Papers by Keyword: Guided Tissue Regeneration

Abstract: The aim of this study was to fabricate 75:25 poly(DL-lactide-co-e-caprolactone), poly(DLL-co-CL) membranes for used in guided tissue regeneration (GTR). The copolymer was synthesized by ring-opening polymerization (ROP) in bulk. The 3-dimensional fiber networks with built-in microporosity membranes were prepared by electrospinning. The pore size was varied between 5-30 μm and the porosity of membrane was 69%. After immersing in phosphate buffered saline (PBS), the membranes were degradable with time, as indicated by molecular weight loss, mass weight loss, reduction of pH of the media and changes in the surface topography and shape of the membranes. However, the in vitro hydrolytic degradation of the membranes was too fast for use as periodontal GTR. The membranes maintained their original shape for the first 4 weeks and the porous structure disappeared within 2 weeks. Results from agar diffusion test suggest the membranes to be non-cytotoxic. In conclusion, the electrospun membrane was non-cytotoxic but the degradation rate was too fast to be used as GTR membrane in periodontal treatment.

Abstract: Previous in vitro studies confirmed an improved cytocompatibility of chitosan-silicate hybrid membranes over chitosan membranes. The main goal of this study was to assess the in vivo histocompatibility of both membranes through subcutaneous implantations at different time periods, 1 week, 1, 2 and 3 months, using a sheep model. Chitosan membranes elicited an exuberant inflammatory response and were consequently rejected. The hybrid chitosan membranes were not rejected and the degree of inflammatory response decreased gradually until the third month of implantation. Histological evaluation also showed that these membranes can be resorbed in vivo. This study demonstrates that the incorporation of silicate into the chitosan solution improves its histocompatibility, indicating that the hybrid chitosan-silicate membranes are suitable candidates to be used in clinical applications.

Abstract: The aim of this study was to evaluate the regenerative effects of chitosan membranes containing tetracycline (TC) applied to surgically created one-wall intrabony defects in beagle dogs. The defects either received chitosan membrane (CH), chitosan membrane containing 0.5%, 1% TC (CH-TC0.5, CH-TC1.0) or flap operation only. The animals were sacrificed 8 weeks after the experimental surgery, and comparative histological and histometric examinations were done. The amount of junctional epithelium migration and connective tissue adhesion did not show any statistically significant differences among the groups. The amount of new cementum regeneration, and new bone regeneration were significantly greater in CH-TC1.0 group than the control (P<0.05). The results suggest that chitosan membrane combined with 1.0% TC may have beneficial effect on the regeneration of bone and cementum in intrabony periodontal defects.

Abstract: The aim of this study is to evaluate treatment effects of novel GBR membranes (PDLLA membranes) applied to bony defects around dental implants on new bone regeneration alone or in combination with bioceramic bone graft (BIO-OSS®) on the mongrel dog model in comparison with collagen membrane (BIO-GIDE®) and therefore to assess the clinical values of the novel GBR membranes and bioceramic bone graft material in dental implantology. 6 implants were placed in bilateral mandibular of each mongrel dog after preparation of mid- crestal defects. The defects on one side were covered with PDLLA membranes alone or with bone graft, while the contra-lateral sides received collagen membranes alone or with bone graft. These animals were sacrificed at 2, 4, 8,12 weeks post the GBR-operation. And gross sample examination, standardized radiographs, 99mTc-MDP SPECT and histomorphometric analysis were taken. All examinations showed similar amounts of newly formed bone beneath both types of barriers. The PDLLA or collagen membrane with bone graft groups showed better results than the membrane used alone groups. The results indicated that PDLLA membranes especially with bioceramic bone graft presented an improved response in dealing with bony defects around implants.

Abstract: This study evaluated the efficacy of periodontal tissue regeneration using guided tissue regeneration (GTR) with a mixture of tooth ash and plaster as a bone substitute material in the treatment of class II furcation defects in dogs. GTR was performed at the site of a surgically formed mandibular premolar bifurcation area in dogs. Four adult dogs were used in the animal study. The animals were in a good periodontal state without any systemic disease. A resorbable membrane (Bio-Gide®, Swiss) and bone graft material using a mixture of tooth ash and plaster were used to examine the biological activity. The defect in the control group was filled a Bio-Gide® only. For the experimental group, the defects were filled with a mixture of tooth ash and plaster and covered by a Bio-Gide®. Oral rinsing with 0.12% chlorhexidine was performed twice a day for 2 weeks. In control group, new bone formation was observed adjacent to the preexisting bone. Soft tissue ingrowth was also noted. In experimental group, new lamellar type trabecular bone formation as well as centum and PDL regeneration was observed in the base of the infrabony pocket. More bone regeneration would be expected when GTR is performed using a mixture of human tooth-ash and plaster of Paris as a bone graft material.

Abstract: Functionally graded materials (FGM) were fabricated for bio-medical applications, (1) implants, (2) dental core and post, (3) guided tissue regeneration (GTR) membranes. (1) FGM implants of Ti/HAP and TiN/HAP with the concentration changing gradually in the longitudinal direction of cylinder were fabricated to optimize both mechanical properties and biocompatibility in each region. Concentration gradient was formed by packing of dry powders into mold. Spark plasma sintering was effective for sintering of non-uniform composition in FGM. Brinel hardness decreased gradually from Ti part to HAP part, which contributes to stress relaxation in the implanted region of bone. In vivo tests showed that osteogenesis and maturation is more advanced in the HAP rich region. (2) FGM dental core and post made of composite resin was fabricated by laser lithography, one of the photo-curing type CAD/CAM systems. The elastic modulus changed gradually from 10.6GPa in core part to 2.9GPa at the apex of post by decreasing the filler content of ceramic powders from 64% to 0% in polymer matrix. Stress analysis using finite element method showed the stress relaxation by further 30 % in FGM, compared with the uniform composite resin. (3) Biodegradable GTR membrane composed of nano HAP/collagen reinforced with PLGA was prepared. The membrane has the three layer structure with the thickness of about 100μm for each where the composition of HAP/collagen is increased from pure PLGA. The graded membrane structure could give the different functions of the high degradation speed and Ca ion release to enhance osteoconductivity for bone remodeling in the high HAP/collagen side and the relatively low degradability to prevent the ingrowth of fibroblasts in the pure PLGA side.