Guided bone regeneration (GBR) is a technique utilizing membrane as a physical barrier to separate and create a secluded space around the bone defect. This permits the regeneration of bone tissue and reduces the fast growth of connective tissues. Moreover, GBR membranes sustain a protected space during tissue-healing period. Nowadays there are many kinds of GBR membranes used in study and practice, and each of them has its characteristic merits and defects respectively. This paper reviews the studies of GBR membranes, with the emphases on the structure and properties of membrane materials as well as their biological functions.
Biocompatible Materials ; Guided Tissue Regeneration ; methods ; trends ; Humans ; Membranes, Artificial ; Polytetrafluoroethylene ; chemistry ; Silicone Gels ; chemistry ; Tissue Engineering ; methods ; Titanium ; chemistry

BACKGROUNDPretreatment with chemical agents could alter the surface chemistry of the silicone gel, which makes it suitable for epithelial migration onto its surface and thus enhances the cytobiocompatibility. This study aimed to evaluate the biological response of the corneal stroma to porous silicone gel pretreated with different chemical agents in vivo.

METHODSThe porous silicone gels were treated with a mixed acid solution containing 23.2% H2SO4 and 0.8% K2Cr2O7 for 10 or 15 minutes or with 30% H2O2 for 15 minutes. Discs (4 mm in diameter) were inserted into interlamellar stromal pockets of New Zealand white rabbits and followed up for a period of 3 months. Clinical evaluations such as corneal infiltration, edema and neovascularization were performed daily. At 3 months, the fibroplasias and collagen deposition were examined under light and scanning electron microscopy (SEM) and by immunohistochemical analysis.

RESULTSPretreatment of the discs obviously decreased conjunctival congestion, discharge, cornea edema, and the extent of neovascularization. More fibroblasts migrated into the pretreated discs than into the control, and collagen was deposited, indicating that the biocompatibility of the corneal replacements was enhanced by the chemical pretreatments. From immunohistochemical analysis, Type I collagen deposition in the pretreated silicone discs was greater than in the control.

CONCLUSIONSChemical treatment of silicone gel is effective in decreasing rabbit corneal inflammation, encouraging fibroblast in-growth, and enhancing tissue compatibility. Pretreated gels show good biological stability when used as a skirt material in Keratoprosthesis (Kpros).

Animals ; Biocompatible Materials ; adverse effects ; chemistry ; Cornea ; drug effects ; ultrastructure ; Corneal Edema ; etiology ; Corneal Stroma ; drug effects ; Microscopy, Electron, Scanning ; Porosity ; Prostheses and Implants ; Rabbits ; Silicone Gels ; adverse effects ; chemistry

Capsular fibrosis and contracture occurs in most breast reconstruction patients who undergo radiotherapy, and there is no definitive solution for its prevention. Simvastatin was effective at reducing fibrosis in various models. Peri-implant capsular formation is the result of tissue fibrosis development in irradiated breasts. The purpose of this study was to examine the effect of simvastatin on peri-implant fibrosis in rats. Eighteen male Sprague-Dawley rats were allocated to an experimental group (9 rats, 18 implants) or a control group (9 rats, 18 implants). Two hemispherical silicone implants, 10 mm in diameter, were inserted in subpanniculus pockets in each rat. The next day, 10-Gy of radiation from a clinical accelerator was targeted at the implants. Simvastatin (15 mg/kg/day) was administered by oral gavage in the experimental group, while animals in the control group received water. At 12 weeks post-implantation, peri-implant capsules were harvested and examined histologically and by real-time polymerase chain reaction. The average capsular thickness was 371.2 μm in the simvastatin group and 491.2 μm in the control group. The fibrosis ratio was significantly different, with 32.33% in the simvastatin group and 58.44% in the control group (P < 0.001). Connective tissue growth factor (CTGF) and transforming growth factor (TGF)-β1 gene expression decreased significantly in the simvastatin group compared to the control group (P < 0.001). This study shows that simvastatin reduces radiation-induced capsular fibrosis around silicone implants in rats. This finding offers an alternative therapeutic strategy for reducing capsular fibrosis and contracture after implant-based breast reconstruction.
Administration, Oral ; Animals ; Breast/*drug effects/metabolism/pathology/radiation effects ; *Breast Implants ; Connective Tissue Growth Factor/genetics/metabolism ; Fibrosis ; Gamma Rays ; Male ; Rats ; Rats, Sprague-Dawley ; Real-Time Polymerase Chain Reaction ; Silicone Gels/*chemistry ; Simvastatin/*pharmacology ; Transforming Growth Factor beta1/metabolism

Capsular fibrosis and contracture occurs in most breast reconstruction patients who undergo radiotherapy, and there is no definitive solution for its prevention. Simvastatin was effective at reducing fibrosis in various models. Peri-implant capsular formation is the result of tissue fibrosis development in irradiated breasts. The purpose of this study was to examine the effect of simvastatin on peri-implant fibrosis in rats. Eighteen male Sprague-Dawley rats were allocated to an experimental group (9 rats, 18 implants) or a control group (9 rats, 18 implants). Two hemispherical silicone implants, 10 mm in diameter, were inserted in subpanniculus pockets in each rat. The next day, 10-Gy of radiation from a clinical accelerator was targeted at the implants. Simvastatin (15 mg/kg/day) was administered by oral gavage in the experimental group, while animals in the control group received water. At 12 weeks post-implantation, peri-implant capsules were harvested and examined histologically and by real-time polymerase chain reaction. The average capsular thickness was 371.2 μm in the simvastatin group and 491.2 μm in the control group. The fibrosis ratio was significantly different, with 32.33% in the simvastatin group and 58.44% in the control group (P < 0.001). Connective tissue growth factor (CTGF) and transforming growth factor (TGF)-β1 gene expression decreased significantly in the simvastatin group compared to the control group (P < 0.001). This study shows that simvastatin reduces radiation-induced capsular fibrosis around silicone implants in rats. This finding offers an alternative therapeutic strategy for reducing capsular fibrosis and contracture after implant-based breast reconstruction.
Administration, Oral ; Animals ; Breast/*drug effects/metabolism/pathology/radiation effects ; *Breast Implants ; Connective Tissue Growth Factor/genetics/metabolism ; Fibrosis ; Gamma Rays ; Male ; Rats ; Rats, Sprague-Dawley ; Real-Time Polymerase Chain Reaction ; Silicone Gels/*chemistry ; Simvastatin/*pharmacology ; Transforming Growth Factor beta1/metabolism