Objective:Based on a literature review and on our own experience, this study proposes sheep as an experimental model to evaluate the bioactive capacity of bone substitute biomaterials, dental implant systems and orthopedics devices. The literature review covered relevant databases available on the Internet from 1990 until to date, and was supplemented by our own experience. Methods:For its resemblance in size and weight to humans, sheep are quite suitable for use as an experimental model. However, information about their utility as an experimental model is limited. The different stages involving sheep experiments were discussed, including the care during breeding and maintenance of the animals obtaining specimens for laboratory processing, and highlighting the unnecessary euthanasia of animals at the end of study, in accordance to the guidelines of the 3Rs Program. Results:All experiments have been completed without any complications regarding the animals and allowed us to evaluate hypotheses and explain their mechanisms. Conclusion:The sheep is an excellent animal model for evaluation of biomaterial for bone regeneration and dental implant osseointegration. From an ethical point of view, one sheep allows for up to 12 implants per animal, permitting to keep them alive at the end of the experiments. Level of Evidence II, Retrospective Study.

The aim of this study was to make a histomorphometric evaluation of the osteogenic potential of anionic collagen matrix as scaffolds; either crosslinked in glutaraldehyde or not cross-linked and, implanted in critical bone defects in rat calvaria. Seventy-two rats were randomly distributed in three groups: anionic collagen scaffolds treated for 24 h of selective hydrolysis (ACSH); anionic collagen scaffolds treated for 24 h of selective hydrolysis and 5 min of crosslinking in glutaraldehyde 0.05% (ACSHGA); empty bone defect (Control), evaluated at the biological points of 15, 45, 90 and 120 days. The results showed that the biomaterials implanted were biocompatible and showed a high osteogenic potential. These biomaterials presented a speed of biodegradation compatible with bone neoformation, which was shown to be associated with angiogenesis inside the scaffolds at all biological points. The percentage of mineralization of ACSH (87%) differed statistically from that found in ACSHGA (66%). It was concluded that the regeneration of critical bone defect was more evident in anionic collagen without crosslinking (ACSH).

The osteogenic behavior of three-dimensional collagenic and anionic matrices (M3DGA) implanted in critical bone defects of 8 mm diameter was morphologically assessed. The defects were performed in the calvaria of 48 adult male (Wistar) rats, and observed at days 15, 30, and 60. The animals were distributed in four groups of equal number: GA1 (M3DGA with 60 min of cross-linking in glutaraldehyde [GA]); GA2 (M3DGA with 30 min of cross-linking in GA); GA3 (M3DGA with 15 min of cross-linking in GA); and G4 (control group, without any implanted biomaterial). The M3DGAs were biocompatible, with mild and regressive chronic granulomatous inflammation, associated with the degradation of their fibers. Furthermore, tissue neovascularization and neomineralization was noted, with statistically significant differences in these amounts among the groups (GA1, GA2, and GA3) and G4. In G4 neoformation was limited to the edges of the defect as well as interstitial fibrosis. Under the experimental conditions and for the parameters analyzed, the M3DGAs had osteogenic behavior, which was more evident in M3DGA 15 min.

ObjectiveThis study aimed to evaluate bone repair in rat dental sockets after implanting nanostructured carbonated hydroxyapatite/sodium alginate (CHA) and nanostructured carbonated hydroxyapatite/sodium alginate containing 5% strontium microspheres (SrCHA) as bone substitute materials.MethodsTwenty male Wistar rats were randomly divided into two experimental groups: CHA and SrCHA (n=5/period/group). After one and 6 weeks of extraction of the right maxillary central incisor and biomaterial implantation, 5 μm bone blocks were obtained for histomorphometric evaluation. The parameters evaluated were remaining biomaterial, loose connective tissue and newly formed bone in a standard area. Statistical analysis was performed by Mann-Withney and and Wilcoxon tests at 95% level of significance.ResultsThe histomorphometric results showed that the microspheres showed similar fragmentation and bio-absorbation (p>0.05). We observed the formation of new bones in both groups during the same experimental periods; however, the new bone formation differed significantly between the weeks 1 and 6 (p=0.0039) in both groups.ConclusionThe CHA and SrCHA biomaterials were biocompatible, osteoconductive and bioabsorbable, indicating their great potential for clinical use as bone substitutes.