The Bioresorption and Guided Bone Regeneration of Absorbable Hydroxyapatite-Coated Magnesium Mesh

Introduction: Nonabsorbable metallic membrane for guided bone regeneration is remained permanently even though after complete healing. There would be metallic exposure followed by the risk of infection; the membrane should be removed for the additional procedure such as implant installation. Since absorbable nonmetallic mesh is absorbed within 3 to 6 months, it is unnecessary to be removed. However, the absorbable membrane shows lower retention, lower mechanical strength, and difficulty of manipulation than the nonabsorbable ones. The purpose of this study is to evaluate the ability of absorbable metallic mesh (hydroxyapatite-coated magnesium mesh) with acceptable mechanical properties and satisfying biocompatibility. Methods: The bioresorption and fate of magnesium were evaluated in Sprague Dawley rat (SD rat) with critical defect of calvarium. The critical defect with a diameter of 8mm was made on calvarium using trephine bur in 18 SD rats. The defected models were divided into 2 groups: the control group (9 SD rat) without mesh and the experimental group (9 SD rat) with the insertion of prototype HAcoated magnesium mesh. The 3 SD rats were sacrificed at 6, 12, and 18 weeks. The histopathological and radiographic examinations were performed afterward. Results: In the control group, there was no specific symptom. The experimental group also showed no specific symptom including swelling and dehiscence related to hydrogen gas formation. From 6 to 18 weeks, the experimental group showed the progressive absorption and fracture of magnesium mesh. However, there was no specific effectiveness of guided bone regeneration in both groups. There was no significant difference in bone volume, bone surface, and bone volume fraction between the negative control group and the group with magnesium mesh (P> 0.05). Conclusion: Hydroxyapatite-coated magnesium mesh showed reasonable process of bioresorption and bony reaction; however, the effectiveness of guided bone regeneration and management of the bioresorption rate should be reconsidered.