The Importance of Understanding Differences in a Critical Size Model: a Preliminary In Vivo Study Using Tibia and Parietal Bone to Evaluate the Reaction with Different Biomaterials

Many researches aim to develop different biomaterials that are compatible with natural tissues. In vitro and in vivo tests are used to evaluate this potential. Our aim was to report the importance of the critical defect’s location for in vivo assays, to evaluate this approach; in vivo studies were performed, using different compositions of biomaterials in two critical size defects: tibia and parietal bone. Polycaprolactone was used as the main polymeric matrix with and without addition of hydroxyapatite. In vivo studies on the standard critical size defect in tibia and parietal bone were performed using Wistars models: 3x2 and 5x1 dimensions, respectively. The animals were sacrificed after 32 days; neobone formation was assessed with the histological data. The in vivo data demonstrated differences between the tibia and parietal bone groups: the influence of the bone on the neobone’s formation was notable. All the tibia defect samples had greater neobone volume when compared to the parietal data. Indeed, these bones have distinct embryology, influence of mechanical forces and vascularization rate that are well known; moreover, these characteristics were demonstrated to be critical for neobone formation.