The effect of magnesium-incorporated hydroxyapatite coating on titanium implant fixation in ovariectomized rats.

PURPOSE

This study compared the effect of magnesium-incorporated hydroxyapatite (MgHA) coating with that of HA coating on implant fixation in ovariectomized (OVX) rats.

MATERIALS AND METHODS

Coatings of HA and MgHA (10 mol% Ca²⁺ replaced by Mg²⁺) were prepared on the surface of titanium substrates using the sol-gel dip-coating method, and powders of HA and MgHA were produced by the same method. The two kinds of materials were then characterized by scanning electron microscopy and x-ray diffraction. Twelve weeks after bilateral ovariectomy, 18 OVX rats received implants in the distal femora; half of the implants were HA-coated and the other half were MgHA-coated. After 12 weeks of healing, rats were selected randomly for histomorphometry, microcomputed tomography evaluation, and biomechanical testing.

RESULTS

Surface characterization analysis demonstrated that the addition of Mg did not dramatically change the surface topography or apatite patterns of the coating. Histomorphometry revealed higher bone-to-implant contact and bone area ratio for MgHA-coated implants than for HA-coated implants. Microcomputed tomographic evaluation revealed improved trabecular parameters and increased osseointegration for MgHA-coated implants. Biomechanical testing revealed that the MgHA coating increased the maximum push-out force and interfacial shear strength compared to the HA coating.

CONCLUSION

Mg incorporated into an HA coating on titanium implants could improve the biologic fixation of implants in osteoporotic bone.