Particulated bone grafts--effectiveness of bone cell supply

OBJECTIVE: The objective of this study was to measure the amount of viable bone cells present in different types of bone graft. MATERIAL AND METHODS: Bone chips were harvested from the trabecular or cortical bone of the mandible or the iliac crest and either milled or not. The average size of unmilled bone particles was 5 x 5 x 5 mm and that of milled was 2 x 2 x 2 mm. Drill sludge was obtained using either a ball reamer, a diamond ball or an implant drill (the latter from mandibular bone and of average dimension 1 x 1 x 1 mm). A measure of 0.5 g of each category was cultured in Dulbecco's modified Eagle's medium with additives for four weeks. Cell counts were performed. An analysis of the osteocalcin synthesis, the alkaline phosphatase (ALP) activity, the collagen types and the concentration of bone-specific collagen cross-links in medium supernatants was performed. RESULTS: Cells stained positively for osteocalcin and ALP in all groups. Bone-specific collagen cross-links could be quantified and collagen of types I and V was present with no difference in all groups. Unmilled spongy bone chips revealed greater cell counts than milled (P<0.05). Spongy bone chips revealed greater cell counts than cortical bone chips (P<0.05). Drill sludge obtained by hard alloy ball reamer showed the least amount of viable cells (P<0.05). CONCLUSIONS: Bone milling reduces the quantity of osteoblasts. Bone obtained by the ball reamer supplies a smaller number of cells than bone obtained by other methods. Unmilled spongy bone chips appear to offer the greatest amount of viable osteoblasts.     

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目的评价前牙区牙槽骨水平宽度不足的患者联合应用骨劈开、骨挤压和骨引导再生术行同期种植体植入的临床效果。方法 2004—2009年福州市第一医院口腔科就诊的前牙区牙缺失伴前牙区牙槽骨水平宽度不足的种植患者28例,联合应用骨劈开、骨挤压,填入骨粉,行骨引导再生术后同期植入40颗种植体,术后4～6个月内完成上部修复。术后1年,通过临床检查、全景片等观察效果。结果术前、后牙槽骨平均宽度分别为(3.2±0.89)mm、(6.5±0.75)mm,平均增加了(3.3±0.34)mm。术后牙槽骨宽度与术前相比,差异有统计意义(t=2.47,P<0.05)。术后无明显并发症发生,种植体行使功能良好,仅1例患者的1颗牙种植失败,种植近期成功率达97.5%。结论对前牙区牙槽骨水平宽度不足的患者,联合应用骨劈开、骨挤压和骨引导再生术行同期种植体植入,可增加骨量,获得种植体的同期植入,减少患者痛苦,改善种植修复的临床效果。     

异种骨移植对牙周骨缺损的作用及研究进展

异种骨移植作为骨缺损修复的常见方法,受到与骨相关学科工作者的关注,由于异种骨移植材料来源丰富,能满足日益增多的病人需求。本文就异种骨的免疫原性、处理方法和在牙周骨缺损修复中的应用及其进展加以综述,为异种骨移植物的基础和临床研究提供依据。     

实验犬磨牙根分叉骨缺损应用组织工程骨修复的效果分析

目的观察以组织工程方法修复大面积根分叉骨缺损的效果。方法以成骨条件培养液培养实验犬骨髓基质细胞(BMSCs)至第3代并以1×106/cm2的密度与猪的脱矿冻干骨(fdDBM)复合培养后回植于犬磨牙根分叉骨缺损区(2.0cm×1.0cm×0.8cm)。术后3个月与6个月取实验开窗区骨制作组织切片或2mm厚的骨磨片,观察新生骨组织形态及骨钙素与Ⅰ型胶原表达情况并作骨磨片的骨密度分析。所得数据用SAS6.12软件作t检验。结果6个月及3个月实验侧骨缺损完全修复。骨切片显示实验侧开窗区新生骨与正常骨无明显区别且Ⅰ型胶原和骨钙素表达亦同正常。X线骨密度数据显示回植后6个月实验组的骨密度高于对照组及回植3个月者。结论以组织工程骨修复大面积根分叉骨缺损是可行的。     

Differential effects of bone graft substitutes on regeneration of bone marrow

Background: This study used a rat tibial marrow ablation model to test the hypothesis that bone remodeling within the medullary canal varies with bone graft materials of different chemical compositions and structural properties, impacting marrow cavity restoration. Bone graft materials were selected based on their relative resorption or degradation in vivo and their osteogenic properties. Methods: Following ablation of the right tibial marrow in male Sabra‐strain rats, materials were implanted in the proximal marrow cavity: poly‐d,l ‐lactide‐co‐glycolide 75 : 25 (PLGA); coralline‐hydroxyapatite (HA), calcium‐sulfate (CaSO4), collagen–HA–tricalcium phosphate granules, anorganic bovine bone mineral, demineralized bone matrix (DBM), 45S5 Bioglass (BG), PLGA with BG 50 : 50, PLGA : BG 80 : 20, and PLGA and PLGA:BG 50 : 50 plus bone marrow (BM). Control tibias were ablated but received no implants. At 2 (endosteal bone healing), 4 (marrow cavity remodeling) and 8 weeks (marrow restoration), six to eight animals per group were euthanized and tibias processed for histomorphometry of proximal and distal medullary canals. Results: Control tibias showed primary bone in proximal and distal medullary canals at 2 weeks, with trabeculae surrounded by cellular marrow. At 4 and 8 weeks, control trabeculae were thinned and marrow had more fat cells. In the treated tibias, trabecular bone volume (TBV) varied with time and was material specific. Most implants supported comparable TBV at 2 weeks. Sites with CaSO4 or DBM exhibited decreased TBV with time whereas trabecular bone was retained in proximal tibias containing other materials, closely juxtaposed to the implants. TBV did not always correlate directly with implant volume, but changes in BM volume were correlated inversely with TBV. Addition of BM increased marrow restoration in sites containing PLGA; however, BM reduced restoration of marrow when added to PLGA : BG. Although the presence of implants in the proximal tibia resulted in retention of trabecular bone, there was a time‐dependent reduction in TBV in distal canals; the rate and extent of the distal TBV reduction were implant dependent. Conclusions: Thus, although many materials can support bone formation in the marrow cavity, bone quality, quantity, and physical relationship to the implant, and its rate of resorption differ in a material‐dependent manner, resulting in differences in the restoration of marrow. Clinical relevance: Bone graft materials should be selected not only for their ability to support new bone formation but also for their impact on the remodeling phase of bone healing.     

Effects of cortical bone perforation on experimental guided bone regeneration

This study was designed to evaluate the effects of cortical bone perforation histologically and histomorphometrically on guided bone regeneration (GBR) in rabbits. After elimination of the periosteum, cortical bone defects of two sizes were made in the external cortical plate of the frontal bone (Group A: 1 x 15 mm; Group B: 3 x 15 mm). A non-resorbable membrane filled with autogenous blood was placed in the experimental area and secured with titanium pins. After 1 and 2 weeks, vascularized connective tissue and new bone were generated in the space surrounding the defects in both the groups. The amount of vascularized connective tissue generated in Group B was greater than that in Group A at 1 week. Alkaline phosphatase (ALP) was expressed on the bone surrounding the perforation. The expression of ALP was more extensive in Group B than in Group A and was proportional to the breadth of perforation. At 2 weeks, the perforated region was almost covered with new bone in Group A. ALP was expressed at the periphery of newly formed bone. The expression of ALP was proportional to the breadth and height of perforation. At 6 weeks, semicircular outgrowth of bone towards the periphery of the perforated region was observed in both the groups. Newly formed bone volume and ALP expression in Group B were more extensive than those in Group A. At 12 weeks, the space was filled with bone and connective tissue in both the groups. There was no difference in ALP expression between Groups A and B. Histomorphometric analysis showed significant differences between both the groups (two-way ANOVA, P<0.01). We conclude that a larger perforation is associated with prompter bone formation in the secluded space during GBR.     

Long-term stability of autogenous bone grafts following combined application with guided bone regeneration

The aim of the study was to compare the long-term stability of membranous and endochondral autogenous bone grafts with or without combined application of guided bone regeneration (GBR). Twenty-five, male, 6-month old, albino rats were used in the study. The animals were divided into four groups (A5, A11, B5 and B11). Group A5 (control): The inferior border of the mandible was exposed in both sides. At one side of the jaw, a calvarial bone graft (baseline -3 x 4 x 0.64 mm) was placed at the inferior border of the mandible and was fixed with a standardized screw-type titanium microimplant. At the contralateral side, an ischiac bone graft (baseline -3 x 4 x 0.87) was transplanted. The healing period was 5 months. Group A11 (control): The animals were treated in the same manner as in Group A5 with the difference that the healing period was 11 months. Group B5 (test): The animals were treated in the same manner as in Group A5 with the difference that an e-PTFE membrane was adapted over the bone graft on each side of the jaw. Group B11 (test): The animals were treated in the same manner as in Group B5 with the difference that 5 months following transplantation the animals were subjected to a second operation and the membranes were removed. The healing period was 11 months. The animals were killed at 5 (Groups A5 and B5) or at 11 months (Groups A11 and B11) following mandibular augmentation and the jaws were defleshed. The width, the length and the thickness/height of the bone graft were evaluated by means of a stereomicroscope. At 5 months, both types of the membrane-treated bone grafts presented increase in all dimensions compared with baseline. However at 11 months, both types of the membrane-treated bone grafts exhibited a decrease in their dimensions which were similar to the baseline measurements. In the control groups, both types of bone graft presented significant resorption both at 5 and at 11 months with the ischiac bone grafts presenting more resorption in width and length than the calvarial bone grafts. It can be concluded that the long-term volume stability of autogenous endochondral and membranous onlay bone grafts combined with GBR is superior to that of autogenous endochondral and membranous onlay bone grafts alone.     

A novel bone scraper for intraoral harvesting: a device for filling small bone defects

AIM: To evaluate histologically the morphology and characteristics of bone chips harvested intraorally by Safescraper, a specially designed cortical bone collector. MATERIAL AND METHODS: Bone chips harvested near a bone defect or in other intraoral sites were grafted into a post-extractive socket or applied in procedures for maxillary sinus floor augmentation or guided bone regeneration. Core biopsies were performed at implant insertion. Undecalcified specimens embedded in PMMA were studied by histology, histochemistry and SEM. RESULTS: Intraoral harvesting by Safescraper provided a simple, clinically effective regenerative procedure with low morbidity for collecting cortical bone chips (0.9-1.7 mm in length, roughly 100 microm thick). Chips had an oblong or quadrangular shape and contained live osteocytes (mean viability: 45-72%). Bone chip grafting produced newly formed bone tissue suitable for implant insertion. Trabecular bone volume measured on biopsies decreased with time (from 45-55% to 23%). Grafted chips made up 50% or less of the calcified tissue in biopsies. Biopsies presented remodeling activities, new bone formation by apposition and live osteocytes (35% or higher). DISCUSSION AND CONCLUSIONS: In conclusion, Safescraper is capable of collecting adequate amounts of cortical bone chips from different intraoral sites. The procedure is effective for treating alveolar defects for endosseous implant insertion and provides good healing of small bone defects after grafting with bone chips. The study indicates that Safescraper is a very useful device for in-office bone harvesting procedures in routine peri-implant bone regeneration.     

骨微环境相关细胞对肿瘤细胞骨转移的作用及机制

肿瘤骨转移是肿瘤转移的重要组成部分。肿瘤骨转移的过程往往会经历肿瘤细胞的定植、休眠及活化等。从肿瘤细胞定植到骨微环境中,再到其休眠激活往往经历一段较长的潜伏期。肿瘤骨转移过程中,骨微环境中的成骨细胞、破骨细胞、骨髓基质细胞、免疫细胞及血管内皮细胞对肿瘤细胞的定植、休眠及活化过程有重要影响。在这个过程中,肿瘤细胞除自身调节外,还通过与骨微环境中的各种细胞发生相互作用。本文针对骨微环境中的相关细胞对肿瘤细胞骨转移的作用及机制研究的现状及进展作一综述。     

两种自体骨粉末修复种植体周围骨缺损的临床研究

目的：评价自体骨夹层法修复种植体周围骨缺损的近期临床效果。方法：48例患者共82颗种植体,植入的种植体唇侧骨壁缺损,其余三个骨壁都存在,随机分为两组：一组为混合法,22例患者39颗种植体,自体骨粉与Bio-Oss骨粉按1：1比例混合修复骨缺损部位。另一组为夹层法,26例患者43颗种植体,局部微量刮取自体骨粉涂于暴露的种植体表面,再覆盖Bio-Oss骨粉,再覆盖生物膜。植入6个月后行上部修复。修复后追踪时间平均24个月。根据临床、X线检查和患者主诉评价修复效果。结果：两组均无种植体脱落,存留率100%,二者差异无统计学意义。其龈袋深度、出血指数、年累计骨吸收量及X线检查均无明显不同。结论：对于骨缺损的病例,采用自体骨夹层法可以应用于临床。近期效果良好,长期效果有待追踪。     

牙槽突裂植骨术后的植骨效果评价

目的通过牙CT的扫描及Matlab7.0软件的应用,评价牙槽突裂植骨术后的骨缺损区的体积变化。方法选取11名单侧完全性牙槽突裂患者,应用牙CT扫描及Matlab7.0软件计算植骨前和植骨后3个月的牙槽突裂空隙体积和所植入骨的体积,并计算术前后体积比值。结果植骨术后骨桥的体积与植骨前牙槽突裂隙的体积比值,最大值可达114.99%,最小值仅有13.36%,平均数为71.80%,变异系数为47.987。结论植骨后存活的骨桥体积变化较大。     

骨替代材料在口腔种植领域中的成骨效果

骨替代材料目前已成为拔牙位点保存术、牙槽嵴骨增量术和上颌窦底提升术的主要材料,而羟磷灰石、磷酸钙和生物活性玻璃以其良好的生物相容性、骨传导性、生物降解性、骨再生能力和骨结合率成为骨替代材料的代表.单一成分骨替代材料的诱导骨再生能力取决于材料本身的表面形貌、结构、成分、孔径和孔隙率.按不同比例复合的新型骨替代材料,可使原单一骨替代材料的性能得以互补.骨替代材料与血小板浓缩物的联合应用,可促进前成骨细胞的增殖与分化,激发成骨细胞的活动,促进血管新生,从而利于骨替代材料存活.骨替代材料与生长因子的联合应用,可获得不同程度骨结合和骨改建,增加材料的细胞黏附率,改善支架的力学性能,在骨愈合早期即能促进新骨形成.随着科技的进步,未来骨替代材料的成骨性能日臻完善,在口腔种植领域的应用前景将会更加广阔.     

Contribution of autogeneic membranous bone chips and bone paste to healing of rabbit skull defects

In skeletal surgery, bone chips and bone paste are often used to facilitate bony repair. However, no comparative investigation between these forms of bone graft implantation has been undertaken. In this study four trephine skull defects were produced in each of 14 adult rabbits and inlays of bone paste and two separate amounts of bone chips were then implanted in each animal. The results were compared relative to a control defect and assessed by gross inspection, light microscopy, and contact radiography after periods of 4 and 15 wk. Bone chips offered only minor advantages over controls in the defects investigated and differences in bony regeneration between the diversified amounts of bone chips were negligible. After bone paste implantation, a cellular and mature bone was rapidly produced. The clinical significance of these findings is discussed.     

Three-dimensional evaluation for augmented bone using guided bone regeneration

OBJECTIVE: This study evaluated new bone regeneration beyond the skeletal envelope within an occlusive titanium cap on rabbit calvaria using microfocus computed tomography images. METHODS: In 10 rabbits, the calvaria was exposed and a circular groove was prepared. After penetrating the marrow, a standard hemispherical titanium cap was placed in the groove and covered with a cutaneous flap. After 1 or 3 months, the animals were killed and the calvariae and titanium caps were dissected. After taking microfocus computed tomography images of the specimens, histological sections were made. The specimens were observed using three-dimensional images constructed from the microfocus computed tomography images, and the histological sections were examined to compute bone parameters. RESULTS: The three-dimensional images and histological specimens showed that new bone formed in flat, cup-like, and dome shapes. The bone parameters trabecular thickness and the proportion of marrow space to the capacity of the titanium cap increased, whereas bone density decreased, and there were significant differences between the 1- and 3-month groups. DISCUSSION: First, a cylinder of new bone formed from the existing bone. Gradually, bone formed along the cap wall and the new tissue formed in a crater indented centrally. Finally, the new tissue formed in the shape of a dome. CONCLUSION: Trabecular bone formed along the wall of the titanium cap, and bone filled the inside of the cap within 3 months.     

种植体周围骨缺损修复的组织学观察

目的 :观察脱钙冻干骨移植物 (DFDBA)在种植体周骨缺损的诱导成骨活性以及重组人骨形成蛋白 -2 (rhBMP -2 )和钛膜对DFDBA成骨作用的影响。方法 :犬股骨植入种植体周围 ,制造 4mm× 3mm× 3mm骨缺损 ,分别采用DFDBA、DFDBA rhBMP -2和DFDBA 钛膜三种不同方法修复种植体周骨缺损 ,术后 4、8、12周 ,组织学观察种植体周骨缺损修复情况。结果 :三组实验动物中 ,植骨创均愈合良好 ,种植体无松动 ,未见种植体周围炎发生。①DFDBA组 :术后 4周即有新生骨小梁形成 ,术后 12周修复骨缺损 ,但新骨组织与宿主骨之间仍见明显分界 ;②DFDBA rhBMP -2组 :成骨过程较早 ,术后 4周即有较多新生骨组织出现 ,术后 8周 ,成骨细胞较为丰富 ,术后 12周新骨组织与宿主骨完全融合 ;③DFDBA 钛膜 :术后 4周即见新生骨小梁沿钛膜生长 ,至术后 12周 ,完全覆盖骨缺损。结论 :DFDBA具有良好的骨诱导和骨引导作用 ,可用于修复种植体周骨缺损 ;rhBMP -2复合DFDBA ,可增强骨诱导作用 ,加速成骨过程 ;钛膜有助于维持骨再生空间 ,阻隔软组织长入 ,引导新骨生长 ,缩短修复过程。