Mechanisms of in Vivo Degradation and Resorption of Calcium Phosphate Based Biomaterials

Abstract

Calcium phosphate ceramic materials are extensively used for bone replacement and regeneration in orthopedic, dental, and maxillofacial surgical applications. In order for these biomaterials to work effectively it is imperative that they undergo the process of degradation and resorption in vivo. This allows for the space to be created for the new bone tissue to form and infiltrate within the implanted graft material. Several factors affect the biodegradation and resorption of calcium phosphate materials after implantation. Various cell types are involved in the degradation process by phagocytic mechanisms (monocytes/macrophages, fibroblasts, osteoblasts) or via an acidic mechanism to reduce the micro-environmental pH which results in demineralization of the cement matrix and resorption via osteoclasts. These cells exert their degradation effects directly or indirectly through the cytokine growth factor secretion and their sensitivity and response to these biomolecules. This article discusses the mechanisms of calcium phosphate material degradation in vivo.

Three‐dimensionally printed polyetherketoneketone scaffolds with mesenchymal stem cells for the reconstruction of critical‐sized mandibular defects

“…PEKK, a subtype of polyaryletherketones, is a thermoplastic material that exhibits exceptional biocompatibility and chemical/thermal stability . Additionally, it is radiolucent, an important characteristic of an implant for tumor surveillance of the head and neck cancer patient . Notably, the OXPEKK formulation (Oxford Performance Materials), printed via selective laser sintering (SLS) is U.S. Food and Drug Administration (FDA)‐approved for implantation and is used in the fields of orthopedic surgery and neurosurgery (FDA 501(k) clearance K142005).…”

“…Additive manufacturing (commonly known as three‐dimensional [3D] printing) offers a tailored approach to tissue engineering by providing anatomically precise, patient‐specific scaffolds onto which stem cells and growth factors can be incorporated. Recent work on bone regeneration has focused on biomaterials such as natural polymers, ceramics, and titanium, which are limited by increased cost, weak mechanical properties, inappropriate degradation time, and potential release of metal ions or other molecules …”

In vitro effects of particulate bone substitute materials on the resorption activity of human osteoclasts

“…Such compound materials, called biphasic bone substitute materials, are available in order to control the velocity of biodegradation by adapting the β-TCP to HA ratio (Chow, 2009;Schopper et al, 2005;Sheikh et al, 2015).…”

[leave for Adam - copyright supporting evidence]Designing patient-specific melt-electrospun scaffolds for bone regeneration

“…The biological and chemical processes associated with the degradation and resorption of various biomaterials has been expertly reviewed in a number of articles. Sheikh et al summarised the mechanisms of calcium phosphate-based biomaterial degradation, concluding that "cement dissolution, disintegration, and fragmentation/particle formation followed by phagocytosis through macrophages and osteoclast mediated resorption is responsible for the biodegradation and resorption of [calcium phosphates] when implanted in vivo" (Sheikh et al, 2015). For synthetic polymer-based scaffolds, such as those fabrication from PLA, PGA and PCL, concerns have been raised as to high local acidic conditions produced by the degradation by-products (Niiranen, Pyhältö, Rokkanen, Kellomäki, & Törmälä, 2004;Rezwan et al, 2006;S.…”