Minimally Invasive Subpericranial Model: Can It Be Used to Study Bone Substitutes?

Abstract

Objective: To evaluate the feasibility and effectiveness of a new approach for craniofacial augmentation by a minimally-invasive subpericranial injection. Three commercially available semi-liquid bioceramic bone-grafting materials were examined for this application in a rat model. Material and Methods: Twenty- four adult male rats were randomly assigned to undergo onlay calvarial grafting by subpericranial injection of three semi-liquid bone void fillers: Norian SRS (calcium phosphate), C hronOs Inject TM (porous beta-tricalcium phosphate), or BonePlast harvested after 24 hours to serve as controls. The rest were studied after 16 weeks . The volume fraction of the following parameters was morphometrically measured: new bone, blood vessels , residual bone filler and inflammation. Results: In all study groups (including controls), histological examination demonstrated that bone fillers were successfully delivered to the desired subpericranial space by the percutaneous injection method . New bone formation was evidenced adjacent to the cranial bone in all the study groups. The Norian filler material survived in a significantly higher volume fraction ( 38.4 % ± 6.5 %) than the C hronOs filler ( 18.8 % ± 1.6 %; P < 0.0001 ) and the BonePlast filler ( 17.8 % ± 1.5 %; P < 0.0001). New bone was formed in all groups, particularly adjacent to the interface of graft material with native bone but only to minimal extent. Conclusion: This new approach for craniomaxillofacial augmentation was successfully demonstrated in a rat model. The Norian filler (calcium phosphate) demonstrated superior space preservation abilities. This model may be further applied to test new injectable bone substitutes in the craniomaxillofacial area.