Reaction of rat connective tissue to implanted dentin tube filled with mineral trioxide aggregate, Portland cement or calcium hydroxide.

The subject of this study was to observe the rat subcutaneous connective tissue reaction to implanted dentin tubes filled with mineral trioxide aggregate, Portland cement or calcium hydroxide. The animals were sacrificed after 7 or 30 days and the undecalcified specimens were prepared for histological analysis with polarized light and Von Kossa technique for mineralized tissues. The results were similar for the studied materials. At the tube openings, there were Von Kossa-positive granules that were birefringent to polarized light. Next to these granulations, there was an irregular tissue like a bridge that was Von Kossa-positive. The dentin walls of the tubes exhibited in the tubules a structure highly birefringent to polarized light, usually like a layer and at different depths. The mechanism of action of the studied materials has some similarity.

In vivo and in vitro evaluation of an Acetobacter xylinum synthesized microbial cellulose membrane intended for guided tissue repair

Background: Barrier materials as cellulose membranes are used for guided tissue repair. However, it is essential that the surrounding tissues accept the device. The present study histologically evaluated tissue reaction to a microbial cellulose membrane after subcutaneous implantation in mice. Furthermore, the interaction between mesenchymal stem cells and the biomaterial was studied in vitro to evaluate its ability to act as cellular scaffold for tissue engineering.Methods: Twenty-five Swiss Albino mice were used. A 10 x 10 mm cellulose membrane obtained through biosynthesis using Acetobacter xylinum bacteria was implanted into the lumbar subcutaneous tissue of each mouse. The mice were euthanatized at seven, 15, 30, 60, and 90 days, and the membrane and surrounding tissues were collected and examined by histology.Results: A mild inflammatory response without foreign body reaction was observed until 30 days post-surgery around the implanted membrane. Polarized microscopy revealed that the membrane remained intact at all evaluation points. Scanning electron microscopy of the cellulose membrane surface showed absence of pores. The in vitro evaluation of the interaction between cells and biomaterial was performed through viability staining analysis of the cells over the biomaterial, which showed that 95% of the mesenchymal stem cells aggregating to the cellulose membrane were alive and that 5% were necrotic. Scanning electron microscopy showed mesenchymal stem cells with normal morphology and attached to the cellulose membrane surface.Conclusion: The microbial cellulose membrane evaluated was found to be nonresorbable, induced a mild inflammatory response and may prove useful as a scaffold for mesenchymal stem cells.

Periapical tissue reactions to calcium hydroxide and MTA after external root resorption as a sequela of delayed tooth replantation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Calcium salts deposition in rat connective tissue after the implantation of calcium hydroxide-containing sealers

This study was conducted to observe the rat subcutaneous connective tissue reaction to implanted dentin tubes that were filled with mineral trioxide aggregate, Sealapex, Calciobiotic Root Canal Sealer (CRCS), Sealer 26, and the experimental material, Sealer Plus. The animals were sacrificed after 7 and 30 days, and the specimens were prepared for histological analysis after serial sections with a hard-tissue microtome. The undecalcified sections were examined with polarized light after staining according to the Von Kossa technique for calcium. At the tube openings, there were Von Kossa-positive granules that were birefringent to polarized light. Next to these granulations, there was irregular tissue, like a bridge, that was Von Kossa-positive. The dentin walls of the tubes exhibited a structure highly birefringent to polarized light, usually like a layer, in the tubules. These results were observed with all the studied materials, except the CRCS, which didn't exhibit any kind of mineralized structure. The results suggest that among the materials studied, the CRCS could have the least possibility of encouraging hard tissue deposition.

Experimental peri-implant tissue breakdown around different dental implant surfaces: Clinical and radiographic evaluation in dogs

Purpose: Tissue reactions to 4 different implant surfaces were evaluated in regard to the development and progression of ligature-induced peri-implantitis. Materials and Methods: In 6 male mongrel dogs, a total of 36 dental implants with different surfaces (9 titanium plasma-sprayed, 9 hydroxyapatite-coated, 9 acid-etched, and 9 commercially pure titanium) were placed 3 months after mandibular premolar extraction. After 3 months with optimal plaque control, abutment connection was performed. Forty-five days later, cotton ligatures were placed around the implants to induce peri-implantitis. At baseline and 20, 40, and 60 days after placement, the presence of plaque, peri-implant mucosal redness, bleeding on probing, probing depth, clinical attachment loss, mobility, vertical bone loss, and horizontal bone loss were assessed. Results: The results did not show significant differences among the surfaces for any parameter during the study (P > .05). All surfaces were equally susceptible to ligature-induced peri-implantitis over time (P < .001). Correlation analysis revealed a statistically significant relationship between width of keratinized tissue and vertical bone loss (r 2 = 0.81; P = .014) and between mobility and vertical bone loss (r 2 = 0.66; P = .04), both for the titanium plasma-sprayed surface. Discussion and Conclusions: The present data suggest that all surfaces were equally susceptible to experimental peri-implantitis after a 60-day period.

Porous polyethylene for tissue engineering applications in diabetic rats treated with calcitonin: Histomorphometric analysis

Purpose: The purpose of this work was to study the bone tissue reaction after porous polyethylene (Polipore) implantation into surgical defects in the parietal bones of rats with streptozotocin-induced diabetes, treated with salmon calcitonin. Materials and Methods: Porous polyethylene implants were placed in bone defects created in 36 adult female rats. The rats were divided into 3 equal groups: diabetic treated with calcitonin (DCa), diabetic (D), and control (C). The animals of the DCa group received applications of salmon calcitonin on alternating days immediately after the surgery until sacrifice. The rats were sacrificed after 15, 30, 60, and 90 days, and the defects were examined histologically and statistically through histomorphometric analysis. Results: Histomorphometric analysis showed that there was no statistically significant difference in the mean quantity of inflammatory cells among all study groups after 15 and 90 days. At 30 days, a statistically significant difference was observed between the D and C groups and the D and DCa groups. At 60 days, there was no statistically significant difference between the D and DCa groups. Discussion: Porous polyethylene can be considered an option for implant material when there are investigations that prove its biocompatibility and stability in the host tissues. Salmon calcitonin positively aided the bone repair and attenuated the inflammatory response until 30 days after the surgery. Conclusion: Porous polyethylene was tolerated by the host tissues in all groups, and moderate chronic inflammatory reaction was observed up to the 90-day period. Salmon calcitonin attenuated the inflammatory response up until 30 days.

Resposta tecidual a implantes de discos de poliuretana de mamona nas formas pré-moldada ou biomassa moldada

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Extraocular muscle fixation to porous polyethylene orbital implants using 2-octyl-cyanoacrylate

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Biomechanical and histologic analysis in aortic endoprosthesis using fibrin glue

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Uso de 2-octil-cianoacrilato na reconstrução da cavidade anoftálmica de coelhos

OBJETIVO: Avaliar a ligação entre músculos oculares extrínsecos e esferas de polietileno poroso usando um bioadesivo. MÉTODOS: Estudo experimental envolvendo 8 coelhos albinos submetidos a enucleação do olho direto com colocação de implante esférico de polietileno poroso de 12 mm de diâmetro unido aos músculos oculares extrínsecos por meio do bioadesivo 2-octil-cianoacrilato. Noventa dias após a cirurgia os animais foram sacrificados e o conteúdo orbitário removido. em 4 animais foi realizado estudo biomecânico, avaliando-se a força de ruptura entre a musculatura e a esfera (grupo implante) e entre a musculatura e a esclera nos olhos contralaterais (grupo controle). Nos outros 4 animais foi realizada análise histológica. RESULTADO: A avaliação biomecânica revelou que a força de ruptura entre esfera-músculo e esclera-músculo foram semelhantes quando se usa o adesivo de cianoacrilato. O exame histológico mostrou reação fibrovascular no local da adesão entre a musculatura e a esfera, sem efeitos deletérios aos tecidos. Ao redor dos implantes foi possível observar pseudocápsula e no interior, neovasos e tecido fibrovascular preenchendo os espaços entre os grânulos do polietileno. CONCLUSÃO: O adesivo 2-octil-cianoacrilato mantém boa força de adesão na união entre os músculos e as esferas de polietileno poroso, com redução do tempo cirúrgico e sem efeitos deletérios aos tecidos orbitais. Desta forma, deve-se considerar o uso do bioadesivo na reconstrução da cavidade anoftálmica.

Comparison of synthetic hydroxyapatite and porous polyethylene implants in eviscerated rabbit eyes

Purpose: Synthetic hydroxyapatite and porous polyethylene (Polipore) spheres were placed in rabbits' eviscerated cavities to evaluate tissue reaction and volume maintenance.Methods. Fifty-six Norfolk albino rabbits underwent unilateral evisceration and implantation of synthetic hydroxyapatite (H group, 28 animals) or porous polyethylene spheres (P group, 28 animals). Postoperative reactions, animal behavior, and socket conditions were monitored. Light microscopy and morphometric evaluation with statistical analysis of the exenterated orbits were performed at 7, 15, 30, 60, 90, 120, and 180 days. Scanning electron microscopy was appraised 7, 60, and 180 days after surgery.Results: Two animals from the H group and 1 from the P group had extrusion 7 days after surgery. Throughout the experimental period, the synthetic hydroxyapatite caused more inflammation than the porous polyethylene material. Ingrowth in the sphere occurred 7 to 15 days after the surgery in both groups, and the tissue reaction became denser at approximate to60 to 90 days, when bony metaplasia began in the H group. Volume maintenance was better in the P group and with a smaller pseudocapsule surrounding the implanted sphere than in the H group.Conclusions: Clinical findings demonstrated mild inflammation inside the sphere and in the pseudocapsule surrounding it and better cavity volume maintenance in the P group animals. The authors consider porous polyethylene a more suitable material than synthetic hydroxyapatite for use in anophthalmic cavity reconstruction.

Injectable gels of anionic collagen : rhamsan composites for plastic correction: Preparation, characterization, and rheological properties

The present article describes the preparation and characterization A anionic Collagen gels obtained from porcine intestinal submucosa after 72 h of alkaline treatment and in the form of rhamsan composites to develop injectable biomaterials for plastic for construction. All materials were characterized by SDS/polyacrylamide gel electrophoresis, infrared spectroscopy, thermal stability, potentiometric titration, rheological properties, and fluidity tests. Biocompatibility was appraised after the injection of anionic collagen:rhamsan composites at 2.5% in 60 North Folk rabbits. Independently of processing, the Collagen's secondary structure was preserved in all cases, and after 72 h of hydrolysis the Collagen was characterized by a carboxyl group content of 346 :L 9, which, at physiological pH, corresponds to an increase of 106 17 negative charges, in comparison to native Collagen, due to the selective hydrolysis of asparagine and glutamine carboxyamide side chain. Rheological studies of composites at pH 7.4 in concentrations of 2, 4, and 6% (in proportions of 75:1 and 50:1) showed a viscoelastic behavior dependent on the frequency, which is independent of concentration and proportion. In both, the concentration of the storage modulus always predominated over the loss modulus (G' > G and delta < 45 degrees). The results from creep experiments confirmed this behavior and showed that anionic collagen:rhamsan composites at pH 7.4 in the proportion of 50:1 are less elastic and more susceptible to deformation in comparison to gels in the proportion of 75:1, independent of concentration. This was further confirmed by flow experiments, indicating that the necessary force for the extrusion of anionic collagen:rhamsan composites, in comparison to anionic Collagen, was significantly smaller and with a smooth flow. Biocompatibility studies showed that the tissue reaction of anionic collagen:rhamsan composites at 2.5% in the proportion of 75:1 was compatible with the application of these gels in plastic reconstruction. These results suggest that the association of Collagen with rhamsan may be a good alternative in the replacement of glutaraidehyde to stabilize the microfibril assembly of commercial Collagen gel preparations. (c) 2005 Wiley Periodicals, Inc.

Ricinus communis biocompatibility histological study in the nose of Cebus apella monkeys

Lesões do tecido ósseo podem ser causadas por fatores congênitos e adquiridos e resultar em deformidade nasal com repercussão estética e funcional. O tratamento cirúrgico desses casos requer reconstruções complexas e frequentemente o uso de biomateriais. O poliuretano derivado do óleo da mamona apresenta uma fórmula com aspectos favoráveis de processabilidade, flexibilidade de formulação, ausência de emissão de vapores tóxicos e baixo custo. Entretanto, a despeito dos resultados favoráveis, estudos referentes ao uso do polímero de mamona, avaliando a reação tecidual no dorso nasal, ainda não foram realizados. OBJETIVO: O objetivo deste estudo consiste em avaliar histologicamente a biocompatibilidade do implante do polímero de mamona no dorso nasal. FORMA DE ESTUDO: Experimental. MATERIAL E MÉTODO: Foram utilizados quatro macacos-pregos da espécie Cebus apella. Um defeito ósseo foi realizado no osso nasal em todos os animais e colocado um implante de polímero de mamona. A eutanásia foi realizada com 270 dias de pós-operatório, e as amostras foram submetidas a estudo histológico. RESULTADOS: Na análise histológica não foi observada a presença de granuloma de corpo estranho ou células fagocitárias. Progressiva formação óssea e maturação foram observadas. CONCLUSÃO: Os resultados macroscópicos e microscópicos mostraram que o implante de polímero de mamona foi biocompatível.

Biocompatibility of an experimental MTA sealer implanted in the rat subcutaneous: Quantitative and immunohistochemical evaluation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação da concentração das fibras do tecido conjuntivo quando da associação de poliglactina 910 e silicone: estudo experimental em ratos

Neste estudo observamos a reação tecidual após implantação de próteses de silicone associadas à poliglactina 910. Telas de borracha de silicone com 1,5 x 1,5cm de diâmetro e 0,7mm de espessura, polifenestradas, foram implantadas no subcutâneo do dorso de ratos.Dois grupos foram observados, no primeiro apenas telas fenestradas eram implantadas, no segundo as fenestrações das telas eram preenchidas com fios de poliglactina 910. Os animais foram observados por 30, 60 e 90 dias quando eram sacrificados e as telas mais o tecido adjacente ressecados. Não se observou diferenças na quantidade de fibras colágenas entre os subgrupos de um mesmo grupo e ou quando comparados com os subgrupos do grupo em estudo. No grupo controle, onde se usou apenas as telas fenestradas de silicone houve uma diferença significante entre as fibras reticulares, em maior número nos grupos de 30 e 60 dias de observação, quando comparadas ao grupo de 90 dias. A poliglactina 910 associada ao silicone não alterou o número de fibras do tecido conjuntivo, contadas nas fenestrações das telas.