β-tcp porous scaffold: part 1. Casting method and structure characterization

Transcription

1 β-tcp porous scaffold: part 1. Casting method and structure characterization D. Hautcoeur, L. Boilet, M. Lasgorceix, V. Lardot, F. Cambier Belgian Ceramic Research Centre S. Chamary, A. Leriche Laboratoire des Matériaux Céramiques et Procédés Associés M. Gonon UMONS-FPMs- Pôle Matériaux Service Science des matériaux INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

2 spongy Bone structure Natural composite of collagen and mineral. 2 types of bone: -cortical with dense structure compact bone -cancellous or trabecular bone with high porosity spongy bone INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

3 Compact bone Spongy bone Porosity Ф : µm %P : 65% Porosity Ф : µm %P : 80% σ c = MPa σ c = a few tenths MPa INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

4 How to mimic natural bone for substitute processing? INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

5 Technologies to processporousceramic: - Stereolithography - PMMA templating - Freeze casting Mechanicalproperties INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

6 Technologies to process porous ceramic 1) Stereolithography 1: laser UV x,y 5 2: feedzone 1 6 3: wiper : paste tank 5: rotation XY 4 8 6: galvanometric mirror 7: photosensible paste 8: polymerisedprototype : manufacturing plate 10: z control INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

7 Technologies to process porous ceramic Manufacturing of parts with complex external and internal shape, with controlled(size and shape) porosity. SIRRIS (Optoform) Lithoz GmbH Debinding and sintering to densify the parts INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

8 Technologies to process porous ceramic Lithoz GmbH Pore type interconnection Spherical channel Pore size 400 µm 800 µm 1 mm INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

9 Technologies to process porous ceramic Human bone INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

10 Technologies to processporousceramic: - Stereolithography - PMMA templating - Freezecasting Mechanicalproperties INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

11 Technologies to process porous ceramic 2) Ceramic slurry infiltration of organic bead skeleton Chemical forming with acetone under pressure - Bonding between PMMA beads (scaffold) - Controlled diameter bonding (Interconnection) depends on time, temperature, pressure INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

12 Technologies to process porous ceramic 1 Shaping 2 Impregnation PMMA beads INISMa-CRIBC 3 Debinding ceramic M. Descamps et al., JECS. 28 (2008) 149 Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

13 Technologies to process porous ceramic 500µm Natural bone β-tcp Scaffolds-initial bead size µm INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

14 Technologies to process porous ceramic Control of pore size depending on PMMA beads size Control of interconnection diameters: id PMMA beads ( µm) id : 60 µm id: 260 µm Control of porosity gradient in pore size and interconnection size INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

15 Technologies to process porous ceramic Possibility to add microporosityby mixing graphite as microporeforming agent. 5% 7% 14% 26% 38% 49% Global Microporosity 100,0% 90,0% 80,0% 70,0% 60,0% 50,0% 40,0% 30,0% 20,0% 10,0% 0,0% 0% 10% 20% 30% 40% 50% graphite content (weight) Controlled macro porosity and micro porosity INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

16 Technologies to processporousceramic: - Stereolithography - PMMA templating - Freezecasting Mechanicalproperties INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

17 Technologies to process porous ceramic 3) Freeze casting by ice-templating water 1 5 steps : 2 Ice 3 4 Gas 5 1. Slurry preparation 2. Freezing (anisotropic structure) 3. Demoulding 4. Freeze drying 5. Sintering 2 Ice growth along ΔT Freezing device INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

18 Technologies to process porous ceramic β-tcp, 30 vol % DM, 3% binder β-tcp, 1 K/min, 3% binder Porosity (%) Pore diameter (µm) 70 P = 50 % Dry matter content (vol %) 40 Cooling rate (K/min) β-tcp, 1 K/min, 3% binder Pore diameter (µm) 350 Pore long axis size: between 150 and 340 µm (dry matter content) between 13 and 210 µm (cooling rate ) small diameter 300 large diameter Dry matter content (vol %) INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

19 Technologies to process porous ceramic Spongy bone Cortical bone INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

20 Technologies to process porous ceramic Techniques Advantages Drawbacks Stereolithography PMMA Templating Freeze casting - Complex designs -High accuracy - Reproducibility - Good structure control -Low cost -Easy - High mechanical properties -Low cost - Good structure control - No debinding step - Expensive photosensitive resins - Cleaning step necessary - Control of the vertical accuracy - Low mechanical properties - Debinding step - Low mechanical properties -- Complex design - Reproducibility -Debinding step -Scaling up? (freezedryer) -Complex design - Reproducibility INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

21 Technologies to process porous ceramic : Mechanical properties - Experimental: compression test -0.5 mm/min and load cell of 10 kn -Determination of apparent elastic modulus and rupture strength. - β-tcp sample INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

22 Mechanical properties Stereolithography(from Lithoz) 6 Compressive strength (MPa) Strain(%) Porosity Compressive strength Apparent elastic modulus 45 % 6 MPa 0.4 GPa INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

23 4 mm Mechanical properties Compressive strength (MPa) PMMA templating Strain(%) 8 mm Porosity Compressive strength Apparent elastic modulus 65 % 5 MPa 0.6 GPa INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

24 Mechanical properties Freeze casting 10 mm Compressive strength (MPa) Strain(%) 10 mm Porosity Compressive strength Apparent elastic modulus 50 % 18 MPa 1.5 GPa INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

25 Compressive strength (MPa) Mechanical properties IT Lithoz Stereolithography PMMA templating Strain(%) INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

26 Conclusions and features Several techniques are used to produce macroporous bioceramics. The choice of the shaping technique has to be done according to the desired pore size range and architecture in relation to the application (implantation site, defect size ). Stereolithography(3D-manufacturing)is promising forproducing specific scaffold with a complex design, not achievable by the usual techniques. Freeze casting is promising owing to the high mechanical properties. INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

27 Conclusions and features Whatabout structure and cell development relation?(next presentation S. Chamary) PMMA templating and freeze casting structure similar to spongy and Complex design with freeze compact bone : Is it possible to casting technique? LASER merge the techniques? machining on the green part 1 cm 9 mm 9 mm INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

28 Aknowledgements This work was supported through a EU program (InterregIV), called Pristimed (N FW ). We acknowledge the FSE and the SPW -DGO6 for their financial support (grant number ECV320600FDOO7F/ /ECOPOR, subvention FIRST DOCTORAT Centre Agréé International) INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

29 INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

30 Mechanical properties 250 Valeurs Experimental expérimentales values 3 regions out off model: Compression strength(mpa) Analytical model 0 30,00 35,00 40,00 45,00 50,00 55,00 60,00 Global porosity(%) INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

31 Mechanical properties 250 Valeurs Experimental expérimentales values 3 regions out off model: Without binder Compression strength(mpa) ,00 35,00 40,00 45,00 50,00 55,00 60,00 Global porosity(%) Without binder = cracks perpendicular to the freezing direction => low mechanical properties INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

32 Mechanical properties Compression strength(mpa) Valeurs Experimental expérimentales values 3 regions out off model: Without binder High freezing rate 28/3/5 28/3/ ,00 35,00 40,00 45,00 50,00 55,00 60,00 Global porosity(%) Binder (>3 wt.%) + high freezing rate => morphology modification + smaller pore size INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

33 Mechanical properties Compression strength(mpa) Valeurs Experimental expérimentales values 3 regions out off model: Without binder High freezing rate High binder content 28/3/1 0 30,00 35,00 40,00 45,00 50,00 55,00 60,00 Global porosity(%) 28/6/1 High binder content => structure with bridges INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)

34 Porosity gradient effect = = µ. Porosity % 70,0 60,0 50,0 40,0 30,0 20, Height (mm) Porosity gradient of about 40% is observed with a plate (3 to 20 mm) where the gradient is about 5%. The porosity gradient for sample process with different conditions = the same tendencies INISMa-CRIBC Avenue Gouverneur Cornez, 4 B-7000 Mons, BELGIUM Tel +32(0)