Guided bone regeneration in dental implant treatment using a bioabsorbable membrane

The aim of this study was to evaluate an osteopromotive technique, using a bioabsorbable membrane, for its ability to restitute bone over buccal fenes-tration and dehiscence defects following fixture installation. 11 patients requiring dental implant treatment and exhibiting sufficient vertical height of the maxilla and compromised bucco-palatal dimensions, as determined clinically and radiographically, were included in the study. 17 Brånemark® titanium fixtures were placed with buccal defects which were augmented by a bioabsorbable membrane, Resolut®. No complications were observed post-operatively. At 6-8 months, abutment connection was performed, and clinical evaluation of the healed defect area was made. The number of exposed buccal threads at fixture installation (median 8; range 2-19), and abutment connection (median 0; range 0-5), respectively, was compared. Out of the 17 fixtures; 14 exhibited complete coverage with bone, whereas 3 showed some remaining threads. A small punch biopsy taken at abutment connection in an area where the membrane had been placed showed a combination of dense connective tissue and bone. Radiographic evaluation of the marginal periimplant bone level is in progress and results to date show a median bone loss of 1.2 mm after a loading period of 4-6 months. Results show that fixture dehiscence and fenestrations, augmented with this bioabsorbable membrane, demonstrate a highly significant amount of new bone formation.     

异种骨移植物Bio-oss胶原和Bio-gide膜对牙周骨下袋影响的临床研究

目的:探讨异种骨移植物Bio-oss胶原和Bio-gide膜治疗牙周骨下袋的临床疗效。方法:随机选择30例牙周骨缺损患者,其中17例25个牙位在翻瓣术时植入Bio-Oss胶原和Bio-gide膜为GTR组。13例25个牙位作翻瓣术为OFD组,术后3,6,12个月回访,通过检查探诊出血指数(BI)、菌斑指数(PLI)、牙周探诊深度(PD)、临床附着丧失(CAL)、龈退缩和牙松动度,X线检查比较两组骨缺损修复情况。结果:GTR组术前PD、CAL和BI分别为7.33mm、8.50mm和2.87,术后6月分别为3.56mm、4.88mm和1.13;术后12月分别为3.71mm、4.76mm、1.25;OFD组术前PD、CAL和BI分别为7.05mm、8.35mm和2.40,术后6月分别为5.12mm、7.05mm和1.68,术后12月分别为5.50mm、7.10mm、1.70;术后6月和12月GTR组和OFD组的PD、CAL和BI均比术前明显改善,术后GTR组的各指标比OFD组均有不同程度改善,两组的CAL、PD有非常显著性差异,BI有显著性差异,GTR组术后松动度明显降低。GTR组术后骨缺损明显改善,OFD组未见明显新骨形成。结论:Bio-oss胶原和Bio-gide膜能明显修复牙周袋,减轻牙周附着丧失和修复骨下袋,促进牙周新附着和新骨形成。     

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.     

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.     

Healing of dehiscence-type defects in implants placed together with different barrier membranes: a comparative clinical study

OBJECTIVE: Premature exposure of membranes used in guided bone regeneration (GBR) results in decreased bone formation. The effect of an expanded polytetrafluoroethylene (e-PTFE) and two collagen membrane on bone healing of buccal dehiscence defects around implants in cases with and without premature membrane exposure was clinically evaluated. METHODS: Three groups were established: Group OS (Ossix, n=73 implants, 41 patients), Group BG (Bio-Gide, n=53 implants, 28 patients) and Group GT (e-PTFE, Gore-Tex, n=34 implants, 17 patients). Defect height and width were measured at the time of implant placement and at second stage surgery. Surface area was calculated as half ellipses. When several implants were placed simultaneously, a mean of their defect width and height was calculated. RESULTS: Mean percentage reduction of defect area (92.2+/-13.78% Group OS, 94.6+/-6.69% Group BG, and 97.3+/-4.91% Group GT) and height (81.6+/-23.19%, 85.4+/-12.26%, and 93.4+/-9.39% respectively) did not show statistically significant differences between groups. Differences between groups were not statistically significant for all parameters when cases without spontaneous membrane exposure were compared. However, differences were significant when spontaneous membrane exposure occurred. Mean percentage reduction of defect area among cases where membrane exposure occurred was 91.5+/-10.86% Group OS, 71.5+/-8.61% Group BG, and 73.7+/-13.97% Group GT. Mean percentage reduction of defect height among cases with membrane exposure was 76.4+/-18.28%, 53.4+/-9.86%, and 49.4+/-11.05%, respectively. CONCLUSIONS: Premature exposure of membranes and subsequent and consequent exposure of implants results in impaired bone healing. Certain barrier membranes, as used in group OS, are apparently capable of supporting gingival healing even when prematurely exposed that could be advantageous in GBR procedures.     

Effect of loading on bone regenerated at implant dehiscence sites in humans

Few investigations have studied the long‐term fate of bone formed following the technique of guided tissue regeneration. The aim of the present study was to evaluate bone fill around implant fixtures with dehiscence defects and to study its response to loading. Ten patients were treated with overdentures supported by 2 fixtures ad modum Brånemark. A third 7 mm x 3.75 mm diameter fixture was placed for the purposes of the study in the most anterior part of the mandible with a dehiscence defect of 4 to 5 mm on the buccal aspect (and 3 to 4 threads exposed) which was covered with a Gore‐Tex membrane and buried beneath the mucosa. Fixtures were exposed after 5 months (stage 2), ball abutments connected and loaded through an overdenture for 1 year. Nine fixtures were functioning well after 1 year of loading, 6 of which were retrieved with a trephine for histological examination and compared with 6 unloaded fixtures retrieved in our previously reported study. The bone area filling the thread profiles (BA%) and the bone to metal contact (BMC%) were measured in the 3 most apical and 3 most coronal thread profiles on the buccal and lingual surfaces. Statistically significant higher BMC% ( P <0.01) were observed in loaded fixtures in the apical regions (buccal: loaded 51%. unloaded 25%; lingual: loaded 49%, unloaded 24%). Differences approached significance for the regeneration site (loaded 22%, unloaded 6%) but were no different for the coronal lingual region (loaded 28%, unloaded 20%). There were no differences for BA%. This study confirms that there is an increase in bone to metal contact with time and following fixture loading and that this may also occur with bone regenerated under Gore‐Tex membranes.     

Comparison of bioabsorbable and bioinert membranes for guided bone regeneration around non‐submerged implants. An experimental study in the mongrel dog.

The aim of this clinical investigation was to evaluate the effect of guided bone regeneration around non-submerged implants using different barrier membranes. Five adult mongrel dogs were used in this investigation. After having all premolars extracted and implant osteotomies performed in the regions of the former premolars, buccal bone defects were created. Subsequently, 3 implants were placed and the defects treated with 1 of the following 3 modalities: a) guided bone regeneration using an expanded polytetrafluoroethylene membrane, b) guided bone regeneration using a bioabsorbable membrane made from a synthetic copolymer of glycolide and lactide and c) no membrane application. Following implant and membrane placement, the mucoperiosteal flaps were repositioned and tightly sutured around the neck of the implants allowing for a non-submerged healing. After a healing period of 6 months, the animals were sacrificed and the specimens processed for histologic evaluation. The clinical pre-treatment defects between the different treatment groups were not statistically different (bioinert membrane group: 4.9 mm; control group: 4.8 mm; bioabsorbable membrane group: 4.5 mm). The remaining histological defects after 6 months of healing amounted to approximately 2.5 mm in the bioinert membrane group, 5.7 mm in the control group and 6.0 mm in the bioabsorbable membrane group. A significant difference was observed between the bioinert membrane group and the other 2 groups. The mineralized bone-to-implant contact in the bioinert membrane group was 51.5%, in the control group 46.3% and in the bioabsorbable membrane group 37.5%. The values between the bioinert membrane group and the bioabsorbable membrane group were statistically different. The results of this study indicate that bone regeneration with bioinert e-PTFE membranes around non-submerged implants is possible. The utilized absorbable polyglycolic/polylactid membrane did not show any bone regenerative effect and the results did not differ from the control group without membrane application.     

A comparative study of barrier membranes as graft protectors in the treatment of localized bone defects. An experimental study in a canine model

Guided bone regeneration is a predictable and well-documented surgical approach for the treatment of deficient alveolar ridges prior to endosseous implant placement. The purpose of this study was to compare a new resorbable membrane (GORE RESOLUT ADAPT Regenerative Membrane, i.e. 67% glycolide (PGA) : 33% trimethyline carbonate (TMC)) with Bio-Gide, a resorbable collagen membrane. Five canines were used in the study. Three saddle-type osseous defects were created bilaterally in edentulous areas of the mandible. The defects were filled with assayed, canine demineralized freeze-dried bone (DFDB) in a thermoplastic gelatin matrix. Using a randomized block design, four sites were covered with PGA : TMC membranes of four different porosities, one site was covered with a collagen membrane and one site consisted of DFDB alone (control). At 3 months, the animals were euthanized and the mandibles were removed en bloc for laboratory processing. A total of 30 sites were reviewed microradiographically and underwent histomorphometric analysis for bone regeneration, soft tissue presence and remaining graft material. All sites exhibited uneventful healing. A significantly higher percentage of bone regeneration was seen in the sites protected by the PGA : TMC membrane. A higher component of soft tissue was visible beneath the collagen membrane as compared with the PGA : TMC membrane. The control sites exhibited noticeable deformation of the regenerated bone secondary to collapse of the overlying periosteum. The authors conclude that the PGA : TMC membrane protected the DFDB-filled defect and allowed a greater amount of bone regeneration than the defect protected by the collagen membrane or the control.     

Healing of marginal defects at implants placed in fresh extraction sockets or after 4-6 weeks of healing. A comparative study

The purpose of this study was to evaluate the clinical healing of buccal marginal defects around implants placed in fresh extraction sockets or after several weeks together with barrier membranes and bone graft. Two implant placement protocols were compared: delayed-immediate sites primarily closed by a rotated (full thickness) palatal flap (RPF) at the time of tooth extraction and implantation after 4-6 weeks (Group 1, 24 patients, n = 31 implants) and immediate procedures (into fresh extraction sockets) primarily closed by a rotated split palatal flap (RSPF) (Group 2, 19 patients, n = 23 implants). One or two proximal maxillary implants were simultaneously placed. Height and width of the marginal defect were measured at the time of implant placement and after 6-8 months, at second stage surgery. For Groups 1 and 2, the mean percentage of the reduced defect height was 91.2% (+/- 9.12) and 77.4% (+/- 16.92), respectively, and the mean percentage area of the reduced defect was 97.2% (+/- 3.85) and 90.2% (+/- 9.15), respectively. Differences between groups were statistically significant. Groups were subdivided according to number of implants placed (one or two). Spontaneous implant cover screw exposure was seen only in Group 2. There was an association between the number of implants simultaneously placed and the occurrence of spontaneous exposure. The mean percentage reduction of the defect height and area was significantly smaller where there was spontaneous exposure. Significant differences were found for mean percentage reduction of the defect height and area only between the two implant subgroups within each group.     

Evaluation of implant osseointegration with different regeneration techniques in the treatment of bone defects around implants: an experimental study in a rabbit model

Aim: The aim of this study was to evaluate the osseointegration of implants placed in areas with artificially created bone defects, using three bone regeneration techniques. Material and methods: The experimental model was the rabbit femur (16), where bone defects were created and implants were placed. The peri‐implant bone defects were filled with a deproteinized bovine bone mineral, NuOss^? (N), NuOss^? combined with plasma rich in growth factors (PRGF) (N+PRGF), NuOss^? covered by an RCM⁶ membrane (N+M), or remained unfilled (control group [C]). After 4 and 8 weeks, the animals were euthanized and bone tissue blocks with the implants and the surrounding bone tissue were removed and processed according to a histological protocol for hard tissues on non‐decalcified ground sections. The samples were studied by light and electron scanning microscopy, histometric analysis was performed to assess the percentage of bone in direct contact with the implant surface and a statistical analysis of the results was performed. Results: In the samples analyzed 4 weeks after implantation, the percentage of bone tissue in direct contact with the implant surface for the four groups were 57.66±24.39% (N), 58.62±20.37% (N+PRGF), 70.82±20.34 % (N+M) and 33.07±5.49% (C). In the samples with 8 weeks of implantation time, the percentage of bone in direct contact was 63.35±27.69% (N), 58.42±24.77% (N+PRGF), 78.02±15.13% (N+M) and 40.28±27.32% (C). In terms of the percentage of bone contact, groups N and N+M presented statistically significant differences from group C in the 4‐week trial test (P<0.05; ANOVA). For the 8‐week results, only group N+M showed statistically significant differences when compared with group C (P<0.05; ANOVA). Conclusion: In conclusion, the NuOss^? granules/RCM⁶ membrane combination presented a percentage of bone contact with the implant surface statistically greater than in the other groups. To cite this article:
Guerra I, Branco FM, Vasconcelos M, Afonso A, Figueiral H, Zita R. Evaluation of implant osseointegration with different regeneration techniques in the treatment of bone defects around implants: an experimental study in a rabbit model.
Clin. Oral Impl. Res. 22 , 2011; 314–322.
doi: 10.1111/j.1600‐0501.2010.02002.x     

两种胶原膜暴露于口腔环境中降解作用的对照研究

目的：本研究通过将两种胶原膜实验性的暴露于动物口腔环境中,探讨其生物降解作用的差别,为两种材料的临床应用提供相关实验依据。方法：健康成年日本大耳白兔8只,体重3.5～4.0kg,雌雄不拘。通过2种外科手术方法制备动物模型。方法1：使用3mm牙龈环切刀,沿上颚中线两侧对称制备圆形粘膜穿孔,潜行分离圆孔周围2mm粘膜组织,将直径5mm的圆形Bio-Gide和海奥胶原膜置入缺损区。方法2：制备边长5mm角形粘膜瓣,潜行分离粘膜瓣周围2mm粘膜组织,将直径5mm的两种胶原膜置入粘膜瓣下,重新复位粘膜瓣并使用可吸收缝线严密缝合。按上述方法在每只动物上颚制备6个缺损,共计48个缺损区,按照随机分组原则,将两种胶原膜按暴露与非暴露分为4组,每组为12个实验样本。术后7天和28天各处死4只动物行大体、组织学观察及图形分析检测膜材料降解吸收替代百分比。结果：1）大体观察：术后7天,两种胶原膜的非暴露组创口已基本愈合,可见炎症反应;两种胶原膜的暴露组呈凹陷状愈合;术后28天,各组的缺损区已愈合,表面无炎症性反应。2）组织学观察：术后7天,两种胶原膜的不同组别均可见大量炎性细胞,但非暴露组相对于暴露组炎症反应较轻,不同处理条件下均可见成纤维细胞浸润;术后28天,两种胶原膜的暴露组炎性细胞减少,成纤维细胞数量增多,两种胶原膜的非暴露组可见炎性细胞浸润、毛细血管增生,成纤维细胞数量增多。3）Bio-Gide胶原膜和海奥口腔修复膜在暴露和非暴露两种处理方式下两者的降解吸收效果无显著性差异（P〉0.05）,但两种胶原膜在暴露条件下降解吸收的程度均高于于非暴露条件（P〈0.05）。结论：1）Bio-Gide胶原膜和海奥口腔修复膜在引导骨再生（GBR）技术中均能起到良好的屏障作用。2）生物胶原膜暴露于口腔环境中将会导致膜的降解吸收加速,增加膜下新生组织感染的风险。     

Bio-degradation of a resorbable collagen membrane (Bio-Gide®) applied in a double-layer technique in rats

Objective: The aim of this study was to evaluate histologically the bio‐degradation of two layers of Bio‐Gide^® (BG) membrane, as compared with that of a single layer. Material and methods: Two circular calvarial bony defects, 5 mm in diameter, were made in 24 Wistar rats. BG membrane, labeled with biotin, was cut into 5‐mm‐diameter disks, and placed in defects either as a mono‐layer membrane (MLM) or as a double‐layer membrane (DLM). Rats were sacrificed after 4 or 9 weeks and histology was performed. Membranes were stained with horseradish peroxidase‐conjugated streptavidin and aminoethyl carbazole as a substrate for detection of biotinylated collagen. The area of collagen and thickness of the residual membranes were measured by image analysis software. Statistical analysis was performed using the non‐parametric Wilcoxon's signed‐ranks test. Results: At 4‐week collagen area per measurement window within the DLM sites (0.09±0.05 mm²) was significantly greater (P<0.01) than that in the MLM sites (0.047±0.034 mm²). At 9 weeks, the collagen area was also greater in the DLM sites (0.037±0.026 mm²) compared with that of the MLM sites (0.025±0.016 mm²); however, this difference did not reach statistical significance. The rate of membrane degradation, calculated as percent membrane lost compared with baseline, was similar for the DLM and MLM at both time points (～60% at 4 weeks and ～80% at 9 weeks). In addition, the residual DLM thickness at 4 weeks (475.5±73.77 μm) was significantly (P<0.01) greater than that of MLM (262.38±48.01 μm). At 9 weeks, membrane thickness was also greater in the DLM sites (318.22±70.45 μm) compared with that of the MLM sites (183.32±26.72 μm); however, this difference did not reach statistical significance. The reduction in thickness between 4 and 9 weeks was 30% for MLM and 33% for DLM. Discussion: The use of a double layer of BG membrane results in a barrier of increased collagen area and thickness, compared with application of a single layer.     

Bioabsorbable materials for guided bone regeneration prior to implant placement and 7-year follow-up: report of 14 cases

BACKGROUND: The purpose of the present study was to evaluate the efficacy of a guided bone regeneration (GBR) procedure prior to implant placement and the long-term outcome of the inserted implants. METHODS: Prior to dental implant placement, GBR procedure was performed on 14 patients (mean age 48 years) using a synthetic hydroxyapatite (HA) spacer under a collagen membrane. After a mean healing period of 8 months, bone biopsies were obtained during the placement of 14 implants. The specimens were processed for histology without demineralization in order to assess bone quality and quantity of the regenerated bone. RESULTS: Both the bone density and the resorption degree of HA particles were relatively varied between samples. The different phenotypes of osteoclasts and multinucleated giant cells and the individual host response could partially explain the unpredictable results in terms of bone remodeling and biomaterial resorption. However, the presence of HA particles in the regenerated bone had no influence on the osseointegration of implants presenting a success rate of 86% after a 7-year observation period. CONCLUSIONS: These results confirm the possibility of regenerating bone by means of bioabsorbable materials, assuring at the same time the long-term success for implants inserted in regenerated sites.     

Evaluation of implants placed with barrier membranes. A restrospective follow-up study up to five years

This follow-up study evaluated clinical and radiographic parameters of dental implants placed in combination with guided bone regeneration with barrier membranes. All implants functioned well up to 60 months after insertion. Forty-one patients, with a total of 72 augmented implants, who participated in a regular maintenance protocol, were investigated. Annual Periotest values (median value, - 3) revealed stable periimplant conditions and sustained osseointegration. At 6 months and annually thereafter up to five years, the radiographic evaluation yielded mean bone losses of 0.8, 1.25, 1.39, 1.42, 1.42 and 1.39 mm, respectively, with a range from 0 to 3.5 mm. No implant failures or losses were recorded. The results demonstrated stable periimplant conditions up to five years after membrane-protected osseous regeneration, with no significant differences in the radiographic bone level in regard to region, jaw or bone graft. Premature membrane exposure resulted in a significantly higher crestal bone loss up to 24 months. The newly formed bone appeared to be able to withstand functional loading for up to 60 months in a predictable manner.     

Treatment of an early implant failure according to the principles of guided tissue regeneration (GTR)

The present case report demonstrates the application of guided tissue regeneration (GTR) in combination with antimicrobial therapy for the treatment of an early implant failure. This treatment approach both prevented further loss of bone as well as led to the regeneration of lost bone. By means of color-converted digital subtraction images, remodelling of the tissues adjacent to the defect was documented as early as one month postsurgically. The images demonstrated "bone-fill" in the apical portion of the defect and resorptive changes at the bone crest. This case report demonstrates that combined regenerative and antimicrobial therapy may be a successful treatment approach restoring osseointegration of dental implants following loss of bone due to infection. Continuously increasing bone-fill inside the defect was documented when comparing the radiograph obtained immediately before the GTR procedure and at months 1, 2, 4, 5 and 6 of the healing period, respectively. Clinical measurement obtained at the time of the surgery and at the time of the membrane removal confirmed the radiographic evidence of bone-fill by demonstrating new tissue resistant to probing in close contact to the implant surface at the site of the previous defect. Antimicrobial therapy included an antibiotic regimen during the 1st month of healing as well as topical rinses with an antiseptic (chlorhexidine) over the entire healing period of 6 months. As a result of this treatment approach, the implant was saved and could be used as an abutment for a bridge reconstruction.