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.     

The bone regenerative effect of platelet-derived growth factor-BB delivered with a chitosan/tricalcium phosphate sponge carrier

BACKGROUND: In order to achieve optimal effects, growth factors including platelet-derived growth factor (PDGF) should be delivered with a biodegradable carrier that will release therapeutic concentrations over a sufficient length of time. The purpose of this study was to evaluate the bone regenerative effect of PDGF-BB delivered with a chitosan/tricalcium phosphate (TCP) sponge carrier in a rat calvarial defect model. METHODS: The PDGF-BB-loaded chitosan/TCP sponge carrier was fabricated by freeze-drying a mixture of chitosan solution and TCP powder and soaking in a PDGF-BB solution. The release kinetics of PDGF-BB loaded onto the sponge were measured in vitro with 125I-labeled PDGF-BB. Chitosan/TCP sponges with and without PDGF-BB were implanted into 8 mm calvarial defects in rats. Rats were sacrificed at 2 and 4 weeks following implantation, and histologic and histomorphometrical examinations were performed. RESULTS: In vitro evaluation demonstrated that an effective therapeutic concentration of PDGF-BB following a high initial burst release was maintained throughout the examination period. In the histologic examination, the chitosan/TCP sponge carrier promoted osseous healing of the rat calvarial defects as compared to controls. The addition of PDGF-BB to the carrier further enhanced bone regeneration. Evidence of the degraded sponge matrix was observed mingled within the newly formed bone without connective tissue encapsulation. CONCLUSIONS: The results of this study support the use of chitosan/TCP sponges as a delivery system for growth factors and demonstrate that PDGF-BB loaded onto chitosan/TCP sponge carriers has an osteogenic effect on bone regeneration in vivo.     

Use of a mineralized collagen membrane to enhance repair of calvarial defects in rats

The aim of the present study was to evaluate mineralized collagen membranes for enhancement of bone regeneration in calvarial defects. Forty adult female Sprague-Dawley rats received calvarial full thickness defects with a diameter of 8 mm. In 20 animals, the defects were covered with a mineralized collagen membrane, and 20 animals served as controls. After 6, 13, 26 and 52 weeks, bone regeneration was evaluated using undecalcified thick-section histometry. There was no clear enhancement of bone regeneration during the first 26 weeks after the operation. Bone regeneration underneath the membrane produced consistently thicker bone, albeit without statistical significance. Accumulation of membrane material occurred in the center of the defects surrounded by multinuclear giant cells during early stages of healing. After complete resorption of the membrane, significantly increased bone formation was seen after 52 weeks in the defects that had received membrane coverage. It was concluded that mineralization in the present form did not increase mechanical strength of the membrane to prevent interference of the membrane with bone regeneration in the defect. The reason for the increase in bone formation after resorption of the membrane after 26 weeks remains to be clarified.     

新型双层骨引导再生壳聚糖膜修复大鼠颅骨缺损的实验研究

目的: 通过比较新型双层壳聚糖膜和Bio-Gide膜对大鼠颅骨缺损的修复效果,评估其作为引导骨再生膜的可行性。方法: 双层壳聚糖膜与MC3T3-E1细胞共培养,应用扫描电子显微镜（scanning electron microscope,SEM）观察细胞对膜的黏附效果;采用cell counting kit-8（CCK-8）法在3、7和10 d检测膜的细胞毒性;选择18只Sprague-Dawley（SD）大鼠,随机分为A、B、C组,在其颅骨中线两侧制作5 mm的极量骨缺损,左侧为实验侧,覆盖双层壳聚糖膜,右侧为对照侧覆盖Bio-Gide膜,分别于术后第2、4及8周时处死各组大鼠,通过大体观察、微计算机体层扫描技术（micro-computed tomography,micro-CT）及组织学方法,评价2种膜修复骨缺损的效果。采用SPSS20.0软件包对结果进行统计学分析。结果: 通过MC3T3-E1细胞在双层壳聚糖膜上培养2 d后的扫描电镜照片,观察到细胞较好地粘附于多孔层上。第3、7及10天时,实验组细胞相对增殖率分别为114.49%、107.17%和98.73%,细胞毒性级别为0或1级,表明膜的细胞毒性轻微。2周时,Bio-Gide膜组的骨形成量（BV）和骨体积分数（BVF、BV/TV）与实验组差异显著（P<0.05）;但在第4和8周时,2组的BV和BVF无显著差异（P>0.05）。结论: 新型双层壳聚糖的体外和体内生物学性能符合GBR技术的要求,具有作为GBR膜的潜力。     

静电纺壳聚糖-聚己内酯纳米纤维膜引导骨再生的体外研究

目的 探讨静电纺壳聚糖（CHS）-聚己内酯(PCL)纳米纤维膜对骨缺损再生作用。方法通过静电纺丝技术制备壳聚糖-聚己内酯纳米纤维膜,以纤维膜作为载体,根据碱性磷酸酶活性和Western 免疫印迹实验结果,探讨纤维膜对细胞成骨分化能力的影响。采用SPSS17.0软件包对数据进行统计学处理。结果静电纺壳聚糖-聚己内酯纳米纤维膜对细胞成骨分化能力的作用显著高于对照组（不含材料组）（P<0.05）。结论静电纺聚己内酯-壳聚糖纳米纤维膜在体外能够促进细胞的成骨分化,为骨缺损及再生修复提供了科学依据。     

Comparable efficacy of silk fibroin with the collagen membranes for guided bone regeneration in rat calvarial defects

PURPOSE

Silk fibroin (SF) is a new degradable barrier membrane for guided bone regeneration (GBR) that can reduce the risk of pathogen transmission and the high costs associated with the use of collagen membranes. This study compared the efficacy of SF membranes on GBR with collagen membranes (Bio-Gide®) using a rat calvarial defect model.

MATERIALS AND METHODS

Thirty-six male Sprague Dawley rats with two 5 mm-sized circular defects in the calvarial bone were prepared (n=72). The study groups were divided into a control group (no membrane) and two experimental groups (SF membrane and Bio-Gide®). Each group of 24 samples was subdivided at 2, 4, and 8 weeks after implantation. New bone formation was evaluated using microcomputerized tomography and histological examination.

RESULTS

Bone regeneration was observed in the SF and Bio-Gide®-treated groups to a greater extent than in the control group (mean volume of new bone was 5.49 ± 1.48 mm³ at 8 weeks). There were different patterns of bone regeneration between the SF membrane and the Bio-Gide® samples. However, the absolute volume of new bone in the SF membrane-treated group was not significantly different from that in the collagen membrane-treated group at 8 weeks (8.75 ± 0.80 vs. 8.47 ± 0.75 mm³, respectively, P=.592).

CONCLUSION

SF membranes successfully enhanced comparable volumes of bone regeneration in calvarial bone defects compared with collagen membranes. Considering the lower cost and lesser risk of infectious transmission from animal tissue, SF membranes are a viable alternative to collagen membranes for GBR.     

Incomplete bone regeneration of rabbit calvarial defects using different membranes

The present study describes the use of a degradable and a non‐degradable material for guided bone regeneration. Forty rabbits were divided into 5 groups. Bicortical defects 15 mm in diameter were prepared in rabbit calvaria. A titanium microplate was placed over the defect to prevent collapse of the membrane. The calvarial defects of 2 groups were covered by an outer expanded polytetrafluoroethylene (e‐FTFE) membrane respectively by a Polyglactin 910 membrane. Bicortical e‐PTFE membranes or Polyglactin 910 membranes were used in 2 other groups. The defects were not covered by membranes in the control group. Undecalcified sections were prepared for histologic evaluation after an observation period of 8 weeks. Complete bone healing of the defects was not observed in any of the specimens. The Polyglactin 910 material lacks physical strength, resulting in collapse of the membrane and brain tissue hemiation into the defects. Subsequently, bone regeneration was impaired. The cellular reactions due to degradation of the material were minor and did not interfere with bone healing. Defects covered bicortically by e‐PTFE membranes revealed the largest amount of regenerated bone. The e‐PTFE membrane induced a severe cellular reaction, but no inhibition of bone regeneration was noted.     

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。     

Evaluation of an in situ formed synthetic hydrogel as a biodegradable membrane for guided bone regeneration

The aim of the present study was to test whether or not the application of an in situ formed synthetic hydrogel made of polyethylene glycol (PEG) used as a biodegradable membrane for guided bone regeneration will result in the same amount of bone regeneration as with the use of an expanded polytetrafluoro-ethylene (ePTFE) membrane. In eight New Zealand White rabbits, four evenly distributed 6 mm diameter defects were drilled into the calvarial bone. Three treatment modalities were evenly distributed among the 32 defects: hydroxyapatite (HA)/tricalciumphosphate (TCP) granules covered at the outer and inner surface with a PEG membrane (test), HA/TCP granules covered at the outer and inner surface with an ePTFE membrane (positive control) and HA/TCP granules alone without membranes (negative control). After 4 weeks, the animals were sacrificed and the calvarial bones were removed. The area fraction of newly formed bone was determined by histomorphometrical analysis of the vertical sections from the middle of the defect and by micro-computed tomography of the entire defect. Multiple regression analysis (SAS GLM) was used to model the amount of new bone formation. The quantitative histomorphometric analysis clearly revealed higher values of newly formed bone for the two membrane groups compared with the negative control group. The average area fractions of newly formed bone measured within the former defect amounted to 20.3+/-9.5% for the PEG membrane, 18.9+/-9.9% for the ePTFE membrane, and 7.3+/-5.3% for the sites with no membrane. The micro-computed tomography also showed higher values of new bone formation for the PEG and for the ePTFE groups compared with the negative control group. The GLM revealed a highly significant effect of the treatment on the amount of bone formation (P=0.0048). The values for the negative control group were significantly lower than the ones found in the PEG membrane group (P=0.0017), whereas the ePTFE membrane group showed no significant difference from the PEG membrane group. It is concluded that the PEG membrane can be used successfully as a biodegradable barrier membrane in the treatment of non-critical-size defects in the rabbit skull, and leads to similar amounts of bone regeneration as an ePTFE membrane.     

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。     

两种新型胶原膜引导骨组织再生的体内外性能研究

目的　研究两种新型胶原膜（鱼胶原、猪胶原）对SD大鼠骨髓间充质干细胞（rat bone marrow mesenchymal stem cells, rBMSCs）成骨分化的影响,并观察其促进SD大鼠颅顶骨缺损修复的效果。方法　利用扫描电镜（SEM）和接触角测量仪表征两种膜的表面形貌及水接触角。在两种膜上培养rBMSCs,并将细胞接种在空白孔板上作为空白对照组。1、3、5、7d时以CCK-8法检测两种膜对rBMSCs增殖的影响,并通过激光共聚焦显微镜观察24h时细胞的粘附与伸展。用碱性磷酸酶（ALP）染色和活性检测,茜素红染色和钙结节半定量测定及实时荧光定量PCR评估两种膜的体外成骨性能。体内实验中,在SD大鼠颅中缝两侧制备直径5mm的骨缺损,在左侧骨缺损区植入鱼胶原膜或猪胶原膜,右侧骨缺损区作为空白对照组,3个月后采用micro-CT检测颅顶骨缺损区骨再生情况。结果　SEM：鱼胶原膜表面致密,猪胶原膜呈疏松多孔的表面。接触角测量仪：猪胶原膜的亲水性强于鱼胶原膜(P<0.05)。CCK-8及激光共聚焦显微镜：细胞在两种膜及空白孔板上24h时铺展良好,7d内稳定增殖。体外成骨性能检测：猪胶原膜上rBMSCs在5 d时的ALP活性、14 d时细胞外基质矿化水平、7d时细胞相关成骨基因Bmp2、Col1、Runx2的表达高于鱼胶原组和空白对照组(P<0.05)。体内成骨实验（3个月）：猪胶原膜促进骨再生明显优于鱼胶原膜和空白对照组（P<0.05）, 鱼胶原膜组和空白对照组无明显差异。结论　猪胶原膜体内外促进骨再生的效果明显优于鱼胶原膜组,具有作为引导骨组织再生膜材料的潜能。     

Enhanced bone augmentation by controlled release of recombinant human bone morphogenetic protein-2 from bioabsorbable membranes

BACKGROUND: The present study was undertaken to determine the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded biodegradable membranes on bone augmentation in a rabbit calvarial model. METHODS: Five microg of rhBMP-2 was loaded into a stiff hemispherical dome membrane made of poly(L-lactide) and tricalcium phosphate (PLLA/TCP). The release kinetics of rhBMP-2 from the membrane were determined in vitro using a human BMP-2 immunoassay. Twelve rhBMP-2-loaded dome membranes (test group) and 12 control dome membranes (control group) were placed on the partial-thickness calvarial defects of 24 rabbits. The animals were sacrificed at 4 and 8 weeks, and undecalcified ground sections were prepared. Newly formed bone area and height were measured histomorphometrically and calculated by percentage ratio to the total submembranous space area and height below the dome. RESULTS: In vitro release results demonstrated that rhBMP-2 was released consistently over a 4-week period following a high initial burst release on the first day. At both 4 and 8 weeks, histomorphometric analysis revealed that the test group showed significantly higher newly formed bone heights and areas than the control group (P < 0.01). In the control group, new bone height was 36.3% of the dome height and the new bone area reached 8.2% of the submembranous space area at 8 weeks, while the test group reached 87.3% and 35.4%, respectively. CONCLUSION: These results suggest that the use of rhBMP-2-loaded PLLA/TCP membranes can result in additional bone augmentation, which is due to the osteoinductive properties of rhBMP-2 released from the membrane during healing.     

国产非降解生物膜引导动物颅骨组织再生的组织学观察

目的 :观察两种国产非降解生物膜引导组织再生的组织学变化 .方法 :选用兔颅骨开窗缺损模型覆盖两种非降解生物膜 ,空白对照 ,术后 2、4、8、12周取材 ,常规制片 ,光镜、透射电镜、扫描电镜观察 .结果 :两种国产非降解生物膜有较好的组织相容性 ,对骨缺损愈合有保护和促进作用 .结论 :临床使用国产非降解生物膜引导组织再生是可行的 .     

壳聚糖-Ⅰ型胶原复合膜的制备及其生物相容性实验研究

目的 了解制备的壳聚糖-Ⅰ型胶原复合膜的理化性能及其与MG63成骨样细胞的生物相容性,以初步探讨其作为引导骨再生屏障膜的可行性.方法 采用提纯的牛肌腱Ⅰ型胶原和壳聚糖,经冷冻干燥,使用热交联、化学交联技术制成壳聚糖-Ⅰ型胶原复合膜(实验组)和Ⅰ型胶原膜(对照组).采用氨基酸含量检测、差示量热扫描法分析牛肌腱Ⅰ型胶原性质和表征,红外光谱、扫描电镜分析2种膜的理化性能.将MG63成骨样细胞接种于2种膜上,MTS法检测细胞1d、3d、5d、7d的增殖情况.结果 牛肌腱Ⅰ型胶原的胶原3股螺旋结构保持较完整,其热变性温度为99.04℃,提热吸收峰为53.54℃,与标准品指标接近,其成分比例及性质表征符合Ⅰ型胶原特征.红外光谱结果表明实验组具备胶原和壳聚糖特征峰表现,并且2种材料之间形成大量氢键,分子间结合良好.扫描电镜显示实验组和对照组膜表面和横切面为多孔结构,实验组膜孔径较大,为10～ 100 μm.MG63成骨样细胞在2组膜上呈明显的增殖趋势,具有较好的细胞相容性.结论 制备的壳聚糖-Ⅰ型胶原复合膜具有优良的结构及生物学性能,可应用于下一步引导骨再生膜材料的研究.     

BMP2/7 heterodimer is a stronger inducer of bone regeneration in peri-implant bone defects model than BMP2 or BMP7 homodimer

This study aimed to compare the effects of bone morphogenetic protein BMP2/7 heterodimer and BMP homodimers on bone regeneration in bone defects model. Identical peri-implant bone defects model were created using proper controls on the frontal skull in 18 minipigs. Collagen sponges with low-dose (30 ng/mL) BMP2/7 heterodimer, BMP2 or BMP7 homodimer were filled in the defects. New bone formation and the expression of type I collagen (Col1), alkaline phosphatase (ALP) and osteocalcin (OCN) were evaluated after 2, 3, and 6 weeks of implantation. BMP2/7 resulted in significantly higher new bone areas percentage in the defect region than BMP2 and BMP7 (p<0.05). Immunohistochemical staining of Col1, ALP and OCN was stronger in BMP2/7 group than BMP2, BMP7 and control group (p<0.05). These results demonstrate that BMP2/7 heterodimer is a stronger inducer of osteoblastogenesis and could be applied at low dose to reduce the cost and side effects of BMP homodimers.     

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.     

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.     

Membrane durability and tissue response of different bioresorbable barrier membranes: a histologic study in the rabbit calvarium

PURPOSE: The objective of the present study was to histologically evaluate barrier durability and host tissue response of new prototype collagen membranes in comparison to clinically available collagen and synthetic polymer membranes. MATERIALS AND METHODS: The experimental study was conducted in 20 rabbits with 4 different healing periods of 2, 6, 12, and 28 weeks. Following surgical exposure of the calvarium, 6 circular bone defects (diameter 4 mm, depth 1.5 mm) were drilled into the outer cortex. After the bone had been removed, each defect was covered with 1 of 6 different membranes: 3 collagen prototype membranes, a Bio-Gide collagen membrane (BG), a glycolide-lactide-trimethylene carbonate Osseoquest membrane (OQ), and a polylactide Atrisorb membrane (AS). Histological analysis was performed following staining with toluidine blue and transversal sectioning of the calvarial bone. RESULTS: All collagen membranes showed similar tissue integration characterized by fibrous encapsulation with differentiation of a periosteumlike tissue upon the external bony surface. One prototype collagen membrane displayed clearly longer membrane integrity. The evaluated synthetic membranes demonstrated extended barrier durability but also exhibited inflammatory foreign-body reactions. DISCUSSION: Recent experimental investigations have shown that degradation of collagen membranes may begin within days to weeks of membrane placement. This was confirmed in the present study. However, 1 of the chemically modified collagen prototype membranes exhibited prolonged membrane integrity in the absence of an inflammatory tissue response. CONCLUSION: Further investigation of the prototype membrane that showed prolonged membrane integrity to evaluate its potential in GBR procedures is needed.     

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.