The use of a new bioresorbable barrier for guided bone regeneration in connection with implant installation. Case reports.

This report presents 4 cases with 6 implant exposures after the installation of Bråemark System® implants which called for treatment applying the guided bone regeneration technique. A bioresorbable barrier (GUIDOR® Matrix Barrier) was used to cover the defects, 4 defects with and 2 without the support of autologous bone chips. Complete bone filling was found in 4 (2 without and 2 with bone chips) and partial filling in 2 (with bone chips) of the treated defects, as registered at the abutment connection 6–7 months after surgery. Besides its ability to serve as a barrier for guided bone regeneration, it was found that the matrix barrier had the following properties; biocompatibility observed as uneventful tissue healing, malleability facilitating the clinical handling and ability to be resorbed within 6 to 7 months, as evaluated by clinical inspection. The observations of the present case reports indicate that the tested barrier may be used for guided bone regeneration in connection with implant installation. It is advisable, however, to use a supporting material to prevent barrier collapse, although bone regeneration can be achieved in certain situations without such material if the defect morphology is favourable.     

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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。     

上颌前牙区骨挤压联合骨引导再生同期种植术的应用

目的：评价上颌前牙区骨挤压联合骨引导再生同期种植术的临床效果.方法：对14例上前牙缺失、牙槽骨厚度为3mm-4mm的患者,联合采用骨挤压、骨引导再生技术,植入Frialit-2种植体17颗,于植入后6个月行二期手术,同时测量牙槽嵴顶增宽的厚度,最终完成烤瓷冠修复.结果：本组共17颗种植体,术后均无明显并发症发生,牙槽嵴顶增宽的厚度平均为2.8mm±0.6 mm,修复完成后观察12-20个月,种植体行使功能良好,无一种植体松动或脱落.结论：对于上颌前牙区牙槽骨吸收的患者,采用骨挤压联合骨引导再生术后行种植体植入,可改善牙槽骨质量,获得满意的近期临床效果.     

异种脱细胞真皮基质引导种植体周围骨缺损再生的研究

目的评价应用异种脱细胞真皮基质引导种植体骨缺损骨再生的临床效果。方法选择2008年7月—2011年7月在我院口腔科接受种植的患者22例,共28颗种植体,其中男12例,女10例,年龄为21～62岁(平均43.8岁)。将28颗种植体植入患者的狭窄形牙槽嵴中,所有种植体的唇、颊侧面均有部分暴露,将羟基磷灰石珊瑚骨粉及自体骨混合物置于骨缺损处,将异种脱细胞真皮基质膜覆盖于骨粉表面。临床观察追踪异种脱细胞真皮基质愈合情况。结果 1例患者于手术1个月左右因局部感染,异种脱细胞真皮基质膜暴露被取出,另有1颗3年后因松动被取出。其余患者术后6个月Ⅱ期手术时,见所有种植体暴露部分完全被再生骨覆盖,种植体暴露部分长度为0。结论异种脱细胞真皮基质具有良好的生物相容性和可降解性,临床上可用作骨组织引导再生膜,促进骨缺损的再生修复。     

Clinical evaluation of guided bone regeneration at exposed parts of Brånemark dental implants with and without bone allograft

This investigation evaluated guided bone regeneration with a polytetrafluoroethylene barrier membrane at exposed parts of Bråemark dental implants with and without concomitant use of decalcified freeze‐dried bone allograft. Density of the regenerated tissue was also determined using a No. 23 probe at a pressure of 25g and was graded from 1 to 5. The higher index was associated with a higher resistance of newly formed tissue to the pressure of the probe. In 19 patients, 23 defects were treated by barrier membrane alone and 11 defects by bone allograft with barrier membrane. The width and the depth of the defects were determined at the time of the implant placement and at the second‐stage implant surgery. When success was defined as 0 mm of residual defect, the mean success rate was 68% for the membrane group and 90% for the membrane group with bone allograft, with no statistically significant difference between the two treatment groups. The two groups did not demonstrate a significant difference in median density index. There was a significant positive relationship between time of membrane coverage and density index. A density index of 4 was only recorded after 7 months of membrane coverage. The present findings suggest beneficial clinical effect with the use of membrane alone and freeze‐dried bone allograft with membrane for guided bone regeneration. This study proposed the use of a novel density index of clinical evaluation of regenerated tissue.     

In vitro and in vivo evaluation of e-PTFE and alkali-cellulose membranes for guided bone regeneration

Guided bone regeneration (GBR) is employed to encourage the formation of new bone in osseous defects by restricting the infiltration of soft tissues. While a variety of membranes have been evaluated for this surgical procedure, the non-resorbable material of choice is currently expanded polytetrafluoroethylene (e-PTFE). A new alkali-cellulose membrane produced by a biotechnological process has been developed as an alternative to e-PTFE for GBR. In this study, the biocompatibility of this novel alkali-cellulose membrane and e-PTFE was compared using tissue culture and an in vivo GBR model. In vitro both materials supported the attachment, migration and differentiation of osteoblast-like cells in culture for up to 3 weeks. The in vivo model was based upon full-thickness transcortical bone defects in the mandibular rami of Sprague-Dawley rats. The right rami were used as controls, contralateral defects being covered bucally and lingually with either e-PTFE or alkali-cellulose membranes. Pathological and histomorphometric analysis was undertaken at 4 and 10 weeks post-implantation. Bone regeneration associated with alkali-cellulose membranes was predominantly endochondral in type in contrast to e-PTFE which induced direct bone formation (intramembranous ossification). The amount of new bone formed in defects was similar for both types of membrane, but alkali-cellulose membranes induced significantly greater inflammatory response; characterized by lymphocytes, macrophages and multinucleated giant cells. Degradation and possible exposure of individual cellulose fibres may account for the poor performance of alkali-cellulose membranes in vivo. This animal and in vitro study indicates that when choosing a non-resorbable membrane for GBR, e-PTFE membranes are likely to perform better than those produced from alkali-cellulose.     

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.     

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.     

钛膜引导骨再生在骨内种植体植入中的应用

目的：总结牙种植术后使用钛膜引导骨再生临床体会。方法：对30例47枚牙种植术中发现骨缺损、骨量不足的患者采用钛膜进行骨引导再生修复骨缺损及骨增量。术后定期观察，对新骨生长情况进行连续临床和X线的观察分析。结果：30例47枚牙种植术中，39枚种植体植入部位使用了钛膜。二期手术时种植体均已与骨组织形成理想的骨融合，顺利完成种植义齿修复。39枚种植体中有15枚种植体术后2个月的X线片可见到种植体封闭螺帽上方骨密度增高影。4月后二期手术切开牙龈时可见到新骨覆盖种植体表面，以骨凿等去除新骨后方可见到封闭螺帽。结论：医用钛膜在种植术中应用有较好的引导骨再生作用，有利于种植术后骨融合期新骨的形成。不可吸收性膜的一些固有缺陷可通过临床正确的设计关在术中严格按照操作要点进行手术，可获得理想的骨再生效果。     

聚四氟乙烯膜和几丁质膜引导骨再生的基础实验研究

目的：探讨国产聚四氟乙烯膜和自制几丁质膜引导骨再生的效果以及骨缺损大小与修复程度的关系，为临床应用提供依据。方法：在犬胫骨上段内侧制作直径5mm和7mm的洞穿形骨缺损，分别覆盖几丁质膜、聚四氟乙烯膜、及钛网加强的聚四氟乙烯膜，不覆盖膜做空白对照。术后2、4、8、12周取材，通过组织学及新骨形成量观察骨再生情况，比较不同的膜材料引导骨再生效果。结果：术后第2周开始，直径5mm和7mm骨缺损区覆盖膜的三组均有骨再生，至12周时骨缺损区已完全为新骨充填，对照组骨缺损区均为纤维结缔组织充填，相差显著。直径5mm和7mm的骨缺损区在膜覆盖后骨再生量无显著差别。结论：几丁质膜、聚四氟乙烯膜及钛网加强的聚四氟乙烯膜均能引导骨再生。     

Osteogenesis by guided tissue regeneration and demineralized bone matrix

AIM: To evaluate in a discriminating capsule model whether bone formation by guided tissue regeneration (GTR) may be influenced by concomitant implantation of demineralized bone matrix (DBM). MATERIALS AND METHODS: Thirty 4-month-old male albino rats of the Wistar strain were used in the study. Following surgical exposure of the mandibular ramus, a hemispherical, Teflon capsule (5.0 mm in diameter), loosely packed with a standardized amount of DBM, was placed with its open part facing the lateral bone surface of the ramus. At the contralateral side, an empty capsule was placed, serving as control. After healing periods of 15, 30, and 120 days, groups of 10 animals were sacrificed and 40-70 microm thick undecalcified sections of the capsules were produced. In the sections, the cross-sectional areas of (1) the space created by the capsule, (2) newly formed bone, (3) DBM particles, (4) loose connective tissue as well as the (5) height of the capsules, and (6) that of the newly formed bone were measured. RESULTS: Increasing bone fill was observed in both test and control sites from 30 to 120 days. After 30 days of healing, the mean amount of bone was approx. 3% of the cross-sectional area of the capsules at the test sites while it was 8% in the control sites (p<0.05). However, no statistically significant differences were observed between the test (46%) and control (64%) sites after 120 days regarding any of the measured parameters (p>0.05). The newly formed bone in the DBM group at 120 days, on the other hand, appeared more dense than that in the control capsules. CONCLUSION: DBM used as an adjunct to GTR did not provide any added effect on bone formation but increased the density of the newly formed bone.     

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.     

改良式引导骨再生术+即刻修复技术在上前牙即刻种植中的应用评价

目的评估一种改良式引导骨再生术(guided bone regeneration,GBR)+即刻修复技术在上前牙即刻种植中的应用效果,特别是美学效果,并探讨其临床技巧及美学影响因素。方法选择15例单颗上前牙进行即刻种植,微创拔牙后即刻植入Replace、Straumann或Ankylos种植体共15枚,采用改良式GBR+即刻修复,均于2 h内完成临时修复。4⁶个月后完成最终修复。种植修复完成后随访66个月后完成最终修复。种植修复完成后随访6²4个月,观察种植体周围软硬组织情况,统计种植义齿存留率、种植修复体与相邻天然牙唇侧牙龈的协调性和患者主观满意度。结果在观察期内,15枚种植体均获得了良好的骨结合,无松动,未见病理性骨吸收,存留率为100%;12枚种植修复体唇侧龈缘位置与邻牙协调无差异,3枚轻度差异;14枚种植修复体与邻牙牙龈颜色质地协调无差异,1枚轻度差异。患者主观满意度VAS平均值为92。结论改良式GBR+即刻修复技术在上前牙即刻种植中,有助于获得理想的前牙美学效果,缩短治疗周期。     

Immunohistochemical characterization of guided bone regeneration at a dehiscence-type defect using different barrier membranes: an experimental study in dogs

Objectives: The aim of the present study was to evaluate immunohistochemically the pattern of guided bone regeneration (GBR) using different types of barrier membranes. Material and methods: Standardized buccal dehiscence defects were surgically created following implant bed preparation in 12 beagle dogs. Defects were randomly assigned to six different GBR procedures: a collagen‐coated bone grafting material (BOC) in combination with either a native, three cross‐linked, a titanium‐reinforced collagen membrane, or expanded polytetrafluorethylene (ePTFE), or BOC alone. After 1, 2, 4, 6, 9, and 12 weeks of submerged healing, dissected blocks were processed for immunohistochemical (osteocalcin – OC, transglutaminase II – angiogenesis) and histomorphometrical analysis [e.g., bone‐to‐implant contact (BIC), area of new bone fill (BF)]. Results: In general, angiogenesis, OC antigen reactivity, and new bone formation mainly arose from open bone marrow spaces at the bottom of the defect and invaded the dehiscence areas along the implant surface and BOC. At 4 weeks, membranes supporting an early transmembraneous angiogenesis also exhibited some localized peripheral areas of new bone formation. However, significantly increasing BIC and BF values over time were observed in all groups. Membrane exposure after 10–12 weeks was associated with a loss of the supporting alveolar bone in the ePTFE group. Conclusion: Within the limits of the present study, it was concluded that (i) angiogenesis plays a crucial role in GBR and (ii) all membranes investigated supported bone regeneration on an equivalent level.     

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.     

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.