Augmentation of intramembraneous bone beyond the skeletal envelope using an occlusive titanium barrier. An experimental study in the rabbit.

The aim of this investigation was to evaluate whether augmentation of intramembraneous bone beyond the skeletal envelope can be predictably achieved by placing a completely occlusive barrier on the skull bone of rabbits, hereby creating a secluded space with bone tissue being the only adjoining tissue. The experiment was carried out in 3 New Zealand white rabbits. In each animal, a midline incision was made down to the bone surface of the skull and a skin‐periosteal flap was raised to expose the skull bone on both sides of the midline. Two prefabricated titanium domes with an inner diameter of 4.5 mm and an inner height of 3.0 mm were installed on each side. The domes were supplied with a horizontal, peripheral flange and a vertical edge, fitting tightly into a circular slit, prepared by a trephine into the skull bone. This arrangement ensured a stable anchorage of the dome and a reliable peripheral sealing of the space. The skin‐periosteal flaps were relocated to cover the domes and sutured. After a healing period of 3 months, the animals were killed and the experimental areas excised and prepared for histological transversal ground sections with each dome in situ. The results demonstrated complete bone fill of all domes, with no signs of ingrowth of other types of tissues, indicating that the use of a barrier with total occlusiveness, sufficient stiffness and stability and reliable peripheral sealing will result in predictable bone augmentation of spaces also beyond the skeletal envelope.     

Bone augmentation ability of autogenous bone graft particles with different sizes: a histological and micro-computed tomography study

Objectives: The purpose of this study was to investigate the augmentation process and ability of autogenous bone graft particles of two different sizes in a vertical augmentation chamber.
Material and methods: The cranial bones of 24 rabbits were used. Two polytetrafluoroethylene chambers were filled with harvested bone from tibia with small bone (SB; 150–400 μm) and large bone (LB; 1.0–2.0 mm) of the same weight. Animals were sacrificed after 1, 2, 4 and 8 weeks. The samples were analyzed by micro-computed tomography (micro-CT) for quantitative analysis, and embedded in polyester resin as non-decalcified specimens for histological analysis. Total bone volume (TBV), bone height (BH) and distribution of bone structure were calculated by micro-CT.
Results: Micro-CT evaluation and histology revealed a significant difference between the investigated specimens. TBV and BH of SB decreased to about 50% of the initial situation, and there was a statistically significant difference between 1 and 8 weeks. In contrast, TBV and BH of LB were almost retained at all experimental time points. Significant differences in TBV and BH were also observed between LB and SB at 8 weeks. Bone volume of SB decreased predominantly in the upper half of the chamber at 4 and 8 weeks. In the histological observations, SB showed favorable new bone formation and rapid bone resorption in a time-dependent manner during the entire experimental period. However, LB exhibited favorable morphological stability and continued new bone formation.  

Conclusion:

SB follows a smooth osteogenic process, whereas it is not effective in volume augmentation. LB is superior to SB in augmentation ability.     

自攻螺纹钛筒应用于垂直骨增量的动物模型研究

目的改进原有兔颅骨垂直骨增量的动物模型。方法对原有兔颅骨垂直骨增量动物模型中提供骨生长空间和屏障作用的钛筒进行改进,钛筒底端设计自攻型螺纹。40只兔子共植入160个钛筒,制备动物模型标本,进行组织学观察。结果40只兔子术区均一期愈合。钛筒与骨面嵌合良好,160个钛筒只出现12个松动,未松动的钛筒内均可见新骨在钛筒提供的空间里向上生长。该兔颅骨垂直骨增量的动物模型能观察骨生成的高度,可以定量检测新骨量。结论新的垂直骨增量动物模型钛筒加工简单,占用兔颅骨面积小,增加了每只兔可植入的样本量,造模手术步骤少,手术操作简单,钛筒稳定性好,钛筒底端皮质骨不穿孔使实验结果有更好的可比性。此模型能客观地反映垂直向的骨增量,模拟临床牙槽嵴增高术。     

一种空间维持装置应用于上颌窦骨增量术的实验研究

目的 观察一种空间维持装置进行上颌窦骨增量术后新骨形成情况,并探究上颌窦黏膜穿孔对该技术的影响。方法 采用纯钛制作上颌窦黏膜提升空间维持装置,3只比格犬拔除上颌后牙构建上颌后牙缺失上颌窦区骨量不足的动物模型,自然愈合3个月后行双侧的上颌窦黏膜提升,随机选取一侧在黏膜完整情况下放入空间维持装置,对侧在黏膜穿孔情况下放入空间维持装置。3个月后处死实验动物,制取标本进行组织学分析。结果 空间维持装置内部可见新骨呈帽状凸起,与提升空间的形态相适应,但尚未充满整个提升的空间,窦底骨与新骨之间界限明显,新骨为未成熟的编织骨,疏松排列的骨小梁交错成网,骨小梁内可见软骨陷窝分布;无骨粉充填的上颌窦骨增量术在黏膜完整、穿孔后新骨面积分别为（8.17±5.63） mm2,（9.92±4.65） mm2,差异没有统计学意义。结论 单纯利用空间维持装置进行的上颌窦骨增量术可以诱导新骨形成,且较小的黏膜穿孔对其没有影响,具体新骨形成机制仍有待探索。     

Sinus graft with biogran, autogenous bone, and PRP: a report of three cases with histology and micro-CT

Three sinuses were grafted with a bioactive glass bone substitute (Biogran) mixed with autogenous bone retrieved from intraoral donor sites. In two of the three sinuses a platelet-rich plasma (PRP) gel was added to the graft. Bone biopsies retrieved after 5, 6, and 15 months were analyzed. Micro-computerized tomography (micro-CT) values of total bone volume/total volume (TBV/TV) were very reliable compared to histomorphometry. Biogran mixed with autogenous bone and PRP seems to have a positive effect in sinus grafting, with TBV/TV values ranging between 40% and 68%. Micro-CT results have never been compared with histomorphometry for the evaluation of grafted biomaterials. Micro-CT evaluation of some morphometric parameters was difficult, because the radiodensities of Biogran and a certain grade of bone mineralization were similar.     

Use of microfocus computerized tomography as a new technique for characterizing bone tissue around oral implants

Qualitative and quantitative analysis of peri-implant tissues around retrieved oral implants is typically done by means of light microscopy on thin histological sections containing the metal surface and the undecalcified bone. It remains, however, a labor-intensive and thus time-consuming job. Moreover, it is a destructive technique that allows tissue quantification in only a limited number of two-dimensional sections. As an alternative, we evaluated the bone structure around screw-shaped titanium implants by means of microfocus computerized tomography (micro-CT) because it presents a number of advantages compared to conventional sectioning techniques: micro-CT is nondestructive, fast, and allows a fully three-dimensional characterization of the bone structure around the implant. Images can be reconstructed in an arbitrary plane, and three-dimensional reconstructions are also possible. Because of its high resolution, individual trabeculae can be visualized. The accuracy of micro-CT was qualitatively evaluated by comparing histological sections with the corresponding CT slices for the same specimen. The overall trabecular structure is very similar according to both techniques. Even very close to the interface, the titanium implant does not seem to produce significant artifacts. Furthermore, because the complete digital data on the trabecular bone structure around the implant is available, it is possible to create finite-element models of the bone-implant system that model the trabeculae in detail so that mechanical stress transfer at the interface can be studied at the level of individual trabeculae. Therefore, micro-CT seems to be very promising for the in vitro assessment of the three-dimensional bone structure around oral implants. Further research will be needed to evaluate its accuracy in a more quantitative way.     

Bone augmentation by means of a stiff occlusive titanium barrier

It has already been shown that occlusive titanium barriers have osteoconductive properties. These barriers, however, cover only a limited surface area and have only been used in animal experiments. The aim of this study was to evaluate bone neogenesis under a pre-shaped titanium barrier placed over the top of the rabbit skull and the top of highly resorbed edentulous upper-jaw bone in patients. Computed tomography (CT) scans made it possible to pre-shape the titanium barrier according to individual bone shape in human experiments. On the rabbit skull, tissue augmentation of up to 6 mm 1 year after barrier placement was observed, while the original thickness of skull bone was on average between 1.5 and 2.5 mm. The bone, which remained histologically immature for 1 year, grew systematically along the titanium surface, illustrating its osteoconductivity. Even after removal of the barrier, on average, 75.3 and 59.4% of the newly created tissue volume was maintained after 3 and 9 months, respectively. Clinical observations on 10 consecutive patients showed that, in those (5/10) in which the barrier remained unexposed for several months, an increase of the jawbone height and width of up to 16 mm could be observed when the barrier was removed after 12-18 months. As in the rabbits at barrier removal, the bone demonstrated a limited degree of mineralization as ascertained from biopsies. This newly formed osteoid tissue allowed the insertion of 33 screw-shaped titanium implants which in most cases (30/33) successfully osseointegrated to support a fixed prosthesis. The surrounding marginal bone level remained stable even up to 5 years after implant placement. Both animal and clinical data demonstrate that guided bone neogenesis under a subperiosteally placed titanium barrier can reach large volumes.     

Bone Regeneration Using a Hollow Hydroxyapatite Space‐Maintaining Device for Maxillary Sinus Floor Augmentation – A Clinical Pilot Study

Background: The mere lifting of the maxillary sinus membrane by implants protruding into the sinus cavity allows the establishment of a void space for blood clot and new bone formation. Purpose: To evaluate bone formation by using a spherical, hollow, and perforated hydroxyapatite space‐maintaining device (HSMD) in a two‐stage sinus lift procedure where residual alveolar bone height was ≤2 mm. Material and Methods: Spherical, hollow, and perforated HSMDs with a diameter of 12 mm were manufactured for this pilot study. Three patients with a residual bone height of 1–2 mm, as verified clinically and radiographically, and in need of a sinus augmentation procedure prior to implant installation were selected for the study. The HSMD and bone formation was evaluated by cone beam computerized tomography (CBCT) 6 months after augmentation procedure. Implants were installed 6 to 9 months after augmentation. The implant sites were prepared by a trephine drill to obtain a specimen of HSMD and bone for histological evaluation. After implant installation, the condition of the sinus membrane adjacent to the HSMD was evaluated endoscopically. After an additional 8 weeks, fixed partial prostheses were fabricated. Results: Bone formation verified by CBCT was found around and inside the device in all three patients after 6 months. Despite the fact that residual bone before augmentation was ≤2 mm, 12‐mm‐long implants with diameter of 4.8 mm could be inserted with preservation of an intact and healthy sinus membrane verified endoscopically. Bone formation inside HSMDs was noted histologically in two out of three HSMDs. Implants were stable and without any marginal bone loss after 1 year of prosthetic loading. Conclusion: A spherical, hollow, and perforated HSMD used in sinus lift procedures can produce a void space for blood clot and new bone formation and subsequent implant installation.     

Use of titanium mesh for staged localized alveolar ridge augmentation: clinical and histologic-histomorphometric evaluation

The use of titanium mesh for localized alveolar ridge augmentation was evaluated by clinical, radiographic, laboratory, and histologic-histomorphometric evaluation. Seventeen patients participated in this study. All patients required localized alveolar ridge augmentation before placement of dental implants. An equal mixture of autogenous bone graft and inorganic bovine mineral (Bio-Oss) was used as a bone graft material. Autogenous bone graft was harvested intraorally. Titanium mesh was submerged for 8.47 months (SD 2.83). Impressions were taken intraorally before bone grafting, 6 months after bone grafting, and 6 months after implant placement. Impressions were used to measure the volume of alveolar ridge augmentation and provide linear laboratory measurements regarding the results of bone augmentation. Bone quality (type II-IV) was recorded during implant surgery. Standardized linear tomographs were taken before bone grafting and before implant placement. A biopsy was harvested with a trephine bur from the grafted area during implant surgery for histologic-histomorphometric evaluation. In all cases the grafted area had adequate bone volume and consistency for placement of dental implants. Early mesh exposure (2 weeks) was observed in 2 patients, and late exposure (>3 months) was observed in 4 patients. Volumetric laboratory measurements indicated 0.86 cc (SD 0.69) alveolar augmentation 1 month after bone grafting, 0.73 cc (SD 0.60) 6 months after bone grafting, and 0.71 cc (SD 0.57) 6 months after implant placement. This indicated 15.11% resorption 6 months after bone grafting, and no further resorption occurred after implant placement. Linear laboratory measurements indicated vertical augmentation of 2.94 mm (SD 0.86) 1 month after bone grafting, 2.59 mm (SD 0.91) 6 months after bone grafting, and 2.65 mm (SD 1.14) 6 months after implant placement. The corresponding measurements for labial-buccal augmentation were 4.47 mm (SD 1.55), 3.88 mm (SD 1.43), and 3.82 mm (SD 1.47). Radiographic evaluation indicated 2.56 mm (SD 1.32) vertical augmentation and 3.75 mm (SD 1.33) labial-buccal augmentation. Histomorphometric evaluation indicated 36.47% (SD 10.05) new bone formation, 49.18% (SD 6.92) connective tissue, and 14.35% (SD 5.85) residual Bio-Oss particles; 44.65% (SD 22.58) of the Bio-Oss surface was in tight contact with newly formed bone. The use of titanium mesh for localized alveolar ridge augmentation with a mixture of autogenous intraorally harvested bone graft and Bio-Oss offered adequate bone volume for placement of dental implants. Intraorally harvested autogenous bone graft mixed with Bio-Oss under a titanium mesh offered 36.47% new bone formation, and 15.11% resorption occurred 6 months after bone grafting.     

Osseointegration around titanium screws placed into the areas between guided bone augmented sites compared with osseointegration around guided bone graft augmented sites in rabbit tibia.

The aim of this study was to compare the degree of osseointegration around titanium screws placed into the areas between guided bone augmented sites and guided bone graft augmented sites in 8 Japanese white rabbit tibia. The skin and periosteum were incised and lifted to expose the inner surfaces of both tibia. Eight rabbits were divided into 2 groups: 1) a guided bone augmentation (GBA) group of 2 rabbits, and 2) a guided bone graft augmentation (GBCA) group of 6 rabbits. In the GBA group, the bone marrow was penetrated several times in both tibial bones. Three titanium screws were inserted into the bone so that the top of each screw was 3 mm above the bone surface and covered with an expanded polytetrafluoroethylene membrane (ePTFE). In the GBGA group autogenous cortical bone (10 mm x 10 mm x 1 mm) was taken from the left tibia and grafted on the inner surface of the right tibial bone, titanium screws being similarly inserted. The surgical site was covered by ePTFE. After healing for 2 months, the animals were euthanatized, and the experimental area was prepared for histological investigation. New bone had formed on the surgical sites in the GBA group and grafted bone had survived in the GBGA group, with no sign of infection or membrane exposure. The degree of osseointegration around the screw was 67.6 +/- 11.2% (mean +/- SD) in the GBA group and 78.8 +/- 11.9% in the GBGA group. There was no significant difference between the groups (p = 0.29). The ratio of mineralized bone to bone marrow was 45.7 +/- 6.2% in the GBA group and 64.4 +/- 4.4% in the GBGA group. There was a significant difference between the groups (p < 0.05). Although there was no significant difference for osseointegration around the screw placed into the GBA and GBGA sites, the quality of newly generated bone or grafted bone was quite different. Therefore, we suggest that predictable bone augmentation beyond the bone surface can be achieved by either the GBA or the GBGA procedure with ePTFE. However, it was difficult to conclude which procedure was superior with respect to the osseointegration around the titanium screw.     

Placement of autogeneic bone chips or bovine bone mineral in guided bone augmentation: a rabbit skull study

PURPOSE: Our primary aim was to use a rabbit guided bone augmentation model to evaluate whether use of autogeneic bone grafts or bovine bone mineral (BBM) combined with a space-making barrier enhances bone augmentation compared with a barrier alone. MATERIALS AND METHODS: Sixteen rabbits were studied. In each rabbit, 2 titanium cylinders, each with 1 titanium lid, were placed subcutaneously in perforated slits made in the cortical bones, with their open ends facing the parietal bones. One cylinder was left empty and the other was filled with either autogeneic skull bone chips or BBM. Bone labels were injected after 4 and 11 weeks. After 12 weeks, the animals were sacrificed to obtain ground sections for histology and histomorphometry. RESULTS: Significantly more tissue was augmented in the 2 test groups than in the control group. Most of the autografts were resorbed, leaving only minute amounts in the upper third of the cylinders. Slender new bone trabeculae were distributed mainly from the contiguous bone plate that had no contact with the remaining graft material. In the BBM group, most of the BBM remained evenly distributed in the cylinder. In the upper third of the cylinder, the BBM was surrounded by soft connective tissue, while in the lower two thirds, mainly mineralized bone enclosed the BBM. Equal amounts of mineralized bone were found in both test groups. Comparisons of contact between bone and BBM on one hand and bone and bone cylinder wall on the other revealed that the greatest bone contact was with the BBM in the lower third of the cylinder. In the middle and upper third of the cylinder, bone-BBM contact and bone-cylinder wall contact were similar. Fluorescent label intensity was higher in the autograft group than in the BBM group. In all 3 groups the intensity of the early label was similar to that of the late label, indicating that the graft materials do not seem to retard mineralization. DISCUSSION: BBM was found to promote as much new bone as did autogeneic bone. In addition, BBM appears to have at least the same osteoconductive properties as titanium, provided BBM is contained in a stable environment. CONCLUSIONS: Placement of autogeneic bone or BBM in conjunction with a stiff space-making barrier generated more tissue than a barrier only. In this model, autogeneic bone chips and BBM augmented similar amounts of new mineralized bone.     

Clinical,Tomographic, and Histological Assessment of Periosteal Guided Bone Regeneration with Cortical Perforations in Advanced Human Critical Size Defects

Background: Large osseous defects that fail to heal spontaneously require ridge augmentation prior to implant placement. The periosteum can act as an effective barrier membrane. Little is known about the influence of bone decortication in enhancing guided bone regeneration outcomes. Purpose: The aim of the present study was a clinical, tomographic, and histological evaluation of bone healing in large defect sites treated with cortical perforations without the use of other membranes but the periosteum. Material and Methods: Ten consecutive patients undergoing ridge augmentation on the pre‐maxilla due to severe bone loss were followed for an average of 35 months. Recipient sites were cortico‐perforated and augmented using a combination of autogenous particulate and block grafts. The periosteal membrane was preserved and it fully covered the autografts. Histological analysis was performed in four sites from a trephine core taken at the time of implant osteotomy preparation. Tomographic assessment (computed tomography [CT] scan) at baseline and post‐augmentation evaluated graft volume maintenance. Results: Recipient sites were re‐entered for implant placement showing good incorporation of the grafts with minimal volume loss. Biopsy specimens showed viable bone rich in osteoblast‐like cells with little or no inflammatory cells. Clinical exam revealed absence of implant transparency, mucosal recession, mobility, bleeding on probing, or suppuration at follow‐up. CT scan evaluation showed an average increased bucco‐lingual width at the recipient site of 8.1 mm ± 0.9 (2.5 fold) versus a 3.2 ± 0.9 at baseline (p < .0001; CI 95%: 4.04–5.71 mm), maintaining on average 98% of the augmented width at 2.9 years. Conclusions: Periosteal preservation seems to be sufficient as a barrier membrane to protect particulate or block osseous grafts provided that good primary closure is achieved. Bone decortication may enhance clinical and histological outcomes. Graft viability (biopsy specimens) and volume maintenance (CT evaluation) remained stable 35 months post‐augmentation.     

Impact of cortical perforations of contiguous donor bone in a guided bone augmentation procedure: an experimental study in the rabbit skull

Background: It has been shown that bone can be augmented beyond the original skeletal envelope by using space‐making barriers. Further, it has been suggested that perforation of the contiguous donor bone enhances bone formation in guided bone augmentation procedures. Purpose: The goal of the present investigation was to evaluate whether perforations into the donor bone marrow through the cortical plate, located contiguous to an extracalvarial experimental space, influence bone generation into this space with regard to augmented bone tissue volume and bone density 3 months postoperatively. Materials and Methods: Two titanium cylinders, each with a titanium lid, were subcutaneously placed with their open ends facing the parietal bones of eight rabbits and secured with miniscrews. The cortical bone plate on the test side was perforated with seven evenly distributed holes, each with a diameter of 1.2 mm, using carbon‐steel burs. Together, these perforations corresponded to about one‐third of the total experimental bone area. The bone on the control side was left intact, and no bleeding occurred during the placement of the titanium lid. The perforation procedure (test side) resulted in various degrees of blood fill. After 3 months, the animals were sacrificed to obtain ground sections for histology and histomorphometry. Results: The cylinders were found to be partly filled with tissue containing slender bone trabeculae and marrow spaces in abundance. The bone consistently reached a higher level at the inner wall compared with the central part of the cylinders (p=.001). Hollow connections between the experimental space and the skull bone marrow were found in the contiguous outer cortical plate in four of the seven control sites. No statistically significant differences could be demonstrated between the perforated test sites and the control sites regarding augmented tissue volume (64.4 ± 18.9% vs. 64.9 ± 22.2%) or bone density, although there was a tendency toward denser bone in the test sites (21.5 ± 11.1%) versus control sites (14.7 ± 5.4%). There was no statistical difference regarding relative bone‐to‐titanium wall contact (27.4 ± 14.7% for test; 38.6 ± 25.9% for control). Thickness (height) and density of the skull bone vault were measured in the area beneath and lateral to the cylinders. No significant differences could be observed regarding these parameters between the test and control side. There were no correlations between thickness (height) or density of donor bone versus amount or density of augmented bone. The degree of immediate blood fill could not be shown to correlate with augmented tissue volume or augmented bone density. Conclusions: In the present model, as observed 3 months postoperatively, cortical perforations of contiguous donor bone or degree of immediate blood fill of an extracalvarial experimental space were not found to enhance augmented tissue volume beyond the skeletal envelope. Although there was a much higher mean value for bone density of augmented bone in the test sites, the large variations failed to show significant intergroup differences.     

Influence of surface roughness of barrier walls on guided bone augmentation: experimental study in rabbits

Background: By using the guided tissue regeneration concept it is possible to augment bone, beyond the skeletal envelope, provided certain biologic, surgical, and barrier-related demands are met. Among barrier-related factors of importance are the surface properties. Purpose: The aim of this study was to evaluate whether different surface roughness of the barrier wall influences the amount and morphology of augmented bone in a secluded space, using a titanium cylinder as barrier device placed on the rabbit skull. Materials and Methods: Cylinders of commercially pure titanium were fabricated by machining, using a turning tool. The inner cylinder wall was either left untreated or grit-blasted with titanium dioxide to increase surface roughness. The topographic profile of the inner surface of two cylinders (1 turned and 1 grit-blasted) was measured in vitro to achieve a numeric characterization of each type of surface topography. Two cylinders, one with grit-blasted and one with turned inner walls, were surgically placed and secured to the skull bone of each of eight rabbits. The plate of the cortical bone, facing the experimental area framed by the cylinder wall was removed, and care was taken to ensure total blood fill of the cylinders. After 3 months, the animals were sacrificed to obtain histology for histomorphometry. Results: The relative volume of augmented tissue in the grit-blasted cylinders (77.9 ± 10.5%) did not differ significantly from that in the turned cylinders (73.4 ± 5.5%, p =.118), neither did the volume of mineralized bone (20.1 ± 8.2% vs. 22.1 ± 7.2%, p =.064). The trabecular density of the augmented bone was higher close to the walls of both the turned and the grit-blasted cylinders compared to the overall trabecular density within the cylinders, but with no significant difference between the two groups. However, the area of mineralized bone in direct contact with the inner surface of the titanium cylinder was significantly larger in the grit-blasted (33.9 ± 13.3%) compared to the turned cylinders (12.0 ± 8.5%, p =.01). Conclusions: The use of titanium barriers with a grit-blasted inner surface compared to barriers with a turned surface resulted in the formation of similar amounts of bone beyond the skeletal envelope of the rabbit skull. However, a larger area of augmented mineralized bone was found in direct contact with the inner surface of the grit-blasted cylinders.     

The use of Straumann® Bone Ceramic in a maxillary sinus floor elevation procedure: a clinical,radiological, histological and histomorphometric evaluation with a 6‐month healing period

Objectives: In this study, we evaluated the quality and quantity of bone formation in maxillary sinus floor elevation procedure using a new fully synthetic biphasic calcium phosphate (BCP) consisting of a mixture of 60% hydroxyapatite and 40% of β‐tricalcium phosphate (Straumann^® Bone Ceramic). Material and methods: A unilateral maxillary sinus floor elevation procedure was performed in six patients using 100% BCP. Biopsy retrieval for histological and histomorphometric analysis was carried out before implant placement after a 6‐month healing period. Results: In this study, the maxillary sinus floor elevation procedure with the use of BCP showed uneventful healing. Radiological evaluation after 6 months showed maintenance of vertical height gained immediately after surgery. Primary stability was achieved with all Straumann^® SLA dental implants of 4.1 mm diameter and 10 or 12 mm length. The implants appeared to be osseointegrated well after a 3‐month healing period. Histological investigation showed no signs of inflammation. Cranial from the native alveolar bone, newly formed mineralized tissue was observed. Also, osteoid islands as well as connective tissue were seen around the BCP particles, cranial from the front of newly formed mineralized tissue. Close bone‐to‐substitute contact was observed. Histomorphometric analysis showed an average bone volume/total volume (BV/TV) of 27.3% [standard deviation (SD) 4.9], bone surface/total volume (BS/TV) 4.5 mm²/mm³ (SD 1.1), trabecula‐thickness (TbTh) 132.1 μm (SD 38.4), osteoid‐volume/bone volume (OV/BV) 7.5% (SD 4.3), osteoid surface/bone surface (OS/BS) 41.3% (SD 28.5), osteoid thickness (O.Th) 13.3 μm (SD 4.7) and number of osteoclasts/total area (N.Oc/Tar) 4.4 1/mm (SD 5.7). Conclusions: Although a small number of patients were treated, this study provides radiological and histological evidence in humans confirming the suitability of this new BCP for vertical augmentation of the atrophied maxilla by means of a maxillary sinus floor elevation procedure allowing subsequent dental implant placement after a 6‐month healing period. The newly formed bone had a trabecular structure and was in intimate contact with the substitute material, outlining the osteoconductive properties of the BCP material. Bone maturation was evident by the presence of lamellar bone. To cite this article:
Frenken JWFH, Bouwman WF, Bravenboer N, Zijderveld SA, Schulten EAJM, ten Bruggenkate CM. The use of Straumann^® Bone Ceramic in a maxillary sinus floor elevation procedure: a clinical, radiological, histological and histomorphometric evaluation with a 6‐month healing period.
Clin. Oral Impl. Res. 21 , 2010; 201–208.
doi: 10.1111/j.1600‐0501.2009.01821.x     

Static and dynamic periosteal elevation: a pilot study in a pig model

The osteoinductive potential of periosteum and bone can be stimulated by elevating the periosteum in a distraction-like modus, but also by an ad-hoc elevation. This was tested and proved in an experiment in 9 Goettingen mini-pigs with elevation heights of 5, 10 and 15 mm. Specially designed and perforated titanium meshes were implanted subperiosteally to compare the dynamic elevation procedure with static shielding. The cumulative results for bone formation underneath the mesh were 66% in dynamic and 67% in non-dynamic elevation. The cumulative results for mineralization of the bone regenerates in comparison with the underlying basal bone of the skull showed independently from the technique applied no difference bigger than 5%. No major difference in bone formation could be observed in this pilot study. The main advantages of dynamic periosteal elevation and static shielding are minimal invasion and morbidity. Periosteal elevation could be applied in cranio-maxillofacial surgery, in preimplantological augmentation and in reconstructive surgery of the skull; applications in other specialties may be possible.     

研究下颌骨侧嵴扩增的兔动物模型的建立

目的:建立下颌骨侧嵴扩增的动物模型,初探rhBMP-2/BG(recombinanthumanbonemorphogeneticprotein-2inbioglass)下颌骨表面和缺损内扩增的可行性。方法:磨牙区唇侧骨皮质表面,预备4～6个5mm骨缺损,一侧骨皮质表面和骨缺损内放置BG/rhBMP-2,另一侧作为空白对照。术后8周大体观察、组织学检查和组织学测量。结果:观测时间内所有植入体固位良好,下颌骨表面明显扩增,材料表面骨组织覆盖;组织学观察皮质骨表面和骨缺损内新骨形成,纤维组织分割BG颗粒,大量新生骨呈编织骨样结构,与BG颗粒直接结合。部分BG颗粒已降解被新骨取代,并与骨皮质表面直接结合,残留颗粒被新骨包围,新骨形成百分比明显高于BG(P<0.05)。结论:下颌骨侧嵴扩增模型可靠、有效。     

Guided bone augmentation around a titanium bone-anchored hearing aid implant in canine calvarium: an initial comparison of two barrier membranes

Background: The placement of a bone-anchored hearing aid (BAHA) implant in young children may be hampered by the presence of thin, poor-quality calvarial bone. The use of extraskeletal guided skull bone augmentation around the titanium implant is one potential solution. Purpose: To compare the effectiveness of a collagen membrane BioSISt (Cook Biotech Inc., Lafayette, IN, USA) and a PGA/PLA barrier membrane, Osseoquest (W.L. Gore & Associates, Flagstaff, AZ, USA) in promoting extraskeletal bone formation, when combined with cancellous bone graft, around a titanium implant in the canine calvarium. The quality and quantity of bone tissue was compared. Materials and Methods: A 4-mm titanium BAHA implant was placed in the cranial parietal bone of 11 dogs. The implant protruded from the bone surface by a measured distance. Two groups, each of three dogs, received an implant, cancellous bone graft, and either a BioSISt or Osseoquest membrane. Three dogs received implant and bone graft (positive controls), and two received an implant only (negative controls). Samples were retrieved at 3, 6, and 9 months after placement. Undecalcified histologic and histomorphometric assessments were made of the augmented bone thickness, and bone gain factors were calculated for each sample group. Results: The process of osseointegration of the implants was ongoing and increased over time. Bone generation occurred with both test membranes and the early trabecular bone that formed, matured, and remodelled to compact bone at 9 months. BioSISt membrane samples showed superior quality and quantity of augmented bone compared with Osseoquest samples that exhibited thinner bone with persistent inflammation. Quantitatively, the BioSISt samples showed statistically greater new bone contact and bone area than both the positive and negative controls, whereas Osseoquest samples did not. The bone gain factor was statistically greater for BioSiSt samples when compared to the positive and negative controls whereas the Osseoquest samples were not. Conclusions: In this study, the collagen BioSISt membrane promoted bone formation of superior quality and quantity compared with the polyglycolic/polylactic acid-based Osseoquest membrane and positive and negative controls over 9 months. Further investigation of the use of the collagen BioSISt membrane for cranial bone augmentation is warranted.     

Dynamic periosteal elevation

The osteoinductive potential of the periosteum can be stimulated by raising the periosteum using a type of distraction. This was tested and confirmed in an animal experiment in 6 Goettingen minipigs. A titanium mesh was implanted beneath the periosteum and then raised. Bone formed underneath the mesh, with rows of micro-pillars similar to those found after osteodistraction. The main advantages of dynamic periosteal elevation are that invasion and morbidity are minimal. Clinically it might be applicable in craniomaxillofacial surgery, in augmentation before implantation, and in reconstruction of the skull.     

Effects of marrow penetration on bone augmentation within a titanium cap in rabbit calvarium

BACKGROUND: Some studies have advocated marrow penetration in guided bone augmentation (GBA), whereas others have shown that bone can be generated without marrow penetration. This study examined the effect of marrow penetration and the optimal rate of penetration. METHODS: In 10 rabbits, the calvarium was exposed, and circular grooves were prepared bilaterally. Within the circular groove, the external cortical surface of the skull was perforated mechanically using a number 4 round bur (experimental site), whereas the bone surface on the other groove (control site) was left intact. The rate of penetration was standardized as 28% for the experimental site and 0% for the control site. Subsequently, two standardized titanium caps with an inner diameter of 8 mm and an inner height of 4 mm were anchored in the prepared grooves. Five rabbits each were euthanized at 1 and 3 months, and the percent area of newly generated tissue and mineralized bone in the newly generated tissue under the titanium cap was determined. RESULTS: Histomorphometric analysis showed significantly increased bone neogenesis in the experimental site at 3 months. The percent area of mineralized bone in the newly generated tissue was consistently higher in the experimental site at 3 months. CONCLUSION: In the rabbit calvarium using a titanium cap GBA model, bone augmentation was significantly greater with marrow penetration than without penetration.