Lateral ridge augmentation using a PCL-TCP scaffold in a clinically relevant but challenging micropig model

Background In implant dentistry, there is a need for synthetic bone substitute blocks to support ridge augmentation in situations where large bone volumes are missing. Polycaprolactone-based scaffolds demonstrated excellent results in bone tissue engineering applications. The use of customized polycaprolactone-tricalcium phosphate (PCL-TCP) displayed promising results from recent rat femur and rabbit calvaria studies. However, data from clinically representative models in larger animals do not exist. Objective To evaluate new bone formation in association with a novel PCL-TCP scaffold in comparison with an autogenous bone block graft for the reconstruction of large dentoalveolar defects in a clinically relevant but challenging pig jaw model. Material and methods Chronic, non-contained one-wall defects were created in the mandible of micropigs and randomly assigned to receive one of the following guided bone regeneration (GBR) procedures for a period of 6 months. (A) Collagen membrane + autogenous block graft or (B) Collagen membrane + PCL-TCP scaffold. Micro computed tomography (mu-CT), histology and histomorphometry were used to assess new bone formation. Results Although mu-CT and histomorphometric analysis demonstrated a slight discrepancy between the measurements, the group utilizing autogenous bone grafts consistently reported superior new bone formation as compared to PCL-TCP scaffolds. When measured using mu-CT, the ratio of bone volume fraction for PCL-TCP scaffolds with respect to autografts yielded a mean efficacy of approximately 51%. Histological examination revealed that under favorable conditions, the new bone matrix and new bone marrow were in direct contact with the PCL-TCP scaffold rods and invading the interstices, suggesting good biocompatibility and high osteoconductivity. Autograft block grafts demonstrated 48.557.4% of pronounced resorption after 6 months following ridge augmentation. Conclusions PCL-TCP scaffolds have demonstrated the potential application for lateral ridge augmentation following a healing period of 6 months in a micropig model.