Effect of rhBMP-2 applied with a 3D-printed titanium implant on new bone formation in rabbit calvariumObjective This study sought to compare the biocompatibility of a three-dimensional (3D)-printed titanium implant with a conventional machined titanium product, as well as the effect of such implant applied with recombinant human Bone Morphogenetic Protein Type 2 (rhBMP-2) for guided bone regeneration.
Methodology Disk-shaped titanium specimens fabricated either by the conventional machining technique or by the 3D-printing technique were compared by MC3T3-E1 cells cytotoxicity assay. New bone formation was evaluated using a rapid prototype titanium cap applied to the calvaria of 10 rabbits, which were divided into two groups: one including an atelopeptide collagen plug on one side of the cap (group I) and the other including a plug with rhBMP-2 on the other side (group II). At six and 12 weeks after euthanasia, rabbits calvaria underwent morphometric analysis through radiological and histological examination.
Results Through the cytotoxicity assay, we identified a significantly higher number of MC3T3-E1 cells in the 3D-printed specimen when compared to the machined specimen after 48 hours of culture. Moreover, morphometric analysis indicated significantly greater bone formation at week 12 on the side where rhBMP-2 was applied when evaluating the upper portion immediately below the cap.
Conclusion The results suggest that 3D-printed titanium implant applied with rhBMP-2 enables new bone formation.
Three-dimensional printing; Bone morphogenetic protein; Osteogenesis
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(A, diameter, 5mm; height, 2mm) and cap (B: diameter, 9mm; height, 4.5mm; thickness, 0.8mm) for 3D printing.
MC3T3-E1 cell counts between the titanium plate (control) and the RP titanium disk (3D print) specimen were significantly different after 48 hours (p< 0.05). Statistical comparisons were performed by the Student's t-test (#, p<0.05; **, p<0.01; ***, p<0.001).
Radiopaque findings, which means new bone formation, are observed from the experimental group I (A) and II (B).
New bone formation is observed more evenly distributed at experimental group I (B) than group II (A).
Specimen from experimental group I at week 6 (A, magnification x1.5, scale bar 2mm) and 12 (B, magnification x1.5, scale bar 2mm; C, box area in image B, magnification x10, scale bar 200mm), and experimental group II at week 6 (D, magnification x1.5, scale bar 2mm) and 12 (E, magnification x1.5, scale bar 2mm; F, box area in image E, magnification x10, scale bar 200mm).