Craft 017991 final publishable report biotip
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- Bu səhifədəki naviqasiya:
- WP5. Implants industrial development
- Fig. 4: Pressure inside the cavity over the shot number for the titanium feedstock, given for fresh feedstock as well as for regranulated feedstock, using Premix binder.
- WP6: Implants evaluation
- WP7 – Dissemination and Exploitation of Project Results.
- Dates Type Type of audience Countries addressed
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Tehnoton has collaborated with partners in order to establish the characteristics of the MIM moulds as stated above, and we have performed the design of MIM moulds and also we have implemented the drawings of the chosen implant. We have started the final design of the mould according to the chosen implant model. We have defined the characteristics of the starting material from which the mould will be manufactured and we have found producers of complete mould packages materials which comply with the chosen characteristics. We have also started to implement into the design of the mould the characteristics and the properties discussed, according to the final implant model, and also we have achieved to elaborate a simulation model for the process of material injection in the mould. The mould design had to be changed to corrections made from other partners. In order to be more precise in the design of the mould and to obtain the final dimensions of the mould we need to receive some information regarding the properties of the injection material, which will be chosen for the injection process. Also this is necessary in order to obtain a better simulation of the injection process in order to solve in a proper manner all the problems that could arise from the designing of the mould. Another problem is that at the meeting in Germany the implant model has been changed. Such a thing implies a new design of the mould. For this to be done we need the drawings of the new implant model as soon as possible. IFAM tested its rapid prototyping production system using titanium powder. Using the standard binder of the system, the contamination level in the sintered parts reached values which are not allowable. IFAM then experimented with a new binder system but found out that the necessary changes of the system could not be performed easily in the scope of this project. Thus it was decided to produce the design prototypes using stainless steel powder, as was already thought about in the proposal, when the STL data for the implants becomes available. IFAM produced some prototypes of two different designs which were provided by FTS. The parts were produced from titanium powder but without measuring the properties. They were intended as design prototypes showing some advantages and disadvantages of the powder route. IFAM analysed the properties of the Pyrogenesis feedstock in order to perform mould filling simulation. The simulation was then performed using the software SigmaSoft as this allows a real 3D-simulation. This simulation revealed that there should be no problems in filling the cavities if injection takes place from the tip of the demonstrators. WP5. Implants industrial development The results of the tests show that despite some difficulties and the narrow processing window it should be possible to mould the demonstrators from this feedstock. This is supported by the weight of the green parts over shot number for fresh and recycled feedstock, as given in fig 5. 
Fig. 4: Pressure inside the cavity over the shot number for the titanium feedstock, given for fresh feedstock as well as for regranulated feedstock, using Premix binder. 
Fig. 5: Weight of the green parts for fresh and for recycled titanium green parts The data was used to simulate the filling of the two geometries for which the STL-data was provided by FTS. The simulation did not reveal any critical behaviour, the two geometries should be filled well. Pressure, temperature and shear rates were well inside the normal levels. 
Filling pressure for demonstrator no. 1 
Shear rate during filling of demonstrator no. 2 
Scheme of 3DP Rapid prototyping system: 1) Spread a thin powder layer; 2) Print the binder into the powder to bond the powders in the cross section of the component; 3) Dry the binder and start the next layer; 4) Remove the bonded part from the excess powder. The component is built layer by layer inside a loose powder bed. At the end, the part is removed from the powder bed and sintered. Depending on the size of the component and on the powder sintering can lead to highly porous or to dense parts. The prototypes depicted in figure below show the two types of designs that were provided by FTS and which had been taken from existing implants.
Fig. 13: Photos of the prototypes prepared by 3DP WP6: Implants evaluation During work package 6 the surface morphology and topography of two commercial implants (3i Microtite (3,25/3,4·10mm) and 3i Nanotite) was determined. Also the biological performance of these two implants was examined. For the Microtite implant the SEM examination revealed the presence of a microroughness consisting of sharp pits 2 μm in diameter. These features look moderate in number and form. The AFM examination of the rough Osseotite surface revealed the presence of consistent surface depressions areas. The maximum vertical distance in a section analysis was 1070 nm. The Ra value of the scanned (8 x 8 μm) rough implant surface was 226 nm and the Rq value was 286 nm.
Moderate microroughness of the rough Microtite implant surface (SEM 600x, 2400x) Due to the delayed receipt of the experimental MIM implants and the necessary long duration of the preparation of the specimens, histomorphometrical measurements were not performed. More specifically, NKUA examined the surface of the received MIM experimental implants and compared them with commercially available dental implants. It is observed either to the flat or to the thread part of the implant high roughness as seen below. 
The images of the SEM are presented in figures a-d. In figure a it is observed that in low resolution many of the threads are deformed with levelled ends of the threads. In figures b (BEI) and c (SEI) the microporosity and microroughness of the surfaces are presented. In high resolution (Fig. d) sintering of the titanium powder particles is revealed and extensive black areas which can be either pores or remaining binders, were detected.  
Figure a Figure b  
Figure c Figure d From the EDS mapping analysis was revealed to be binder remnants due to the high carbon concentration in them. The roughness of the flat area of the MIM implant expressed by the parameters Ra and Rq parameters present high values. These values are much higher than the values recorded in commercial dental implants. As it can be seen from the experimental results the as-received MIM experimental implant its surface is extremely rough and extensive binder remnants were recorded. The biological performance of the experimental implants in comparison with well documented commercial dental implants was evaluated. Specimens included commercial dental implants were examined histologically. Microtomographical, microradiological tests revealed that the experimental implants were not osseointegrated three weeks after their implantation. Specimens that concluded the experimental implants from animals that were sacrificed six weeks after the implantation revealed that, although osseointegration was improved, optimum results were not succeeded as it happens with the commercial nanotreated dental implants. WP7 – Dissemination and Exploitation of Project Results. Responsible partner: Pyrogenesis. The exploitation committee was formed composing from managing directors of the SME participants and is lead by Mr Alex Littlejohn from DTS. Its first task is to collect potentially exploitable results from the project. Follows a table with dissemination actions
Results were also presented in the IADR/CED conference held in Thessalonica the 26-29 September of 2007 Yüklə 219,35 Kb. Dostları ilə paylaş:
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