http://hdl.handle.net/2117/3118 Fri, 24 May 2013 01:51:11 GMT 2013-05-24T01:51:11Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/19153 Title: Friction coefficients and wear rates of different orthodontic archwires in artificial saliva Authors: Alfonso, M.V.; Espinar, Eduardo; Llamas, José María; Rupérez de Gracia, Elisa; Manero Planella, José María; Barrera, J.M; Solano, E.; Gil Mur, Francisco Javier Abstract: The aim of this paper is to analyze the influence of the nature of the orthodontic archwires on the friction coefficient and wear rate against materials used commonly as brackets (Ti–6Al–4V and 316L Stainless Steel). The mate- rials selected as orthodontic archwires were ASI304 stainless steel, NiTi, Ti, TiMo and NiTiCu. The array archwire’s materials selected presented very similar roughness but different hardness. Materials were chosen from lower and higher hardness degrees than that of the brackets. Wear tests were carried out at in artificial saliva at 37 C. Results show a linear relationship between the hardness of the materials and the friction coefficients. The material that showed lower wear rate was the ASI304 stainless steel. To prevent wear, the wire and the brackets have high hardness values and in the same order of magnitude. Thu, 09 May 2013 14:46:28 GMT http://hdl.handle.net/2117/19153 2013-05-09T14:46:28Z Alfonso, M.V.; Espinar, Eduardo; Llamas, José María; Rupérez de Gracia, Elisa; Manero Planella, José María; Barrera, J.M; Solano, E.; Gil Mur, Francisco Javier no The aim of this paper is to analyze the influence of the nature of the orthodontic archwires on the friction coefficient and wear rate against materials used commonly as brackets (Ti–6Al–4V and 316L Stainless Steel). The mate- rials selected as orthodontic archwires were ASI304 stainless steel, NiTi, Ti, TiMo and NiTiCu. The array archwire’s materials selected presented very similar roughness but different hardness. Materials were chosen from lower and higher hardness degrees than that of the brackets. Wear tests were carried out at in artificial saliva at 37 C. Results show a linear relationship between the hardness of the materials and the friction coefficients. The material that showed lower wear rate was the ASI304 stainless steel. To prevent wear, the wire and the brackets have high hardness values and in the same order of magnitude. http://hdl.handle.net/2117/19031 Title: High-resolution PLA-based composite scaffolds via 3-D printing technology Authors: Serra, Tiziano; Planell Estany, Josep Anton; Navarro Toro, Melba Eugenia Abstract: Fabrication of new biodegradable scaffolds that guide and stimulate tissue regeneration is still a major issue in tissue engineering approaches. Scaffolds that possess adequate biodegradability, pore size, interconnectivity, bioactivity and mechanical properties in accordance with the injured tissue are required. This work aimed to develop and characterize three-dimensional (3-D) scaffolds that fulfill the aforementioned requirements. For this, a nozzle-based rapid prototyping system was used to combine polylactic acid and a bioactive CaP glass to fabricate 3-D biodegradable scaffolds with two patterns (orthogonal and displaced double layer). Scanning electron microscopy and micro-computer tomography showed that 3-D scaffolds had completely interconnected porosity, uniform distribution of the glass particles, and a controlled and repetitive architecture. Surface properties were also assessed, showing that the incorporation of glass particles increased both the roughness and the hydrophilicity of the scaffolds. Mechanical tests indicated that compression strength is dependent on the scaffold geometry and the presence of glass. Preliminary cell response was studied with primary mesenchymal stem cells (MSC) and revealed that CaP glass improved cell adhesion. Overall, the results showed the suitability of the technique/materials combination to develop 3-D porous scaffolds and their initial biocompatibility, both being valuable characteristics for tissue engineering applications. Mon, 29 Apr 2013 10:31:29 GMT http://hdl.handle.net/2117/19031 2013-04-29T10:31:29Z Serra, Tiziano; Planell Estany, Josep Anton; Navarro Toro, Melba Eugenia no Biodegradable, Composite, Polylactic acid, Rapid prototyping, Scaffold Fabrication of new biodegradable scaffolds that guide and stimulate tissue regeneration is still a major issue in tissue engineering approaches. Scaffolds that possess adequate biodegradability, pore size, interconnectivity, bioactivity and mechanical properties in accordance with the injured tissue are required. This work aimed to develop and characterize three-dimensional (3-D) scaffolds that fulfill the aforementioned requirements. For this, a nozzle-based rapid prototyping system was used to combine polylactic acid and a bioactive CaP glass to fabricate 3-D biodegradable scaffolds with two patterns (orthogonal and displaced double layer). Scanning electron microscopy and micro-computer tomography showed that 3-D scaffolds had completely interconnected porosity, uniform distribution of the glass particles, and a controlled and repetitive architecture. Surface properties were also assessed, showing that the incorporation of glass particles increased both the roughness and the hydrophilicity of the scaffolds. Mechanical tests indicated that compression strength is dependent on the scaffold geometry and the presence of glass. Preliminary cell response was studied with primary mesenchymal stem cells (MSC) and revealed that CaP glass improved cell adhesion. Overall, the results showed the suitability of the technique/materials combination to develop 3-D porous scaffolds and their initial biocompatibility, both being valuable characteristics for tissue engineering applications. http://hdl.handle.net/2117/19029 Title: Modular polylactic acid microparticle-based scaffolds prepared via microfluidic emulsion/solvent displacement process: Fabrication, characterization, and in vitro mesenchymal stem cells interaction study Authors: Salerno, Aurelio; Levato, R.; Mateos Timoneda, Miguel Angel; Engel López, Elisabeth; Netti, Paolo Antonio; Planell Estany, Josep Anton Abstract: The present study reports a novel approach for the design and fabrication of polylactic acid (PLA) microparticle- based scaffolds with microstructural properties suitable for bone and cartilage regeneration. Macroporous PLA scaffolds with controlled shape were fabricated by means of a semicon- tinuous process involving (1) microfluidic emulsification of a PLA/ethyl lactate solution (5% w/v) in a span 80/paraffin oil so- lution (3% v/v) followed by (2) particles coagulation/assembly in an acetone/water solution for the development of a continu- ous matrix. Porous scaffolds prepared from particles with monomodal or bimodal size distribution, overall porosity ranges from 93 to 96%, interparticles porosity from 41 to 54%, and static compression moduli from 0.3 to 1.4 MPa were man- ufactured by means of flow rate modulation of of the continu- ous phase during emulsion. The biological response of the scaffolds was assessed in vitro by using bone marrow-derived rat mesenchymal stem cells (MSCs). The results demonstrated the ability of the scaffolds to support the extensive and uni- form three-dimensional adhesion, colonization, and prolifera- tion of MSCs within the entire construct Mon, 29 Apr 2013 09:13:27 GMT http://hdl.handle.net/2117/19029 2013-04-29T09:13:27Z Salerno, Aurelio; Levato, R.; Mateos Timoneda, Miguel Angel; Engel López, Elisabeth; Netti, Paolo Antonio; Planell Estany, Josep Anton no green solvent, microfluidic, microstructure, stem cells, scaffold The present study reports a novel approach for the design and fabrication of polylactic acid (PLA) microparticle- based scaffolds with microstructural properties suitable for bone and cartilage regeneration. Macroporous PLA scaffolds with controlled shape were fabricated by means of a semicon- tinuous process involving (1) microfluidic emulsification of a PLA/ethyl lactate solution (5% w/v) in a span 80/paraffin oil so- lution (3% v/v) followed by (2) particles coagulation/assembly in an acetone/water solution for the development of a continu- ous matrix. Porous scaffolds prepared from particles with monomodal or bimodal size distribution, overall porosity ranges from 93 to 96%, interparticles porosity from 41 to 54%, and static compression moduli from 0.3 to 1.4 MPa were man- ufactured by means of flow rate modulation of of the continu- ous phase during emulsion. The biological response of the scaffolds was assessed in vitro by using bone marrow-derived rat mesenchymal stem cells (MSCs). The results demonstrated the ability of the scaffolds to support the extensive and uni- form three-dimensional adhesion, colonization, and prolifera- tion of MSCs within the entire construct http://hdl.handle.net/2117/18535 Title: In silico evaluation of a new composite disc substitute with a L3-L5 lumbar spine finite element model Authors: Noailly, Jérôme; Ambrosio, Luigi; Tanner, K. Elizabeth; Planell Estany, Josep Anton; Lacroix, Damien Jerome Abstract: When the intervertebral disc is removed to relieve chronic pain, subsequent segment stabilization should restore the functional mechanics of the native disc. Because of partially constrained motions and the lack of intrinsic rotational stiffness ball-on-socket implants present many disadvantages. Composite disc substitutes mimicking healthy disc structures should be able to assume the role expected for a disc substitute with fewer restrictions than ball-on-socket implants. A biomimetic composite disc prototype including artificial nucleus fibre-reinforced annulus and endplates was modelled as an L4–L5 disc substitute within a L3–L5 lumbar spine finite element model. Different device updates, i.e. changes of material properties fibre distributions and volume fractions and nucleus placements were proposed. Load- and displace- ment-controlled rotations were simulated with and without body weight applied. The original prototype reduced greatly the flexibility of the treated segment with signifi- cant adjacent level effects under displacement-controlled or hybrid rotations. Device updates allowed restoring large part of the global axial and sagittal rotational flexibility predicted with the intact model. Material properties played a major role, but some other updates were identified to potentially tune the device behaviour against specific motions. All device versions altered the coupled interseg- mental shear deformations affecting facet joint contact through contact area displacements. Loads in the bony endplates adjacent to the implants increased as the implant stiffness decreased but did not appear to be a strong limi- tation for the implant biomechanical and mechanobiolog- ical functionality. In conclusion, numerical results given by biomimetic composite disc substitutes were encouraging with greater potential than that offered by ball-on-socket implants Tue, 02 Apr 2013 10:58:37 GMT http://hdl.handle.net/2117/18535 2013-04-02T10:58:37Z Noailly, Jérôme; Ambrosio, Luigi; Tanner, K. Elizabeth; Planell Estany, Josep Anton; Lacroix, Damien Jerome no When the intervertebral disc is removed to relieve chronic pain, subsequent segment stabilization should restore the functional mechanics of the native disc. Because of partially constrained motions and the lack of intrinsic rotational stiffness ball-on-socket implants present many disadvantages. Composite disc substitutes mimicking healthy disc structures should be able to assume the role expected for a disc substitute with fewer restrictions than ball-on-socket implants. A biomimetic composite disc prototype including artificial nucleus fibre-reinforced annulus and endplates was modelled as an L4–L5 disc substitute within a L3–L5 lumbar spine finite element model. Different device updates, i.e. changes of material properties fibre distributions and volume fractions and nucleus placements were proposed. Load- and displace- ment-controlled rotations were simulated with and without body weight applied. The original prototype reduced greatly the flexibility of the treated segment with signifi- cant adjacent level effects under displacement-controlled or hybrid rotations. Device updates allowed restoring large part of the global axial and sagittal rotational flexibility predicted with the intact model. Material properties played a major role, but some other updates were identified to potentially tune the device behaviour against specific motions. All device versions altered the coupled interseg- mental shear deformations affecting facet joint contact through contact area displacements. Loads in the bony endplates adjacent to the implants increased as the implant stiffness decreased but did not appear to be a strong limi- tation for the implant biomechanical and mechanobiolog- ical functionality. In conclusion, numerical results given by biomimetic composite disc substitutes were encouraging with greater potential than that offered by ball-on-socket implants http://hdl.handle.net/2117/18465 Title: Fibroblast adhesion and activation onto micro-machined titanium surfaces Authors: Guillem Martí, Jordi; Delgado Garoña, Luis María; Godoy Gallardo, Maria; Pegueroles Neyra, Marta; Herrero, Mariano; Gil Mur, Francisco Javier Abstract: Objectives: Surface modifications performed at the neck of dental implants, in the manner of micro-grooved surfaces, can reduce fibrous tissue encapsulation and prevent bacterial colonization, thereby improving fibrointegration and the formation of a biological seal. However, the applied procedures are technically complex and/or time consuming methods. The aim of this study was to analyse the fibroblast behaviour on modified titanium surfaces obtained, applying a simple and low-cost method Fri, 22 Mar 2013 09:11:38 GMT http://hdl.handle.net/2117/18465 2013-03-22T09:11:38Z Guillem Martí, Jordi; Delgado Garoña, Luis María; Godoy Gallardo, Maria; Pegueroles Neyra, Marta; Herrero, Mariano; Gil Mur, Francisco Javier no Objectives: Surface modifications performed at the neck of dental implants, in the manner of micro-grooved surfaces, can reduce fibrous tissue encapsulation and prevent bacterial colonization, thereby improving fibrointegration and the formation of a biological seal. However, the applied procedures are technically complex and/or time consuming methods. The aim of this study was to analyse the fibroblast behaviour on modified titanium surfaces obtained, applying a simple and low-cost method http://hdl.handle.net/2117/17124 Title: A low elastic modulus Ti-Nb-Hf alloy bioactivated with an elastin-like Authors: González, Marta; Salvagni, Emiliano; Rodríguez Cabello, J.C.; Rupérez de Gracia, Elisa; Gil Mur, Francisco Javier; Manero Planella, José María; Peña, Javier Abstract: b-type titanium alloys with low Young’s modulus are desirable to reduce stress shielding effect and enhance bone remodeling for implants used to substitute failed hard tissue. For biomaterials application, the surface bioactivity is necessary to achieve optimal osseointegration. In the previous work, the low elastic modulus (43 GPa) Ti-25Nb-16Hf (wt %) alloy was mechanically and microstructurally characterized. In the present work, the biological behavior of Ti-25Nb- 16Hf was studied. The biological response was improved by surface modification. The metal surface was modified by oxygen plasma and subsequently silanized with 3-chloropropyl (triethoxy)silane for covalent immobilization of the elastin-like polymer. The elastin-like polymer employed exhibits RGD bioactive motives inspired to the extracellular matrix in order to improve cell adhesion and spreading. Upon modification, the achieved surface presented different physical and chemical properties, such as surface energy and chemical composition. Subsequently, osteoblast adhesion, cell numbers, and differentiation studies were performed to correlate surface properties and cell response. The general tendency was that the higher surface energy the higher cell adhesion. Furthermore, cell culture and immunofluorescence microscopy images demonstrated that RGD-modified surfaces improved adhesion and spreading of the osteoblast cell type. Thu, 13 Dec 2012 10:32:19 GMT http://hdl.handle.net/2117/17124 2012-12-13T10:32:19Z González, Marta; Salvagni, Emiliano; Rodríguez Cabello, J.C.; Rupérez de Gracia, Elisa; Gil Mur, Francisco Javier; Manero Planella, José María; Peña, Javier no b-type titanium alloys with low Young’s modulus are desirable to reduce stress shielding effect and enhance bone remodeling for implants used to substitute failed hard tissue. For biomaterials application, the surface bioactivity is necessary to achieve optimal osseointegration. In the previous work, the low elastic modulus (43 GPa) Ti-25Nb-16Hf (wt %) alloy was mechanically and microstructurally characterized. In the present work, the biological behavior of Ti-25Nb- 16Hf was studied. The biological response was improved by surface modification. The metal surface was modified by oxygen plasma and subsequently silanized with 3-chloropropyl (triethoxy)silane for covalent immobilization of the elastin-like polymer. The elastin-like polymer employed exhibits RGD bioactive motives inspired to the extracellular matrix in order to improve cell adhesion and spreading. Upon modification, the achieved surface presented different physical and chemical properties, such as surface energy and chemical composition. Subsequently, osteoblast adhesion, cell numbers, and differentiation studies were performed to correlate surface properties and cell response. The general tendency was that the higher surface energy the higher cell adhesion. Furthermore, cell culture and immunofluorescence microscopy images demonstrated that RGD-modified surfaces improved adhesion and spreading of the osteoblast cell type. http://hdl.handle.net/2117/17116 Title: Plasma functionalization of titanium surface for repulsion of blood platelets Authors: Cvelbar, Uros; Modic, Martina; Kovac, J; Lazovic, S; Filipic, G; Vujosevic, D; Junkar, Ita; Elersic, Kristina; Brühl, S.P.; Canal Barnils, Cristina; Belmonte, Thierry; Mozetic, Miran Abstract: Thrombosis and restenosis are the most common problems during insertion of biocompatible implants like titanium stents into human blood, due to aggregation of platelets on their surfaces. Because of this reason, we studied the response of blood platelets to a plasma treated titanium surface. The aim was to design a functionalized surface which would repel blood platelets or prevent their adhesion. Therefore, we functionalized surfaces with low-temperature inductively coupled oxygen plasma treatment, which in the first stage cleaned the surface of titanium, and in the second promoted incorporation of oxygen functional groups as well as the growth of a titanium dioxide film. In this paper we show that oxygen atoms or oxygen containing groups play an important role in the repulsion of platelets and their deactivation. At the same time, increased surface temperature of samples either through sequential thermal deactivation in oven at 150 °C or heating the surface with ion bombardment during the treatment, lowers the oxygen content and the surface repulsion for platelets. Wed, 12 Dec 2012 10:57:16 GMT http://hdl.handle.net/2117/17116 2012-12-12T10:57:16Z Cvelbar, Uros; Modic, Martina; Kovac, J; Lazovic, S; Filipic, G; Vujosevic, D; Junkar, Ita; Elersic, Kristina; Brühl, S.P.; Canal Barnils, Cristina; Belmonte, Thierry; Mozetic, Miran no Thrombosis and restenosis are the most common problems during insertion of biocompatible implants like titanium stents into human blood, due to aggregation of platelets on their surfaces. Because of this reason, we studied the response of blood platelets to a plasma treated titanium surface. The aim was to design a functionalized surface which would repel blood platelets or prevent their adhesion. Therefore, we functionalized surfaces with low-temperature inductively coupled oxygen plasma treatment, which in the first stage cleaned the surface of titanium, and in the second promoted incorporation of oxygen functional groups as well as the growth of a titanium dioxide film. In this paper we show that oxygen atoms or oxygen containing groups play an important role in the repulsion of platelets and their deactivation. At the same time, increased surface temperature of samples either through sequential thermal deactivation in oven at 150 °C or heating the surface with ion bombardment during the treatment, lowers the oxygen content and the surface repulsion for platelets. http://hdl.handle.net/2117/16838 Title: Drug delivery properties of macroporous polystyrene solid foams Authors: Canal Barnils, Cristina; Aparicio, Rosa María; Vílchez, Alejandro; Esquena, Jordi; García-Celma, María José Abstract: Purpose. Polymeric porous foams have been evaluated as possible new pharmaceutical dosage forms. Methods. These materials were obtained by polymerization in the continuous phase of highly concentrated emulsions prepared by the phase inversion temperature method. Their porosity, specific surface and surface topography were characterized, and the incorporation and release of active principles was studied using ketoprofen as model lipophilic molecule. Results. Solid foams with very high pore volume, mainly inside macropores, were obtained by this method. The pore morphology of the materials was characterized, and very rough topography was observed, which contributed to their nearly superhydrophobic properties. These solid foams could be used as delivery systems for active principles with pharmaceutical interest, and in the present work ketoprofen was used as a model lipophilic molecule. Conclusions. Drug incorporation and release was studied from solid foam disks, using different concentrations of the loading solutions, achieving a delayed release with short lag-time Mon, 05 Nov 2012 12:32:31 GMT http://hdl.handle.net/2117/16838 2012-11-05T12:32:31Z Canal Barnils, Cristina; Aparicio, Rosa María; Vílchez, Alejandro; Esquena, Jordi; García-Celma, María José no Purpose. Polymeric porous foams have been evaluated as possible new pharmaceutical dosage forms. Methods. These materials were obtained by polymerization in the continuous phase of highly concentrated emulsions prepared by the phase inversion temperature method. Their porosity, specific surface and surface topography were characterized, and the incorporation and release of active principles was studied using ketoprofen as model lipophilic molecule. Results. Solid foams with very high pore volume, mainly inside macropores, were obtained by this method. The pore morphology of the materials was characterized, and very rough topography was observed, which contributed to their nearly superhydrophobic properties. These solid foams could be used as delivery systems for active principles with pharmaceutical interest, and in the present work ketoprofen was used as a model lipophilic molecule. Conclusions. Drug incorporation and release was studied from solid foam disks, using different concentrations of the loading solutions, achieving a delayed release with short lag-time http://hdl.handle.net/2117/16837 Title: Biomateriales textiles: plasma para regular la liberación de fármacos Authors: Canal Barnils, Cristina Abstract: Materiales textiles encuentran aplicaciones como biomateriales para la reparación y regeneración de distintas patologías tanto en tejidos blandos como en tejidos duros y su uso como sistemas de liberación controlada de fármacos reportaría numerosas ventajas. La modificación superficial de las fibras a nivel nanométrico mediante plasma de baja temperatura puede ser utilizada como herramienta para modular las interacciones biomaterial-fármaco y por tanto, conseguir una liberación controlada de los principios activos. Mon, 05 Nov 2012 12:23:22 GMT http://hdl.handle.net/2117/16837 2012-11-05T12:23:22Z Canal Barnils, Cristina no Materiales textiles encuentran aplicaciones como biomateriales para la reparación y regeneración de distintas patologías tanto en tejidos blandos como en tejidos duros y su uso como sistemas de liberación controlada de fármacos reportaría numerosas ventajas. La modificación superficial de las fibras a nivel nanométrico mediante plasma de baja temperatura puede ser utilizada como herramienta para modular las interacciones biomaterial-fármaco y por tanto, conseguir una liberación controlada de los principios activos. http://hdl.handle.net/2117/16836 Title: Active species in N2 and N2-O2 afterglows for surface treatments Authors: Ricard, André; Pointu, Anne Marie; Villeger, Sandrine; Canal Barnils, Cristina Abstract: Production of active species is studied in N2 and in N2-O2 afterglows of electrical discharges at low and atmospheric gas pressures. They are produced in microwave discharges in a large range of gas pressures from a few Torr to 100 Torr and in corona discharges at atmospheric gas pressure. The active species in N2 afterglows are the N-atoms which are in the range of a few percents in the afterglows. The effect of O2 molecules in low percentages in low pressure N2 microwave plasmas and as impurity in corona N2 discharges is specially analysed. The interaction of N and O-atoms with surfaces is studied for bacteria decontamination and for transmission of N-atoms though porous membranes. The processes of bacteria decontamination in N2-O2 afterglows are described for low pressure microwave and atmospheric pressure corona discharges. Transmission of N-atoms through porous membranes is studied at medium pressure (10100 Torr) microwave afterglows. Mon, 05 Nov 2012 12:14:45 GMT http://hdl.handle.net/2117/16836 2012-11-05T12:14:45Z Ricard, André; Pointu, Anne Marie; Villeger, Sandrine; Canal Barnils, Cristina no Production of active species is studied in N2 and in N2-O2 afterglows of electrical discharges at low and atmospheric gas pressures. They are produced in microwave discharges in a large range of gas pressures from a few Torr to 100 Torr and in corona discharges at atmospheric gas pressure. The active species in N2 afterglows are the N-atoms which are in the range of a few percents in the afterglows. The effect of O2 molecules in low percentages in low pressure N2 microwave plasmas and as impurity in corona N2 discharges is specially analysed. The interaction of N and O-atoms with surfaces is studied for bacteria decontamination and for transmission of N-atoms though porous membranes. The processes of bacteria decontamination in N2-O2 afterglows are described for low pressure microwave and atmospheric pressure corona discharges. Transmission of N-atoms through porous membranes is studied at medium pressure (10100 Torr) microwave afterglows. http://hdl.handle.net/2117/16815 Title: Calcium phosphate cements as drug delivery materials Authors: Ginebra Molins, Maria Pau; Canal Barnils, Cristina; Español Pons, Montserrat; Pastorino, David; Montufar Jiménez, Edgar Benjamin Abstract: Calcium phosphate cements are used as synthetic bone grafts, with several advantages, such as their osteoconductivity and injectability. Moreover, their low-temperature setting reaction and intrinsic porosity allow for the incorporation of drugs and active principles in the material. It is the aim of the present work to: a) provide an overview of the different approaches taken in the application of calcium phosphate cements for drug delivery in the skeletal system, and b) identify the most significant achievements. The drugs or active principles associated to calcium phosphate cements are classified in three groups, i) low molecular weight drugs; ii) high molecular weight biomolecules; and iii) ions. Mon, 29 Oct 2012 16:18:51 GMT http://hdl.handle.net/2117/16815 2012-10-29T16:18:51Z Ginebra Molins, Maria Pau; Canal Barnils, Cristina; Español Pons, Montserrat; Pastorino, David; Montufar Jiménez, Edgar Benjamin no Calcium phosphate cements are used as synthetic bone grafts, with several advantages, such as their osteoconductivity and injectability. Moreover, their low-temperature setting reaction and intrinsic porosity allow for the incorporation of drugs and active principles in the material. It is the aim of the present work to: a) provide an overview of the different approaches taken in the application of calcium phosphate cements for drug delivery in the skeletal system, and b) identify the most significant achievements. The drugs or active principles associated to calcium phosphate cements are classified in three groups, i) low molecular weight drugs; ii) high molecular weight biomolecules; and iii) ions. http://hdl.handle.net/2117/16661 Title: Comparative study on AISI 440 and AISI 420B stainless steel for dental drill performance Authors: Albertini, M.; Herrero Climent, M.; Lázaro, Pedro; Ríos, Jose Vicente; Gil Mur, Francisco Javier Abstract: One of the most usual causes of the failure in dental implant osseointegration is the increase of the temperature above 47 °C during the drilling of the bone because it produces irreversible osteonecrosis. The result is weakened contact of implants with bone and possible loss of rigid fixation. Many studies about the design of the drill bit, contact forces, drill speed, drill point angle and feed-rate have been made. However, in all studies a martensitic stainless steel (AISI 440) has been used. The aim of this study was to determine the behavior of AISI420B stainless steel with higher hardness, higher heat conductivity and lower wear than the conventional stainless steel used in oral implantology. This steel showed adequate temperature increases, with or without irrigation, and a decrease of the weight lost of the drills with use. Fri, 05 Oct 2012 11:34:15 GMT http://hdl.handle.net/2117/16661 2012-10-05T11:34:15Z Albertini, M.; Herrero Climent, M.; Lázaro, Pedro; Ríos, Jose Vicente; Gil Mur, Francisco Javier no Biomaterials, Drill, Stainless steel, Wear One of the most usual causes of the failure in dental implant osseointegration is the increase of the temperature above 47 °C during the drilling of the bone because it produces irreversible osteonecrosis. The result is weakened contact of implants with bone and possible loss of rigid fixation. Many studies about the design of the drill bit, contact forces, drill speed, drill point angle and feed-rate have been made. However, in all studies a martensitic stainless steel (AISI 440) has been used. The aim of this study was to determine the behavior of AISI420B stainless steel with higher hardness, higher heat conductivity and lower wear than the conventional stainless steel used in oral implantology. This steel showed adequate temperature increases, with or without irrigation, and a decrease of the weight lost of the drills with use. http://hdl.handle.net/2117/16504 Title: Preparation of biodegradable polylactide microparticles via a biocompatible procedure Authors: Levato, R.; Mateos Timoneda, Miguel Angel; Planell Estany, Josep Anton Abstract: PLA MPs are prepared via a novel and toxic-chemical-free fabrication route using ethyl lactate, a green solvent and FDA-approved aroma. MPs are obtained by a solution jet break-up and solvent displacement method. Adjusting flow parameters allows the tuning of MPs size between 60 and 180 mm, with reduced polydispersity. Morphological analysis shows microporous particles with Janus-like surface. A fluorophore is successfully loaded into the MPs during their formation step. This versatile green solvent-based procedure is proven to be suitable for drug encapsulation and delivery applications. The method may be extended to different droplet generation techniques. Mon, 17 Sep 2012 09:37:54 GMT http://hdl.handle.net/2117/16504 2012-09-17T09:37:54Z Levato, R.; Mateos Timoneda, Miguel Angel; Planell Estany, Josep Anton no Biocompatibility, Biodegradable, Green solvents, Microparticles, Poly(lactic acid) PLA MPs are prepared via a novel and toxic-chemical-free fabrication route using ethyl lactate, a green solvent and FDA-approved aroma. MPs are obtained by a solution jet break-up and solvent displacement method. Adjusting flow parameters allows the tuning of MPs size between 60 and 180 mm, with reduced polydispersity. Morphological analysis shows microporous particles with Janus-like surface. A fluorophore is successfully loaded into the MPs during their formation step. This versatile green solvent-based procedure is proven to be suitable for drug encapsulation and delivery applications. The method may be extended to different droplet generation techniques. http://hdl.handle.net/2117/16290 Title: Biological decontamination using high and reduced pressure nitrogen afterglows Authors: Sarrette, Jean-Philippe; Cousty, Sarah; Clement, Frank; Canal Barnils, Cristina; Ricard, André Abstract: Typical results quantifying the antibacterial efficiencies of high and reduced pressure nitrogen afterglows are presented, using the same microbiological protocol. In parallel, the diffusion of the nitrogen atoms through different polymer membranes is studied. Wed, 18 Jul 2012 11:26:43 GMT http://hdl.handle.net/2117/16290 2012-07-18T11:26:43Z Sarrette, Jean-Philippe; Cousty, Sarah; Clement, Frank; Canal Barnils, Cristina; Ricard, André no Typical results quantifying the antibacterial efficiencies of high and reduced pressure nitrogen afterglows are presented, using the same microbiological protocol. In parallel, the diffusion of the nitrogen atoms through different polymer membranes is studied. http://hdl.handle.net/2117/15519 Title: Reduction of Ni release and improvement of the friction behaviour of NiTi orthodontic archwires by oxidation treatments Authors: Espinar, Eduardo; Llamas, José María; Michiardi, Alexandra; Ginebra Molins, Maria Pau; Gil Mur, Francisco Javier Abstract: This work studies NiTi orthodontic archwires that have been treated using a new oxidation treatment for obtaining Ni-free surfaces. The titanium oxide on the surface significantly improves corrosion resistance and decreases nickel ion release, while barely affecting transformation temperatures. This oxidation treatment avoids the allergic reactions or toxicity in the surrounding tissues produced by the chemical degradation of the NiTi. In the other hand, the lack of low friction coefficient for the NiTi superelastic archwires makes difficult the optimal use of these materials in Orthodontic applications. In this study, the decrease of this friction coefficient has been achieved by means of oxidation treatment. Transformation temperatures, friction coefficient and ion release have been determined. Thu, 08 Mar 2012 09:08:19 GMT http://hdl.handle.net/2117/15519 2012-03-08T09:08:19Z Espinar, Eduardo; Llamas, José María; Michiardi, Alexandra; Ginebra Molins, Maria Pau; Gil Mur, Francisco Javier no This work studies NiTi orthodontic archwires that have been treated using a new oxidation treatment for obtaining Ni-free surfaces. The titanium oxide on the surface significantly improves corrosion resistance and decreases nickel ion release, while barely affecting transformation temperatures. This oxidation treatment avoids the allergic reactions or toxicity in the surrounding tissues produced by the chemical degradation of the NiTi. In the other hand, the lack of low friction coefficient for the NiTi superelastic archwires makes difficult the optimal use of these materials in Orthodontic applications. In this study, the decrease of this friction coefficient has been achieved by means of oxidation treatment. Transformation temperatures, friction coefficient and ion release have been determined.