Osteopontin and bone metabolism in healing cranial defects in rabbits

Non-collagen proteins such as bone sialoprotein and osteopontin (OPN) form 10% of the extracellular bone matrix. In this study, the influence of OPN on bone repair was investigated. Human OPN (Innogenetics) was produced by a recombinant technique and bonded onto the surface of hydroxyapatite (Interpore 200). Thirty rabbits were divided into six equal groups. A circular defect (10mm) was prepared in each parietal bone. In four rabbits of each group the left and right defects were filled with either OPN-coated hydroxyapatite (OPN-HA) or non-coated hydroxyapatite (HA). One sham animal of each group received no implants. The animals were killed after 1, 2, 6, 12, 18 and 30 weeks. The histological sections were scanned and analysed digitally. There were no statistically significant differences in total bone formation between defects filled with OPN-HA and HA. Bone formation at the borders of the healing area was significantly higher in defects filled with OPN-HA than in those filled with HA. Less bone formation was noted in the OPN-HA and HA groups at the centre of the healing area than at the borders of the healing area and the dural area. Although some animals in the sham group showed a high level of bone formation in the dural area, this was not significantly different to that in the dural area of the other groups. There was no sign of infection or tissue rejection of the graft.     

Biomechanical evaluation of rat skull defects, 1, 3, and 6 months after implantation with osteopromotive substances

PURPOSE: To compare the mechanical strength of surgically created and healed rat calvarial defects having been filled with three different osteopromotive substances: hydroxyapatite, intramembraneous demineralised bone matrix (DBM), and autogenous bone chips. MATERIAL: Sixty adult male Wistar rats were divided into three groups of 20 animals, each group representing healing times of one, three, or six months. METHODS: Identical 5mm bilateral critical size defects were trephined into the parietal bones and hydroxyapatite, DBM, or autogenous bone chips were implanted into the defects, or left as unfilled controls. The repaired defects were evaluated biomechanically using a modified punch out test 1, 3, or 6 months postoperatively. RESULTS: The maximum load carried in the DBM group was significantly higher than in the bone chips, hydroxyapatite, and control groups after one month of healing. The mean bone strength did not increase significantly after the first month of healing in any of the groups. The DBM group showed a significantly higher load to failure than the other groups at all three observation periods. The mean maximum load to failure of the bone chips and hydroxyapatite groups was slightly higher than in the control group; however the difference was not statistically significant. None of the control experimental bone defects demonstrated any bone formation. CONCLUSION: Defects filled with hydroxyapatite and bone chips were not significantly stronger than unfilled controls, whereas defects filled with DBM were significantly stronger than all other defects after 1, 3, and 6 months of healing.     

碳酸化羟基磷灰石支架及其细胞因子复合物修复鼠胫骨缺损的实验研究

目的:通过动物实验检测碳酸化羟基磷灰石支架材料(carbonated hydroxyapatite,CAP)的骨传导性和生物吸收性。并探讨骨形成蛋白-2(rhBMP-2)、重组人巨噬细胞集落刺激因子(rhM-CSF)对CAP成骨特性和生物吸收的影响。方法:选取45只雄性SD大鼠,制备双侧胫骨临界性骨缺损模型,以复合骨形成蛋白-2(rhBMP-2)的碳酸化羟基磷灰石支架材料、复合重组人巨噬细胞集落刺激因子(rhM-CSF)的碳酸化羟基磷灰石支架材料、单纯的碳酸化羟基磷灰石支架材料作为实验组,羟基磷灰石(hydroxyapatite,HAP)作为对照组,植入大鼠胫骨缺损处,并设立空白对照组。术后2、4和8周,通过组织学观察对比新骨形成和材料吸收降解情况。结果:实验组和对照组材料均能完全充填骨缺损,材料界面与骨组织结合紧密,显示了良好的生物相容性和成骨性能。随着植入时间的延长,实验组材料可逐渐降解并被新生骨爬行替代,而对照组未见显著降解和新生骨替代。rhM-CSF能够促进碳酸化羟基磷灰石材料的降解,与CAP组、CAP/rhBMP-2复合物组比较,差异有统计学意义。结论:CAP具有出色的骨传导性和生物吸收性,是一种良好的骨再生移植物。且该支架材料的成骨性和生物降解能够被成骨及破骨细胞因子所调控。     

辛伐他汀4种给药方法影响大鼠骨缺损愈合的实验研究

目的探讨辛伐他汀的4种给药方式对骨缺损愈合的影响。方法在40只SD大鼠胫骨上建立3mm的骨缺损模型，械侧缺损部位不作处理设为空白对照组、右侧分别给予单纯骨粉修复（A组）、单纯骨粉修复加局部注射辛伐他汀（B组）、局部骨粉复合2.5％辛伐池汀（C组）和骨粉复合15.0％辛伐他汀（D组）修复。术后第4周、8周分别处死各组大鼠，观察骨缺损区成骨情况，结果C组局部愈合正常，无破溃及组织反应，缺损处骨量和骨密度增加明显（比A组高32％．P〈0.05），镜下成骨细胞多，纤维组织最少，整体愈合效果最佳；而B组和D组局部都有破溃及类排斥反应性奶酪状分泌物，缺损局部骨量及骨密度与A组相比没有明显增加（P〉0.05）．炎性细胞及纤维组织较多．个别大鼠局部发生骨折。A组骨密度较空白组高，未见局部有破溃和组织反应，缺损侧胫骨未见完全骨折。而空白组缺损未完全骨性愈合．局部皮肤无破溃及类排除反应．部分大鼠局部发生骨折，结论骨粉复合一定浓度的辛代他汀对正常大鼠的胫骨缺损愈合有促进作用。     

The effect of a biphasic ceramic on calvarial bone regeneration in rats

Bioactive ceramics (calcium phosphate ceramics, hydroxyapatite ceramics) are now extensively used in oral surgery. The purpose of this study was to assess the effect of a new biphasic ceramic (Ceraform) on the osteogenesis in a rat calvarial defect model. Fifteen Wistar rats were used in this study. Two symmetrical 3-mm wide defects were created in the skull of each rat. The left defect was left empty as a control and the right defect was filled with the ceramic. The rats were sacrificed at day 30, and the calvarial specimens were processed for qualitative and quantitative histological examinations. The material exhibited no adverse effects, but no bone healing was noted either. No statistical difference regarding bone regeneration was observed between the 2 defects (P > .05). This study showed that Ceraform did not elicit any inflammatory reaction; however, it had no effect on bone regeneration, and this material seems suitable only as a space-maintaining material.     

Histomorphometric evaluation of bone regeneration using allogeneic and alloplastic bone substitutes.

PURPOSE: The purpose of this investigation was to assess bone regeneration in critical sized defects in the rabbit calvarium using allogeneic and alloplastic bone substitutes. MATERIALS AND METHODS: Thirty New Zealand White rabbits were divided into 3 groups of 10 animals each. Bilateral 15 mm x 17 mm calvarial defects were made in the parietal bones of each animal. Group 1 had demineralized bone matrix (DBM) gel placed in one defect, while the other defect was left unfilled and served as the control. Group 2 had one defect filled with calcium hydroxide (CaOH)-treated DBM gel and the other defect filled with DBM gel. Group 3, the calcium-phosphate cement group, had Norian CRS (Norian Corp, Cupertino, CA) placed on one side and Bone Source (Howmedica Leibinger, Dallas, TX) placed on the contralateral side. Five animals in each group were killed at 6 and 12 weeks. Data analysis included qualitative assessment of the calvarial specimens and radiographic evaluation. Histomorphometric analysis was used to quantify the amount of new bone within the defects. RESULTS: Histomorphometric analysis showed that DBM gel-treated defects had significantly more new bone at 12 weeks compared with all other groups. There was no significant difference between defects filled with CaOH-treated DBM gel and those filled with DBM gel at 12 weeks. In group 3, Norian CRS- and Bone Source-treated defects were not statistically different from the unfilled controls. CONCLUSION: DBM gel was an effective allogeneic bone substitute that showed reliable osseous healing of critical size defects in the rabbit calvarium. The addition of CaOH to DBM gel did not significantly improve the bone regenerative capacity of the DBM gel. Both Norian CRS and Bone Source did not promote bone regeneration in this animal model.     

The use of hydroxyapatite and autogenous cancellous bone grafts to repair bone defects in rats

Bone grafts are frequently used in the treatment of bone defects. Bone harvesting can cause postoperative complications and sometimes does not provide a sufficient quantity of bone. Therefore, synthetic biomaterials have been investigated as an alternative to autogenous bone grafts. The objective of this study was to evaluate the repair of bone defects by autogenous cancellous bone grafts or porous bioceramic discs of hydroxyapatite/phosphate cement mixture. Two 5-mm diameter defects were made in the skulls of rats and filled with the bioceramic material or cancellous bone. The rats were sacrificed 2, 4, 8 and 24 weeks after surgery and tissue samples were analyzed by radiography and histology. By the 24th week, the defects filled with autogenous cancellous bone grafts or bioceramic material showed similar volumes of bone tissue within the defect. However, defects treated with bioceramic material were almost completely closed as a result of the joining of ceramic fragments and the neoformed bone tissue, while those filled with autogenous grafts showed several areas filled with connective tissue. These results indicated that the osteointegration of bioceramic fragments allowed the reconstruction of parietal bone defects without the need for a bone graft.     

Reconstruction of cranial bone defects using a quick-setting hydroxyapatite cement and absorbable plates

We examine the 6-month histology of a quick-setting hydroxyapatite cement (Mimix), with and without absorbable plates (LactoSorb), after placement in critical size defects made in the skull of 20 New Zealand white rabbits. Two 10-mm-diameter parietal defects were made in each rabbit. One defect was placed on each side of the sagittal suture. In 10 animals, the left defect was filled with Mimix alone, and in the other 10, an absorbable plate was placed across the base of the left defect before Mimix placement. The right-sided defect served as a control in all animals, with no material placed in or across this defect. The rabbits were killed 6 months postoperatively. A bone pathologist performed histologic examinations of the specimens looking specifically for evidence of inflammatory reaction and bone formation. There was no inflammation around the dura or any other negative histologic reaction in either the study groups or the control. Growth of new bone into the Mimix was found along the periphery in all specimens. We found no migration or displacement of the Mimix from any of the calvarial defects.     

Effect of GBR in combination with deproteinized bovine bone mineral and/or enamel matrix proteins on the healing of critical-size defects

OBJECTIVES: To evaluate the effect of guided bone regeneration (GBR) in combination with or without deproteinized bovine bone mineral (DBBM) and/or an enamel matrix derivative (EMD) on the healing of critical-size calvarial defects. MATERIAL AND METHODS: Forty rats were used. In all animals, a standardized critical-size calvarial defect was created surgically. The animals were randomly allocated into 4 groups of 10 animals each. Group A: One calvarial defect was left untreated, while the galeal and the cerebral aspect of the contralateral defect were covered with a bioresorbable membrane (GBR). Group B: One calvarial defect was filled with EMD, while the contralateral defect was treated with GBR and EMD. Group C: One defect was filled with DBBM, while the contralateral defect was treated with combination of GBR and DBBM. Group D: One defect was filled with DBBM combined with EMD, while the contralateral defect was treated with combination of GBR, DBBM and EMD. The healing period was 4 months. Five specimens from each group were macerated and the length, the width and the vertical dimension (thickness) of the remaining defect were evaluated by a stereomicroscope. The remaining specimens in each group were analyzed histologically. RESULTS: The defects of the macerated specimens that were left untreated or were treated only by EMD, DBBM and combination of EMD and DBBM did not present predictably complete healing of the defects. All the defects where GBR was applied alone or combined with DBBM and/or EMD presented always complete healing (P<0.05). The combined use of GBR with EMD and/or DBBM did not offer any significant advantage above GBR alone in terms of healing of the length and the width of the defect. However, the vertical dimension of the defect was significantly higher (P<0.05) in the GBR-treated specimens of Groups C and D. The histological analysis supported these findings. CONCLUSION: The predictability of bone formation in critical-size defects depends mainly on the presence or absence of barrier membranes (GBR). The combined use with deproteinized bovine bone mineral and/or enamel matrix proteins did not significantly enhance the potential for complete healing provided by the GBR procedure.     

Repair of cranial bone defects with calcium phosphate ceramic implant or autogenous bone graft

Autogenous bone grafts have frequently been used in the treatment of bone defects; however, this procedure can cause clinical complications after surgery. Besides, the amount of available bone is sometimes insufficient. Therefore, synthetic biomaterials have been researched as an alternative to autogenous bone graft implants. The objective of this study was to evaluate the repair of bone defects treated with compact autogenous bone graft or porous calcium phosphate ceramics. Three defects 3 mm in diameter were produced in the skull of 21 rats. One the defects was produced in the frontal bone, which remained empty, while the others were produced in the right and left parietal bones, which were filled respectively with ceramics and autogenous bone graft. The animals were sacrificed 1, 2, 4, and 24 weeks after surgery and analyzed by light microscopy and radiography. In the twenty-fourth week, the defects filled with autogenous bone graft and ceramics had similar volumes of newly formed bone tissue. The ceramics offered favorable conditions to bone tissue growth. Thus, we concluded that the calcium phosphate ceramic implant proved to be effective in repairing defects produced in the skull of rats.     

Calcium sulfate and PTFE nonporous barrier for regeneration of experimental bone defects

The aim of the study was to evaluate the possibility to obtain guided bone regeneration with two types of physical barriers (calcium sulfate and PTFE nonporous barrier) in surgical defects created in rat parietal bones. In the right parietal bone the calcium sulfate barrier filled out the whole defect and in the left parietal bone the barrier of PTFE was positioned in the floor and externally to the surgical defect. After 7, 14, 30 and 45 days four animals were sacrificed in each period and the bone containing the defects were submitted to the microscopic analysis. The results of the study revealed that the PTFE barrier was more effective for bone regeneration in shallow transcortical defects compared to the calcium sulfate. However, additional experiments are necessary to determine if calcium sulfate would be successful in other bone defects types or the use of the material under another consistence could complement the results obtained in this work.     

Lack of repair of rat skull critical size defect treated with bovine morphometric protein bound to microgranular bioabsorbable hydroxyapatite

The ability of a pool of bovine bone morphogenetic proteins bound to synthetic microgranular hydroxyapatite (BMPb-HA) to stimulate bone repair was determined in rat critical size defects. An 8-mm diameter defect was created in the calvaria of 25 rats. In 15 rats, the defects were filled with BMPb-HA homogenized with blood (experimental group), and in 10 rats the defects were filled only with blood clots (control). The calvariae of experimental rats were collected 1, 3 and 6 months after surgery and of the control rats at the end of surgery and 6 months thereafter. The morphometric results obtained in the radiographs showed an absence of new bone formation at 1 and 3 months post-surgery and, histologically, the defects were filled with fibrous connective tissue and numerous foci of a foreign body-type granulomatous reaction around hydroxyapatite agglomerates. At the end of 6 months, the number and size of the granulomatous foci decreased and the area of the defects was reduced by 22% compared to the 0-hour control due to the formation of new bone at their borders, although the mean area was similar to the 6-month control. We conclude that the use of BMPb-HA in the treatment of critical size bone defects of the rat skull leads to the formation of a foreign body-type granulomatous reaction that markedly inhibits new bone formation, suggesting that synthetic microgranular hydroxyapatite does not represent a good carrier for BMP-induced bone formation.     

Closure of rabbit calvarial critical-sized defects using protective composite allogeneic and alloplastic bone substitutes

This study evaluated the repair of critical-sized cranial vault defects in thirty New Zealand white rabbits using various allogeneic and alloplastic bone substitutes designed to provide mechanical protection to the brain as well as osteoinductivity. The strategies employed included demineralized bone matrix (DBM), a putty used in combination with a rigid resorbable plating system as a protective covering and calcium phosphate cement (CPC) combined with native partially purified bone morphogenetic protein (BMP). Bilateral critical-sized defects measuring 15 mm in diameter were created in the parietal bones of 30 adult male New Zealand white rabbits. They were divided into three groups with ten animals in each. Group 1 had one defect left unfilled as a control while autogenous bone was placed in the defect on the other side. In Group 2 a rigid resorbable copolymer membrane, Lactosorb (Lorenz Surgical, Jacksonville, Florida), was placed over both defects to cover them and protect the underlying tissues. The pericranial aspect of one defect was left unfilled while the other defect was filled with DBM putty. Group 3 had a CPC, Mimix (Lorenz Surgical, Jacksonville, Florida), placed into one of the defects while the defect on the other side was filled with the same CPC in combination with BMP in a concentration of 25 mg/mL. Bone healing was assessed clinically, radiographically, and histomorphometrically. All unfilled controlled defects, the defects covered with the resorbable Lactosorb membrane and those filled with calcium phosphate cement alone, healed with a fibrous scar. Defects reconstructed with DBM putty in combination with the resorbable Lactosorb membrane and calcium phosphate in combination with BMP healed with bone bridging the entire defect. This was obvious radiographically where the defects appeared completely filled with a dense radiopaque tissue. Histological analysis demonstrated that specimens where DBM putty was used in combination with the resorbable Lactosorb membrane had 67.7% new bone fill at 6 weeks and 84.0% at 12 weeks. Resorption of DBM particles was evidenced by the presence of osteoclastic activity and by the significant decrease in the size of the demineralized bone particles. In the calcium phosphate groups where BMP was added to the bioimplant there was 45.8% new bone formation at 12 weeks. The utilization of a composite consisting of DBM with resorbable Lactosorb membrane or a composite of calcium phosphate cement composite with BMP promoted complete closure of critical-sized calvarial defects in New Zealand white rabbits with viable new bone at 12 weeks. The complete bone bridging observed with these composites suggests that they could be used to enhance the protection of intracranial contents following craniofacial surgical procedures.     

Use of wounds in the parietal bone of the rat for evaluating bone marrow for grafting into periodontal defects

The value of autogenous marrow as a bone graft material was examined. Holes ∼ 2 mm in diameter were made in. the right and left parietal bones of 9 middle –aged Wistar-strain albino rats weighing ∼ 500 g. Bone marrow was obtained from the medullary cavity of the femur and immediately placed into the left hole, while the right served as a control. All animals were killed 12 weeks postoperatively. Their calvaria were examined radio graphically and by routine histological methods. It was found that whereas the control defects never healed, those grafted with autogenous marrow were consistently filled with a bone ossicle. These findings suggest that bone marrow grafts, may be of value in periodontal therapy.     

Mixture of hyaluronic acid,chondroitin 6 sulphate and dermatan sulphate used to completely regenerate bone in rat critical size defect model

Skeletal bone losses are mainly filled with autologous graft or artificial materials. Osteoblasts are essential to maintain bone homeostasis and bone repair through a matrix synthesis. We have previously demonstrated that adherence and regenerative matrix composition are fundamental to bone healing, even in critical situations. In this work the critical size defect technique was used to evaluate the systemic activity on bone regeneration of a novel mixture of extracellular polysaccharides. A 5 mm diameter hole was made in each parietal bone of male Wistar rats. The right parietal bone hole was filled with a mixture of hyaluronic acid, chondroitin 6 sulphate, and dermatan sulphate mixed with 2.5% NaCl solution, while the left hole was left free of material and untreated and considered as control. Twenty-one days after surgery, the holes and surrounding tissues were examined visually, using X-rays, and by histological staining. Using the matrix substitute, bone healing was almost complete after 21 days in the treated hole and always complete in the control side due to some systemic effect. Neovascularization was also observed along with organized trabecular bone on both sides. No abnormal bone growth or connective tissue abnormalities were noted. At the end of the experiment, 95.1% (±3.2) bone healing (n = 20) was observed on the treated side; conversely, healing bone and histological structure were better on the control side.     

Bone healing in surgically created defects treated with either bioactive glass particles, a calcium sulfate barrier, or a combination of both materials. A histological and histometric study in rat tibias

OBJECTIVE: The purpose of this study was to histologically analyze the influence of bioactive glass and/or a calcium sulfate barrier on bone healing in surgically created defects in rat tibias. MATERIAL AND METHODS: Sixty-four rats were divided into 4 groups: C (control), CS (calcium sulfate), BG (bioactive glass), and BG/CS (bioactive glass/calcium sulfate). A surgical defect was created in the tibia of each animal. In Group CS, a calcium sulfate barrier was placed to cover the defect. In Group BG the defect was filled with bioactive glass. In Group BG/CS, it was filled with bioactive glass and protected by a barrier of calcium sulfate. Animals were sacrificed at 10 or 30 days post-operative. The formation of new bone in the cortical area of the defect was evaluated histomorphometrically. RESULTS: At 10 days post-operative, Group C presented significantly more bone formation than Groups CS, BG, or BG/CS. No statistically significant differences were found between the experimental groups. At 30 days post-operative, Group C demonstrated significantly more bone formation than the experimental groups. Groups CS and BG/CS showed significantly more bone formation than Group BG. No statistically significant differences were found between Group CS and BG/CS. CONCLUSIONS: (a) the control groups had significantly more bone formation than the experimental groups; (b) at 10 days post-operative, no significant differences were found between any of the experimental groups; and (c) at 30 days post-operative, the groups with a calcium sulfate barrier had significantly more bone formation than the group that used bioactive glass only.     

Cortical bone regeneration with a synthetic cell-binding peptide: a histologic and histomorphometric pilot study

PepGen P-15 is a combination natural anorganic bovine-derived hydroxyapatite matrix (ABM) coupled with a synthetic cell-binding peptide (P-15). This material has been reported to enhance bone formation in periodontal osseous defects. The aim of this study was to assess the effect of ABM/P-15 on the healing of cortical bone defects in rabbits. Five New Zealand rabbits were used. Two 8-mm bone defects were created in each tibia. Eight defects were filled with PepGen P-15, 8 defects with PepGen P-15 Flow, and 4 defects were used as a control group. A total of 20 defects were created. All rabbits were killed at 4 weeks. Block sections containing the defects were retrieved and the specimens processed for light microscopy examination. Newly formed bone was present in both test groups, whereas, in the control-group, only a scarce quantity of newly formed bone was present and the cortical defects had not been filled by the regenerated bone. Statistical evaluation showed that there were statistically significant differences between control sites and sites treated with P-15 and P-15 Flow (P = 0.0001), and also between sites treated with P-15 and P-15 Flow (P = 0.0001), respectively. No acute inflammatory infiltrate cells were visible in both of these groups. Both PepGen P-15 and PepGen P-15 Flow enhanced new bone formation in the cortical drilled defects, whereas control defects showed very little newly formed bone.     

Reconstruction of large cranial defects in nonimmunosuppressed experimental design with human dental pulp stem cells

The main aim of this study is to evaluate the capacity of human dental pulp stem cells (hDPSC), isolated from deciduous teeth, to reconstruct large-sized cranial bone defects in nonimmunosuppressed (NIS) rats. To our knowledge, these cells were not used before in similar experiments. We performed two symmetric full-thickness cranial defects (5 x 8 mm) on each parietal region of eight NIS rats. In six of them, the left side was supplied with collagen membrane only and the right side (RS) with collagen membrane and hDPSC. In two rats, the RS had collagen membrane only and nothing was added at the left side (controls). Cells were used after in vitro characterization as mesenchymal cells. Animals were euthanized at 7, 20, 30, 60, and 120 days postoperatively and cranial tissue samples were taken from the defects for histologic analysis. Analysis of the presence of human cells in the new bone was confirmed by molecular analysis. The hDPSC lineage was positive for the four mesenchymal cell markers tested and showed osteogenic, adipogenic, and myogenic in vitro differentiation. We observed bone formation 1 month after surgery in both sides, but a more mature bone was present in the RS. Human DNA was polymerase chain reaction-amplified only at the RS, indicating that this new bone had human cells. The use of hDPSC in NIS rats did not cause any graft rejection. Our findings suggest that hDPSC is an additional cell resource for correcting large cranial defects in rats and constitutes a promising model for reconstruction of human large cranial defects in craniofacial surgery.     

Repair of bone defects treated with autogenous bone graft and low-power laser

Because bone healing at the graft site is similar to a fracture repair, the purpose of the present study was to evaluate the effects of low-power laser irradiation on the repair of rat skull defects treated with autogenous bone graft. A defect measuring 3 mm in diameter was produced in the left parietal bone and filled with an autogenous bone graft obtained from the right parietal bone. The animals were divided into 3 groups of 20 rats each: nonirradiated control, irradiated with 5.1 J/cm, and irradiated with 10.2 J/cm. The laser (2.4 mW, 735 nm, 3.4 x 10 W/cm, 3-mm spot size) was applied three times per week for 4 weeks. Greater volume of newly formed bone was observed in the irradiated group with 10.2 J/cm. In both irradiated groups, a greater volume of newly formed bone occurred only in the first 2 weeks. The results demonstrated that laser irradiation at the grafted site stimulated osteogenesis during the initial stages of the healing process in a skull defect of the rat and that this effect was dose dependent.     

Combined implantation of particulate dentine, plaster of Paris, and a bone xenograft (Bio-Oss) for bone regeneration in rats.

The purpose of this study is to assess the combination of particulate dentine and plaster as bone substitute material in calvarial bone defects in rats, and to compare it with a bone xenograft (Bio-Oss). MATERIAL AND METHODS: Forty rats were assigned randomly to five groups and each group was further divided into two subgroups, 8 and 16 weeks after implantation. The defect was filled with different graft materials in each group: Group 1, defects were filled with particulate dentine and plaster using a 2:1 ratio; Group 2, defects were filled with particulate dentine; plaster, and Bio-Oss using a 2:1:1 ratio; Group 3, defects were filled with plaster and Bio-Oss using a 1:1 ratio; Group 4, defects were filled with Bio-Oss only; and Group 5, untreated control defects. Histological sections and histomorphometric analysis of defects were obtained at 8 and 16 weeks postoperatively. RESULTS: New bone formation was highest in Group 4, followed by Group 3, than Group 2, Group 1, and finally the control group. CONCLUSION: The combination of particulate dentine and plaster is an alternative bone substitute, although it is less effective than Bio-Oss.