Biological behavior of magnesium-substituted hydroxyapatite during bone repair.

G G Santos,S R A Santos,V L C Nunes,F B Miguel,A M Rossi,S M O C Marinho

doi:10.1590/1519-6984.217769

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.

Highlights

The use of ceramic biomaterials, in order to replace and/or aid in the regeneration of bone tissue, has been documented for more than a century
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

Summary

Introduction

The use of ceramic biomaterials, in order to replace and/or aid in the regeneration of bone tissue, has been documented for more than a century. Among the different types of ceramics used in bone regenerative techniques, calcium phosphates (CaP) are part of the widely used group of materials, especially synthetic HA This biomaterial is similar to components of the mineral phase of the bone tissue, biocompatible, bioactive, with excellent osteoconductivity and absence of local or systemic toxicity, and with no risk of disease transmission (Vallet-Regí and González-Calbet, 2004; Yuasa et al, 2004). It serves as a framework for the cellular events that occurr during tissue regeneration, which make bone neoformation possible in association with its structure. Depending on the method used during the synthesis and processing of the materials, the HA may have a slow or rapid degradation rate, which will determine its clinical applications

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