A comparative study of the biodegradability of calcium-alkali-orthophosphate ceramics in vitro and in vivo

Bioactive calcium phosphate cerarnics have been widely used for bone regeneration. However, depending on the clinical application, these materials need to exhibit varying degrees of biodegradability. For example, in clinical applications in which implants are to be inserted into the regenerated site, rapid biodegradability is more important compared to applications in which this is not the case. Therefore, there have been numerous efforts to develop novel materials with a higher solubility compared to tricalciurn phosphate JCP). Among the various calcium phosphate materials which are currently clinically available, TCP possesses the highest solubility and biodegradability. The most reliable method for evaluating a bone substitute material's capability to degrade and promote bone formation and osseous regeneration is by performing histomorphometric measurements on ex vivo specimens front animal experiments. Animal studies, however, are very cost-intensive. Furthermore, due to an increasing focus on animal ethics, there has been an ongoing search for alternative in vitro methods which can contribute to reducing the number of animal experiments. Consequently, this study compares an in vitro method for evaluating the biodegradability of novel calcium-alkali-orthophosphate ceramic particulates - by using solubility measurements - to histortiorphometric evaluation of the biodegradability of these materials by determining the decrease of particle size in histological sections which were obtained Subsequent to implantation in vivo using a sheep model.