新型GBR胶原膜的早期动物体内植入实验研究

目的:探讨新型国产GBR胶原膜体内植入后,诱导早期膜下成骨的能力。方法:实验于2013年10月~2014年3月在沈阳军区总医院动物实验中心完成。选取小型巴马猪,于双侧下颌骨骨体处用牙科裂钻制备8mm×8mm全层骨缺损3个,分别应用实验胶原膜、Bio-gide^@、无覆盖膜覆盖骨缺损。术后1个月处死动物,分别在处死前1、2周分别肌肉注射四环素溶液与二甲酚橙溶液。固定样本后,制备硬组织切片。分别在荧光显微镜及光学显微镜下(甲苯胺蓝、亚甲基蓝-酸性品红染色)观测膜的降解程度及膜下新骨生成能力,评价材料膜下骨形成量和骨成熟程度。结果:实验组胶原膜具备良好的屏障作用,膜下新生骨矿化程度良好;骨小梁排列整齐,但新生骨量少于对照组。 结论:新型国产胶原膜在1个月时无明显降解,具备良好的膜下成骨能力,需进行实验组胶原膜的改性,以增加膜下成骨量。     

作为GBR屏障膜的新型胶原膜的体内植入效果分析

［摘要］ 目的 探讨Ⅰ型胶原和矿化Ⅰ型胶原合成的胶原膜作为GBR屏障膜在动物体内植入后,诱导早期膜下成骨的能力。方法 实验于2013年10月—2014年3月在沈阳军区总医院动物实验中心完成。选取小型巴马猪双侧下颌骨,分别于下颌骨骨体处用牙科裂钻制备8 mm×8 mm全层骨缺损3个,分别应用实验胶原膜覆盖、Bio-gide@覆盖、无覆盖膜骨缺损区。术后1个月处死动物,在处死前1、2周分别肌肉注射四环素溶液与二甲酚橙溶液。固定样本后,制备硬组织切片。分别在荧光显微镜及光学显微镜下（甲苯胺蓝、亚甲基蓝-酸性品红染色）观测膜的降解程度及膜下新骨生成能力,评价材料膜下骨形成量和骨成熟程度。结果 实验组胶原膜具备良好的屏障作用,膜下新生骨矿化程度良好;骨小梁排列整齐,但新生骨量少于Bio-gide@覆盖组;无覆盖膜骨缺损区新生骨组织骨小梁排列混乱,新生骨量少。 结论 新型胶原膜在1个月时体内无明显降解,具备良好的膜下成骨能力,下一步需进行实验组胶原膜的改性,以增加胶原膜膜下成骨量。     

Tetracycline impregnation delays collagen membrane degradation in vivo

BACKGROUND: Guided tissue and bone regeneration using bioabsorbable collagen membranes is a common practice. Collagen promotes progenitor cell adhesion, chemotaxis, homeostasis, and physiologic degradation with low immunogenicity, which makes it an ideal material for barrier preparation. Collagen membranes have to maintain integrity for a proper time, thus ensuring successful cell exclusion. Early collagen membrane degradation is detrimental for the success of regenerative procedures. This in vivo study was conducted to evaluate the effect of soaking collagen membranes in different tetracycline hydrochloride (TCN) concentration solutions on its degradation. METHODS: Five mm disks of collagen membrane were soaked in either 100 mg/ml TCN (group 100) or 50 mg/ml TCN (group 50); a group of non-treated disks served as controls. All disks were labeled with aminohexanoyl-biotin-N-hydroxy-succinimide ester (biotin) and implanted in rat calvaria bone. Block sections were taken after 3 weeks and histological slides stained with horseradish peroxidase (HRP) to detect remnants of biotinylated collagen. Staining intensity was analyzed by image-analysis software taking quadruplicate measurements of a 500 microm2 area each. Data were analyzed using analysis of variance (ANOVA) with repeated measures and paired t test with Bonferroni correction. RESULTS: Staining intensity of membranes in group 100 was > 5-fold higher than the control while group 50 exhibited > 11-fold higher intensity than the control and > 2.5-fold higher than the 100. All of these differences were statistically significant (P < 0.001). CONCLUSION: Soaking collagen membranes in 50 mg/ml TCN solution is a useful, practical, and simple tool to slow membrane degradation.     

A feasibility study evaluating an in situ formed synthetic biodegradable membrane for guided bone regeneration in dogs

Purpose: The aim was (1) to evaluate the soft‐tissue reaction of a synthetic polyethylene glycol (PEG) hydrogel used as a barrier membrane for guided bone regeneration (GBR) compared with a collagen membrane and (2) to test whether or not the application of this in situ formed membrane will result in a similar amount of bone regeneration as the use of a collagen membrane. Material and methods: Tooth extraction and preparation of osseous defects were performed in the mandibles of 11 beagle dogs. After 3 months, 44 cylindrical implants were placed within healed dehiscence‐type bone defects resulting in approximately 6 mm exposed implant surface. The following four treatment modalities were randomly allocated: PEG+autogenous bone chips, PEG+hydroxyapatite (HA)/tricalcium phosphate (TCP) granules, bioresorbable collagen membrane+autogenous bone chips and autogenous bone chips without a membrane. After 2 and 6 months, six and five dogs were sacrificed, respectively. A semi‐quantitative evaluation of the local tolerance and a histomorphometric analysis were performed. For statistical analysis, repeated measures analysis of variance (ANOVA) and subsequent pairwise Student's t‐test were applied (P<0.05). Results: No local adverse effects in association with the PEG compared with the collagen membrane was observed clinically and histologically at any time‐point. Healing was uneventful and all implants were histologically integrated. Four out of 22 PEG membrane sites revealed a soft‐tissue dehiscence after 1–2 weeks that subsequently healed uneventful. Histomorphometric measurement of the vertical bone gain showed after 2 months values between 31% and 45% and after 6 months between 31% and 38%. Bone‐to‐implant contact (BIC) within the former defect area was similarly high in all groups ranging from 71% to 82% after 2 months and 49% to 91% after 6 months. However, with regard to all evaluated parameters, the PEG and the collagen membranes did not show any statistically significant difference compared with sites treated with autogenous bone without a membrane. Conclusion: The in situ forming synthetic membrane made of PEG was safely used in the present study, revealing no biologically significant abnormal soft‐tissue reaction and demonstrated similar amounts of newly formed bone for defects treated with the PEG membrane compared with defects treated with a standard collagen membrane.     

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。     

Ossification of a novel cross-linked porcine collagen barrier in guided bone regeneration in dogs

BACKGROUND: Collagen membranes for guided bone regeneration (GBR) and guided tissue regeneration (GTR) are used extensively as bioabsorbable barriers. Cross-linking of collagen increases its biodurability and enables the control of its degradation kinetics and barrier function. A novel cross-linking technology was used to produce a porcine type I collagen membrane (GLYM). The purpose of this study was to evaluate the safety, efficacy, and degradation kinetics of GLYM compared to a non-cross-linked bilayer type I and III porcine collagen membrane (BCM) in surgically created defects in dogs. METHODS: After tooth extraction, two mandibular bilateral critical size defects were created in 12 beagle dogs that were randomly assigned to one of five groups: GLYM + bovine bone mineral (BBM), BCM + BBM, BBM alone, sham-operated, or GLYM alone. Dogs were euthanized after 8, 16, and 24 weeks, and sites were prepared for qualitative, semiquantitative, and quantitative light microscopy analyses. RESULTS: Membrane-protected sites displayed bone filling between the BBM particles with almost complete restoration of the original ridge morphology that increased with time up to 16 weeks and remained unchanged at 24 weeks. Both membranes showed marked degradation within 16 to 24 weeks, with BCM inconsistency that was undetectable in one of four sites at 8, 16, and 24 weeks. Membrane ossification was observed in all GLYM sites and in only one BCM site, which progressed with time to 24 weeks. Bone increased by approximately 1 mm on the lingual side, where the GLYM membrane was in direct contact with bone. CONCLUSIONS: Both membranes were safe and effective in supporting bone regeneration in critical size alveolar ridge defects in dogs and completely degraded within 24 weeks with marked BCM inconsistency. In areas of direct contact with bone, all GLYM sites were progressively ossified with time and augmented the original alveolar ridge. To the best of our knowledge, this is the first report of complete ossification of a collagen barrier membrane in GBR procedures.     

A randomized, controlled clinical trial to evaluate a new membrane for guided bone regeneration around dental implants

Objectives: The use of barrier membranes in guided bone regeneration (GBR) procedures for the treatment of alveolar bone defects is common practice. The objective of this study was to test whether a synthetic bioresorbable polyethylene glycol (PEG) hydrogel membrane could result in a similar amount of vertical bone fill as a standard collagen membrane, both combined with a membrane supporting material.
Material and methods: The study enrolled 37 patients requiring implant treatment with an expected osseous defect in the posterior maxilla or mandible. After raising a mucoperiosteal flap, the implant sites were prepared and dental implants placed. The defect height was then measured and defects <3 mm were excluded from the study. Defects were grafted with bovine bone mineral and randomly covered with either a collagen membrane (control group, 18 patients) or a PEG hydrogel membrane (test group, 19 patients), which is applied as a liquid. After a healing period of 6 months, surgical re-entry was performed and the change in vertical bone height from baseline evaluated.
Results: Well-vascularized hard tissue was apparent at all sites and the regenerated bone was similar to the surrounding native bone. Mean vertical defect fill after 6 months was 5.63±1.84 mm at test sites and 4.25±1.16 mm at control sites, and the mean defect fills were 94.9% and 96.4% at test and control sites, respectively. More soft tissue complications were observed with the PEG membrane (e.g., delayed or incomplete wound healing) but all sites recovered uneventfully.
Conclusions: The new PEG hydrogel membrane was as successful as a standard collagen membrane in the treatment of bony dehiscence defects around dental implants with simplified clinical handling.     

Vivosorb, Bio-Gide, and Gore-Tex as barrier membranes in rat mandibular defects: an evaluation by microradiography and micro-CT

Objectives: The objectives of this study were to determine whether a new degradable synthetic barrier membrane (Vivosorb^®) composed of poly(dl ‐lactide‐?‐caprolactone) (PDLLCL) can be useful in implant dentistry and to compare it with collagen and expanded polytetrafluoroethylene (ePTFE) membranes. Material and methods: In 192 male Sprague–Dawley rats, a standardized 5 mm circular defect was created through the right angle of the mandible. New bone formation was evaluated by post‐mortem microradiography and micro‐CT (μCT) imaging. Four groups (control, PDLLCL, collagen, ePTFE) were evaluated at three time intervals (2, 4, and 12 weeks). In the membrane groups the defects were covered; in the control group the defects were left uncovered. Data were analysed using a multiple regression model. Results: New bone formation could be detected by post‐mortem microradiography in 130 samples and by μCT imaging in 112 samples. Bone formation was progressive in 12 weeks, when the mandibular defect was covered with a membrane. Overall, more bone formation was observed underneath the collagen and ePTFE membranes than the PDLLCL membranes. Conclusions: In contrast to uncovered mandibular defects, substantial bone healing was observed in defects covered with a PDLLCL membrane. However, bone formation in PDLLCL‐covered defects tended to be less than in the defects covered with collagen or ePTFE. The high variation in the PDLLCL samples at 12 weeks may be caused by the moderate adherence of this membrane to bone compared with collagen. These results indicate that further study is needed to optimize the properties of PDLLCL membranes.     

A comparison of two types of electrospun chitosan membranes and a collagen membrane in vivo

BackgroundElectrospun chitosan membranes subjected to post-spinning processes using either triethylamine/tert-butyloxycarbonyl (TEA/tBOC) or butyryl-anhydride (BA) modifications to maintain nanofiber structure have exhibited potential for use in guided bone regeneration applications. The aim of this study was to evaluate ability of the modified membranes to support healing of bone-grafted defects as compared to a commercial collagen membrane.MethodTEA/tBOC-treated and BA-treated chitosan membranes were characterized for fiber morphology by electron microscopy, residual trifluoroacetic acid by¹⁹F NMR and endotoxin level using an endotoxin quantitation kit (ThermoScientific, US). Chitosan membranes were cut into 12 mm diameter disks. An 8 mm calvarial defect was created in each of 48 male rats and then filled with Bio-Oss (Geistlich, US) bone graft. The grafted defects were covered with either (1) TEA/tBOC-treated chitosan membrane (2) BA-treated chitosan membrane or (3) the control BioMend Extend (Zimmer Biomet, US) collagen membrane. After 3 and 8 weeks, the rats were euthanized and calvaria was retrieved for microCT and histological analyses (n = 8/group/time points).ResultsBoth TEA/tBOC-treated and BA-treated membranes were composed of nanofibers in the ～231 to ～284 nm range respectively, exhibited no TFA salt residue and low endotoxin levels (≤0.1 ± 0.01 EU/membrane). All membranes supported increased bone growth from 3 weeks to 8 weeks though there was no significant difference among the membrane types. However, TEA/tBOC treated and BA treated chitosan membranes both showed significantly greater bone density (～6% greater at 3 weeks and ～8% greater at 8 weeks) as compared to BioMend Extend collagen membrane at both time points (p = 0.0002).ConclusionsChitosan membranes supported better bone healing based on bone density than the collagen membrane.     

Acceleration of de novo bone formation with a novel bioabsorbable film: a histomorphometric study in vivo

Objective:  Different types of barrier membranes have been used in periodontal applications for the technology of guided tissue regeneration (GTR). The aim of this study was to characterize the biological effect of novel calcium alginate film (CAF) on bone tissue regeneration by using rabbit mandible defects model.
Methods:  A critical size defect (5 mm in diameter) was created in the bilateral corner of mandible of 45 adult rabbits. The defects were covered with CAF served as the experimental group, or conventional collagen membrane (CCM) or left empty as the controls. Animals were killed after 1, 2, 4, 6 and 8 weeks. Morphological and histomorphometric studies were performed to evaluate their bone regeneration pattern and biological effects.
Results:  Histological sections showed that bone regeneration pattern was centripetal in growth from defect rim. The quantitative histometry analysis revealed a significantly greater percentage of newly generated bone in CAF defects than that in CCM defects and empty defects from 2 to 6 weeks post-operation ( P  < 0.01). After 6 and 8 weeks, significantly more mature lamella bone had formed with CAF than with CCM. Empty control defects showed bone formation starting from the defect margins and incomplete healing even after 8 weeks.
Conclusion:  The CAF guided early bone growth and appeared more effective as a bioabsorbable GTR membrane than CCM. This study with mandible defect model suggests that bone defects augmented with CAF may offer most promising results from a histological and histomorphometric perspective.     

Ossification of a collagen membrane cross-linked by sugar: a human case series

BACKGROUND: Collagen membranes cross-linked by glycation (GLYM) for guided bone regeneration (GBR) and guided tissue regeneration (GTR) are used extensively with proven safety and efficacy. Complete GLYM ossification, when placed in contact with bone, was described in a canine jaw model, suggesting that GLYM may serve as an ossification substrate. The purpose of this case series was to histologically evaluate GLYM in GBR procedures in humans. METHODS: We retrospectively selected seven consecutive patients with implant-related bony defects who underwent GBR with GLYM. Six defects had bone grafts, and one had a barrier alone. Selection criteria were primary closure upon post-surgical examination and tissue that was 2- to 3-mm thick over the implant's cover screw. Tissue was removed when the implants were uncovered after 20 to 29 weeks. Decalcified sections were stained and analyzed under light microscopy. RESULTS: In five of seven specimens, GLYM was identified and preserved its barrier effect. The mean membrane thickness was 0.17 +/- 0.054 mm. In two cases, the bone grafts under the membrane were embedded in new bone, whereas in five cases, they were embedded in fibrous connective tissue. Formation of new dense bone was observed along the side of the membrane facing the original bone, and various degrees of membrane ossification were evident in all five cases. CONCLUSIONS: GLYM maintained its barrier effect in five of seven cases for 25 weeks and induced dense new bone along its interface with underlying tissues. To the best of our knowledge, this is the first report on GLYM ossification in humans with direct mineral apposition on glycated collagen and suggests a new concept of tissue-integrated active barriers.     

Tetracycline modulates collagen membrane degradation in vitro.

BACKGROUND: Structural integrity of implanted bioabsorbable barrier membranes should be preserved for a sufficient time to ensure expected results. Collagen membranes are degraded by metalloproteinases (MMP). Their degradation rate can be altered either by enhancing structural integrity or by delaying the degradation process using MMP inhibitors. Tetracyclines (TTC) present inhibitory effects on matrix MMP. Immersing membranes in TTC solution before implantation can delay their degradation. The purpose of the present study was to evaluate the effect of collagen membranes immersed in varying TTC concentration solutions on the rate of their degradation in vitro. METHODS: Collagen bioabsorbable membranes were prepared as 5 mm diameter membrane discs. Membranes were then incubated at 4 degrees C for 24 hours, in either phosphate buffered saline (PBS, Ca2+ and Mg2+ free) or with TTC-HCl dissolved in PBS concentrations of 5 mg/ml, 50 mg/ml or 100 mg/ml. After rinsing, membranes were incubated with either bacterial collagenase or cultures of human bone lineage cells. Membrane degradation was studied on days 2, 4, 7, and 14. Two- and 3-way analysis of variance was used to analyze results. RESULTS: Samples supplemented with bacterial collagenase exhibited a statistically significant interaction between changes of free protein in the medium, antibiotic concentration used for the immersion, presence of collagenase in the medium, and incubation time (P<0.0001). Membranes incubated with bone cells exhibited similar degradation trends. CONCLUSIONS: Collagen membranes immersed in 50 mg/ml TTC solution exhibited the longest degradation time, both in the clostridial collagenase and the human bone cell lineage assays. Immersion in a 50 mg/ml TTC solution before implantation will delay their degradation.     

Comparative analysis of collagen membranes for the treatment of implant dehiscence defects

Guided bone regeneration (GBR) evolved from the concept of guided tissue regeneration (GTR) and has been used for reconstructing sites with bone deficiencies associated with dental implants. For GBR, the use of absorbable collagen membranes has been increasing, but, at present, scientific information on the use of collagen membranes for GBR is limited. This study was aimed to clinically and histomorphometrically compare two collagen membranes, Bio-Gide(R) and BioMend ExtendTM, for the treatment of implant dehiscence defects in eight mongrel dogs. Implant dehiscence defects were surgically created in edentulous ridges, followed by the placement of three endosseous implants bilaterally in the mandible. Each implant dehiscence defect was randomly assigned to one of three treatment groups: (1) control (no membrane), (2) porcine dermis collagen barrier (Bio-Gide) or (3) bovine tendon collagen barrier (BioMend Extend). Dogs were sacrificed at 4 and 16 weeks (four dogs each) after treatment. Histomorphometric analysis included percentage linear bone fill (LF), new bone-to-implant contact (BIC) and area of new bone fill (BF). The results of the study revealed no significant differences among groups for any parameter at 4 weeks. However, at 16 weeks, more LF, BIC, and BF were noted in the membrane-treated groups than controls. BioMend Extend-treated defects demonstrated significantly greater BIC than control (P < 0.05) at this time point. BIC at 16 weeks was significantly greater than 4-week BIC (P < 0.05). Membrane exposure occurred in 9 out of 15 sites examined, resulting in significantly less LF and BIC than the sites without membrane exposure (P < 0.05). The results of this study indicate that: (1) GBR treatment with collagen membranes may significantly enhance bone regeneration, manifested at late stage (16 weeks) of healing; and (2) space maintenance and membrane coverage were the two most important factors affecting GBR using bioabsorbable collagen membranes.     

Guided bone regeneration around endosseous implants with anorganic bovine bone mineral. A randomized controlled trial comparing bioabsorbable versus non-resorbable barriers

BACKGROUND: Guided bone regeneration (GBR) is a viable treatment for osseous defects surrounding dental implants. Controversy exists regarding the choice of barrier membrane used and the method of membrane fixation to achieve GBR. METHODS: This study compared the efficacy of a porcine-derived bioabsorbable collagen membrane and an expanded polytetrafluoroethylene (ePTFE) membrane (non-resorbable) for GBR using a bovine bone xenograft/autograft bone composite in defects surrounding dental implants. The study also examined the effect of primary barrier fixation on GBR. Defect size was recorded at Stage 1 and 2 surgeries (performed 6 months apart). Forty-eight subjects (41% males, 59% females) requiring GBR were treated with either collagen (23) or ePTFE (25) barriers, respectively. Implants were titanium self-tapping screw-type. In 34 GBR sites, barrier fixation was achieved with polylactic acid resorbable pins. The remaining barriers were secured with the implant cover screw and/or embedded beneath the flaps. RESULTS: At 6 months, a decrease in defect width (collagen barrier 1.95 +/- 0.60 mm, ePTFE barrier 2.65 +/- 0.56 mm), length (collagen barrier 2.65 +/- 0.61 mm, ePTFE barrier 2.26 +/- 0.66 mm), and circumference (degrees) (collagen barrier 57.7 +/- 18.7, ePTFE barrier 80.2 +/- 19.9) was observed for both membranes. A significant number (chi2, P = 0.041) of postoperative complications occurred when barrier fixation was lacking at initial surgery. Furthermore, a significant difference (P <0.05) in the success of GBR with respect to defect size was observed when barrier fixation was taken into account. CONCLUSIONS: In conclusion, both collagen and ePTFE barriers proved suitable for achieving GBR of osseous defects surrounding dental implants. The results of this study stress the importance of barrier fixation at the time of initial surgery.     

Periosteal distraction osteogenesis and barrier membrane application: an experimental study in the rat calvaria

Background: Distraction of the periosteum results in the formation of new bone in the gap between the periosteum and the original bone. We postulate that the use of a barrier membrane would be beneficial for new bone formation in periosteal distraction. Methods: To selectively influence the contribution of the periosteum, a distraction plate with perforations was used alone or covered by a collagen barrier membrane. All animals were subjected to a 7‐day latency period and a 10‐day distraction period with a rate of 0.1 mm/day. Four animals per group with or without a barrier membrane were sacrificed at 2, 4, and 6 weeks after the end of the distraction. The height of new bone generated relative to the areas bound by the parent bone and the periosteum was determined by histomorphometric methods. Results: New bone was found in all groups. At the periphery of the distraction plate, significant differences in bone height were found between the hinge and the distraction screw for the group without barrier membrane at 2 weeks (0.39 ± 0.19 mm) compared to 4 weeks (0.84 ± 0.44 mm; P = 0.002) and 6 weeks (1.06 ± 0.39 mm; P = 0.004). Differences in maximum bone height with and without a barrier membrane were observed laterally to the distraction plate at 2 weeks (1.22 ± 0.64 versus 0.55 ± 0.14 mm; P = 0.019) and 6 weeks (1.61 ± 0.56 versus 0.73 ± 0.33 mm; P = 0.003) of the consolidation period. Conclusion: Within the limitations of the present study, the application of a barrier membrane may be considered beneficial for new bone formation induced by periosteal distraction.     

Resorption rates of 2 commercially available bioresorbable membranes

Abstract The respective resorption rates of recently commercialized collagen versus polylactic acid-citric acid ester membranes were compared. 16 rabbits were implanted with 2 mmx4 mm pieces of membrane of both types in the alveolar mucosa just apically to the incisors on either side of the mouth. 1 animal was sacrificed on day 0, just after the operation. The others were sacrificed at 1. 2, 3, 5, 7, 9 and 12 weeks. The specimens were prepared for histologic examination. Observations showed that the cross-linked collagen membranes induced severe inflammation and were resorbed within 2 weeks. The polylactic acid-citric acid ester polymer barriers produced a much more moderate infiltrate and were still not totally resorbed at 12 weeks. Although resorption rates in the rabbit may not be similar to those observed in humans, it seems that the durability of the polymer barrier is more adequate for guided tissue regeneration than the cross-linked collagen.     

Long-term bio-degradation of cross-linked and non-cross-linked collagen barriers in human guided bone regeneration

OBJECTIVE: This double-blind study clinically and histologically evaluated long-term barrier bio-durability of cross-linked and non-cross-linked collagen membranes (CLM and NCLM) in sites treated by guided bone regeneration procedures. MATERIALS AND METHODS: In 52 patients, 52 bony defects were randomly assigned to treatment with either a CLM or a NCLM. Post-surgical spontaneous membrane exposures were recorded. Before implant placement, full-thickness standard soft tissue discs were retrieved wherever suitable for histologic examination. RESULTS: Spontaneous membrane exposure was observed in 13 (50%) CLM sites and in six (23.1%) NCLM sites (P<0.05). Clinical healing at exposed sites lasted 2-4 weeks. CLM were histologically intact in all non-perforated sites, were interrupted in five perforated sites, and undetected in four. NCLMs were undetected in all 18 specimens examined. In three non-perforated CLM sites, bone apposition and ossification at or within the membrane was observed. CONCLUSIONS: CLMs were more resistant to tissue degradation than NCLMs, and maintained integrity during the study. Neither membrane was resistant to degradation when exposed to the oral environment. CLMs were associated with a higher incidence of tissue perforations. In non-perforated sites, CLM ossification at or within the membrane was occasionally observed.     

Systemic tetracycline delays degradation of three different collagen membranes in rat calvaria

Objectives: The aim of this study was to quantitatively evaluate the effect of systemic tetracycline (TTC) on the degradation of three different collagen membranes. Materials and methods: Collagen membranes were cut into 5 mm diameter membrane discs and labeled with aminohexanoyl‐biotin‐N‐hydroxy‐succinimide ester. One membrane disc each of a non‐cross‐linked [BioGide^® (BG)], glutaraldehyde cross‐linked [BioMend Extend^® (BM)], and ribose cross‐linked [Ossix^? (OS)] was implanted on the calvaria of 40 Wistar rats. Another 10 biotinylated collagen membrane discs from each membrane type were processed for histologic observation and served as baseline; half of them (five from each group) were also treated with formic acid to inspect possible interference with biotinilazation of collagen by formic acid used during the decalcification process. A 10 mg/kg dose of TTC (50% of the minimal recommended antibacterial dose) to the experimental (20 animals) and saline to the control (20 animals) group was administered intramuscularly every 3 days. From each group, block sections were retrieved in half of the animals after 14 days and in the remaining after 28 days. Decalcified tissue histology was stained with streptavidin horseradish peroxidase. A computer‐assisted program measured the membranes' collagen contents. Statistical analysis consisted of analysis of variance (ANOVA) with repeated measures. Results: No statistically significant differences in collagen contents were appreciated between biotinylated non‐implanted membranes treated or not treated by formic acid. Systemic TTC had a different effect on the bio‐degradation of the membranes: while it significantly decreased the resorption of two of the membranes (BG and BM), it had minimal influence on the ribose cross‐linked membrane (OS). ANOVA with repeated measures, tests of within‐subjects effects, showed a statistically significant difference between the membranes (P<0.001), within the membranes at the different time‐points (P<0.001), a significant interaction between membranes and time and between the membranes and administered TTC (P<0.001). Test of between‐subject effects revealed a statistically significant interaction with time and with TTC (P<0.001). Conclusions: Systemically administered TTC in sub‐antibacterial doses may offer a possible treatment alternative to reduce bio‐degradation and enhance bio‐durability of certain collagen membranes. The findings of the present study could have clinical application in large non‐self‐contained bone defects, where prolonged membrane barrier functions are desirable.     

Observations on a new collagen barrier membrane in 16 consecutively treated patients. Clinical and histological findings.

BACKGROUND: Space-maintaining capacity, cell disclusive potential, and stability over time are crucial factors to achieving sufficient bone augmentation with membrane barriers. The case series presented here assessed a new collagen barrier used in bone augmentation. Clinically, the healing pattern, especially in cases of secondary healing, was studied. METHODS: Soft tissue healing was documented by photographs, and the size of the dehiscences calculated by image analysis. The measurements were performed on digitized photographs. During reentry, barrier remnants were dissected and histologically evaluated. RESULTS: The mean value for dehiscences was 35.5 mm2; all dehiscences healed within 4 weeks after the exposure became evident. The difference was statistically significant between the week 2 and week 6 visits (P = 0.008) for each previously exposed site. The histologic observation of barrier remnants revealed direct apposition of fibrous and bone tissues on the membrane surface. CONCLUSION: In cases of membrane exposure, gingival dehiscences always disappeared in the following weeks without affecting the healing process. Histologic results showed barrier stability over a 6-month period, promoting bone regeneration.