Enhancement of bone volume in guided bone augmentation by cell transplants derived from periosteum: an experimental study in rabbit calvarium bone

Bone morphology is genetically encoded and it is usually difficult to change its structure without invasive surgery. We have tried to stimulate bone augmentation by a combination of guided bone regeneration techniques and cell transplants with collagen scaffolds for the suitable skeletal framework. In vitro-expanded tibia periosteum cells were used to promote osteogenesis with collagen scaffolds and titanium (Ti) or poly-L-lactic acid (PLLA) caps as barriers to create a space facing connective tissue under calvarium skin. This approach was assessed in the defective skull bone of a rabbit model. After a 12-week healing period, histomorphometric analyses were performed to determine the percentage of newly formed mineralized tissue in the cap. The mean percentage of newly formed mineralized tissue within the cap was 15.4%+/-3.99 for the Ti cap group, 15.5%+/-4 for the PLLA cap group, 6.19%+/-4.94 for the PLLA cap+collagen carrier group and 23.1%+/-23.1 for the PLLA+collagen carrier+cell transplants group. The cell transplant group showed a significantly higher value than other groups (P<0.05, Wilcoxon signed rank test, Mann-Whitney U-test). This approach of guided bone augmentation and cultured cell transplants with collagen carrier exhibited significantly greater morphogenesis of mineralized tissue than the control over a 12-week experimental period.     

利用兔胫骨干骺端骨缺损模型对骨代用品研究的实验方法探讨

目的：探讨利用兔胫骨干骺端骨缺损模型在研究骨代用品成骨效能,降解反应中的优缺点。方法：制备兔胫骨干骺端骨缺损模型,放入骨代用品,一定时间点后取样。作放射学,组织形态学及荧光染色观察。结果：通过放射学,组织形态学及荧光染色观察,利用该模型可清楚地观察到骨代用品的成骨能力及降解特性。结论：采用兔胫骨干骺端骨缺损模型,解剖部位相对恒定,能提供足够的空间反映出骨代用品的成骨效能及降解反应。     

Studies on dentin grafts to bone defects in rabbit tibia and mandible; development of an experimental model

Abstract – Background and Aim: Dentin contains bone morphogenic protein which is important in bone induction and dentin can act as a slow releasing carrier. This property may possibly be used as an alternative or supplement to bone grafting to defective areas after trauma prior to treatment with osseointegrated implants. Hence, the objective of this study was to investigate if dentin can be used as a graft in bone defects in an experimental rabbit model. Materials and Methods: Eight New Zealand White Rabbits were used to prepare bone cavities either in the angle of the mandible or tibia. Six of the eight tibial and six of the eight mandibular bone defects were filled with dentin blocks from human premolars which were extracted for orthodontic treatment. Two mandibular and two tibial bone cavities were used as controls and all the rabbits were sacrificed after 3 months. Radiographic and histological examinations were performed. Results: There was a difference in healing pattern between the mandibular and tibial defects. In the mandible, the dentin blocks were resorbed to a larger extent and more often surrounded by fibrous tissue, probably due to the fact that the dentin blocks were mobile because of the thin mandibles and muscular activity in that area. Only some dentin blocks were ankylosed with the mandibular bone. In the tibia however, all dentin blocks were fused to bone over a large area. Osseous replacement resorption was seen. In control cavities, bone formation was seen but was never complete. No signs of inflammatory changes were seen in any fused grafts. Conclusions: Dentin grafts have a potential to be incorporated in bone without inflammation and can be used as bone inducer and later replaced by bone. Thus, rabbit tibia served as a better model for further studies of this phenomenon when compared to the mandible.     

Comparison between combined cortical and cancellous bone graft and cancellous bone graft in alveolar cleft: Retrospective study of complications during the first six months post-surgery

BackgroundIn patients with alveolar cleft, alveolar bone graft is usually performed before the permanent maxillary canine or incisor eruption and using cancellous bone harvested from the iliac crest. The authors sought to compare the early complication rate in patients who received cancellous bone graft alone and cortical bone graft in addition to cancellous bone to reconstruct the nasal floor.MethodsFor this observational, retrospective, monocentric study, patients with alveolar cleft who underwent autologous alveolar bone graft and gingivoperiosteoplasty at Montpellier Hospital were divided into two groups: group A, who had cortical and cancellous bone graft; and group B, who had only cancellous bone graft. Both groups were followed for 6 months after surgery, and complications were recorded.ResultsIn total, 319 grafts (group A, 163; group, 156) were performed from June 1999 to May 2016. The major complication rates were 8% and 5.8% in group A and B, respectively, and were not significantly different (p = 0.52). Similarly, the rates of minor complications and of donor site morbidity were not different between groups.ConclusionsThis preliminary study shows that adding a cortical bone graft for the nasal floor reconstruction does not increase the risk of complications in 6 months following the graft. Long-term benefits such as alveolar height and a piriform aperture symmetrisation will have to be analysed to study the contribution of the technique.     

兔下颌骨来源骨髓间充质干细胞的体外培养及鉴定

目的:探讨兔下颌骨来源的骨髓间充质干细胞(BMMSCs)体外分离、培养并对下颌骨来源的BMMSCs进行鉴定.为骨组织工程提供种子细胞.方法:取兔下颌骨中的骨松质,采用密度梯度离心法分离单个核细胞,贴壁培养,取P2或P3代BMMSCs进行检测.倒置显微镜下观察细胞形态;MTT法测定细胞增殖并绘制细胞生长曲线;克隆形成实验计算克隆形成率;向成骨细胞、脂肪细胞、骨骼肌细胞多向诱导分化;流式细胞仪检测细胞表面抗原标记.采用SPSS16.0软件包对数据进行统计学分析.结果:细胞经传代后形态一致,呈梭形或三角形;细胞生长曲线显示,下颌骨BMMSCs经历潜伏期、对数生长期和平台期;克隆形成率为37％;成骨及成脂诱导形成钙结节及脂滴,茜素红及油红O染色呈阳性;成骨骼肌诱导desmin抗原标记阳性;流式细胞仪检测结果显示,所获得的下颌骨BMMSCs纯度较高.CD90和CD146表面标记阳性率分别为98.7％、98.1％.结论:从兔下颌骨分离的BMMSCs纯度较高,有强大的自我复制、增殖特性和体外多向诱导分化潜能,有望成为骨组织工程的种子细胞.     

Allogeneic bone grafting of calvarial defects: an experimental study in the rabbit

The purpose of this study was to investigate the incorporation of fresh frozen irradiated membranous allogeneic bone grafts into critical size calvarial defects in the rabbit. Fifteen rabbits had calvarial defects prepared. Twelve rabbits received allogeneic grafts and three received autogenous bone grafts. The rabbits were sacrificed at 9 and 12 months postoperatively, and the specimens were examined radiologically, histopathologically and with fluorescence microscopy. Neovascularization, bone marrow regeneration and new bone formation was evident throughout the grafts however revitalization of the entire graft was incomplete at 12 months. This study revealed that the FFI membranous grafts were well incorporated into rabbit calvarial defects.     

髂骨松质骨移植修复牙槽嵴裂21例临床分析

目的:分析影响牙槽嵴裂修复术后效果的因素.方法:对2003-2007年收治的21例牙槽嵴裂患者,采用髂骨松质骨移植修复,术后随访3～12个月,拍摄X线片,分析患者年龄、裂隙类型、手术方法以及植骨来源对手术效果的影响.结果:①手术成功率为95.24%.临床成功率为90.48%;②植骨效果与植骨年龄有关;③单侧牙槽嵴裂手术成功率优于双侧牙槽嵴裂.结论:①手术年龄以9～11岁尖牙萌出前较为合适,年龄越小,植骨成功的可能性越大;②髂骨是良好的供骨源;③良好的植骨床形成、创口的无张力严密缝合是手术成功的关键.     

Evaluation of an anorganic bovine-derived mineral with P-15 hydrogel bone graft: preliminary study in a rabbit cranial bone model

Objectives: The present investigation aimed to assess the bone‐regenerative potential of two formulations of anorganic bovine‐derived mineral bound to a P‐15 (ABM/P‐15) bone graft – the particulate and the hydrogel forms – in a delayed healing rabbit cranial defect model. Material and methods: Ten adult male New Zealand White rabbits were used to create two 8 mm transcortical cranial defects per rabbit and each one received randomly the test material (ABM/P‐15 carboxymethyl cellulose (CMC)‐hydrogel graft), the standard control material (ABM/P‐15 particulate graft) or remained empty as a negative control. The defects were allowed to heal for 2 and 4 weeks. Qualitative and quantitative histological outcomes were assessed on undecalcified sections. Results: In the defects grafted with the test material, at both time points, there was a marked random migration of the bone substitute particles. As a consequence, the space maintenance provision was lost and new bone formation was reduced compared with the control particulate graft material. The histomorphometric analysis showed that the control material attained better results, with an average of 13.8 ± 1.9% and 18.2 ± 4.4% of new bone at 2 and 4 weeks, compared with 8.5 ± 2.4% and 13 ± 2.9% for the test material. These differences were significant at 2 weeks (P≤0.05), but not at 4 weeks (P>0.05). Additionally, there was a significant difference in the total area of mineralized tissue (new bone plus particles), favoring the standard control over the test material: 43.2 ± 14.4% vs. 14.2 ± 5.3% at 2 weeks and 56.9 ± 4.2% vs. 24.2 ± 9.6% at 4 weeks, respectively. Conclusions: The test ABM/P‐15 CMC‐hydrogel graft material behaved in this animal model by migration of the graft particles, what determined an unpredictable osseoconduction and, consequently, a decreased quality and quantity of bone regeneration as compared with the osseopromotive behavior exhibited by the standard particulate form of the ABM/P‐15 control graft. It is therefore suggested to restrain the application of the hydrogel graft form in non‐contained anatomical bone defects.     

Anisotropic elastic properties of cancellous bone from a human edentulous mandible

The elastic moduli have not been reported for cancellous bone from the edentulous mandible. Accurate values are needed for finite element modeling of the mandible. The aim of this study was to determine elastic modulus values in three orthogonal directions for cancellous bone taken from an edentulous jaw and to relate these values to apparent density and volume fraction. Seven samples were obtained from the edentulous mandible of a 74-year-old female. Young's modulus was determined by compression testing of cubes cut with the faces aligned with the anatomic axes. Bone volume fraction averaged 0.33 (SD 0.14) and apparent density averaged 0.55 g/cc (SD 0.29). Young's modulus was greatest in the mesio-distal direction (mean 907 MPa, SD 849 MPa), followed by the bucco-lingual (mean 511 MPa, SD 565 MPa) and infero-superior direction (mean 114 MPa, SD 78 MPa). The infero-superior direction was less than the bucco-lingual (P = 0.03) and mesio-distal (P = 0.002). The mesio-distal and bucco-lingual directions could not be shown to be different (P = 0.32). This suggests a model of transverse isotropy for cancellous bone in the jaw, where the symmetry axis is along the infero-superior (weakest) direction.     

Autologous cranial particulate bone graft: an experimental study of onlay cranioplasty

The purpose of this study was to determine whether particulate bone graft maintains its volume when used for onlay cranioplasty. Twenty-five adult, male, New Zealand white rabbits were divided into 5 groups (n = 5/group). Groups 1 to 3 were controls: group 1, untreated; group 2, sham procedure; and group 3, burring the cortical surface. Group s 4 and 5 had augmentation of the parietal bones with particulate graft harvested from the frontal bone with a brace and bit. The particulate graft was placed on native parietal bone (group 4) or on parietal bone that had been abraded to punctuate bleeding with an electric burr (group 5). Volume maintenance and osseointegration of the grafts were determined by micro-computed tomography and histology. At 16 weeks postoperatively, the mean (SD) volumes of the parietal bones in control groups 1, 2, and 3 were 555.8 (29.2), 550.8 (36.8), and 539.0 (39.0) mm, respectively. Immediately after cranioplasty, the mean (SD) volumes of augmented parietal bone were 846.0 (10.8) mm for group 4 and 831.8 (11.8) mm for group 5. Sixteen weeks postoperatively, 100% of the group 4 grafts had resorbed (551.8 [SD, 24.0] mm), and parietal volume was no different from controls (P = 0.89). Group 5 maintained 54.2% of volume (695.6 [SD, 22.0] mm), which was greater than those of the controls (P < 0.0001). Particulate graft may be used for onlay cranioplasty if the recipient site is burred. Approximately one half of the onlay graft is resorbed, and its original shape is not maintained.     

Early revascularization of membranous inlay bone graft in canine mandible model

The early revascularization of a membranous inlay bone graft in a canine mandible was investigated using bone scans and histological examinations. Eight 5-month-old mongrel dogs were used as the subjects. The inlay bone graft, a 1- x 2-cm critically sized bone, was completely separated from the lower border of the canine mandible and then refixed to the original site. Bone scans and histological examinations were performed in the first, second, third, and fourth postoperative weeks. The bone scan in the first postoperative week revealed radioisotope uptake on the margin of the grafted bone with an isotope count that was 21% of the normal bone uptake. In the second postoperative week, the radioisotope uptake in the grafted bone increased to 52% of the normal bone uptake. In the third and fourth postoperative weeks, the isotope uptakes were 111% and 124%, respectively. The histological findings in the first postoperative week showed an absence of osteoblastic activity and 6 viable blood vessels in a field magnified x 200, which was the equivalent of 25% of the vessels of the normal bone. In the second postoperative week, osteoblastic activity was noted, and the number of viable blood vessels increased to 15, that is, 63% of the vessels of the normal bone. In the third postoperative week, there was an increase in osteoblastic activity, and the number of viable blood vessels was 21, that is, 88% of the vessels of the normal bone. In the fourth postoperative week, there was a marked increase in osteoblastic activity with the number of vessels reaching 23, that is, 96% of the normal bone. In summary, revascularization of the membranous inlay bone graft began within the first week after the bone graft and thereafter gradually increased. In the third postoperative week, revascularization returned to a near-normal value compared with the value of the adjacent normal mandibular bone.     

Repair of the extracranial facial nerve defect by autogenous vein graft: an experimental study]

In this study, we repaired the extracranial facial nerve defect of rabbit using an autogenous vein graft and compared the results with conventional autogenous nerve graft in function and morphology. A 1 cm segment of the extracranial morphology. A 1 cm segment of the extracranial facial nerve was removed in 30 rabbits, the defect was repaired by a segment of vein or by a segment of nerve or without repair. The gross observation, histologic and histochemical examination, electrophysiological study and nerve fascicle graphics analysis were performed at 4, 8, 12, 20 weeks. The results of this study demonstrated that an autogenous vein as a non-nervous tissue graft can repair the extracranial facial nerve defect. 20 weeks after operation, the results with vein graft were superior to nerve graft.     

Evaluation of bone response to various anorganic bovine bone xenografts: an experimental calvaria defect study

This in vivo study investigated the in vivo performance of two newly developed synthetic bone substitutes and compared them to commercially available xenografts (Bio-Oss, Geistlich Pharma AG, Switzerland; OsteoGraf, Dentsply, USA). The materials were tested in a rabbit calvaria model, and the bone forming properties were observed at 4 and 8 weeks after implantation by means of histomorphometry and micro computed tomography (micro-CT). Defects without any graft material were used as negative controls. Micro-CT showed that all materials tested presented new bone formation that filled the defects at both time points, whereas the negative control presented less bone formation, with soft tissue infiltration into the defects. Comparable bone fill percentages were observed for histomorphometric and micro-CT results. Even though no statistically significant difference was found quantitatively between all of the bone graft substitute groups, a higher mean decrease in graft material filling the defects, along with higher remodelling activity, was evident for the experimental materials compared to the commercially available xenografts at 8 weeks. The results indicate that the experimental materials possess high degradability, along with osteoconduction comparable to commercially available xenografts.     

Intramembraneous bone tissue responses to calcium sulfate: an experimental study in the rabbit maxilla

Objectives: The purpose of this study was to histologically examine the responses of intramembraneous bone to calcium sulfate (CaS) and evaluate the resorption and replacement process. Material and methods: Fourteen rabbits were used in this study. Defect healing without any filling material was compared with CaS. Five millimetres wide and 4 mm deep defects were drilled with a trephine bur on both sides of the edentulous space between the incisors and the molars. Test vs. control sites were randomly selected and thereby compared in each animal. The animals were killed after 2, 4 and 8 weeks for histological examination. Results: After 2 weeks, the specimens showed a great extent of degradation of CaS. No signs of the material could be seen after 4 and 8 weeks. There were no statistically significant differences in bone regeneration between the test and control sites within the 8 weeks group in this study. However, there was tendency of more blood vessels in the test sites after 4 weeks of healing. Conclusion: The present study showed that CaS does not interfere with intramembraneous bone healing. In this animal model, the CaS exhibited resorption/degradation early in the healing process while seemingly stimulating angiogenesis. However, there was no significant increase in bone regeneration in the sites treated with CaS during an 8 week period of healing and observation time, as compared with a control defect. To cite this article:
Dasmah A, Sennerby L, Rasmusson L, Hallman M. Intramembraneous bone tissue responses to calcium sulfate: an experimental study in the rabbit maxilla.
Clin. Oral Impl. Res. xx , 2011; 000–000.
doi: 10.1111/j.1600‐0501.2010.02129.x     

Transplantation of free tibial periosteal graft on alveolar bone defect in adult rabbit

The healing of bone defect in eight adult rabbits was studied. The age range of animals was 5-23 months. The bone defects were made symmetrically in the inferior surface of the mandibles. At the defect site the root surface of continuously erupting mandibular incisors was exposed. On the left side, the bone defect was covered with a local periosteal flap (control side) and on the right side the defect was covered with a free periosteal graft from the tibia (test side). The healing of bone defects and the amount of new bone were studied. The quality of the bone formed was investigated histologically. The findings of this investigation led to the following conclusions: (1) The bone defects healed on both sides. The amount of bone on the control side was identical to that in the anatomical region. On the test side the amount of bone formed was in seven cases two to threefold that formed on the control side. (2) The histological study proved that the bone formed was lamellar bone, being identical on both the control and the test side. (3) The ages of the animals or the length of follow-up time did not affect the amount of new bone, the healing of the defect or the quality of new bone. (4) The eruption of the incisors was symmetrical. In this study the free periosteal graft from the tibia led to better bone formation than the local periosteal flap in the induced bone defects of the tooth-bearing region in the mandible of the adult rabbit.     

The effect of heat on bone regeneration: an experimental study in the rabbit using the bone growth chamber

A dividable titanium implant that, after insertion in the tibial metaphysis of an experimental animal, permits a numerical estimation of ingrowing bone was used to evaluate the effects of a defined temperature rise on bone regeneration. Heating the test implants to 47 degrees C or 50 degrees C for 1 minute caused significantly reduced bone formation in the implants, while no significant effects were observed after heating to 44 degrees C for 1 minute. The results reflect the importance of controlling the heat produced during surgery to avoid impaired bone regeneration.