate Composites Bonded to Dentin: A Study in Failure Modality



Justin N. O'Donnell, Gary E. Schumacher, Joseph M. Antonucci, Drago Skrtic


Aims. The objective of this study was to measure the adhesive strength to dentin, work to fracture, and failure modes of three resin composites (with differing fillers) and one commercial compomer after 24 h, 1 week, 1, 3 and 6 months of aqueous exposure. Flat dentin surfaces were acid-etched, primed, and photopolymerized. Composites were applied, photo-cured, and debonded in shear. The resin used in each composite was identical: ethoxylated bisphenol A dimethacrylate, triethylene glycol dimethacrylate, 2-hydroxyethyl methacrylate and methacryloxyethyl phthalate. Fillers consisted of as-made and milled amorphous calcium phosphate (am-ACP and m-ACP, respectively), and a strontium-containing glass (Sr-glass) at respective mass fractions of 40, 60, and 75 percent.Findings. 90 % of the fracture surfaces in this study showed adhesive failure, with most of these occurring at the dentin/primer interface. 52 % of failures after 24 h immersion occurred at the primer/composite interface. After six months of aqueous exposure, 80 % of specimens failed at the dentin/primer interface, with a 42 % overall reduction in bond strength. Conclusions. Milled ACP composites showed initial mechanical advantages over am-ACP composites and the compomer, and produced a higher incidence of a failure mode consistent with stronger adhesion. Evidence is provided which suggests that milled ACP composites may offer enhanced potential in clinical bonding applications.
Journal of Biomedical Materials Research-Applied Biomaterials


amorphous calcium phosphate, failure mode, polymerization shrinkage stress, shear bond strength, work to fracture


O'Donnell, J. , Schumacher, G. , Antonucci, J. and Skrtic, D. (2008), Adhesion of Amorphous Calcium Phosphate Composites Bonded to Dentin: A Study in Failure Modality, Journal of Biomedical Materials Research-Applied Biomaterials, [online], (Accessed June 20, 2024)


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Created December 22, 2008, Updated October 12, 2021