| ObjectiveGuided bone regeneration (GBR) has been proved to be a reasonably reliable technique in the treatment of insufficient bone volume around dental implants. The aim of the present study is to evaluate whether or not the chitosan-collagen membranes when used as barrier membranes without any bone substitutes for GBR will result in more amount of bone regeneration compared with a standard absorbable collagen membrane in a dog dehiscence-type defect model. For further improve biological properties of guided bone regeneration membrane, collagen-chitosan nanofiber membrane were prepared by electrospinning, and the bi-layer membrane is made by the composite of chitosan-collagen freeze-fried membrane and nanofiber membrane.Methods(1)1%and2%medium-molecular weight chitosan solution and0.1%collagen solution were mixed at volume ratio of2:1, then the compound solutions were casted in the clean glass plates, followed by successively freezing in the4℃,-20℃,-80℃for24hours, and freeze-dried into membranes in the vacuum freeze dryer. The obtained chitosan/collagen membranes can be named as E (made from1%chitosan and collagen solution) and H (made from2%chitosan and collagen solution). The right mandibular premolars and the first molar were extracted in each of10beagle dogs. Four months later, acute buccal dehiscence-type defects were surgically created following implant site preparation. Defects were randomly assigned to four different groups:(1) chitosan/collagen membrane-E,(2) chitosan/collagen membrane-H,(3) Bio-gide collagen membrane,(4) control. The animals were sacrificed after4(3animals),8(3animals) and12(4animals) weeks of healing interval for histological observation and histomorphometrical analysis including defect length (DL), new bone height (NBH), bone-to-implant contact (BIC) and area of new bone fill (BA).(2) The mixture of7%collagen solution,3%chitosan solution and7%polyethylene oxide (PEO) solution were electrospinned to fabricate nanofiber membrane, and the surface morphology was observed by scanning electron microscopy. In the electrospinning process, the chitosan-collagen freeze-fried membrane was composited with nanofiber membrane to form bi-layer membrane.Results(1) Newly formed bone was observed in all the groups and became mature with time. At8weeks, increased mean NBH and BIC values were obtained for all the groups, especially for the membranes treated sites, mean NBH values of1.1±0.11mm1.48±0.07mm were statistically significantly higher than the mean value of0.74±0.12mm of untreated groups (P<0.05). At12weeks, the membranes treated groups obtained more mean NBH, BIC, BA values compared with the untreated group. The H groups showed the highest mean BH, BIC and BA values, and the mean NBH value of1.91±0.25mm was statistically significantly higher than the untreated group of1.20±0.34mm (P<0.05). However, no statistically significant differences were found between membrane groups and untreated group and among the membranes treated groups in BIC and BA.(2) The mixture of7%collagen solution,3%chitosan solution and7%PEO by mass ratio of5:1:4was electrospinned to obtain smooth, uniform nanofibers under the voltage at12kV, the flow rate of0.1ml/h, receiving distance of12cm.When combined with chitosan-collagen freeze-fried membrane, bi-layer membrane showed freeze-fried membrane side is porous structure, the other side is nanofibrous structure.ConclusionThe results of this study demonstrated that the developed chitosan/collagen membranes can enhance bone regeneration, and obtained similar amounts of newly formed bone compared with defects regenerated with a standard collagen membrane. The mixture of collagen, chitosan and PEO solution can be electrospinned to obtain smooth and uniform nanofibers, and the bi-layer membrane can be prepared by composite the chitosan-collagen freeze-fried membrane and nanofibrous membrane. |
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