ABSTRACT
Abstract The aim of this study was to analyze the biological behavior and osteogenic potential of magnesium (Mg) substituted hydroxyapatite (HA) microspheres, implanted in a critical bone defect, considering that this ion is of great clinical interest, since it is closely associated with homeostasis and bone mineralization. For the purpose of this study, 30 rats were used to compose three experimental groups: GI - bone defect filled with HA microspheres; GII - bone defect filled with HA microspheres replaced with Mg; GIII - empty bone defect; evaluated at biological points of 15 and 45 days. The histological results, at 15 days, showed, in all the groups, a discrete chronic inflammatory infiltrate; biomaterials intact and surrounded by connective tissue; and bone neoformation restricted to the borders. At 45 days, in the GI and GII groups, an inflammatory response of discrete granulomatous chronic type was observed, and in the GIII there was a scarce presence of mononuclear inflammatory cells; in GI and GII, the microspheres were seen to be either intact or fragmented, surrounded by fibrous connective tissue rich in blood vessels; and discrete bone neoformation near the edges and surrounding some microspheres. In GIII, the mineralization was limited to the borders and the remaining area was filled by fibrous connective tissue. It was concluded that the biomaterials were biocompatible and osteoconductive, and the percentage of Mg used as replacement ion in the HA did not favor a greater bone neoformation in relation to the HA without the metal.
Resumo O objetivo deste estudo foi analisar o comportamento biológico de microesferas de hidroxiapatita (HA) substituída com magnésio (Mg) durante o reparo de defeito ósseo crítico, tendo em vista que este íon é de grande interesse clínico, pois está intimamente associado à homeostasia e à mineralização óssea. Para tanto, utilizou-se 30 ratos para compor três grupos experimentais: GI - defeito ósseo preenchido com microesferas de HA; GII - defeito ósseo preenchido com microesferas de HA substituída com Mg; GIII (controle) - defeito ósseo vazio; avaliados nos pontos biológicos de 15 e 45 dias. Os resultados histológicos evidenciaram, aos 15 dias, discreto infiltrado inflamatório crônico e neoformação óssea restrita às bordas, em todos os grupos. Nos grupos GI e GII, os biomateriais mantiveram-se íntegros e circundados por tecido conjuntivo frouxo. Aos 45 dias, notou-se resposta inflamatória do tipo crônica granulomatosa discreta nos grupos GI e GII, e no GIII presença escassa de células inflamatórias mononucleares. As microesferas implantadas no GI e GII mantiveram-se, em sua maioria, íntegras e envolvidas por tecido conjuntivo fibroso. Notou-se discreta neoformação óssea próxima às bordas e circunjacente a algumas microesferas. No GIII, a mineralização limitou-se às bordas e a área remanescente foi preenchida por tecido conjuntivo fibroso. Conclui-se que os biomateriais foram biocompatíveis, bioativos, osteocondutores e apresentaram biodegradação lenta, indicando seu grande potencial para em aplicações clínica como biomaterial de preenchimento.
Subject(s)
Animals , Rats , Durapatite , Magnesium , Osteogenesis , Biocompatible Materials , Bone RegenerationABSTRACT
BACKGROUND: Rabbit model of distal femoral bone defect has been widely used to test bone tissue engineering materials for bone defects. However, there is no uniform standard for the size of the cylindrical bone defect model of the rabbit femoral condyle, which ranges 5-9 mm in diameter and 8-12 mm in depth. OBJECTIVE: To establish the bone defect model of adult rabbit femoral condyle with different sizes and to determine the critical bone defect size of the femoral condyle METHODS: Eighteen male New Zealand White rabbits aged 6 months were randomly divided into three groups according to the diameter of bone defect: 5 mm diameter group, 6 mm diameter group, and 7 mm diameter group. The defect depth was 10 mm. These rabbits underwent bilateral radial surgery, a total of 12 sides. Computed Tomography (CT) scan and three-dimensional reconstruction were performed at 1 day, 4, 8, 12 weeks after surgery. The CT-Hedberg score was used to evaluate the healing of bone defects. The rabbits were sacrificed at 12 weeks after surgery, and the femoral condyle specimens were taken out. Healing of the defect was analyzed by gross observation and hematoxylin-eosin staining. The study protocol was approved by the Animal Ethics Committee of Xuzhou Medical University. RESULTS AND CONCLUSION: All rabbits survived after surgery. The gross observation showed that the defect of 5 mm diameter group was filled with new bone tissue, the femoral condyle was well shaped, and the bone defect was completely repaired. In 6 mm and 7 mm diameter groups, depressed deformation was obviously observed in the defect area, with less new bone tissue, and the defect was was not repaired. The CT images showed that the defect area of 5 mm diameter group gradually decreased, and the broken ends of the defect were bridged. In the defect area of 6 mm and 7 mm diameter groups, only a small amount of new bone tissue was implanted, and the defect area was slightly reduced. At the 12th week after surgery, the cortical bone structure of 5 mm diameter group was intact and continuous, the femoral condyle was well shaped, and the bone defect was completely repaired. The defects of 6 mm and 7 mm diameter groups were partially or not repaired, and the defect cavity was still visible in the 7 mm diameter group. The CT-Hedberg scores of 6 mm diameter group were significantly lower than those of 5 mm diameter group at different time points (P 0.05). Histological results showed that there were irregular trabecular structures in the defect area of 5 mm diameter group, with a large amount of new bone tissue. In the other two groups, there were some new bone trabeculae around the bone defect, but the defect area was less filled with new bone tissue. During the 12-week observation period, the femoral condyle defect with a diameter of > 6 mm and a depth of 10 mm could not heal spontaneously, while the defect with a diameter of < 6 mm could be completely repaired, which met the criteria of critical bone defect. Therefore, the diameter of < 6 mm could be used as the critical bone defect size of rabbit femoral condyle.
ABSTRACT
To prevent post-extraction resorption and preserve the integrity of the alveolar ridges, the placement of bone grafts at the time of extraction is recommended. Bovine bone grafts are biocompatibile and osteoconductive, allowing new bone apposition by osteoprogenitor cells. Although there are trademarks recognized internationally regarding bovine bone grafts, they are expensive and even difficult to acquire. Therefore, domestic industry development of high quality biomaterials will reduce the public health high costs in the dental field. Here, we evaluated and compared the effects of an Argentinean manufactured bovine bone graft (Synergy Bone Matrix) with a bovine bone graft recognized for its osteoconductive effects (Bio-Oss), on bone healing in an experimental model in rats. We created critical sized bone defects in rat tibiae and filled them with either one of the bovine bone grafts or control. Clinical responses, X-ray findings, bone mineral density, and histological parameters were evaluated. No abscess, encapsulation, suppuration or inflammation of lymphatic nodes were observed. Radiographically, all implants were amalgamated to the surrounding bony margins, suggesting proper healing. On the other hand, control tibiae exhibited no signs of recovery and remained either unfilled or showed fibrous tissue formation. No statistical differences were observed in BMC and BMD between tibiae filled with Synergy Bone Matrix or Bio-Oss. Histological analysis revealed particles of both bone grafts surrounded by laminar bone tissue indicating osteoconductivity, without any inflammatory sign. This preliminary study suggests that Synergy Bone Matrix, as well as Bio-Oss, present similar properties of biocompatibility and osteoconductivity. (AU)
Para prevenir la resorción post-exodoncia y preservar la integridad de los rebordes alveolares, se recomienda la colocación de injertos óseos en el momento de la extracción. Los injertos de hueso bovino son biocompatibles y osteoconductivos, permitiendo nueva aposición ósea por células osteoprogenitoras. Existen marcas internacionales de injertos de hueso bovino, pero resultan caros e incluso difíciles de adquirir. Por ello, la elaboración de biomateriales de alta calidad, nacionales, reduciría los altos costos de salud pública en odontología. En este estudio, se evaluaron y compararon los efectos de un injerto de hueso bovino fabricado en Argentina (Synergy Bone Matrix) versus un injerto de hueso bovino reconocido por sus efectos osteoconductivos (Bio-Oss), en el proceso de cicatrización ósea en un modelo experimental en ratas. Para ello, creamos un defecto óseo crítico en tibia de rata el cual se rellenó con uno de los injertos de hueso bovino o control. Se evaluó: respuesta clínica y radiográfica, densidad mineral ósea e histología. No se observaron abscesos, encapsulación, supuración o inflamación de los ganglios linfáticos. Radiográficamente, todos los implantes se integraron a los márgenes óseos circundantes, sugiriendo una cicatrización adecuada. Por el contrario, las tibias control no mostraron signos de recuperación con formación de tejido fibroso. No se observaron diferencias estadísticas en las BMC y BMD entre las tibias Synergy Bone Matrix o Bio-Oss. La histología reveló partículas de ambos injertos óseos rodeadas por tejido óseo laminar indicando osteoconductividad sin signos inflamatorios. Este estudio preliminar sugiere que Synergy Bone Matrix presenta propiedades similares de biocompatibilidad y osteoconductividad que Bio-Oss. (AU)
Subject(s)
Animals , Rats , Tibia/cytology , Biocompatible Materials/therapeutic use , Bone Resorption/prevention & control , Bone Transplantation/veterinary , Argentina , Radiology , Surgery, Oral , Bone Development , Bone Diseases, Developmental/chemically induced , Bone Diseases, Developmental/diagnostic imaging , Bone Density , Bone Transplantation/rehabilitation , Rats, Wistar/anatomy & histology , Rats, Wistar/surgery , Ketamine/administration & dosage , Acepromazine/administration & dosage , Lymph Nodes/diagnostic imagingABSTRACT
Abstract The aim of this study was to analyze the biological behavior and osteogenic potential of magnesium (Mg) substituted hydroxyapatite (HA) microspheres, implanted in a critical bone defect, considering that this ion is of great clinical interest, since it is closely associated with homeostasis and bone mineralization. For the purpose of this study, 30 rats were used to compose three experimental groups: GI - bone defect filled with HA microspheres; GII - bone defect filled with HA microspheres replaced with Mg; GIII - empty bone defect; evaluated at biological points of 15 and 45 days. The histological results, at 15 days, showed, in all the groups, a discrete chronic inflammatory infiltrate; biomaterials intact and surrounded by connective tissue; and bone neoformation restricted to the borders. At 45 days, in the GI and GII groups, an inflammatory response of discrete granulomatous chronic type was observed, and in the GIII there was a scarce presence of mononuclear inflammatory cells; in GI and GII, the microspheres were seen to be either intact or fragmented, surrounded by fibrous connective tissue rich in blood vessels; and discrete bone neoformation near the edges and surrounding some microspheres. In GIII, the mineralization was limited to the borders and the remaining area was filled by fibrous connective tissue. It was concluded that the biomaterials were biocompatible and osteoconductive, and the percentage of Mg used as replacement ion in the HA did not favor a greater bone neoformation in relation to the HA without the metal.
Resumo O objetivo deste estudo foi analisar o comportamento biológico de microesferas de hidroxiapatita (HA) substituída com magnésio (Mg) durante o reparo de defeito ósseo crítico, tendo em vista que este íon é de grande interesse clínico, pois está intimamente associado à homeostasia e à mineralização óssea. Para tanto, utilizou-se 30 ratos para compor três grupos experimentais: GI - defeito ósseo preenchido com microesferas de HA; GII - defeito ósseo preenchido com microesferas de HA substituída com Mg; GIII (controle) - defeito ósseo vazio; avaliados nos pontos biológicos de 15 e 45 dias. Os resultados histológicos evidenciaram, aos 15 dias, discreto infiltrado inflamatório crônico e neoformação óssea restrita às bordas, em todos os grupos. Nos grupos GI e GII, os biomateriais mantiveram-se íntegros e circundados por tecido conjuntivo frouxo. Aos 45 dias, notou-se resposta inflamatória do tipo crônica granulomatosa discreta nos grupos GI e GII, e no GIII presença escassa de células inflamatórias mononucleares. As microesferas implantadas no GI e GII mantiveram-se, em sua maioria, íntegras e envolvidas por tecido conjuntivo fibroso. Notou-se discreta neoformação óssea próxima às bordas e circunjacente a algumas microesferas. No GIII, a mineralização limitou-se às bordas e a área remanescente foi preenchida por tecido conjuntivo fibroso. Conclui-se que os biomateriais foram biocompatíveis, bioativos, osteocondutores e apresentaram biodegradação lenta, indicando seu grande potencial para em aplicações clínica como biomaterial de preenchimento.
ABSTRACT
PURPOSE: This study aims to validate the effect of autoclaved autogenous bone (AAB), incorporating Escherichia coli-derived recombinant human bone morphogenetic protein-2 (ErhBMP-2), on critical-sized, segmental radius defects in rabbits. Delivery systems using absorbable collagen sponge (ACS) and fibrin glue (FG) were also evaluated. METHODS: Radius defects were made in 12 New Zealand white rabbits. After autoclaving, the resected bone was reinserted and fixed. The animals were classified into three groups: only AAB reinserted (group 1, control), and AAB and ErhBMP-2 inserted using an ACS (group 2) or FG (group 3) as a carrier. Animals were sacrificed six or 12 weeks after surgery. Specimens were evaluated using radiology and histology. RESULTS: Micro-computed tomography images showed the best bony union in group 2 at six and 12 weeks after operation. Quantitative analysis showed all indices except trabecular thickness were the highest in group 2 and the lowest in group 1 at twelve weeks. Histologic results showed the greatest bony union between AAB and radial bone at twelve weeks, indicating the highest degree of engraftment. CONCLUSION: ErhBMP-2 increases bony healing when applied on AAB graft sites. In addition, the ACS was reconfirmed as a useful delivery system for ErhBMP-2.