Engineered Bioceramic Implants For Repair Of Radiation-compromised Mandibular Defects

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Background: The common factor that makes post-traumatic or post-oncologic defects difficult to treat is the compromised wound bed necessitating reliable reconstructive methods to re-establish form and function. The current study aimed to elucidate the effect of 3D-printed β-tricalcium phosphate scaffolds coated with a bioactive molecule, dipyridamole (DIPY) - an indirect agonist of the adenosine A 2A receptor, via different coating techniques to regenerate critically sized mandibular defects in an irradiated rabbit model of compromised wound healing. Methods: Skeletally mature New Zealand White rabbits (N=37 total) were acquired of which N=6 rabbits did not receive radiation (non-irradiated cohort), whereas N=31 received a total of 36 Gy radiation prior to surgery (irradiated cohort). Surgical intervention was performed to induce unilateral, critically sized, 10 mm full-thickness mandibular defects. The defects induced in the non-irradiated animal cohort received an uncoated scaffold (3DP-NI). On the other hand, defects in the irradiated animal cohort were either (i) left empty (CTRL); (ii) filled with an uncoated scaffold (3DP-I); a scaffold coated with DIPY via (iii) dip-coating (3DPDC-I) or (iv) drop-casting (3DPP-I) in a randomized fashion. Results: After 8 weeks, the CTRL group showed mandibular fracture post-surgery, causing partial or complete defect collapse. Significantly greater bone formation (Bone%) was observed in the 3DP-NI group (27.34% 2.85) relative to 3DP-I (20.92% 2.91) and 3DPDC-I (16.43% 3.68) ( p <0.001 and p =0.026, respectively) (Figure 1) . On the other hand, homogenous bone formation was seen between 3DP-NI (27.34% 2.85) and 3DPP-I (22.08% 4.34) ( p =0.173), but no significant differences in Scaffold% was observed ( p >0.545) (Figure 2) . Conclusion: The 3D-printed bioceramic scaffolds effectively provided mechanical stability at the defect site, but more importantly, drop-casting of DIPY (3DPP-I) qualitatively and quantitatively elicited the desired osteogenic response to overcome vascular compromise in the treatment of critically sized defects in this compromised maxillofacial wound healing model. Figure 1. Volumetric reconstructions of (i) 3DP-NI, (ii) 3DP-I, (iii) 3DPDC-I, and (iv) 3DPP-I groups from the buccal perspective showing bone (yellow) and scaffold (purple). Figure 2. A. Comparison of the presence of (i) Bone% and (ii) Scaffold% within the defect site among the different treatment groups.© 2026. Plastic Surgery Research Council | All rights reserved |*Source: https://ps-rc.org/meeting/Program/2026/31.cgi*

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