To observe the collagen-hydroxylaptite composite in the repair of bone defect, ten minipigs were chosen to make a mandibular dafect measuring 2 cm in diameter and the composite was implanted, while the use of autogenous bone graft and the blank wese served as control. On the 4, 8, 12, 24 and 48 weeks after the operation, the animals were sacrificed and the samples were examined under light microscope. The result showed that: no infection or necrosis occurred. The composite coalesced with host bone and the outcome was similar to that of the autogenous bone graft. No foreign body giant cells or vacuum left from osteonecrosis was observed. It was suggested that the composite had the advantage of abundant supply, easy to handle and no harm. The biocompatibility was good and might be hopeful as a bone substitute.
In order to investigate the stability of Hydroxyapatite (HA) coated material, the plasma-sprayed coatings of HA were divided into four groups: 1. Keeping in water vapour at 125 degrees C, with a pressure of 0.15 MPa for 6 hr; 2. Heating at 650 degrees C in air for half an hr; 3. Keeping in water vapour at 490 degrees C, with a pressure of 0.01 MPa for 2 hr; and 4. The control. The XRD, FTIR analysis and the dissolution test were carried out. The results showed: 1. The degree of crystalization in XRD analysis was 3. gt; 1. gt; 2. gt; 4.; 2. The ampitude of OH- peak in FTIR analysis was 3. gt; 1. gt; 2. gt; 4. and 3. The dissolution rate in tris-HCl buffer was 3. lt; 1. lt; 2. lt; 4. The conclusions were 1. The treating with water vapour could decrease the transformation temperature which was needed to convert the amorphous phase into cystalline phase; 2. Water vapour treatment could accelerate the transformation of Z-TCP, TCPM into crystalline HA; 3. Water vapour treatment could promote the structural integrity of plasma--sprayed coated of and HA and 4. Water vapour treatment could lower the dissolution rate of HA coated in Tris-HCl buffer.
Abstract To restore the bone defect after curettage of bone cyst, hydroxyapatite bioactive microcrystal glass (HBG) was used. From 1990 to 1995, HBG was applied in 17 cases. The bone involved were humerus, femur, tibia and fibula. Among them, 6 were complicated with pathological fracture. After eradication of the focus, the cyst was filled in ZnCl2 powder and irrigated with saline, then particles or segments of HBG were implanted into the cavity. The fracture were fixed with Enders rod. All the extremities were immobilized with plaster splint for about 6 to 8 weeks. Three months later, the lower limbs began to have functional exercises. By X-ray examination, the border between HBG and bone was clear in 2 weeks, after 1 month the clear border become blurred, and 2 months after operation, HBG was intermingled with bone. After 1 year there was neither absorption of bone nor HBG. No recurrence of the aptic lesion occurred in 1 year. HBG was a kind of artificial bone composed of hydroxyapatite and bioactive microcrystal glass, the latter contained silicon.It was characterized by its bioactivity, osteoinductivity and good tissue compatibility. The microcrystal would facilitate the growth of osseous tissues, which caused HBG intermingled with the surrounding bone. The source of HBG was abundant. It might be an ideal artificial bone.
Objective To evaluate the biocompatibility and safety of a novel orthopedics materials-graded zirconia(ZrO2)hydroxyapatite(HA) composite biomaterials. Methods First, ultrafine powers of ZrO2 and HA powder were prepared by chemical precipitation method, then graded ZrO2-HA composite was synthesized by dry-laying and sintering method. After the physiological saline and culture medium extracts of the composite were prepared, four experiments were conducted as follows:① The mouse acute toxic test consists of 2 groups(n=10). The extracts were intravenously injected to mice in the first group, and physiological saline to mice in the second group. The dose was 50 g/kg. Their toxicity manifestation, morality and the change of weight were recorded.② The standard curve of proliferation and metabolism of L929 cells was established. ③ The cytotoxinic test consists of 3 groups: materials group (extracts of the materials), positive control group (culture fluid with 0.64% phenol), and negative control group (RPMI-1640 culture fluid). Each of three was cultured with cell suspension, and then the morphology of the cells was observed, the relative proliferation rate (RGR) was calculated, and the toxicity was classified. ④ In vitrohemolytic test was divided into 3 groups: extracts, sterile distilled water (positive control) and 0.9% physiological saline. In each of three, 0.2 ml anticoagulant diluted fresh rabbit blood was added. The percentage of hemolysis was tested. ⑤ The muscle and implantation test were divided into 4 groups(n=3). The composite biomaterials were implanted into pygal muscleson either side and lateral condyles of femurs. After surgery, the rats of four groups were sacrificed at 12 and 24 weeks respectively.Tissue slice and scanning electronic microscopy were performed. Results General acute toxic test: no mouse died within 3 weeks; no toxicity symptom or adverse effects were shown within 3 days. The weight of materials group increased by 3.57±0.49 g, and the control group by 3.62±0.61 g, showing no statistically significant difference（Ρgt;0.05）.The standard curve of L929 cell perliferation and metabolism showed that their existed a positive correlation between the number of L929 cells and the perliferation. ③ Cytotoxinic test: cytosomes in the positive control group diminished and appeared round, there were pyknotic nucleus, the attached cells agglomerated; the toxicity was level Ⅳ. The morphology of cells in materials groupand negative control group was normal, and the number of them increased; the toxicity was level Ⅰand level 0, respectively. The MTT color experiments showed that positive control group was significantly lower than materials group and negative control group, showing statistically significant difference (Plt;0.01); there was no statistically significant difference between materials group and negative group.④ Hemolytic test: in vitrohemolytic rate of negative control group was0, of positive control group was 100%, and of materials group was 1.66%, which accords with the standard that hemolytic rate should be lower than 5% specified in ISO. ⑤ Implant test:No apparent rejection reaction took place after the composite was implanted; the composite bonded with the bones of the receptors firmly, which had good bonedinduced effect. Conclusion Graded ZrO2-HA composite bioceramic has good biocompatibility and is suitable for orthopedic biomaterials.
Objective To investigate and compare the osteogenic potential of three kinds of calcium phosphate ceramic as carriers for recombinant human bone morphogenetic protein-2(rhBMP-2) in vivo.Methods BCPceramics (HA,TCP,HA/TCP) impregnated with rhBMP-2 (experimental groups) and without rhBMP-2(control groups) were implanted into 6 muscles pockets on the dorsum of 3month-old Wistar rabbits. The rabbits were sacrificed 2, 4 and 8 weeks after implantation and bone induction was estimated by alkaline phosphatase(ALP) activity measurement. The implants were also examined histologically and histomorphometrically by HE staining and computerized graphical analysis. Results The ALPactivity of implants withrhBMP-2 was higher than that of control groups(P＜0.05), but there was no difference between 2 and 4 weeks in experimental groups. In all experimental groups,theimplants exhibited that new bone formation increased with the lapse of time. The amount of new bone formation is more in -HA/rhBMP-2 group than in the other two group in the 2nd and 4th weeks, but there was no difference between them (P＞0.05).In the 8th week, the amount of bone formation was most in HA/TCP with -rhBMP-2, and was more than that in the 2nd and 4th weeks. Whereas in control groups, there was only fibrous connective tissue. Conclusion HA/TCP- is a good carriers of rhBMP-2 and can be used as bone substitutes clinically.
Repair of bone defect by compound of bone morphogenic protein (BMP) and its prior bone matrix gelatin (BMG) was compared with repair by BMP with hydroxyapatite(HA). The results showed that the BMP/BMG group was found fibrous callus in the bone defect in 4th week. In 8th week a large quantity of osseos trabecula was found. In 12th week the BMP was absorbed completely and was replaced by newly formed bone. In 16th week the recanalization appeared in the bone cavity. While in the BMP/HA group, although the fibrous callus was appeared in the 4th and 8th weeks, the HA was not absorbed. In the 12th and 16th weeks the change was similar to that in the 8th week and no recanalization of bone marrow cavity. It was suggested the BMP/BMG compound might be an ideal material to repair the bone defect.
AbstractThe implantation of combined hydroxyapatite (HAP) and autogenous red bone marrow (BM) was used to repair bone defect resulting from fibrodysplasia of bone in one case. After one year, the specimen was studied under optical and electronic scanning microscopes in order to study the biological features, histological changes and osteogenesis of hydroxyapatite implanted in the body. The results showed that there was not any inflammatory, toxic, or immune reaction in the tissue surrounding HAP-BM, and that HAP implanted was almost completely replaced by newly formed bone, and was firmly united to the surrounding bony tissue. This indicated that in the body HAP had a good biocompatibility and that HAP-BM provided the scaffold for osseous ingrowth as wellas boneinduction substances. The whole result was to that of the autogenous bone graft.
Bovine bone morphogenetic proteingelatin-hydroxyapatite (bBMP-G-HA) was prepared and its efficacy in bone repair of the diaphyseal defects of radii of rats was studied. The results suggested that bBMPG-HA was osteogenetic and capable of being resorbed, and might be used clinically as a new substitute for bone graft.
Objective To investigate the influence of different dose levels of hydroxyapatite/tricalcium phosphate (HA/TCP) on the proliferation and alkalinephosphatase (ALP) activity of rabbit osteoblasts. Methods Three different doselevels of HA/TCP (10%, 40%, 70%) were co-cultivated with rabbit osteoblasts respectively. The proliferation and ALP expression capacity of osteoblasts were examined with MTT method and enzyme histochemistry once every 24 hours until 5 days. Three control groups of other materials were treated and examined in the sameway: rabbit osteoblasts as normal control; polyvinylchloride as positive control; titanium alloy as negative control. Results There was remarkable timeeffect relationship in the proliferation of osteoblasts. Ten percent HA/TCP did not affect osteoblasts growth while 40% HA/TCP could slow the cell growth rate down though time-effect relationship still existed. The proliferation of osteoblasts stagnated when co-cultivated with 70% HA/TCP. On the other hand, 10% HA/TCP could cause reversible damage on ALP activity of osteoblasts, whereas when the dose was40%, and the cultivation lasted 6 days the damage was irreversible. Three different dose levels of titanium alloy (10%, 40%, 70%) had no effect on the proliferation or ALP activity of osteoblasts. Conclusion Dosage is an important factor affecting the biocompatibility evaluation of biomaterial. It suggests that dose choosing should be more specified upon each individual biomaterial. It also indicates that ALP may be a good supplementary index of the cell compatibility of material.
OBJECTIVE To confirm membrane-guided tissue regeneration in the healing course of segmental bone defects and study the mechanism. METHODS Segmental, 1 cm osteoperiosteal defects were produced in both radii of 12 rabbits. One side was covered with hydroxyapatite/polylactic acid(HA/PLA) membrane encapsulated as a tube. The contralateral side served as an untreated control. Healing courses were detected by radiographic and histologic examinations. RESULTS All control sides showed nonunion, whereas there were consistent healing pattern in test sides. CONCLUSION Membrane technique can promote bone regeneration.