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1.
J Prosthet Dent ; 119(2): 299-304, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28645662

RESUMO

STATEMENT OF PROBLEM: Conventionally, maxillofacial prostheses are fabricated by hand carving the missing anatomic defect in wax and creating a mold into which pigmented silicone elastomer is placed. Digital technologies such as computer numerical control milling and 3-dimensional (3D) printing have been used to prepare molds, directly or indirectly, into which a biocompatible pigmented silicone elastomer can be placed. PURPOSE: The purpose of this in vitro study was to develop a silicone elastomer that could be 3D printed directly without a mold to create facial or body prostheses by varying its composition. MATERIAL AND METHODS: The room temperature vulcanizing silicone composition was divided into 2 components which were mixed 1:1 to initiate polymerization in the printer before printing began. Different types of moderators and thixotropic agents were used, and the base composition was varied to obtain 11 formulations. The specimens were printed and polymerized from these formulations and tested for tear and tensile strength and hardness. Ten readings of the specimens were recorded for tear and tensile strength and 6 for hardness. Results were analyzed using ANOVA (α=.05). Visual assessment of uncured printed specimens was undertaken for 5 formulations to assess any differences in their ability to hold their shape after printing. RESULTS: The tear and tensile strength of the 11 formulations with varying moderators, thixotropic agents, and base compositions were statistically similar to each other (P>.05). Five of 11 formulations were chosen for the visual assessment as they had sufficient thixotropic agent to avoid slumping while printing. The specimens showed varied slumping behavior until they polymerized. The filler content was increased in the selected formulation, and the tear and tensile strength of the formulation was increased to 6.138 kNm-1 and 3.836 MPa; these increases were comparable to those of commercial silicones currently used for the fabrication of facial prostheses. CONCLUSIONS: The optimum combination of mechanical properties implies the use of one of the formulations as a suitable material for the 3D printing of facial prostheses.


Assuntos
Prótese Maxilofacial , Impressão Tridimensional , Silicones/uso terapêutico , Materiais Biocompatíveis/uso terapêutico , Desenho Assistido por Computador , Técnicas In Vitro , Desenho de Prótese
2.
Macromol Rapid Commun ; 39(4)2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29210493

RESUMO

Silicone elastomers have broad versatility within a variety of potential advanced materials applications, such as soft robotics, biomedical devices, and metamaterials. A series of custom 3D printable silicone inks with tunable stiffness is developed, formulated, and characterized. The silicone inks exhibit excellent rheological behavior for 3D printing, as observed from the printing of porous structures with controlled architectures. Herein, the capability to tune the stiffness of printable silicone materials via careful control over the chemistry, network formation, and crosslink density of the ink formulations in order to overcome the challenging interplay between ink development, post-processing, material properties, and performance is demonstrated.


Assuntos
Materiais Biocompatíveis/química , Elastômeros/química , Silicones/química , Materiais Biocompatíveis/síntese química , Elastômeros/síntese química , Tinta , Porosidade , Impressão Tridimensional , Reologia , Silicones/síntese química
3.
Adv Mater ; 29(26)2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28452163

RESUMO

Silica inks are developed, which may be 3D printed and thermally processed to produce optically transparent glass structures with sub-millimeter features in forms ranging from scaffolds to monoliths. The inks are composed of silica powder suspended in a liquid and are printed using direct ink writing. The printed structures are then dried and sintered at temperatures well below the silica melting point to form amorphous, solid, transparent glass structures. This technique enables the mold-free formation of transparent glass structures previously inaccessible using conventional glass fabrication processes.

4.
J Craniofac Surg ; 23(3): 638-44, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22565873

RESUMO

Microporous scaffolds designed to improve bony repair have had limited success; therefore, we sought to evaluate whether time-released porous scaffolds with or without recombinant bone morphogenetic protein 2 (rhBMP-2) could enhance stem cell osteoinduction. Custom-made 15/85 hydroxyapatite/ß-tricalcium phosphate scaffolds were left empty (E) or filled with rhBMP-2 (E+), calcium sulfate (CS), or CS and rhBMP-2 (CS+). All scaffolds were placed in media and weighed daily. Conditioned supernatant was analyzed for rhBMP-2 and then used to feed human adipose-derived mesenchymal stem cells (ASCs). Adipose-derived mesenchymal stem cell ALP activity, OSTERIX expression, and bone nodule formation were determined. E scaffolds retained 97% (SD, 2%) of the initial weight, whereas CS scaffolds had a near-linear 30% (SD, 3%) decrease over 60 days. E+ scaffolds released 155 (SD, 5) ng of rhBMP-2 (77%) by day 2. In contrast, CS+ scaffolds released only 30 (SD, 2) ng (10%) by day 2, and the remaining rhBMP-2 was released over 20 days. Conditioned media from E+ scaffolds stimulated the highest ALP activity and OSTERIX expression in ACSs on day 2. However, after day 6, media from CS+ scaffolds stimulated the highest ALP activity and OSTERIX expression in ASCs. Adipose-derived mesenchymal stem cells exposed to day 8 CS+-conditioned media produced significantly more bone nodules (10.1 [SD, 1.7] nodules per high-power field) than all other scaffolds. Interestingly, day 8 conditioned media from CS scaffolds simulated significantly more bone nodules than either E or E+ scaffold (P < 0.05 for both). Time-released hydroxyapatite/ß-tricalcium phosphate porosity provides sustained growth factor release, enhances ASC osteoinduction, and may result in better in vivo bone formation.


Assuntos
Tecido Adiposo/citologia , Proteína Morfogenética Óssea 2/farmacologia , Regeneração Óssea/fisiologia , Fosfatos de Cálcio/farmacologia , Durapatita/farmacologia , Células-Tronco Mesenquimais/metabolismo , Engenharia Tecidual/instrumentação , Tecidos Suporte , Fator de Crescimento Transformador beta/farmacologia , Fosfatase Alcalina/metabolismo , Análise de Variância , Sulfato de Cálcio/farmacologia , Técnicas de Cultura de Células , Diferenciação Celular , Ensaio de Imunoadsorção Enzimática , Humanos , Porosidade , Proteínas Recombinantes/farmacologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator de Transcrição Sp7 , Coloração e Rotulagem , Fatores de Transcrição/metabolismo
5.
J Craniofac Surg ; 23(1): 304-8, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22337431

RESUMO

Solid freeform fabrication techniques such as direct write technology can be used to fabricate tissue-engineering scaffolds in 3 dimensions with high levels of reproducibility and precision. These can comprise complex structures made of osteoconductive, remodelable lattices to conduct bone ingrowth and solid barriers to prevent soft tissue invasion. As such, they act as a combination of bone graft and barrier membrane. Results from animal studies have shown that these structures fill rapidly with healing bone and can conduct bone across critical-size defects to fill large defects in rabbit skull. Results indicate that this technology can be used to produce both off-the-shelf and custom-fabricated bone graft substitutes. These may initially be used to restore alveolar ridge defects, but could also be used, in the future, to repair or replace complex craniofacial bone defects such as cleft palate defects. In the more distant future, these technologies could be combined with controlled-release bioactive substances such as growth factors and pharmaceuticals to regenerate complex structures comprising multiple tissue types.


Assuntos
Substitutos Ósseos/química , Desenho Assistido por Computador , Ossos Faciais/cirurgia , Crânio/cirurgia , Tecidos Suporte/química , Implantes Absorvíveis , Animais , Materiais Biocompatíveis/química , Doenças Ósseas/cirurgia , Regeneração Óssea/fisiologia , Remodelação Óssea/fisiologia , Fosfatos de Cálcio/química , Técnicas de Cultura de Células , Coloides/química , Preparações de Ação Retardada , Durapatita/química , Módulo de Elasticidade , Peptídeos e Proteínas de Sinalização Intercelular/uso terapêutico , Osteogênese/fisiologia , Osso Parietal/patologia , Porosidade , Desenho de Prótese , Coelhos , Engenharia Tecidual/instrumentação , Engenharia Tecidual/métodos , Viscosidade
6.
J Biomed Mater Res A ; 83(3): 747-58, 2007 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-17559109

RESUMO

The in vivo bone response of 3D periodic hydroxyapatite (HA) scaffolds is investigated. Two groups of HA scaffolds (11 mm diameter x 3.5 mm thick) are fabricated by direct-write assembly of a concentrated HA ink. The scaffolds consist of cylindrical rods periodically arranged into four quadrants with varying separation distances between rods. In the first group, HA rods (250 microm in diameter) are patterned to create pore channels, whose areal dimensions are 250 x 250 microm(2) in quadrant 1, 250 x 500 microm(2) in quadrants 2 and 4, and 500 x 500 microm(2) in quadrant 3. In the second group, HA rods (400 microm in diameter) are patterned to create pore channels, whose areal dimensions of 500 x 500 microm(2) in quadrant 1, 500 x 750 microm(2) in quadrants 2 and 4, and 750 x 750 microm(2) in quadrant 3. Each group of scaffolds is partially densified by sintering at 1200 degrees C prior to being implanted bilaterally in trephine defects of skeletally mature New Zealand White rabbits. Their tissue response is evaluated at 8 and 16 weeks using micro-computed tomography, histology, and scanning electron microscopy. New trabecular bone is conducted rapidly and efficiently across substantial distances within these patterned 3D HA scaffolds. Our observations suggest that HA rods are first coated with a layer of new bone followed by subsequent scaffold infilling via outward and inward radial growth of the coated regions. Direct-write assembly of 3D periodic scaffolds composed of micro-porous HA rods arrayed to produce macro-pores that are size-matched to trabecular bone may represent an optimal strategy for bone repair and replacement structures.


Assuntos
Regeneração Óssea , Substitutos Ósseos , Durapatita , Tecidos Suporte , Animais , Tinta , Teste de Materiais , Porosidade , Coelhos , Fraturas Cranianas/terapia
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