Development of strong and bioactive calcium phosphate cement as a light-cure organic–inorganic hybrid

Abstract

In this research, light cured calcium phosphate cements (LCCPCs) were developed by mixing a powder phase (P) consisting of tetracalcium phosphate and dicalcium phosphate and a photo-curable resin phase (L), mixture of hydroxyethylmethacrylate (HEMA)/poly acrylic-maleic acid at various P/L ratios of 2.0, 2.4 and 2.8 g/mL. Mechanical strength, phase composition, chemical groups and microstructure of the cured cements were evaluated at pre-set times, i.e. before and after soaking in simulated body fluid (SBF). The proliferation of Rat-derived osteoblastic cells onto the LCCPCs as well as cytotoxicity of cement extracts were determined by cell counting and 3-{4,5-dimethylthiazol-2yl}-2,5-diphenyl-2H-tetrazolium bromide assay after different culture times. It was estimated from Fourier transforming infrared spectra of cured cements that the setting process is ruled by polymerization of HEMA monomers as well as formation of calcium poly-carboxylate salts. Microstructure of the cured cements consisted of calcium phosphate particles surrounded by polymerized resin phase. Formation of nano-sized needlelike calcium phosphate phase on surfaces of cements with P/L ratios of 2.4 and 2.8 g/mL was confirmed by scanning electron microscope images and X-ray diffractometry (XRD) of the cured specimen soaked in SBF for 21 days. Also, XRD patterns revealed that the formed calcium phosphate layer was apatite phase in a poor crystalline form. Biodegradation of the cements was confirmed by weight loss, change in molecular weight of polymer and morphology of the samples after different soaking periods. The maximum compressive strength of LCCPCs governed by resin polymerization and calcium polycarboxylate salts formation was about 80 MPa for cement with P/L ratio of 2.8 g/mL, after incubation for 24 h. The strength of all cements decreased by decreasing P/L ratio as well as increasing soaking time. The preliminary cell studies revealed that LCCPCs could support proliferation of osteoblasts cultured on their surfaces and no cytotoxic effect was observed for the extracts of them.

Salmon calcitonin‐loaded PLGA microspheres/calcium phosphate cement composites for osteoblast proliferation

“…No obvious difference was observed between the composites and CPC, indicating that the addition of different SCT‐PLGA MS contents had no effect on the hydration reaction of CPC. This was in accordance with an earlier study …”

Self-Setting Calcium Orthophosphate Formulations

“…Addition of 20 wt% of acrylamide and 1 wt% ammonium polyacrylate to the liquid increased the compressive and tensile strength of α-TCP formulation by 149% and 69% (55 and 21 MPa), respectively due to a dual setting mechanism ( i.e ., both inorganic and organic phases were set simultaneously) [508]. Other types of the dual setting formulations containing calcium orthophosphates are known as well [509,510,511]. A positive influence of polyamide fibers [512] and bioactive glass [513,514,515,516] is also known.…”

Designing dental composites with bioactive and bactericidal properties

“…Towards this goal, several ion-releasing resin-based CaP cements have been proposed as potential cavity liner materials due to their ability to neutralize acid solution and to induce the remineralization of mineral-deficient carious dentine [5]. However, their relative weak antibacterial activity indicates the need for incorporation of other antibacterial agents in order to develop strong antibacterial composite materials for clinical use.…”