Biological behavior of magnesium-substituted hydroxyapatite during bone repair

Abstract

The aim of this study was to analyze the biological behavior and osteogenic potential of magnesium (Mg) substituted hydroxyapatite (HA) microspheres, implanted in a critical bone defect, considering that this ion is of great clinical interest, since it is closely associated with homeostasis and bone mineralization. For the purpose of this study, 30 rats were used to compose three experimental groups: GI -bone defect filled with HA microspheres; GII -bone defect filled with HA microspheres replaced with Mg; GIII -empty bone defect; evaluated at biological points of 15 and 45 days. The histological results, at 15 days, showed, in all the groups, a discrete chronic inflammatory infiltrate; biomaterials intact and surrounded by connective tissue; and bone neoformation restricted to the borders. At 45 days, in the GI and GII groups, an inflammatory response of discrete granulomatous chronic type was observed, and in the GIII there was a scarce presence of mononuclear inflammatory cells; in GI and GII, the microspheres were seen to be either intact or fragmented, surrounded by fibrous connective tissue rich in blood vessels; and discrete bone neoformation near the edges and surrounding some microspheres. In GIII, the mineralization was limited to the borders and the remaining area was filled by fibrous connective tissue. It was concluded that the biomaterials were biocompatible and osteoconductive, and the percentage of Mg used as replacement ion in the HA did not favor a greater bone neoformation in relation to the HA without the metal. Comportamento biológico de hidroxiapatita substituída com magnésio durante o reparo ósseoResumo O objetivo deste estudo foi analisar o comportamento biológico de microesferas de hidroxiapatita (HA) substituída com magnésio (Mg) durante o reparo de defeito ósseo crítico, tendo em vista que este íon é de grande interesse clínico, pois está intimamente associado à homeostasia e à mineralização óssea. Para tanto, utilizou-se 30 ratos para compor três grupos experimentais: GI -defeito ósseo preenchido com microesferas de HA; GII -defeito ósseo preenchido com microesferas de HA substituída com Mg; GIII (controle) -defeito ósseo vazio; avaliados nos pontos biológicos de 15 e 45 dias. Os resultados histológicos evidenciaram, aos 15 dias, discreto infiltrado inflamatório crônico e neoformação óssea restrita às bordas, em todos os grupos. Nos grupos GI e GII, os biomateriais mantiveram-se íntegros e circundados por tecido conjuntivo frouxo. Aos 45 dias, notou-se resposta inflamatória do tipo crônica granulomatosa discreta nos grupos GI e GII, e no GIII presença escassa de células inflamatórias mononucleares. As microesferas implantadas no GI e GII mantiveram-se, em sua maioria, íntegras e envolvidas por tecido conjuntivo fibroso. Notou-se discreta neoformação óssea próxima às bordas e circunjacente a algumas microesferas. No GIII, a mineralização limitou-se às bordas e a área remanescente foi preenchida por tecido conjuntivo fibroso. Conclui-se que os biomateriais foram biocompatíveis, bioativos...

Applications of Biodegradable Magnesium-Based Materials in Reconstructive Oral and Maxillofacial Surgery: A Review

“…Sartori et al demonstrated in an in vivo study conducted on sheep that MgHA provides osteoconductive structural support during the process of bone regeneration [ 50 ]. Santos et al concluded in an in vivo experiment that MgHA, when implanted in a critical bone defect in rat calvaria, is a biocompatible and osteoconductive biomaterial [ 51 ]. A clinical study by Grigolato et al showed that MgHA, used as a bone substitute in a mandibular defect due to ameloblastoma, exhibits excellent biological behavior and high osseointegration potential [ 52 ].…”

Resorbable Mg2+-Containing Phosphates for Bone Tissue Repair

“…Thus, application of magnesium-based implants can develop the strength of the new bone at the implantation site. Mg-substituted hydroxyapatite exhibits high bioactivity and increased osteoconductivity and osteointegration, as an extracellular inorganic matrix [59][60][61]. During the degradation of Mg-based implants, the temporarily accumulated magnesium ions in the implantable bone matrix can be extracted into the circulatory system with no effects on their concentration in the blood serum [58].…”

Resorbable Mg²⁺-Containing Phosphates for Bone Tissue Repair

“…The inclusion of magnesium in hydroxyapatite structure reduces crystal size and crystal order by replacing calcium with magnesium [57], So Mg-based implants application can improve the strength of the new bone at the implantation site. Mg-substituted HAP exhibits high bioactivity and increased osteoconductivity and osseointegration, as an extracellular inorganic matrix [58][59][60]. During the degradation of Mgbased implants, the temporarily stored magnesium ions in the implantable bone matrix can be gradually released into the circulatory system without affecting the concentration of magnesium ions in the blood serum [57].…”