Synthesis of chitosan/hydroxyapatite membranes coated with hydroxycarbonate apatite for guided tissue regeneration purposes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Composites PVDF-TrFE/BT used as bioactive membranes for enhancing bone regeneration

In this paper a piezoelectric composite membranes were developed for charge generator to promoter bone regeneration on defects sites. Is known that the osteogenesis process is induced by interactions between biological mechanisms and electrical phenomena. The membranes were prepared by mixing Barium Titanate (BT) powders and PVDF-TrFE (PVDF:TrFE = 60:40 mol%) on dimethylformamide medium. This precursor solution was dried and crystallized at 100degreesC for 12 hours. Composites membranes were obtained by following methods: solvent casting (SC), spincoating (SP), solvent extraction by water addition (WS) and hot pressing (HP).The microstructural analysis performed by SEM showed connectivity type 3-0 and 3-1 with high homogeneity for samples of ceramic volume fraction major than 0.50. Powder agglomerates within the polymer matrix was evidenced were observed for composites with the BT volume fraction major than 40%. The composite of ceramic fraction of 0.55 presented the best values of remanent polarization (similar to33 muC/cm(2)), but the flexibility of these composites with the larger ceramic fraction was significantly affected.For in vivo evaluation PVDF-TrFE/BT 90/10 membranes with 3cm larger were longitudinally implanted under tibiae of male rabbit. After 21 days the animals were sacrificed. By histological analyses were observed neo formed bone with a high mitotic activity. In the interface bone-membrane was evidenced a pronounced callus formation. These results encourage further applications of these membranes in bone-repair process.

On the interaction of bovine serum albumin with ionic surfactants: Temperature induced EPR changes of a maleimide nitroxide reflect local protein dynamics and probe solvent accessibility

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Latex use as an occlusive membrane for guided bone regeneration

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

Rapid determination of desorption efficiency, and analysis of solvent mixtures for occupational exposure studies

An analytical procedure has been developed for simultaneous determination of solvent mixture vapors to enable evaluation of occupational exposure. To determine the desorption efficiency the volatile components of the solvent mixtures were generated from a glass tube filled with glass wool. This device is easy to prepare and use. These vapors were then collected in activated charcoal tubes and analyzed by capillary gas chromatography. The method was tested with a mixture of 22 solvents, including aliphatic and aromatic hydrocarbons, alcohols, ethers, esters, and ketones, oil at low concentrations. All the components were defected. When a 99: 1 mixture of carbon disulfide-dimethylformamide was used for desorption the efficiency was > 75% for most of the solvents.

Natural rubber latex used as drug delivery system in guided bone regeneration (GBR)

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

Forest natural regeneration and biomass production after slash and burn in a seasonally dry forest in the Southern Brazilian Amazon

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

Characterization of castor oil based polyurethane films prepared with N-methyl-2-pyrrolidinone as a solvent

Molecular mobility in castor oil based polyurethane was investigated with thermally stimulated depolarization current (TSDC) measurements and alternating-current (ac) dielectric relaxation spectroscopy. Three peaks could be observed in TSDC thermograms from 173 to 373 K. The relaxation located at 213 K could be attributed to the change in the molecular chain due to the interaction between the isocyanate and the solvent, and it was well fitted with the Vogel-Fulcher-Tammann equation. The other two peaks were located at 274 and 365 K and could be attributed to interfacial polarization and space charge, respectively. (c) 2005 Wiley Periodicals, Inc.

Studies of gastric mucosa regeneration and safety promoted by Mouriri pusa treatment in acetic acid ulcer model

Ethnopharmacological Relevance: Mouriri pusa Gardn. (Melastomataceae) is a medicinal plant commonly used by people living in the Cerrado to treat gastrointestinal disturbances. This medicinal plant has shown intense gastroprotective action in rodent gastric lesion, but still there are no data about its healing effect on gastric mucosa.Aim of the Study: To evaluate the methanolic extract (MeOH) obtained from Mouriri pusa leaves for its effect on the cicatrisation process of gastric ulcer.Mterials and Methods: The healing effects on gastric ulcers inducted by subserosal injection of acetic acid were evaluated by macroscopic and microscopic measures, imunohistochemistry and cell counting in rats treated with MeOH extract of Mouriri pusa (250 mg/kg, p.o./daily) for 14 or 30 days. The toxicity of Mouriri pusa was also evaluated by body and organ weight measure and clinical biochemical parameters.Results: Mouriri pusa treatments lasting 14 and 30 days showed elevated mucus secretion (PAS) and thicker regenerative gastric mucosa, denoting increased cell proliferation, which was confirmed by PCNA immunohistochemical analysis. Moreover, there was important cell recruitment (neutrophils and mast cells) to the site of the ulcer, which is an important factor in ulcer healing. No toxic effect was observed in all parameters evaluated. Phenolic compounds present in the MeOH extract like tannins, flavonoids and epicatechin are the probable agents involved in the healing effects of this medicinal plant.Conclusions: These findings showed a potential effect of Mouriri pusa in increasing regeneration of damaged gastric mucosa with safety for human use. (C) 2007 Elsevier B.V. All rights reserved.

In vitro cultivation of canine multipotent mesenchymal stromal cells on collagen membranes treated with hyaluronic acid for cell therapy and tissue regeneration

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

Action of nicotine and ovariectomy on bone regeneration after tooth extraction in rats

Purpose: The purpose of this study was to evaluate the effects of nicotine and ovariectomy on alveolar bone regeneration after exodontias in rats.Materials and Methods: For 30 days, sham ovariectomized (OVX)/NaCl, sham OVX/nicotine, OVX/NaCl, and OVX/nicotine animals were given 2 daily injections of saline or hemisulfate of nicotine. After this period, exodontic procedures were carried out and treatment continued up to the time of euthanasia on clays 7 and 14 when the alveoli were removed for further analyses.Results: The data confirmed that nicotine significantly delays the alveolar regeneration process after dental extraction in rats and showed that the association of nicotine with ovariectomy exacerbates these results.Conclusion: These results indicate that nicotine potentiated the effect of estrogen deficiency on bone regeneration induced by ovariectomy. (c) 2010 American Association of Oral and Maxillofacial Surgeons Oral Maxillofac Surg 68:2675-2681, 2010

Evaluation of Centrifuged Bone Marrow on Bone Regeneration Around Implants in Rabbit Tibia

Objective: To evaluate the bone regeneration of cervical defects produced around titanium implants filled with blood clot and filled with centrifuged bone marrow (CBM) by means of histomorphometric analysis.Materials and Methods: Twelve rabbits received 2 titanium implants in each right tibia, with the upper cortical prepared with a 5-mm drill and the lower cortex with a 3-mm-diameter drill. Euthanasia was performed to allow analysis at 7, 21, and 60 days after operation. The samples were embedded in light curing resin, cut and stained with alizarin red and Stevenel blue for a histomorphometric analysis of the bone-to-implant contact (BIC) and the bone area around implant (BA). The values obtained were statistically analyzed using the nonparametric Kruskal-Wallis test (P = 0.05).Results: At 60 days postoperation, the groups had their cervical defects completely filled by neo-formed bone tissue. There was no statistically significant difference between the groups regarding BIC and BA during the analyzed periods.Conclusion: There was no difference in the bone repair of periimplant cervical defects with or without the use of CBM. (Implant Dent 2012;21:481-485)

Bone regeneration in surgically created defects filled with autogenous bone: an epifluorescence microscopy analysis in rats

Although the search for the ideal bone substitute has been the focus of a large number of studies, autogenous bone is still the gold standard for the filling of defects caused by pathologies and traumas, and mainly, for alveolar ridge reconstruction, allowing the titanium implants installation. Objectives: The aim of this study was to evaluate the dynamics of autogenous bone graft incorporation process to surgically created defects in rat calvaria, using epifluorescence microscopy. Material and methods: Five adult male rats weighing 200-300 g were used. The animals received two 5-mm-diameter bone defects bilaterally in each parietal bone with a trephine bur under general anesthesia. Two groups of defects were formed: a control group (n=5), in which the defects were filled with blood clot, and a graft group (n=5), in which the defects were filled with autogenous bone block, removed from the contralateral defect. The fluorochromes calcein and alizarin were applied at the 7th and 30th postoperative days, respectively. The animals were killed at 35 days. Results: The mineralization process was more intense in the graft group (32.09%) and occurred mainly between 7 and 30 days, the period labeled by calcein (24.66%). Conclusions: The fluorochromes showed to be appropriate to label mineralization areas. The interfacial areas between fluorochrome labels are important sources of information about the bone regeneration dynamics.

Tissue Reaction to a Triantibiotic Paste Used for Endodontic Tissue Self-regeneration of Nonvital Immature Permanent Teeth

Introduction: The endodontic regenerative procedure (ERP), which is an alternative to calcium hydroxide induced apexification, involves the use of a triple antibiotic paste (TAP) as a dressing material. The aim of this study was to evaluate the response of rat subcutaneous tissue to implanted polyethylene tubes that were filled with TAP or calcium hydroxide. Methods: Thirty rats received 2 individual implants of polyethylene tubes filled with TAP or calcium hydroxide paste (CHP) and another empty tube as a control. Thirty additional rats received 2 individual implants consisting of polyethylene tubes filled with dressing material carriers (macrogol and propylene glycol) and a sham procedure. After 7, 15, 30, 60, and 90 days, 12 animals were euthanized, and the tubes and surrounding tissue were removed and processed for histology by using glycol methacrylate and stained with hematoxylin and eosin. The histological score ranged from 0 to 3 depending on the content of inflammatory cells; the fibrous capsule was considered thin or thick, and necrosis and calcification were recorded as present or absent. The results were analyzed using the Kruskal-Wallis test. Results: Both dressing materials induced moderate reactions at 7 and 15 days. These reactions were similar to the control (P>.05) and reduced in intensity (to mild) from day 30 onward (P>.05). The carriers did not interfere with the reaction of the dressing materials. Conclusions: TAP and CHP were biocompatible over the different experimental periods examined. (J Endod 2012;38:91-94)

Orthodontic movement after periodontal regeneration of class II furcation: a pilot study in dogs

Purpose: the effect of orthodontic movement on the periodontal tissues of maxillary second pre-molars, after regenerative treatment for class II furcations, was evaluated in four mongrel dogs.Material and Methods: Class II furcation lesions were created. After 75 days they were treated with bovine bone mineral matrix and guided tissue regeneration with absorbable membrane. After 2 months of daily plaque control, each of the dog's furcation pre-molars was randomly assigned to a test or control group. Orthodontic appliances were placed on both sides of the maxilla using third pre-molars and canines as anchorages. In the test group, bodily orthodontic movement of the second pre-molars was performed in the mesial direction for 3 months while control pre-molars remained unmoved. The dogs were sacrificed for histometric and histologic analyses.Results: There were no statistically significant differences between the two groups in total bone and biomaterial areas or linear extension of periodontal regeneration on the radicular surfaces. In the test group, however, there was a tendency to a greater quantity of bone and a lesser quantity of biomaterial.Conclusion: the orthodontic movement was not pre-judicial to the results obtained with the regenerative periodontal treatment.