Alloplastic and Implant Materials for Bone Grafting: a Literature Review

Bone reconstruction aft er trauma, infection, tumour or congenital genetic disorder is an important subject of modern medicine usually relying on bone graft ing materials. Autologous bone or autograft is still considered the “gold standard” most eff ective in bone defect reconstruction and osseous regeneration. Having the advantages of autograft ing, a series of issues remain related to a limited donor material, painful graft taking and the risk of putative complications (nonunions, graft rejection, infection, iatrogenic fractures, post-microsurgery arteriovenous shunt thrombosis, etc.). Th erefore, improved biomaterials are demanded to adequately meet the autograft criteria. Choosing optimal graft materials becomes relevant, aside to the rationale of selecting new surgical techniques. Th e osteoconductive and osteoinductive property evaluation in modern osteoplastic materials comprises a research avenue into optimal graft development for osseous correction in maxillofacial surgery, neurosurgery, traumatology and orthopaedics. Such biomaterials can be combined with alloplastic graft s to attain the required properties of osteoconduction, osteoinduction and osteogenesis. Th is analytic literature review focuses on current state-of-the-art in alloplastic graft ing that, in our opinion, grounds the progress of auto- and allograft innovative development.

Porous Titanium Granules in comparison with Autogenous Bone Graft in Femoral Osseous Defects: A Histomorphometric Study of Bone Regeneration and Osseointegration in Rabbits

Background. The high resorption rate of autogenous bone is a well-documented phenomenon that can lead to insufficient bone quality and quantity in an augmented area. Nonresorbable bone substitutes might perform better than autogenous bone in certain applications if they are able to provide adequate bone formation and graft osseointegration. Purpose. The aim of this study was to compare the osseous regeneration and graft integration in standardized defects in the rabbit femur treated either with porous titanium granules or autogenous osseous graft. Materials and Methods. Standardized femoral osseous defects were surgically induced in 45 New Zealand rabbits. Fifteen were treated with porous titanium granules (TIGRAN™-PTG) and membrane (PTGM), 15 with autogenous graft and membrane (AGM), and 15 with membrane alone (CM, control). At six weeks, the defects were assessed histologically and histomorphometrically. Results. PTGM as compared to AGM presented similar percentages of newly formed bone tissue, but a significantly higher fraction of the region of interest was filled with the bone substitute material. Accordingly, the composite of new bone plus bone substitute material showed significantly higher volumes for PTGM. Yet, the smaller amount of remaining autogenous bone was far better osseointegrated than the titanium granules, which in large regions showed no connection to newly formed bone. Both PTGM and AGM as compared to CM presented higher values of newly formed bone. Conclusions. This study demonstrated that PTG was similarly effective as autogenous osseous graft in achieving osseous regeneration while PTG performed markedly better in graft volume stability. The resulting higher total percentage of new bone combined with the bone substitute material in PTG could provide a superior foundation for implant placement.

PHYSIOLOGICAL AND REPARATIVE OSTEOGENESIS IN THE NORM AND UNDER CONDITIONS OF SELENIUM DEFICIENCY

The study presents the results of investigation of selenium deficiency condition on the bone tissue and healing post-traumatic bone defects under conditions of selenium deficiency.The experimental part of the study was performed on 63 randomized brand albino male rats of 3-month age. Peculiarities of the reparative osteogenesis were studied on the model of a traumatic injury simulated one-type in the proximal meta-diaphysis of the femoral bone irrespective of the experimental conditions in the frontal plane in the form of perforated defect. The defect was made by means of a drill 1mm in diameter.The results of the study are indicative of a negative effect of selenium deficiency produced on physiological and reparative osteogenesis manifested by inhibition of the process and associated with disorders in the formation of osseous regeneration, deterioration of the structural-functional state of the osseous tissue, development of degenerative-necrotic changes in the osseous tissue and epiphyseal cartilage.

REPARATIVE OSTEOGENESIS IN NORMAL STATE AND UNDER CONDITIONS OF IODINE DEFICIENCY

The study presents the results of investigation of iodine deficiency condition on the bone tissue and healing post-traumatic bone defects under conditions of iodine deficiency.The experimental part of the study was performed on 63 randomized brand albino male rats of 3-month age. Peculiarities of the reparative osteogenesis were studied on the model of a traumatic injury simulated one-type in the proximal meta-diaphysis of the femoral bone irrespective of the experimental conditions in the frontal plane in the form of perforated defect. The defect was made by means of a drill 1mm in diameter.The results of the study are indicative of a negative effect of iodine deficiency produced on reparative osteogenesis manifested by inhibition of the process and associated with disorders in the formation of osseous regeneration, deterioration of the structural-functional state of the osseous tissue, development of degenerative-necrotic changes in the osseous tissue and epiphyseal cartilage.

Supplementation with 45S5 Bioactive Glass Reduces In Vivo Resorption of the β-Tricalcium-Phosphate-Based Bone Substitute Material Vitoss

Compared to other materials such as 45S5 bioactive glass (BG), β-tricalcium phosphate (β-TCP)-based bone substitutes such as Vitoss show limited material-driven stimulation of osteogenesis and/or angiogenesis. The unfavorable degradation kinetics of β-TCP-based bone substitutes may result in an imbalance between resorption and osseous regeneration. Composite materials like Vitoss BA (Vitoss supplemented with 20 wt % 45S5-BG particles) might help to overcome these limitations. However, the influence of BG particles in Vitoss BA compared to unsupplemented Vitoss on osteogenesis, resorption behavior, and angiogenesis is not yet described. In this study, Vitoss and Vitoss BA scaffolds were seeded with human mesenchymal stromal cells before subcutaneous implantation in immunodeficient mice for 10 weeks. Scaffold resorption was monitored by micro-computed tomography, while osteoid formation and vascularization were assessed by histomorphometry and gene expression analysis. Whilst slightly more osteoid and improved angiogenesis were found in Vitoss BA, maturation of the osteoid was more advanced in Vitoss scaffolds. The volume of Vitoss implants decreased significantly, combined with a significantly increased presence of resorbing cells, whilst the volume remained stable in Vitoss BA scaffolds. Future studies should evaluate the interaction of 45S5-BG with resorbing cells and bone precursor cells in greater detail to improve the understanding and application of β-TCP/45S5-BG composite bone substitute materials.