Tissue engineering application combining epoxidized natural rubber blend and mesenchymal stem cells in in vivo response.

This study aimed to investigate biocompatibility, integration, and tissue host response of the Poly (Lactic-co-Glycolic acid) (PLGA)/Poly (isoprene) (PI) epoxidized (PLGA/PIepox) innovative scaffold combined with adipose derived mesenchymal stem cells (ADSC). We implanted the scaffold subcutaneously on the back of 18 female rats and monitored them for up to 14 days. When compared to controls, PLGA/PIepox + ADSC demonstrated an earlier vascularization, a tendency of inflammation reduction, an adequate tissue integration, higher cell proliferation, and a tendency of expression of collagen decreasing. However, 14 days post-implantation we found similar levels of CD31, Ki67 and AE1/AE3 in PLGA/PIepox when compared to control groups. The interesting results, lead us to the assumption that PLGA/PIepox is able to provide an effective delivery system for ADSC on tissue host. This animal study assesses PLGA/PIepox + ADSC in in vivo tissue functionality and validation of use, serving as a proof of concept for future clinical translation as it presents an innovative and promising tissue engineering opportunity for the use in tissue reconstruction.

Mechanical properties, in vitro and in vivo biocompatibility analysis of pure iron porous implant produced by metal injection molding: A new eco-friendly feedstock from natural rubber (Hevea brasiliensis).

Metal injection molding (MIM) has become an important manufacturing technology for biodegradable medical devices. As a biodegradable metal, pure iron is a promising biomaterial due to its mechanical properties and biocompatibility. In light of this, we performed the first study that manufactured and evaluated the in vitro and in vivo biocompatibility of samples of iron porous implants produced by MIM with a new eco-friendly feedstock from natural rubber (Hevea brasiliensis), a promisor binder that provides elastic property in the green parts. The iron samples were submitted to tests to determine density, microhardness, hardness, yield strength, and stretching. The biocompatibility of the samples was studied in vitro with adipose-derived mesenchymal stromal cells (ADSCs) and erythrocytes, and in vivo on a preclinical model with Wistar rats, testing the iron samples after subcutaneous implant. Results showed that the manufactured samples have adequate physical, and mechanical characteristics to biomedical devices and they are cytocompatible with ADSCs, hemocompatible and biocompatible with Wistars rats. Therefore, pure iron produced by MIM can be considered a promising material for biomedical applications.

In situ drug release measuring in α-TCP cement by electrochemical impedance spectroscopy.

The use of drug delivery systems is a good technique to leave the right quantity of medicine in the patient's body in a suitable dose, because the drug application is delivered directly to the affected region. The current techniques such as HPLC and UV-Vis for the drug delivery calculation has some disadvantages, as the accuracy and the loss of the sample after characterization. With the aim of reducing the amount of material used during the characterization and have a non-destructive test with instantaneous results, the present paper shows the possibility of using electrochemical impedance spectroscopy (EIS) to have a drug delivery measurement during the release phenomena for a calcium phosphate cement (CFC) delivery system with gentamicin sulfate (GS) and lidocaine hydrochloride (LH), at a ratio of 1% and 2%, respectively. The equivalent circuit and the chemical mechanism involved during the measurements have been proposed as a tool to determine the drug delivery profile. The method has been compared with the UV-Vis technique. XRD was realized to verify conditions, before and after release. It was possible to verify the potential for using EIS as an instant technique to quantify drug delivery.

Tissue-engineered solution containing cells and biomaterials-an in vitro study: A perspective as a novel therapeutic application.

Some biomaterial scaffolds can positively interfere with tissue regeneration and are being developed to successfully repair the tissue function. The possibility of using epithelial cells combined with biomaterials appears to be a new option as therapeutic application. This combination emerges as a possibility for patients with Mayer-Rokitansky-Kuster-Hauser syndrome which requires vaginal repair and can be performed with tissue-engineered solution containing cells and biomaterials. It is expected that tissue-engineered solution containing cells and biomaterials would promote tissue repair in a more efficient, modern, and safe way. This study tested the efficiency of tissue-engineered solution containing human malignant melanoma cell line (HMV-II) and different biomaterials, including Cellprene®, Membracel®, and poly lactic-co-glycolic acid/epoxidized polyisoprene. The cells adhered better on poly lactic-co-glycolic acid/epoxidized polyisoprene, and it was found that tissue-engineered solution may also contain mesenchymal stem cells cultivated on poly lactic-co-glycolic acid/epoxidized polyisoprene. Histological, immunofluorescence, and scanning electron microscopy analyses were performed. These initial in vitro results suggest that tissue-engineered solution containing cells and poly lactic-co-glycolic acid/epoxidized polyisoprene is a potential for tissue reconstruction.

Polydimethylsiloxane/nano calcium phosphate composite tracheal stents: Mechanical and physiological properties.

In this study, we report the production and characterization of tracheal stents composed of polydimethylsiloxane/nanostructured calcium phosphate composites obtained by reactive synthesis. Tracheal stents were produced by transfer molding, and in vivo tests were carried out. PDMS was combined with H3 PO4 and Ca(OH)2 via an in situ reaction to obtain nanoparticles of calcium phosphate dispersed within the polymeric matrix. The incorporation of bioactive inorganic substances, such as calcium phosphates, improved biological properties, and the in situ reaction allowed tight coupling of particles to the matrix. Results showed the presence of the nanoparticles of DCPA and CDHA. The porosity generated during mixing decreased the tensile strength and tear properties. Composites presented higher values of cell viability compared with those for PDMS. In vivo tests indicated the presence of inflammatory tissue 30 days after implantation in both cases. Thus, the present biomaterial shows potential for application in tracheal disease, however further evaluation is needed. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 545-553, 2019.

Avaliação da combinação de poli (ácido láctico-co-glicólico) e poli-isopreno (Cellprene®): estudo histológico em ratos / Evaluation of the combination of poly (Lactic-Co-Glycolic Acid) and polyisoprene (Cellprene®) materials: histological study in rats

Resumo Introdução A quantidade e qualidade óssea na implantodontia é um fator de alta relevância quando se tem por objetivo instalar implantes e reabilitar pacientes. No entanto, essa disponibilidade é comprometida na maioria dos casos, havendo a necessidade da busca de novos biomateriais, membranas e substâncias para uma regeneração mais favorável. Objetivo: O objetivo deste estudo foi avaliar a resposta da neoformação óssea em defeitos críticos em calvárias de ratos utilizando scaffolds de fibras de blenda polimérica a partir de poli (ácido láctico-co-glicólico) e poli-isopreno (Cellprene®). O projeto foi aprovado pelo Comitê de Ética em Experimentação Animal. Material e método Neste estudo, foram utilizados 36 ratos (Rattus Norvegicus), variação albinus, Holtzman, adultos. Os animais foram submetidos à tricotomia na região da calota craniana e à confecção de defeitos ósseos circulares bilaterais com 5 mm de diâmetro. Os animais foram divididos em três grupos: GC - defeito sem colocação de biomaterial; GCol - scaffolds de colágeno (Bio-Gide, da empresa Geistlich Pharma Ag - Biomaterials); GPoli - scaffolds de fibras de blenda polimérica a partir de poli (ácido láctico-co-glicólico - Cellprene®). Cada grupo foi avaliado em quatro períodos experimentais (7, 15, 30 e 60 dias). Após esses períodos, os animais foram sacrificados, e as peças passaram por tramitação laboratorial de rotina e inclusão em parafina. Foram obtidos cortes semisseriados e corados pela técnica de hematoxilina e eosina para análise histométrica e histológica. Foi executada análise histométrica para avaliar a composição do tecido ósseo reparado (% osso). Os dados obtidos foram analisados estatisticamente com nível de significância de 95%. Resultado Foi verificado que o GCol apresentou maior preenchimento do defeito nos períodos de 30 e 60 dias em comparação aos GC e GPoli. Conclusão Os scaffolds de fibras de blenda polimérica a partir de poli (ácido láctico-co-glicólico) e poli-isopreno (Cellprene®) não apresentaram vantagens quando utilizados em defeitos críticos.

Abstract Introduction The bone quantity and quality in implant dentistry is a highly relevant factor when it aims the use of implants and rehabilitation in patients. However, this availability is compromised in most cases, with the need to research new biomaterials, membranes and substances for more favorable regeneration. Objective: The aim of this study was to evaluate the response of bone neoformation in critical defects in rat calvaries using polymeric blend fiber scaffolds from Poly (Lactic-Co-Glycolic Acid) and Polyisoprene (Cellprene®). The project was approved by the Animal Experimentation Ethics Committee. Material and method In this study 36 rats (Rattus Norvegicus), variation albinus, Holtzman, adults were used. The animals had trichotomy in the region of the skull and the confection of bilateral circular bone defects with a diameter of 5 mm. The animals were divided into 3 groups: Group GC - defect without biomaterial placement, Group GCol - collagen scaffolds (Bio-Gide, from Geistlich Pharma Ag - Biomaterials), Group GPoli - polymeric blend fiber scaffolds from Poly (Lactic-Co-Glycolic Acid)-Polyisoprene. Each group was evaluated in 4 experimental periods (7, 15, 30 and 60 days). After these periods the animals were sacrificed and the pieces underwent routine laboratory procedures and paraffin embedding. Semi-serial sections were obtained and stained by hematoxylin and eosin technique for histometric and histological analysis. Histometric analysis was performed to evaluate the composition of repaired bone tissue (% Bone). The data obtained were statistically analyzed with a significance level of 95%. Result It was found that the GCol group presented greater defect filling in the 30 and 60 days periods compared to the GC and GPoli groups. Conclusion Polymer blend fiber scaffolds from Poly (Lactic-Co-Glycolic Acid) and Polyisoprene (Cellprene®) did not have advantages when used in critical defects.

Fiber-reinforced silicone for tracheobronchial stents: An experimental study.

A trachea is a tubular structure composed of smooth muscle that is reinforced with cartilage rings. Some diseases can cause sagging in smooth muscle and cartilaginous tissue. The end result is reduction (narrowing) of the trachea diameter. A solution to this problem is the use of tracheal stents, which are small tubular devices made of silicone. One is inserted into the trachea to prevent or correct its constriction. The purpose of tracheal stent use is to maintain cartilage support that would otherwise be lost in the airway. Current tracheal stent models present limitations in terms of shape and characteristics of the silicone used in their production. One of the most important is the large thickness of the wall, which makes its placement difficult; this mainly applies to pediatric patients. The wall thickness of the stent is closely related to the mechanical properties of the material. This study aims to test the reinforcement of silicone with three kinds of fibers, and then stents that were produced using fiber with the best compressive strength characteristics. Silicone samples were reinforced with polypropylene (PP), polyamide (PA), and carbon fiber (CF) at concentrations of 2% and 4% (vol%), which then underwent tensile strength and Shore A hardness testing. Samples with fiber showed good characteristics; surface analyses were carried out and they were used to produce stents with an internal diameter of 11 or 13mm and a length of 50mm. Stents underwent compression tests for qualitative evaluation. Samples with 2% and 4% CF blends showed the best mechanical performance, and they were used to produce stents. These samples presented similar compressive strengths at low deformation, but stents with a 4% CF blend exhibited improved compressive strength at deformations greater than 30-50% of their diameter (P ≤ 0.05). The addition of 2% and 4% CF blends conferred greater mechanical strength and resistance to the silicone matrix. This is particularly true at low deformation, which is the condition where the stent is used when implanted. In the finite element compression strength tests, the stent composite showed greater compression strength with the addition of fiber, and the results were in accordance with mechanical compression tests performed on the stents. In vivo tests showed that, after 30 days of post-implantation in sheep trachea, an inflammatory process occurred in the region of the trachea in contact with the stent composite and with the stent without fiber (WF). This response is a common process during the first few days of implantation.

Methacrylate-based root canal sealer containing chlorexidine and α-tricalcium phosphate.

The aim of this study was to develop and to characterize a methacrylate-based root canal sealer containing chlorhexidine (CHX) and α-tricalcium phosphate (α-TCP). Experimental dual cure methacrylate-based sealer was produced containing 0, 2.5, or 5 wt% of CHX and 0, 25, or 50 wt% of α-TCP. Experimental sealers were evaluated based on flow, film thickness, radiopacity, degree of conversion (DC), degradation in water, pH and antibacterial activity. Flow ranged from 15.09 ± 0.11 to 17.47 ± 0.42 mm. All groups presented mean film thickness lower than 50 µm and had radiopacity equivalent to 3 mmAl. DC was higher than 60% for all compositions. The weight loss (WL) ranged 0.12-3.47%. The groups containing 5% of CHX presented the highest WL and the lower pH values after 28 days of water immersion. All chlorexidine-compositions exhibited antibacterial efficacy against Enterococcus faecalis on direct contact and agar diffusion tests. CHX and α-TCP addition at an experimental methacrylate-based root canal sealer influenced the physicochemical properties and provided antibacterial properties. The incorporation of CHX and α-TCP could be an alternative to antibacterial sealers with potential to improve periapical healing in endodontic treatments. © 2017 Wiley Periodicals, Inc. J Biomater Res Part B: 106B: 1439-1443, 2018.

Different post-processing conditions for 3D bioprinted α-tricalcium phosphate scaffolds.

The development of 3D printing hardware, software and materials has enabled the production of bone substitute scaffolds for tissue engineering. Calcium phosphates cements, such as those based on α-tricalcium phosphate (α-TCP), have recognized properties of osteoinductivity, osteoconductivity and resorbability and can be used to 3D print scaffolds to support and induce tissue formation and be replaced by natural bone. At present, however, the mechanical properties found for 3D printed bone scaffolds are only satisfactory for non-load bearing applications. This study varied the post-processing conditions of the 3D powder printing process of α-TCP cement scaffolds by either immersing the parts into binder, Ringer's solution or phosphoric acid, or by sintering in temperatures ranging from 800 to 1500 °C. The porosity, composition (phase changes), morphology, shrinkage and compressive strength were evaluated. The mechanical strength of the post-processed 3D printed scaffolds increased compared to the green parts and was in the range of the trabecular bone. Although the mechanical properties achieved are still low, the high porosity presented by the scaffolds can potentially result in greater bone ingrowth. The phases present in the scaffolds after the post-processing treatments were calcium-deficient hydroxyapatite, brushite, monetite, and unreacted α-TCP. Due to their chemical composition, the 3D printed scaffolds are expected to be resorbable, osteoinductive, and osteoconductive.

Repair of bone defects using adipose-derived stem cells combined with alpha-tricalcium phosphate and gelatin sponge scaffolds in a rat model.

OBJECTIVES: This study aimed to evaluate the potential of adipose-derived stem cells (ASCs) combined with a modified α-tricalcium phosphate (α-TCP) or gelatin sponge (GS) scaffolds for bone healing in a rat model. MATERIAL AND METHODS: Bone defects were surgically created in the femur of adult SHR rats and filled with the scaffolds, empty or combined with ASCs. The results were analyzed by histology and histomorphometry on days seven, 14, 30, and 60. RESULTS: Significantly increased bone repair was observed on days seven and 60 in animals treated with α-TCP/ASCs, and on day 14 in the group treated with GS/ASCs, when compared with the groups treated with the biomaterials alone. Intense fibroplasia was observed in the group treated with GS alone, on days 14 and 30. CONCLUSIONS: Our results showed that the use of ASCs combined with α-TCP or GS scaffolds resulted in increased bone repair. The higher efficacy of the α-TCP scaffold suggests osteoconductive property that results in a biological support to the cells, whereas the GS scaffold functions just as a carrier. These results confirm the potential of ASCs in accelerating bone repair in in vivo experimental rat models. These results suggest a new alternative for treating bone defects.

Repair of bone defects using adipose-derived stem cells combined with alpha-tricalcium phosphate and gelatin sponge scaffolds in a rat model

Abstract Objectives This study aimed to evaluate the potential of adipose-derived stem cells (ASCs) combined with a modified α-tricalcium phosphate (α-TCP) or gelatin sponge (GS) scaffolds for bone healing in a rat model. Material and Methods Bone defects were surgically created in the femur of adult SHR rats and filled with the scaffolds, empty or combined with ASCs. The results were analyzed by histology and histomorphometry on days seven, 14, 30, and 60. Results Significantly increased bone repair was observed on days seven and 60 in animals treated with α-TCP/ASCs, and on day 14 in the group treated with GS/ASCs, when compared with the groups treated with the biomaterials alone. Intense fibroplasia was observed in the group treated with GS alone, on days 14 and 30. Conclusions Our results showed that the use of ASCs combined with α-TCP or GS scaffolds resulted in increased bone repair. The higher efficacy of the α-TCP scaffold suggests osteoconductive property that results in a biological support to the cells, whereas the GS scaffold functions just as a carrier. These results confirm the potential of ASCs in accelerating bone repair in in vivo experimental rat models. These results suggest a new alternative for treating bone defects.

Dimensional evaluation of patient-specific 3D printing using calcium phosphate cement for craniofacial bone reconstruction.

The 3D printing process is highlighted nowadays as a possibility to generate individual parts with complex geometries. Moreover, the development of 3D printing hardware, software and parameters permits the manufacture of parts that can be not only used as prototypes, but are also made from materials that are suitable for implantation. In this way, this study investigates the process involved in the production of patient-specific craniofacial implants using calcium phosphate cement, and its dimensional accuracy. The implants were previously generated in a computer-aided design environment based on the patient's tomographic data. The fabrication of the implants was carried out in a commercial 3D powder printing system using alfa-tricalcium phosphate powder and an aqueous solution of Na2HPO4 as a binder. The fit of the 3D printed implants was measured by three-dimensional laser scanning and by checking the right adjustment to the patient's anatomical biomodel. The printed parts presented a good degree of fitting and accuracy.

Development and testing of an absorbable spring for cranial expansion in rabbits.

OBJECTIVE: Use of metal springs for treatment of craniosynostosis is gaining ground in the surgical armamentarium, as these springs simplify operative technique, help to avoid extended approaches, and thus minimize morbidity. Nevertheless, these devices have to be removed eventually. The purpose of this study was to perform cranial expansion with a fully integrated, biodegradable polymer spring in an animal model and to assess the efficacy of and histological reaction to this device. MATERIAL AND METHODS: This was an experimental, unblinded, prospective study. Twelve female New Zealand rabbits (Oryctolagus cuniculus) aged 6 weeks were randomly allocated to two groups. Control animals underwent linear craniectomy alone. Intervention animals underwent craniectomy with placement of a poly(lactic-co-glycolic acid)/polyisoprene (PLGA/PI) copolymer blend spring for cranial expansion transverse to the ostectomy. Expansion was measured radiographically over 12 weeks with amalgam markers. At the end of the experiment period, histological analysis was performed to quantify inflammatory reaction. RESULTS: The copolymer blend springs had a mean strength of 4.2N. In the intervention group, cranial expansion at the frontal markers was 9.6-11.67 mm (significantly greater than in controls). Histological analysis showed minor inflammatory reactions. CONCLUSION: In this animal model, cranial expansion by linear craniectomy followed by bioabsorbable spring placement was feasible and well tolerated by adjacent tissues.

α-Tricalcium phosphate cements modified with ß-dicalcium silicate and tricalcium aluminate: physicochemical characterization, in vitro bioactivity and cytotoxicity.

Biocompatibility, injectability and in situ self-setting are characteristics of calcium phosphate cements which make them promising materials for a wide range of clinical applications in traumatology and maxillo-facial surgery. One of the main disadvantages is their relatively low strength which restricts their use to nonload-bearing applications. α-Tricalcium phosphate (α-C3P) cement sets into calcium-deficient hydroxyapatite (CDHA), which is biocompatible and plays an essential role in the formation, growth and maintenance of tissue-biomaterial interface. ß-Dicalcium silicate (ß-C2S) and tricalcium aluminate (C3A) are Portland cement components, these compounds react with water to form hydrated phases that enhance mechanical strength of the end products. In this study, setting time, compressive strength (CS) and in vitro bioactivity and biocompatibility were evaluated to determine the influence of addition of ß-C2S and C3A to α-C3P-based cement. X-ray diffraction and scanning electron microscopy were used to investigate phase composition and morphological changes in cement samples. Addition of C3A resulted in cements having suitable setting times, but low CS, only partial conversion into CDHA and cytotoxicity. However, addition of ß-C2S delayed the setting times but promoted total conversion into CDHA by soaking in simulated body fluid and strengthened the set cement over the limit strength of cancellous bone. The best properties were obtained for cement added with 10 wt % of ß-C2S, which showed in vitro bioactivity and cytocompatibility, making it a suitable candidate as bone substitute.

Cranial vault reconstruction with bone morphogenetic protein, calcium phosphate, acellular dermal matrix, and calcium alginate in mice.

PURPOSE: To evaluate experimental cranial vault reconstructions, by combining bone morphogenetic protein type 2 (BMP-2) and different matrices. METHODS: Fourty-nine animals were initially included (seven per group). We designed an experimental, open, prospective and comparative study, divided in seven groups: 1 - BMP-2+calcium phosphate (BT); 2 - BMP-2+acellular dermal matrix (BM); 3 - BMP-2+calcium alginate (BA); 4 - TCP; 5 - MDM; 6 - ALG; 7 - Bone autograft (BAG). A bone failure was created in left parietal bone of adult male mice. At the same procedure reconstruction was performed. After five weeks, animals were sacrificed, and reconstruction area was removed to histological analysis. After exclusion due to death or infection, thirty-eight animals were evaluated (BT=5; BM=6; BA=6; TCP=7; MDM=3; ALG=6; BAG=5). RESULTS: A higher incidence of infection has occurred in MDM group (57%, P=0.037). In cortical fusion, groups BAG, TCP, and BMP-2+TCP (BT) obtained the best scores, comparing to the others (P=0.00846). In new bone formation, groups BT, BAG, and TCP have presented the best scores (P=0.00835). When neovascularization was considered, best groups were BMP-2+MDM (BM), BMP-2+ALG (BA), TCP, and MDM (P=0.001695). BAG group was the best in bone marrow formation, followed by groups BT and TCP (P=0.008317). CONCLUSIONS: Bone morphogenetic protein type 2 increased bone regeneration in experimental skull reconstruction, especially when combined to calcium phosphate. Such association was even comparable to bone autograft, the gold-standard treatment, in some histological criteria.

Cranial vault reconstruction with bone morphogenetic protein, calcium phosphate, acellular dermal matrix, and calcium alginate in mice

PURPOSE: To evaluate experimental cranial vault reconstructions, by combining bone morphogenetic protein type 2 (BMP-2) and different matrices. METHODS: Fourty-nine animals were initially included (seven per group). We designed an experimental, open, prospective and comparative study, divided in seven groups: 1 - BMP-2+calcium phosphate (BT); 2 - BMP-2+acellular dermal matrix (BM); 3 - BMP-2+calcium alginate (BA); 4 - TCP; 5 - MDM; 6 - ALG; 7 - Bone autograft (BAG). A bone failure was created in left parietal bone of adult male mice. At the same procedure reconstruction was performed. After five weeks, animals were sacrificed, and reconstruction area was removed to histological analysis. After exclusion due to death or infection, thirty-eight animals were evaluated (BT=5; BM=6; BA=6; TCP=7; MDM=3; ALG=6; BAG=5). RESULTS: A higher incidence of infection has occurred in MDM group (57%, P=0.037). In cortical fusion, groups BAG, TCP, and BMP-2+TCP (BT) obtained the best scores, comparing to the others (P=0.00846). In new bone formation, groups BT, BAG, and TCP have presented the best scores (P=0.00835). When neovascularization was considered, best groups were BMP-2+MDM (BM), BMP-2+ALG (BA), TCP, and MDM (P=0.001695). BAG group was the best in bone marrow formation, followed by groups BT and TCP (P=0.008317). CONCLUSIONS: Bone morphogenetic protein type 2 increased bone regeneration in experimental skull reconstruction, especially when combined to calcium phosphate. Such association was even comparable to bone autograft, the gold-standard treatment, in some histological criteria. .

ß-Dicalcium silicate-based cement: synthesis, characterization and in vitro bioactivity and biocompatibility studies.

ß-dicalcium silicate (ß-Ca2 SiO4, ß-C2 S) is one of the main constituents in Portland cement clinker and many refractory materials, itself is a hydraulic cement that reacts with water or aqueous solution at room/body temperature to form a hydrated phase (C-S-H), which provides mechanical strength to the end product. In the present investigation, ß-C2 S was synthesized by sol-gel process and it was used as powder to cement preparation, named CSiC. In vitro bioactivity and biocompatibility studies were assessed by soaking the cement samples in simulated body fluid solutions and human osteoblast cell cultures for various time periods, respectively. The results showed that the sol-gel process is an available synthesis method in order to obtain a pure powder of ß-C2 S at relatively low temperatures without chemical stabilizers. A bone-like apatite layer covered the material surface after soaking in SBF and its compressive strength (CSiC cement) was comparable with that of the human trabecular bone. The extracts of this cement were not cytotoxic and the cell growth and relative cell viability were comparable to negative control.

Cimento de alfa-fosfato tricálcico de dupla pega no preenchimento de cavidade anoftálmica – estudo clínico / Double-setting a-tricalcium phosphate cement for the completion of anophthalmic cavity – clinical study

Foi avaliada a conveniência do emprego do cimento de alfa-fosfato tricálcico de dupla pega como implante para o preenchimento de cavidade anoftálmica de cães. Os animais foram provenientes do Serviço de Oftalmologia do Hos- pital Veterinário, da Universidade Estadual Paulista – Câmpus de Jaboticabal e de uma clínica privada. O trabalho foi realizado em dois anos. A idade dos pacientes oscilou entre 2 a 11 anos e o peso de 9 a 50 kg. Os implantes variaram de 19 a 25 mm de diâmetro. O edema local foi observado em todos os animais durante o pós-operatório imediato. Das dez cirurgias realizadas em sete animais, em nove (90%) o resultado estético foi satisfatório, enquanto em um (10%) foi insatisfatório, devido a complicações que levaram à remoção do implante. A utilização do cimento de alfa-fosfato tri- cálcico de dupla pega no preenchimento de cavidade anoftálmica mostrou-se factível e é uma alternativa que possibilita boa aparência estética após a remoção do bulbo do olho.

The double-setting alpha-tricalcium phosphate bone cement was evaluated as an orbital implant for filling the ano- phthalmic cavity of dogs. The animals were from the Ophthalmology Unit of the Veterinary Hospital, Universidade Estadual Paulista – Jaboticabal, and from a private veterinary clinic. The study was conducted during two years. The patients’ age ranged from 2-11 years old, and their weight from 9-50 kg. The implants ranged from 19 to 25 mm in diameter. Local edema was observed in all animals during the immediate postoperative period. Of the ten performed surgeries in seven animals, a satisfactory, aesthetic result was observed in nine (90%) while in one (10%) of them it was unsatisfactory due to complications that led to the implant removal. The use of the double-setting alpha-tricalcium phosphate bone cement to fill anophthalmic sockets is feasible and could be an alternative to improve the cosmetic appearance after eyeball removal.

Development of dual-setting calcium phosphate cement using absorbable polymer.

Calcium phosphate cements used as bone substitutes generally have low mechanical strength compared with the bones of the human body. To solve these needs, we have incorporated hydrogels in the manufacture of samples made of alpha-tricalcium phosphate (α-TCP) cement, developing a system of dual-setting cement. This study aimed to produce composite materials by combining α-TCP powder and hydrogels. The composites were prepared using the synthesized powder and four different formulations of hydrogels, using either poly(N-vinyl-2-pyrrolidone) or poly(N-vinyl-2-pyrrolidone-co-acrylic acid), with either azobisisobutyronitrile or ammonium persulfate as initiator. The properties of all composites were evaluated through measuring compressive strength and apparent density and through X-ray diffraction and scanning electron microscopy. The composites showed compressive strengths of around 24 MPa. Soaking the samples in simulated body fluid formed a layer of hydroxyapatite-like crystals on the surface of some samples, showing the bioactivity of the newly developed cements and their potential use as biomaterial.

Calcium phosphate cement scaffolds with PLGA fibers.

The use of calcium phosphate-based biomaterials has revolutionized current orthopedics and dentistry in repairing damaged parts of the skeletal system. Among those biomaterials, the cement made of hydraulic grip calcium phosphate has attracted great interest due to its biocompatibility and hardening "in situ". However, these cements have low mechanical strength compared with the bones of the human body. In the present work, we have studied the attainment of calcium phosphate cement powders and their addition to poly (co-glycolide) (PLGA) fibers to increase mechanical properties of those cements. We have used a new method that obtains fibers by dripping different reagents. PLGA fibers were frozen after lyophilized. With this new method, which was patented, it was possible to obtain fibers and reinforcing matrix which furthered the increase of mechanical properties, thus allowing the attainment of more resistant materials. The obtained materials were used in the construction of composites and scaffolds for tissue growth, keeping a higher mechanical integrity.