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.     

Histological morphology of the e‐FTFE/tissue interface in humans subjected to guided bone regeneration in conjunction with oral implant treatment

The purpose of the present investigation was to study the histological morphology of the e‐PTFE membrane/tissue interface in 5 humans subjected to GBR treatment in conjunction with oral implant treatment. Oral implants (Bråemark System®) were inserted in extraction sockets 1 to 2 months after extraction of periodontally diseased teeth. The implants were placed approximately 2 mm below the surrounding bone margins. Specially designed 3 mm high cover‐screws with horizontal slits for tissue ingrowth were applied to the implants and covered with e‐FIFE membranes (GoreTex Augmentation Material). Reentry was made 7 months later, except in 1 case where the membrane was removed 1 month postoperatively due to exposure and infection. In the remaining 4 sites, circular biopsies comprising membranes, tissues and cover‐screws were retrieved. The specimens were fixated, processed and sectioned for light‐ and transmission electron microscopy. The space between the membrane and the cover‐screw was occupied by fibrous tissue and varying amounts of bone. A cell‐ and vessel‐rich fibrous tissue separated the bone from the membrane in the majority of the specimens. The membrane itself was penetrated by fibrous tissue. Fibroblasts and macrophages were the main cell types found in the fibrous issue. The presence of irregularly shaped cells and unevenly distributed collagen fibres, indicated that the absence of bone formation may be due either to micromovements in the e‐PTFE/tissue interface or to formation of fibrous tissue underneath the membrane by penetrating fibroblasts or a combination of these 2 phenomena.     

Alveolar ridge preservation with guided bone regeneration and a synthetic bone substitute or a bovine‐derived xenograft: a randomized,controlled clinical trial

Objectives: The aim of this randomized, controlled clinical trial was to compare the potential of a synthetic bone substitute or a bovine‐derived xenograft combined with a collagen membrane to preserve the alveolar ridge dimensions following tooth extraction. Methods: Twenty‐seven patients were randomized into two treatment groups following single tooth extraction in the incisor, canine and premolar area. In the test group, the alveolar socket was grafted with Straumann Bone Ceramic^® (SBC), while in the control group, Bio‐Oss^® deproteinized bovine bone mineral (DBBM) was applied. In both groups, a collagen barrier was used to cover the grafting material. Complete soft tissue coverage of the barriers was not achieved. After 8 months, during re‐entry procedures and before implant placement, the horizontal and vertical dimensions of the residual ridge were re‐evaluated and trephine biopsies were performed for histological analysis in all patients. Results: Twenty‐six patients completed the study. The bucco‐lingual dimension of the alveolar ridge decreased by 1.1±1 mm in the SBC group and by 2.1±1 in the DBBM group (P<0.05). Both materials preserved the mesio‐distal bone height of the ridge. No differences in the width of buccal and palatal bone plate were observed between the two groups. The histological analysis showed new bone formation in the apical part of the biopsies, which, in some instances, was in direct contact with both SBC and DBBM particles. The coronal part of the biopsies was occupied by a dense fibrous connective tissue surrounding the SBC and DBBM particles. Conclusion: Both biomaterials partially preserved the width and the interproximal bone height of the alveolar ridge. To cite this article:
Mardas N, Chadha V, Donos N. Alveolar ridge preservation with guided bone regeneration and a synthetic bone substitute or a bovine‐derived xenograft: a randomized, controlled clinical trial.
Clin. Oral Impl. Res. 21 , 2010; 688–698.     

引导骨组织再生膜应用于自身骨移植的研究现状

自身骨移植是种植术前骨增量的一种重要的技术手段。对于在常规骨移植后是否在移植物上覆盖引导骨组织再生膜,临床上存在着较大争议。笔者拟就引导骨组织再生膜在自身骨移植中的应用研究作一综述。     

功能等级引导骨再生膜的研究进展

引导骨再生（GBR）是一种利用屏障膜实现骨组织再生的治疗方法。GBR膜的应用作为GBR术的关键,可以封闭骨缺损区,阻止非成骨细胞长入,为骨组织的再生创造一个良好的环境。然而,目前市面上的GBR膜往往缺乏骨诱导潜力和抗菌活性。为了实现屏障膜的多种功能需求,许多学者致力于研究具有梯度空间结构和功能的复合膜。本文将回顾功能等级GBR膜的研究进展并对其未来发展方向进行展望,为GBR膜的进一步研究提供思路。     

Biological effects of drug-loaded biodegradable membranes for guided bone regeneration

The biological effects of drug-loaded biodegradable novel membrane for guided bone regeneration (GBR) was evaluated. The membranes were polyglycolic acid mesh coated with poly-L-lactic acid containing flurbiprofen, tetracycline or PDGF-BB. Porous structure was generated in the membranes by using a phase inversion method. The membrane was less toxic, nicely biodegradable and biocompatible for 8 wk after implantation in the dorsal skin of the rat. The drugs released from the membranes were shown to be effective for new bone formation. Tetracycline, flurbiprofen or PDGF-BB loaded membrane was markedly effective for osteoid tissue and new bone formation in the bony defect prepared in rat calvaria to compare with that by unloaded membrane. These results suggested that drug-loaded biodegradable barrier membrane might be a potential tool for GBR in periodontal therapy.     

Long-term follow-up of autogenous canine transplants with application of guided bone regeneration

The aim of this study was to evaluate the aesthetics and outcome of autotransplantation of impacted canines unsuitable for orthodontic realignment using a combination of surgery with guided bone regeneration and orthodontic treatment. Ten severely impacted canines in nine consecutive patients (mean age 14.8 years) were included. The recipient mesiodistal space was created orthodontically and the recipient socket prepared using dental implant drills. Following transplantation, bone defects were grafted using guided bone regeneration, teeth were aligned and occlusions adjusted orthodontically. Patients were followed-up every 6 months for an average of 7.1 years (range 2–11 years). The mean pink aesthetic score was 13.33 ± 0.87. Pocket depths were less than 3 mm. Radiographic examination showed an uninterrupted periodontal space and lamina dura in seven cases, unclear periodontal space in two, and replacement resorption in one case. The analysis showed that canine transplantation combined with guided bone regeneration and orthodontic treatment gives acceptable and predictable aesthetic results.     

Interdisciplinary treatment planning for orthodontic‐prosthetic implant anchorage in a partially edentulous patient

Successful orthodontic treatment is characterized by optimal anchorage control. Teeth or groups of teeth are united to counteract biomechanical reactive forces during orthodontic treatment. These classic anchorage control mechanisms are less efficient or even non-existent in partially edentulous patients who are missing multiple posterior teeth. However, osseointegrated oral implants ad modum Br-vemark can provide optimal anchorage control for orthodontic tooth alignment and rehabilitation of occlusion through prosthetic implant restorations. Careful multidisciplinary planning based on complex diagnostic wax setup casts to determine exact implant location and orientation in line with future orthodontic tooth displacements and prosthetic implant crown restorations is the most important step in the overall treatment planning.     

引导骨再生屏障膜改良的研究进展

引导骨再生术是解决骨组织缺损问题的重要技术,引导骨再生屏障膜在其中发挥着不可替代的作用。引导骨再生膜是防止成纤维细胞进入骨缺损部位的屏障,同时可促进成骨细胞的黏附、增殖和骨组织再生。由于目前广泛应用于引导骨再生的胶原膜尚存在一些缺陷,探索具有更优良性质的引导骨再生屏障膜成为一个重要的课题。因此出现了从抗菌性的改良、成骨性的改良和新材料的研发等多方面的努力以改良引导骨再生膜。本文回顾了近年来引导骨再生膜改进的研究成果和进展,展望了未来相关研究的发展方向,为进一步展开骨再生及修复的相关研究工作提供参考。     

引导骨再生屏障膜改良的研究进展

引导骨再生术是解决骨组织缺损问题的重要技术,引导骨再生屏障膜在其中发挥着不可替代的作用。引导骨再生膜是防止成纤维细胞进入骨缺损部位的屏障,同时可促进成骨细胞的黏附、增殖和骨组织再生。由于目前广泛应用于引导骨再生的胶原膜尚存在一些缺陷,探索具有更优良性质的引导骨再生屏障膜成为一个重要的课题。因此出现了从抗菌性的改良、成骨性的改良和新材料的研发等多方面的努力以改良引导骨再生膜。本文回顾了近年来引导骨再生膜改进的研究成果和进展,展望了未来相关研究的发展方向,为进一步展开骨再生及修复的相关研究工作提供参考。     

Augmentation of the rat jaw with autogeneic cortico-cancellous bone grafts and guided tissue regeneration

The aim of the present study was to evaluate the effect of augmenting the maxillary alveolar ridge and the lateral aspect of the mandible with onlay autogeneic cortico-cancellous bone grafts that were covered with e-PTFE membranes. The experiment was carried out in 51 rats. In 15 rats, the edentulous maxillary jaw between the incisor and the first molar was augmented by means of an autogeneic ischiac bone graft that was fixed with a gold-coated microimplant. In one side, the graft was covered with an e-PTFE membrane, while the other side, which served as control, was treated without a membrane. In the other 36 rats, the lateral aspect of the mandible was augmented in both sides by means of an autogeneic ischiac bone graft that was fixed with a gold-coated or a titanium microimplant. In one side, the augmented area was covered with an e-PTFE membrane, while the contralateral side was treated without a membrane. Histological analysis at 60, 120 and 180 days after augmentation of the maxilla showed that, in the case of the test sites (where most of the membranes were either exposed or lost), the bone grafts presented extensive resorption and there was a lack of bone continuity between the graft and the recipient site. Similar findings were made at the non-membrane-treated control sides. In the case of augmentation of the mandible with membranes, the bone grafts were not resorbed, but were integrated into newly formed bone at the recipient site. In the control sides, the grafts presented varying degrees of resorption and integration into the recipient bone. It is concluded that, in comparison to bone grafting alone, onlay ischiac bone grafting combined with guided tissue regeneration eliminates the risk of bone graft resorption and ensures integration of the graft into newly formed bone at the recipient site, provided that closure of the operated area can be maintained during healing.     

Alveolar bone formation at dental implant dehiscence defects following guided bone regeneration and xenogeneic freeze‐dried demineralized bone matrix

The present study evaluated rate and extent of alveolar bone formation in dental implant dehiscence defects following guided bone regeneration(GBR) and implantation of xenogeneic freeze‐dried demineralized bone matrix (xDBM). A total of 16 titanium plasma‐sprayed (TPS) and 16 hydroxyapatite‐coated (HA) titanium cylinder implants were inserted in 4 mongrel dogs following extraction of the mandibular premolar teeth. Four implant sites per jaw quadrant (2 TPS and 2 HA implant sites) were prepared into extraction sockets in each dog. Buccal alveolar bone was removed to create 3 x 5 mm dehiscence defects. Two jaw quadrants in separate animals received GBR, GBR+xDBM, xDBM (control), or gingival flap surgery alone (GFS; control). Thus, four conditions were available for each implant type (TPS or HA): GBR, GBR+xDBM; xDBM and GFS. The animals received fluorescent bone labels to allow observations of rate and extent of bone formation. Animals were sacrificed at 12 weeks postsurgery and block sections were harvested for histologic analysis. There were no apparent histologic differences between TPS and HA implant defects. GBR and GBR+xDBM resulted in almost complete bone closure of the dental implant dehiscence defect. Rate of bone formation appeared higher following GBR alone. Extent of bone formation appeared somewhat greater following GBR+xDBM; however, delayed. xDBM alone did not adequately resolve the bony defect. In conclusion, GBR results in rapid, clinically relevant bone closure of dental implant dehiscence defects. Adjunctive implantation of xDBM does not appear to significantly improve the healing response in the model used.     

A systematic review of the survival of implants in bone sites augmented with barrier membranes (guided bone regeneration) in partially edentulous patients

The aim of the present systematic review was to assess the survival of implants in regenerated bone applying the method of guided bone regeneration (GBR) compared with the survival of implants in non-regenerated bone. Studies to be included in this review needed to provide at least 12-month results following prosthetic reconstruction of titanium implants in bone regenerated by GBR with or without membrane supporting materials. The outcome measures were implant survival described as presence of implant, implant success (according to the criteria in the respective study), absence of clinical implant mobility, absence of implant fracture, absence of progressive peri-implant crestal bone loss as assessed on radiographs without clinical signs of peri-implant infection, absence of peri-implant infection with suppuration. A MEDLINE search and a hand search of relevant scientific journals were conducted including studies from the year 1990 to May 2001. A total of 11 studies could be identified fulfilling the inclusion criteria. All studies except two had the characteristics of case series or cross-sectional surveys. The two different studies had both test and control implants included in their analysis and qualified as controlled clinical trials. Cumulative success or survival rates, respectively, for implants in regenerated bone ranged from 100% after 5 years to 79.4% after 5 years of function. Regarding survival data, no significant differences were found in the controlled clinical trials between implants in regenerated compared to implants in non-regenerated bone. Within the limits of this systematic review characterized by second and third levels of evidence, the following conclusions can be drawn: The survival rate of implants placed into sites with regenerated/augmented bone using barrier membranes varied between 79% and 100% with the majority of studies indicating more than 90% after at least one year of function. The survival rates obtained in the present systematic review are similar to those generally reported for implants placed conventionally into sites without the need for bone augmentation.     

Bone regeneration in extraction sites after immediate placement of an e‐PTFE membrane with or without a biomaterial. A report on 12 consecutive cases.

The efficacy in restoring a buccal dehiscence after tooth extraction has been studied in12 consecutive cases using guided bone regeneration with (6 patients) or without (6 patients) a biomaterial (DFDBA or Bio Oss®) beneath an e‐PTFE membrane. A correlation between the clinical impression of density at drilling time and the histological signs of bone formation has been evaluated too. The membrane was removed after 6 or 9 months and a biopsy was performed. Clinically, GBR was highly predictable for regeneration of the alveolar bone after tooth extraction with buccal dehiscence. The histology fully confirmed the clinical and radiographical results, showing bone formation in all cases with individual variations in the amount of bone formed. 6‐month biopsies from the membrane sites had lamellar bone with large medullary spaces, while a good bone density was observed at 9 months. The membrane/biomaterial sites demonstrated mineralization and large amounts of allograft at 6 months. Thus, bone regeneration seems to take more time when grafting material is used.     

GBR技术应用于上前牙种植骨缺损的临床研究

目的：评估引导骨再生技术（GBR）在上前牙不同类型骨缺损种植修复中的效果。方法：对35例上前牙牙槽骨缺损种植的患者采用GBR技术进行骨增量,其中29例种植体周围骨缺损患者仅采用GBR技术,在植体植入骨床后,同期植入Bio～oss人工骨粉,表面盖Bio～gide可吸收性胶原膜;6例牙槽骨缺损患者采用移植自体块状骨联合Bio～oss人工骨粉,盖Bio～gide可吸收性胶原膜,5～6个月后行Ⅱ期种植体植入术。结果：所有患者在植体植入术后6～12个月临床观察种植体与骨结合良好,软组织形态与周围组织一致,行冠或桥修复,修复后12个月随诊复查无种植体失败。结论：引导骨再生技术皆能有效地对上前牙不同类型骨缺损进行骨增量,符合美学种植要求。     

Effect of bovine bone and collagen membranes on healing of mandibular bone blocks: a prospective randomized controlled study

Aim: The aim of the present study was to evaluate if the use of deprotenized bovine bone mineral (DBBM) and collagen barrier membranes (CM) in combination with mandibular bone block grafts could reduce bone block graft resorption during healing. Methods: A prospective randomized controlled study has been designed. Twenty‐two ridges presenting horizontal alveolar deficiency (crest width <4 mm) and at least two adjacent missing teeth were included in the study. In the control group, one or multiple mandibular blocks were used to gain horizontal augmentation of the ridge. In the test group, DBBM granules were added at the periphery and over the graft. The reconstructions were covered by two layers of CM. Implants were placed 4 months after grafting. Direct measurements of crest width were performed before and immediately after bone augmentation, and immediately before implant placement. Results: Statistical analysis showed no significant differences in crest width between test and control groups at baseline and immediately after grafting. Mean augmentation at first surgery in the test group was 4.18 vs. 4.57 mm in the control group. Final gain obtained at the time of implant placement was 3.93 mm in the test and 3.67 mm in the control groups. The difference in mean graft resorption between test and control sites was statistically significant (0.25 mm in the test group vs. 0.89 mm in the control group, P=0.03). Complications seem to occur more often in the test group (complications recorded in three cases in the test group vs. one complication recorded in the control group). In all cases, implants could be placed in the planned sites and a total of 55 implants were placed (28 in the test group and 27 in the control group). All implants could be considered successfully integrated at the 24‐month follow‐up visit. Conclusion: The results from this study showed that the addition of bovine bone mineral and a CM around and over a mandibular bone block graft could minimize graft resorption during healing. On the other hand, the use of bone substitutes and barrier membranes in combination with block grafts increased the frequency of complications and the difficulty of their management. To cite this article:
Cordaro L, Torsello F, Morcavallo S, Mirisola di Torresanto V. Effect of bovine bone and collagen membranes on healing of mandibular bone blocks: a prospective randomized controlled study.
Clin. Oral Impl. Res. 22 , 2011; 1145–1150.
doi: 10.1111/j.1600‐0501.2010.02093.x     

Alveolar distraction osteogenesis vs. vertical guided bone regeneration for the correction of vertically deficient edentulous ridges: a 1-3-year prospective study on humans

The purpose of this prospective study was to compare vertical guided bone regeneration (GBR) and vertical distraction osteogenesis (DO) for their ability in correcting vertically deficient alveolar ridges and their ability in maintaining over time the vertical bone gain obtained before and after implant placement. Eleven patients (group 1) were treated by means of vertical GBR with autogenous bone and e-PTFE membranes, while 10 patients (group 2) were treated by means of DO. In group 1, six patients received implants at the time of GBR (subgroup 1A), while five patients had implants placed at the time of membrane removal (subgroup 1B). In group 2, implants were placed at the time of distraction device removal. A total of 25 implants were placed in group 1 and 34 implants were placed in group 2 patients. Three to 5 months after implant placement, patients were rehabilitated with implant-borne dental prostheses. The following parameters were evaluated: (a) bone resorption of the regenerated ridges before and after implant placement; (b) peri-implant clinical parameters 1, 2, and 3 years after prosthetic loading of implants; (c) survival and success rates of implants. Bone resorption values before and after implant placement were significantly higher in group 1. The results suggested that both techniques may improve the deficit of vertically resorbed edentulous ridges, although distraction osteogenesis seems to be more predictable as far as the long-term prognosis of vertical bone gain is concerned. Implant survival rates as well as peri-implant clinical parameters do not differ significantly between the two groups, whereas the success rate of implants placed in group 2 patients was higher than that obtained in group 1 patients.