The effect of calcium phosphate ceramic composition and structure on in vitro behavior. I. Dissolution

Abstract

Synthetic calcium phosphate ceramic (CPC) surfaces can be transformed to a biological apatite through a sequence of reactions which include dissolution, precipitation, and ion exchange. By virtue of the reactions being material-dependent, it is important to determine parametric rate effects. In this study we focused on the effect of stoichiometry and crystal structure of CPCs on the dissolution kinetics. Monophase, biphase, and multiphase CPCs with a Ca/P ratio equal to or greater than 1.5 were studied. The experiments were performed in a calcium- and phosphate-free Tris buffer solution at pH 7.3. The dissolution behavior of the CPCs studied was found to vary over a wide range. The dissolution rate of the monophase CPCs increased in the order of stoichiometric hydroxyapatite, calcium deficient hydroxyapatite, oxyhydroxyapatite, beta-tricalcium phosphate, alpha-tricalcium phosphate, and tetracalcium phosphate. Dissolution of biphase and multiphase CPCs increased prorated the concentration of more soluble component.

Bone tissue engineering: A review in bone biomimetics and drug delivery strategies

“…122 On the basis of the composition and stoichiometry of a calcium-phosphate ceramic, important physical properties such as degradation rate, modulus, and processability can be changed. [123][124][125][126] Research on TCP materials has revealed that the degradation rate is too rapid in vivo, while synthetic versions of HAp degrade too slowly to allow native tissue integration. This phenomenon motivated the development of BCP and bio-glasses which have tunable (to some degree) degradation rates based on the relative magnitude of TCP (more commonly b-TCP) and HAp in a composite ceramic.…”

In vitro degradation of calcium phosphates: Effect of multiscale porosity, textural properties and composition

“…Although degradation of CaP has been assessed in different solutions [31][32][33][34][35], the simulation of the resorption process by osteoclasts requires working in solutions at acidic pH. This is because resorption by mature osteoclast proceeds through the development of a tight ring-like zone of adhesion (i.e.…”

Interlaboratory studies on in vitro test methods for estimating in vivo resorption of calcium phosphate ceramics

“…The discontinuous measurement techniques include pharmacopoeia methods such as the BP (British Pharmacopoeia) and USP (United States Pharmacopeia) methods and other intermittent sampling-and-analysis methods [29,30]. The pH values ranged from ≈3 to 7.4 in these dissolution tests.…”