Degradation and Biocompatibility of AZ31 Magnesium Alloy Implants In Vitro and In Vivo: A Micro-Computed Tomography Study in Rats

Abstract

In current orthodontic practice, miniscrew implants (MSIs) for anchorage and bone fixation plates (BFPs) for surgical orthodontic treatment are commonly used. MSIs and BFPs that are made of bioabsorbable material would avoid the need for removal surgery. We investigated the mechanical, degradation and osseointegration properties and the bone-implant interface strength of the AZ31 bioabsorbable magnesium alloy to assess its suitability for MSIs and BFPs. The mechanical properties of a Ti alloy (TiA), AZ31 Mg alloy (MgA), pure Mg and poly-L-lactic acid (PLA) were investigated using a nanoindentation test. Also, pH changes in the solution and degradation rates were determined using immersion tests. Three-dimensional, high-resolution, micro-computed tomography (CT) of implants in the rat femur was performed. Biomechanical push-out testing was conducted to calculate the maximum shear strength of the bone-implant interface. Scanning electron microscopy (SEM), histological analysis and an evaluation of systemic inflammation were performed. MgA has mechanical properties similar to those of bone, and is suitable for implants. The degradation rate of MgA was significantly lower than that of Mg. MgA achieved a significantly higher bone-implant bond strength than TiA. Micro-CT revealed no significant differences in bone density or bone-implant contact between TiA and MgA. In conclusion, the AZ31 Mg alloy is suitable for both MSIs and BFPs.

Automated ex-situ detection of pitting corrosion and its effect on the mechanical integrity of rare earth magnesium alloy - WE43

“…Because magnesium chloride has a greater solubility in water, local corrosion (pitting) occurs in these areas [46]. Additionally, the corrosion rate can be calculated as described in ASTMG31 -12a [44] (5) where V H2 is the hydrogen gas volume in mL and ρ is the density in g/ cm 3 . M is the molecular weight in g/mol, A is the exposed surface area in cm 2 , and t is the overall immersion time in hours.…”

“…Magnesium alloys show great potential as biodegradable alternatives to permanent metallic orthopaedic implants as they are osteo-inductive [1][2][3][4][5][6] and their mechanical properties are comparable to native bone, thereby avoiding stress-shielding complications raised by traditional metallic implants [7]. Magnesium-based implants could eliminate the need for second surgeries for implant removal, thus reducing additional trauma and recovery time to the patient.…”

Long Term Evaluation of Biodegradation and Biocompatibility In-Vivo the Mg-0.5Ca-xZr Alloys in Rats

“…The selection of animal model was established following the published literature on testing Mg alloys which evaluate their biocompatibility and biodegradation in vivo behavior closer to this study [5][6][7][13][14][15]17,[19][20][21][22][23][24][25][26].…”

Biologically modified implantation as therapeutic bioabsorbable materials for bone defect repair

“…Kawamura et al. [ 48 ] confirmed adding aluminum (Al) or Zn to Mg alloys could facilitate the corrosion resistance of Mg alloys to simulated body fluid ( Fig. 7 ).…”