The influence of a biomaterial on the closure of a marginal hard tissue defect adjacent to implants. An experimental study in the dog

OBJECTIVES: The present experiment was performed to determine the influence of Bio-Oss on hard tissue formation at sites that, following implant installation, presented a 1-1.25 mm wide marginal defect. MATERIAL AND METHODS: Four Labrador dogs were used. The premolars and first molars on both sides of the mandible were extracted. After 3 months, mucoperiosteal flaps were elevated and three experimental sites were prepared for implant installation in each side of the mandible. A step drill was used to widen the marginal 5 mm of the canal. Thus, following the placement of the implant (3.3 x 10 mm, SLA surface, Straumann AG, Waldenburg, Switzerland) a circumferential gap, about 1-1.25 wide and 5 mm deep, remained lateral to the titanium rod. The test sites in the left side of the mandible were first filled with a deproteinized cancellous bone mineral (Bio-Oss). The defect sites in the right side of the mandible (control sites) were left for spontaneous healing. A resorbable barrier membrane (Bio-Gide) was placed to cover the implant and the bone tissue in two sites of each quadrant, while the third site was left without membrane placement. The flaps were repositioned to cover all defect sites and were sutured. After 4 months of healing, block biopsies of each implant site were dissected and processed for ground sectioning. RESULTS: It was demonstrated that at 4 months, all types of defects were filled with newly formed bone and that the biomaterial placed in the marginal defect in conjunction with implant installation during healing became incorporated in the newly formed bone tissue. A high degree of contact was established between the Bio-Oss particles and the newly formed bone. CONCLUSION: Bio-Oss became integrated with the newly formed bone. In the model used, Bio-Oss did not enhance the process of bone formation and defect closure.     

Deproteinized bovine bone (Bio-Oss) and bioactive glass (Biogran) arrest bone formation when used as an adjunct to guided tissue regeneration (GTR): an experimental study in the rat

OBJECTIVES: Grafting of deproteinized bovine bone or bioactive glass has been suggested as an adjunct to guided tissue regeneration (GTR) for the treatment of periodontal and peri-implant bone defects but the influence of these materials on bone formation is not clarified. The aim of the study was to examine the long-term influence of deproteinized bovine bone (Bio-Oss) or bioactive glass (Biogran) on bone formation produced by GTR. MATERIAL AND METHODS: Eighteen rats were used. Following incisions along the inferior border of the mandible, muscle-periosteal flaps were raised to expose the mandibular ramus. Rigid, hemispherical, Teflon capsules (6 mm internal diameter and 1 mm peripheral collar) loosely packed with a standardized quantity of either deproteinized bovine bone (test group 1) or bioactive glass (test group 2), or empty capsules (control group) were then placed with their open part facing the lateral surface of the ramus (one capsule per animal). After 1 year, the capsules were removed by a reentry operation, and the animals were sacrificed. Histological specimens of the augmented sites were prepared, and the volumes of (1). newly formed bone, (2). graft particles, and (3). soft connective tissue in the space originally created by the capsule were estimated by a point-counting technique in three to four histological sections, taken by uniformly random sampling. RESULTS: Limited bone formation was observed in the two test groups. The major part of the space originally created by the capsules was occupied by graft particles embedded in connective tissue. The mean volume of newly formed bone occupied only 23% of the total space in the animals grafted with Bio-Oss and 12.6% in those grafted with Biogran. In the control animals, however, 88.2% (p<0.01) of the space was filled with newly formed bone. There were no signs of ongoing bone formation in any of the three experimental groups. CONCLUSION: It is concluded that grafting of Bio-Oss or Biogran as an adjunct to GTR arrests bone formation.     

Healing of human extraction sockets filled with Bio-Oss

The aim of this study was to investigate the healing of human extraction sockets filled with Bio-Oss particles (Geistlich Pharma AG, Wolhusen, Switzerland). In 21 subjects, providing a total of 31 healing sites, at least one tooth was scheduled for extraction and the extraction sites for implant therapy. The dimensions of the alveolar ridge at the extraction sites were considered insufficient and required augmentation concomitant with tooth extraction. There were three treatment groups. In group A, the extraction sockets were covered with a Bio-Gide membrane (Geistlich Pharma AG) and in group B the extraction sockets were filled with Bio-Oss. The extraction sockets in group C were left to heal spontaneously. Biopsies from the extraction sites were collected at the time of implant installation. Samples from group A showed large amounts of lamellar bone and bone marrow and small proportions of woven bone. Sites grafted with Bio-Oss (group B) were comprised of connective tissue and small amounts of newly formed bone surrounding the graft particles. Only 40% of the circumference of the Bio-Oss particles was in contact with woven bone. Sites from group C were characterized by the presence of mineralized bone and bone marrow.     

Gentamicin used as an adjunct to GTR

OBJECTIVES: To evaluate in a discriminating "capsule" model whether local application of gentamicin may have an added effect on bone formation produced by Bio-Oss and guide tissue regeneration (GTR). MATERIAL AND METHODS: Thirty male 3-month-old Wistar rats were used. After elevation of muscle-periosteal flaps, a rigid hemispherical Teflon capsule, loosely packed with 0.025 g of Bio-Oss impregnated with 2 mg/ml gentamicin sulfate (Garamycin), was placed with its open part facing the lateral bone surface of the mandibular ramus (test) in one side of the jaw. A capsule filled only with Bio-Oss (control) was placed on the contralateral side of the jaw. After healing periods of 1, 2 and 4 months, groups of 10 animals were sacrificed and the specimens were processed for histological examination. The volumes of (1) the space created by the capsule, (2) newly formed bone, (3) Bio-Oss particles, (4) loose connective tissue, and (5) acellular space in the capsule were estimated by a point-counting technique in three to four histological sections of each specimen, taken by uniformly random sampling. RESULTS: The histological evaluation showed limited but increasing bone fill in the capsules from 1 to 4 months in both the test and control sides. After 4 months, the newly formed bone occupied 11.9% (CV: 0.39) of the space created by the capsules at the test sides versus 13.2% (CV: 0.41) at the control sides. There was no statistical significant difference between test and control specimens at any observation time (p>0.05). CONCLUSION: It is concluded that local application of gentamicin has no added effect on bone formation when combined with Bio-Oss and GTR.     

Physicochemical characterization of two deproteinized bovine xenografts

Calcium phosphate salts, or more specifically hydroxyapatite, are products of great interest in the fields of medical and dental science due to their biocompatibility and osteoconduction property. Deproteinized xenografts are primarily constituted of natural apatites, sintered or not. Variations in the industrial process may affect physicochemical properties and, therefore, the biological outcome. The purpose of this work was to characterize the physical and chemical properties of deproteinized xenogenic biomaterials, Bio-Oss (Geistlich Biomaterials, Wolhuser, Switzerland) and Gen-Ox (Baumer S.A., Brazil), widely used as bone grafts. Scanning electron microscopy, infrared region spectroscopy, X-ray diffraction, thermogravimetry and degradation analysis were conducted. The results show that both materials presented porous granules, composed of crystalline hydroxyapatite without apparent presence of other phases. Bio-Oss presented greater dissolution in Tris-HCl than Gen-Ox in the degradation test, possibly due to the low crystallinity and the presence of organic residues. In conclusion, both commercial materials are hydroxyapatite compounds, Bio-Oss being less crystalline than Gen-Ox and, therefore, more prone to degradation.     

Healing of extraction sockets and surgically produced - augmented and non-augmented - defects in the alveolar ridge. An experimental study in the dog

OBJECTIVES: The current experiments had three aims (i) to determine whether the absence of the periodontal ligament (PDL) may alter features of the healing of an extraction socket, (ii) to examine if there were differences in the proportion of different tissues in resolved extraction sockets and surgically produced defects after 3 months of healing, (iii) to study the influence of different biomaterials on the healing of surgically produced bone defects. MATERIAL AND METHODS: Extraction sites: In five dogs, the 4th mandibular pre-molars were hemi-sected and the distal roots were removed. The extraction socket of one of the pre-molars was instrumented to eliminate all remnants of the PDL tissue. The socket of the contra-lateral pre-molar was left without instrumentation. The dogs were sacrificed after 3 months of healing. Defect sites: In five dogs, the pre-molars and 1st molars on both sides of the mandible were first removed and 3 months of healing allowed. After this interval three standardized cylindrical defects were prepared in each side of the mandible. The defects were 3.5 mm in diameter and 8 mm deep. In each quadrant one defect was grafted with Bio-Oss Collagen, one with Collagen Sponge and one defect was left non-grafted. The dogs were sacrificed 3 months after the grafting procedure. RESULTS: Extraction sites: The two categories of extraction sockets did not differ with respect to gross morphological features. The tissue of the extraction sites, apical of a newly formed bone bridge, was dominated by bone marrow. Few trabeculae of lamellar bone were also present. Defect sites: The non-augmented defect was sealed by a hard-tissue bridge. In the central and apical portions of the defect bone marrow made up about 61%, and mineralized bone 39% of the tissues. The invagination of the surface of this crestal bone was 0.8+/-0.3 mm. The defect augmented with Collagen Sponge was covered by a hard-tissue bridge 38% of the tissue within the defect was made up of bone marrow while the remaining 62% was occupied by mineralized bone. The invagination of the hard-tissue bridge was on the average 0.6+/-0.1 mm. In defects augmented with Bio-Oss Collagen the biomaterial occupied a substantial portion of the tissue volume. Eighty-five percent of the periphery of the Bio-Oss particles were found to be in direct contact with newly formed mineralized bone. Woven bone and bone marrow made up 47% and 26% of the newly formed tissue. The invagination of the most coronal part of the bone defect was 0.1+/-0.1 mm. CONCLUSION: Sockets that following tooth removal had their PDL tissue removed exhibited similar features of healing after 3 months as sockets which had the PDL retained. The tissues present in an extraction site appeared to be more mature than those present in a surgically produced defect of similar dimension. The Bio-Oss Collagen augmented defect exhibited less wound shrinkage than the non-augmented defect.     

Anorganic porous bovine-derived bone mineral (Bio-Oss) and ePTFE membrane in the treatment of peri-implantitis in cynomolgus monkeys

The purpose of the present study was to evaluate the effect of anorganic porous bovine-derived bone mineral (Bio-Oss) and expanded polytetrafluoroethylene (ePTFE) membrane in the treatment of peri-implantitis. A total of 64 implants with a titanium plasma-sprayed (TPS) surface was inserted in eight cynomolgus monkeys (Macaca fascicularis). After a 3-month healing period with plaque control, experimental peri-implantitis characterized by a bone loss of 4-6 mm was induced during a period of 9-18 months. Surgical treatment involving Bio-Oss+membrane, Bio-Oss, membrane, or a conventional flap procedure (control) only was carried out. The animals were sacrificed six months after treatment. Evaluation by clinical parameters, radiography including quantitative digital subtraction radiography, histology, and stereology demonstrated healthy peri-implant tissue irrespective of the applied surgical procedure. However, the amount of re-osseointegration and the total amount of bone (Bio-Oss and regenerated bone) were significantly higher in defects treated with membrane-covered Bio-Oss as compared with the other three treatment procedures. A mean bone-to-implant contact of 36% was obtained within defects treated with membrane-covered Bio-Oss. The corresponding values for the three other treatment procedures were 13-23%. The Bio-Oss particles were in general highly integrated within the regenerated bone, but the particles in the occlusal part of the defects were entirely surrounded by connective tissue irrespective of membrane coverage. The present study demonstrates that surgical treatment involving Bio-Oss covered by an ePTFE membrane is a useful treatment modality of experimental peri-implantitis around implants with a TPS surface in cynomolgus monkeys. However, the treatment outcome is not as encouraging as seen with membrane-covered autogenous bone graft particles documented in a study with same experimental design.     

Effect of Tisseel on healing after periodontal flap surgery.

The purpose of this investigation was to evaluate the effect on healing of fast and slow absorbable Tisseel in combination with periodontal flap surgery. Mucoperiosteal flaps were raised on the buccal aspect of maxillary premolars and mandibular premolars and first molars in 4 beagle dogs. The underlying buccal, interproximal and inter-radicular bone was then removed to a level of approximately 5 mm apically to the original bone crest and half way into the interdental spaces and bifurcations. The exposed root surfaces were curetted in order to remove the periodontal ligament tissue, and a notch was made in the root surface at the base of the defects. On the control teeth, the flaps were sutured immediately after creation of the defects, while on the test teeth, a layer of fast (group I) or slow (group II) absorbable Tisseel was applied between the curetted roots and the subsurface of the flaps prior to suturing. Postoperatively, the teeth were brushed 2 x weekly. The dogs were sacrificed after 4 months. Histological analysis revealed that the amounts of new attachment and bone regrowth were similar in the test and control groups, although the results tended to be most favorable for the group of teeth treated with fast absorbable Tisseel (Group I).     

血管化腓骨组织瓣游离移植修复下颌骨缺损

目的:探讨血管化腓骨修复各型下颌骨缺损的可行性。方法:对14例因各种原因所致下颌骨缺损患者采用血管化游离腓骨瓣同期移植修复。结果:骨瓣存活成功率100%;下颌骨形状和功能恢复良好。术后3个月摄片示移植骨无吸收,骨段愈合良好。面部外形恢复均达到满意或较为满意。所有患者均能正常行走,无1例出现踝关节不稳定。结论:游离腓骨瓣血供良好,骨量充足,可塑性强,特别是对全下颌骨缺损的修复,具有目前临床常用的其他自体骨组织瓣不可比拟的优点,是下颌骨缺损修复重建的最佳方法之一。     

Lateral ridge augmentation by the use of grafts comprised of autologous bone or a biomaterial. An experiment in the dog

OBJECTIVE: The present investigation was performed to determine if a block of Bio-Oss used as an onlay graft can be used as a scaffold for new bone formation. MATERIAL AND METHODS: Five mongrel dogs were used. The mandibular premolars were extracted. On both sides of the mandible, the buccal bone plate was resected and defects, about 25 mm long, 8 mm high and 5 mm wide, were produced After 3 months of healing, a second surgical procedure was performed. In the left side, a block of Bio-Oss was adjusted to the buccal bone wall. The graft had the shape of a cylinder and was retained with a miniscrew and covered with a collagen membrane. In the contra-lateral side of the mandible, a block biopsy was first obtained from the ascending ramus. This bone graft had the shape of a cylinder that was 8 mm in diameter and 3 mm thick. The graft was transferred to the experimental site, adjusted to the buccal wall, retained with a miniscrew, and covered with a membrane. The flaps were repositioned and closed with sutures to ensure a complete coverage of the experimental sites. After 6 months of healing, the dogs were sacrificed and the experimental sites dissected. The biopsies were processed for ground sectioning. The sections were stained in toluidine blue, examined in the microscope, and a number of histo- and morphometric assessments made. RESULTS: The study demonstrated that cortical bone used as an onlay graft in the lateral aspect of the alveolar ridge, during a 6-month period of healing integrated with the host bone but underwent marked peripheral resorption. Thus, close to 30% of the height and 50% of the length of the graft was replaced with connective tissue. It was further observed that while the dimensions of a graft which contained a scaffold of cancellous bovine bone mineral remained unchanged, only moderate amounts of new bone formed at the base of this graft. CONCLUSION: Grafts of autologous cortical bone, placed on the surface of a one-wall defect, may undergo marked resorption during healing. A similar graft of Bio-Oss may retain its dimension, and limited amounts of new bone will form within the biomaterial.     

Fate of bone formed by guided tissue regeneration with or without grafting of Bio-Oss or Biogran. An experimental study in the rat

OBJECTIVES: The aim of the study was to examine whether bone produced by guided tissue regeneration (GTR) in combination with Bio-Oss or Biogran is stable on a long-term basis. MATERIAL AND METHODS: Fifty-four, 3-month-old Wistar rats were divided into three groups and rigid, hemispherical, teflon capsules were placed with their open part facing the lateral surface of the exposed mandibular ramus (one capsule per animal). In the first group, the capsules were loosely packed with a standardized quantity of Bio-Oss, in the second group with Biogran, and in the last group were left empty. After 1 year of healing, the capsules were removed. Six animals from each of the 3 experimental groups were killed immediately after capsule removal (baseline), or 3 or 6 months after re-entry. The volume of (1) newly formed bone, (2) remaining biomaterial particles, and (3) soft connective tissue in the space originally created by the capsule was estimated by a point-counting technique in three to four histological sections, taken by uniformly random sampling. RESULTS: While considerable bone formation had occurred in the empty control capsules, only limited bone formation was observed in the two test groups. The major portion of the space originally created by the capsules in the test groups was occupied by biomaterial particles embedded in connective tissue. At baseline, the mean volume of newly formed bone occupied 23% of the original capsule space in the animals grafted with Bio-Oss, 12.6% in those implanted with Biogran, and 94.1% in those that received empty control capsules. Six months after capsule removal, the corresponding values were 21.5%, 13.2%, and 91.7%, respectively. No statistically significant differences were observed between baseline, and the 3-, and 6-month observation times in terms of bone volume for any of the three treatment groups (p>0.05). CONCLUSION: Bone produced by GTR with and without implantation of Bio-Oss, or Biogran, is stable on a long-term basis, but bone formation is obstructed by implantation of these biomaterials.     

下颌骨肌瓣联合面颈胸旋转皮瓣修复下颌骨放射性骨坏死

目的:探讨下颌骨肌瓣联合面颈胸旋转皮瓣修复下颌骨放射性骨坏死清创术后下颌骨合并颊部软组织缺损的效果。方法:采用下颌骨肌瓣联合面颈胸旋转皮瓣修复6例因难治性下颌骨放射性骨坏死清创术后缺损。结果:应用下颌骨肌瓣联合面颈胸旋转皮瓣修复下颌骨放射性骨坏死清创术后缺损,所有皮瓣均存活良好,未出现供区并发症。所有患者语言、吞咽功能良好,面部外形满意。随访16～24个月,平均20.6个月,患者病情均无复发。结论:下颌骨肌瓣联合面颈胸旋转皮瓣制备简单、快速,适合同期修复下颌骨放射性骨坏死清创术后下颌骨"L"形缺损合并颊部软组织缺损。     

Bone quality at the implant site after reconstruction of a local defect of the maxillary anterior ridge with chin bone or deproteinised cancellous bovine bone

The purpose of this study was to investigate the quality of bone at grafted implant sites in the anterior maxilla. Grafting of these sites was necessary because of insufficient bone volume in a buccopalatinal direction (width at the top of the crest 1-3mm). Reconstruction was performed with chin bone (N=5), chin bone and a resorbable Bio-Gide((R)) GBR membrane (N=5) or Bio-Oss((R)) spongiosa granules in combination with a Bio-Gide((R)) GBR membrane (N=5). Biopsies were taken prior to implantation, i.e. 3 months after grafting with chin bone, and 6 months after grafting with Bio-Oss((R)). Evaluation was done by assessing the histological and histomorphometric characteristics of full-length biopsies taken from the actual implant site. Both areas with non-vital bone and areas with apposition of bone and remodelling phenomena were observed in the chin bone group at the time of placement of the implants. Similar results were observed at implant sites reconstructed with a chin bone graft covered by a membrane. In the chin bone group without and with a GBR membrane, the mean total bone volume (TBV) was 55.2+/-6.8% and 57.7+/-11.5%, respectively; the marrow connective tissue volume (MCTV) was 44.8+/-6.8% and 42.3+/-11.5%, respectively. Remnants of the resorbable GBR membrane were not detected. In the Bio-Oss((R)) group, at implant placement some newly formed bone was observed in the connective tissue surrounding the Bio-Oss((R)) particles (mean TBV (newly formed bone) 17.6+/-14.5%), but most particles were surrounded by connective tissue. No convincing signs of remodelling were observed (mean remaining Bio-Oss((R)) volume 40.5+/-9.3%; mean MCTV 41.9+/-13.1%). No implants were lost during follow up (12 months). At the time of placement of the implants the grafting material (either chin bone or Bio-Oss((R))) is still not fully replaced by new vital bone. In case of Bio-Oss((R)), most of the grafting material is even still present. Despite these differences, the 1-year clinical results were very good and comparable between the various grafting techniques applied.     

Orthodontic movement in bone defects augmented with Bio-Oss. An experimental study in dogs

OBJECTIVE: To study if it was possible to move, by orthodontic means, a tooth into an area of the jaw that had been augmented with Bio-Oss. MATERIAL AND METHODS: 5 beagle dogs were used. The 1st, 2nd, and 4th mandibular premolars on each side were removed. The defect at the left 4th premolar site was filled with a biomaterial (Bio-Oss) while the corresponding defect in the right side was left for spontaneous healing. 3 months later, an orthodontic device was inserted in each side of the mandible. The device was designed to allow distal, bodily movement of the 3rd premolars. When the experimental teeth had been moved into the extraction sites of the 4th premolars, the animals were sacrificed and biopsies of the premolar-molar regions of the mandible sampled. The tissues were prepared for histological analysis using standard procedures. In the sections, 3 zones were identified: zone A=the bone tissue within the distal portion of the previous extraction site (4th premolar), zone B=the pressure side of the 3rd premolar, zone C=the tension side of the 3rd premolar. The area occupied by mineralized bone, Bio-Oss particles and bone marrow was determined by a point counting procedure. The width of the periodontal ligament as well as the percentage of the root surface (in zone B) that exhibited resorption was determined. RESULTS: The findings demonstrated that it was possible to move a tooth into an area of an alveolar ridge that 3 months previously had been augmented with a biomaterial. It was also demonstrated that 12 months after grafting, Bio-Oss particles remained as inactive filler material in the not utilized part of zone A. The biomaterial was not present in zone C but present in small amounts in zone B. CONCLUSION: During the orthodontic tooth movement the graft material (Bio-Oss) was degraded and eliminated from the part of the alveolar ridge that was utilized for the experiment. In the non-utilized part of the ridge the biomaterial, however, remained as a seemingly inactive filler material.     

The use of ramus autogenous block grafts for vertical alveolar ridge augmentation and implant placement: a pilot study

PURPOSE: This study presents a clinical, radiographic, laboratory, and histologic/histomorphometric analysis of the use of mandibular ramus block autografts for vertical alveolar ridge augmentation and implant placement. MATERIALS AND METHODS: Autogenous block autografts were fixed at the recipient site with fixation screws while a mixture of autogenous bone marrow and inorganic bovine material (Bio-Oss) was used at the periphery. All grafts appeared well incorporated at the recipient site during reentry surgery. RESULTS: Radiographic measurements revealed an average of 6.12 mm vertical ridge augmentation 1 month after surgery and 5.12 mm 4 to 6 months after surgery. Laboratory volumetric measurements revealed an average of 0.91 mL alveolar ridge augmentation 1 month after surgery and 0.75 mL 6 months postoperatively. Linear laboratory measurements revealed 6.12 mm of vertical ridge augmentation 1 month postoperatively and 4.37 mm 4 to 6 months after surgery. Histologic evaluation indicated signs of active remodeling in all the specimens. Histomorphometric analysis of the peripheral particulate bone indicated bone present at 34.33% of the grafted area, while 42.17% of the area was occupied by fibrous tissue and 23.50% by residual Bio-Oss particles. DISCUSSION: The results demonstrated the potential of mandibular block autografts harvested from the ascending ramus to maintain their vitality. Volumetric resorption rate of 17.58% and radiographic resorption rate of 16.34% were in accordance with previously published literature. Early exposure appeared to compromise the results, while late exposures did not affect the vitality of the block autografts. CONCLUSION: Mandibular block autografts can maintain their vitality when used for vertical alveolar ridge augmentation. Inorganic bovine mineral (Bio-Oss) can be used at the periphery of the block graft when mixed with autogenous bone marrow.     

Bio-Oss骨代用品同引导骨再生膜联合应用效果的观察

目的 通过组织学观察Bio-Oss作为骨移植材料同引导骨再生膜技术联合应用治疗牙槽骨局部骨缺损及种植体周围骨缺损的临床效果。方法 从6例牙槽骨局部缺损患者的6处骨再生区取少量骨组织，采取Donath硬组织切片磨片技术行组织学观察。结果 组织学显示浅红色新生骨同淡黄色的Bio-Oss颗粒区别明显，Bio-Oss颗粒表面有新骨形成，并与之紧密结合。未见纤维结缔组织长入包裹Bio-Oss颗粒及炎症细胞浸润。结论 Bio-Oss骨有良好的生物相容性和骨引导作用，作为骨移植材料同引导骨再生膜技术联合应用的效果是可靠的。     

Simultaneous flapless implant placement and peri-implant defect correction: an experimental pilot study in dogs

BACKGROUND: Minimally invasive implant surgery allows clinicians to place implants in less time, without extensive flaps, and with less bleeding and postoperative discomfort. The purpose of this study was to evaluate a new surgical technique by which implants are inserted in a deficient alveolar ridge using a flapless technique simultaneously with a peri-implant defect correction that is performed using a subperiosteal tunneling procedure. METHODS: Bilateral, horizontal defects of the alveolar ridge were created in the mandibles of five mongrel dogs. After 3 months of healing, one implant was placed on each side of the mandible by a flapless procedure. The exposed threads of the implant on one side of the mandible were covered with a 1:1 autogenous bone/xenograft mixture using a subperiosteal tunneling technique. Four months later, biopsies of the implant sites were taken and prepared for ground sectioning and analysis. RESULTS: All implants were well osseointegrated with the host bone. All of the peri-implant defects at the test sites were covered with tissue that resembled bone. In all specimens, a mixture of bone, connective tissue, and residual bone particles was observed in the graft area. In the control sites, where no graft was used, none of the exposed threads on any implants were covered with new bone. CONCLUSION: This preliminary report indicates the potential use of a minimally invasive flapless technique as a substitute for a more invasive implant placement and ridge augmentation procedure.     

nHA/BG涂层与Bio-Oss骨粉修复种植体骨缺损的实验研究

目的:评价生物玻璃/纳米羟基磷灰石(nHA/BG)涂层与Bio-Oss骨粉在种植体骨缺损中引导骨再生的效果。方法:选取6只Beagle犬,拔除两侧下颌前磨牙。3个月后预备种植窝,同时颊侧制造裂隙状骨缺损(2.25 mm×3 mm×4 mm)。按照分组植入种植体和骨粉,A组为nHA/BG+Bio-Oss,B组为nHA/BG+血凝块愈合,C组为微米级HA+Bio-Oss。术后2周、处死前2周和3 d分别进行四环素、钙黄绿素和茜素红荧光标记。术后8周和16周处死动物,行大体观察和组织学测量。采用SPSS13.0软件包对数据进行统计学分析。结果:3组骨-种植体结合率(BIC)在8周时分别为30%、18%、21%,16周时分别为61%、53%、46%;缺损区新骨面积(RA)在8周时分别为(2.1±0.6)mm3、(1.4±1.0)mm3、(0.6±0.1)mm3,16周时分别为(4.2±0.7)mm3、(2.2±1.2)mm3、(1.2±0.6)mm3。各组8周与16周的BIC和RA相比均有显著差异(P<0.05);8周时,A、C 2组的BIC和RA相比有显著差异(P<0.05),16周时,A、B 2组的RA相比有显著差异(P<0.05)。结论:在种植体周围2.25 mm骨缺损区,nHA/BG涂层能促进种植体-Bio-Oss替代骨-骨的骨结合。     

VEGF与Bio-Oss在兔新生骨中协同作用的实验研究

目的：将Bio—Oss按不同比例与兔自体碎骨混合后修复兔牙槽骨缺损，检测VEGF的表达水平，探讨VEGF与Bio—Oss之间可能存在的协同作用。方法：选用新西兰大白兔24只，拔出其左侧下颌中切牙，去除唇舌侧骨板，制造穿通性骨缺损。4周后，随机分为4组，每组6只。分别以单纯Bio—Oss（实验组1）、Bio—Oss：自体碎骨质量比1：1（实验组2）、Bio—Oss：自体碎骨质量比1：2（实验组3）、单纯自体骨（对照组）修复骨缺损模型。分别在术后1、3个月提取标本，进行大体标本观察，免疫组织化学方法检测各组标本中VEGF的表达情况。结果：随Bio—Oss充填比例的增加，VEGF的表达明显增强（P〈0．01），对照组VEGF的表达较各实验组明显弱（P〈0．01），术后3个月VEGF的表达较术后1个月明显减弱（P〈0．01）。结论：VEGF与Bio—Oss在新生骨形成中可能存在协同性关系。     

Healing around implants placed in bone defects treated with Bio‐Oss®. An experimental study in the dog.

The aim of the present experiment was to (i) study the healing after 3 and 7 months of bone defects filled with cancellous bovine bone mineral and (ii∥ compare the healing around implants placed in normal bone and in defects filled with bovine bone mineral. 5 beagle dogs, about l-year-old, were used. At baseline, extractions of all mandibular left and right premolars were performed. Bone defects were prepared in the left mandibular quadrant. The defect was immediately filled with natural bovine cancellous bone mineral particles (Bio-Oss®, Geistlich Sons Ltd. Wolhusen, Switzerland). No resective surgery was performed in the right jaw quadrant. In both quadrants the flaps were adjusted to allow full coverage of the edentulous ridge and sutured. 3 months later, 2 dogs (group I) were euthanized and biopsies from the premolar regions obtained and prepared for histologic analysis. The 3 remaining dogs (group II) were at this time interval (3 months) subjected to implant installation in the premolar region of both the right and left mandibular jaw quadrants. 2 fixtures of the ITI Dental Implant System (Straumann, Waldenburg, Switzerland; solid-screw; 8 x 3.3 mm) were installed in each side. The fixtures in the test side were placed within the previously grafted defect area, while the fixtures in the control side were placed in normally healed extraction sites. A 4 month period of plaque control was initiated. At the end of this period, a clinical examination including assessment of plaque and soft tissue inflammation was performed and radiographs obtained from the implant sites. Biopsies were harvested and 4 tissue samples were yielded per dog, each including the implant and the surrounding soft and hard peri-implant tissues. The biopsies were processed for ground sectioning or “fracture technique” and the sections produced were subjected to histological examination. The volume of the hard tissue that was occupied by clearly identified Bio-Oss® particles was reduced between the 3- and 7-month intervals. This indicates that with time, Bio-Oss® becomes integrated and subsequently replaced by newly formed bone. In other words, this xenograft fulfils the criteria of an osteoconductive material. It was also observed that 4 months after implant installation, the titanium/hard tissue interface at test and control sites exhibited, from both a quantitative and qualitative aspect, a similar degree of “osseointegration”.