Bone grafted with β‐TCP granules in the rabbit: A microcomputed tomographic, histologic, Raman microspectrometric, and Raman imaging study

Abstract

Bone grafting with synthetic substitutes is now the preferred technique in maxillofacial surgery. The biocompatibility of biomaterials such as betatricalcium phosphate (β-TCP) necessitates animal experimentation. Here, six rabbits received β-TCP granules in a hole drilled in the femoral condyle and were compared with ungrafted holes with a similar critical size defect on the control-lateral side. Microcomputed tomography confirmed that new bone trabeculae had invaded the grafted zone after 28 days, whereas only minimal remodeling had occurred at the margins of the hole in control rabbits. Histological sections, after polymethylmethacrylate (pMMA) embedding, evidenced a direct apposition of bone onto the granules. In some areas, osteoid tissue remained unmineralized, sandwiched between the biomaterial and fully calcified bone. Raman analysis was used to characterize the differences between the calcium/phosphate biomaterial and the bone matrix containing hydroxyapatite. Luminescence of β-TCP was evidenced with a 785-nm laser used for biological analysis but not with a 532-nm laser. The ν1 phosphate allowed a clear differentiation of bone and the biomaterial as the subpeaks were not similar (960 cm −1 for bone, 949 and 970 cm −1 for β-TCP). Hydration (derived from identification of pMMA at 813 cm −1) and crystallinity could be determined. Raman imaging allowed the precise localization of these different peaks or ratios; luminescence peaks of β-TCP also allowed a clear differentiation of the material from bone.