Calcium Orthophosphate (CaPO4) Containing Composites for Biomedical Applications: Formulations, Properties, and Applications

The goal of this review is to present a wide range of hybrid formulations and composites containing calcium orthophosphates (abbreviated as CaPO4) that are suitable for use in biomedical applications and currently on the market. The bioactive, biocompatible, and osteoconductive properties of various CaPO4-based formulations make them valuable in the rapidly developing field of biomedical research, both in vitro and in vivo. Due to the brittleness of CaPO4, it is essential to combine the desired osteologic properties of ceramic CaPO4 with those of other compounds to create novel, multifunctional bone graft biomaterials. Consequently, this analysis offers a thorough overview of the hybrid formulations and CaPO4-based composites that are currently known. To do this, a comprehensive search of the literature on the subject was carried out in all significant databases to extract pertinent papers. There have been many formulations found with different material compositions, production methods, structural and bioactive features, and in vitro and in vivo properties. When these formulations contain additional biofunctional ingredients, such as drugs, proteins, enzymes, or antibacterial agents, they offer improved biomedical applications. Moreover, a lot of these formulations allow cell loading and promote the development of smart formulations based on CaPO4. This evaluation also discusses basic problems and scientific difficulties that call for more investigation and advancements. It also indicates perspectives for the future.

Octacalcium phosphate/gelatin composite facilitates bone regeneration of critical-sized mandibular defects in rats: A quantitative study

Background. Regeneration of bone defects remains a challenge for maxillofacial surgeons. The present study aimed to compare the effects of octacalcium phosphate (OCP) and the combination of octacalcium phosphate/gelatin (OCP/Gel) on mandibular bone regeneration in rats

Methods. In the present study, 36 male Sprague-Dawley rats were used. The animals were randomly assigned to the following experimental groups: OCP (n=12), OCP/Gel (n=12), and the control group (n=12). Defects were created in the rat mandibles and filled with 10 mg of OCP and OCP/Gel disks in the experimental groups. In the control group, however, no substance was administered. Samples were taken on days 7, 14, 21 and 56, respectively, after the implantation. Sections (5 µ) were prepared and stained by H&E. The sections were studied, and the volume fraction of newly formed bone was measured by Dunnett's T3 test based on the significance level (P=0.05).

Results. In the experimental groups, the new bone formation began from the margin of defects 7‒14 days after the implantation. During the healing process, the newly formed bone healed a larger area of the defects and grew structurally. In the control group, the defects were primarily filled with dense connective tissue, and only a small amount of new bone was formed. The present study showed a statistically significant difference in the volume of newly formed bone between the experimental groups and the control group (P<0.001).

Conclusion. OCP/Gel composite can be beneficial in the healing process of mandibular bone defects.

Formation and stability of well-crystallized metastable octacalcium phosphate at high temperature by regulating the reaction environment with carbamide

The formation and stability of pure well-crystallized metastable OCP were regulated under carbamide-mediated reaction conditions through the co-existing conversion mechanisms.