Improving bone defect healing using magnesium phosphate granules with tailored degradation characteristics

• Published in: Dental materials 2024-03, Vol.40 (3), p.508-519
• Main Authors: Schröter, Lena, Kaiser, Friederike, Küppers, Oliver, Stein, Svenja, Krüger, Benjamin, Wohlfahrt, Philipp, Geroneit, Isabel, Stahlhut, Philipp, Gbureck, Uwe, Ignatius, Anita
• Format: Article
• Language: English
• Subjects: Bone augmentation; Bone regeneration; Farringtonite; Magnesium phosphate; Struvite
• ISSN: 0109-5641; 1879-0097
• DOI: 10.1016/j.dental.2023.12.019

Dental implant placement frequently requires preceding bone augmentation, for example, with hydroxyapatite (HA) or β-tricalcium phosphate (β-TCP) granules. However, HA is degraded very slowly in vivo and for β-TCP inconsistent degradation profiles from too rapid to rather slow are reported. To shorten the healing time before implant placement, rapidly resorbing synthetic materials are of great interest. In this study, we investigated the potential of magnesium phosphates in granular form as bone replacement materials. Spherical granules of four different materials were prepared via an emulsion process and investigated in trabecular bone defects in sheep: struvite (MgNH4PO4·6H2O), K-struvite (MgKPO4·6H2O), farringtonite (Mg3(PO4)2) and β-TCP. All materials except K-struvite exhibited promising support of bone regeneration, biomechanical properties and degradation. Struvite and β-TCP granules degraded at a similar rate, with a relative granules area of 29% and 30% of the defect area 4 months after implantation, respectively, whereas 18% was found for farringtonite. Only the K-struvite granules degraded too rapidly, with a relative granules area of 2% remaining, resulting in initial fibrous tissue formation and intermediate impairment of biomechanical properties. We demonstrated that the magnesium phosphates struvite and farringtonite have a comparable or even improved degradation behavior in vivo compared to β-TCP. This emphasizes that magnesium phosphates may be a promising alternative to established calcium phosphate bone substitute materials. [Display omitted] •Fabrication of three different magnesium phosphate granules (struvite, K-struvite, farringtonite) via emulsion technique.•Magnesium phosphate granules show an accelerated degradation behavior (K-struvite > farringtonite > struvite) in sheep.•Magnesium phosphate granules appear highly promising as bone substitutes for future clinical use.