Monitoring an Analysis of Perturbations in Fusion Deposition Modelling (FDM) Processes for the Use of Biomaterials.

During an FDM production process, there are different external disturbances to the characteristics of the machine that can affect to the production process. These disturbances will cause the final result differs from the desired one. Moreover, these disturbances, such as temperature or chamber humidity, are extremely important in case of using biocompatible materials. The use of these kind of materials with not controlled environment, can cause them to modify or loss of their properties; what will make the product unusable. Apart from these external disturbances, the conditions of the machine to which the material is subjected must also be considered, such as temperature, vibrations or extrusion speed. The monitoring of all these data will allow to know the conditions to which the product was exposed during the process. In this way, it will be able to verify the validity of the final product. For these reasons, the purpose of this work is to monitor the conditions of production of structures with biocompatible materials by fused deposition modelling (FDM) technique. This monitoring will allow us to obtain a report that guarantee the technical and geometrical characteristics of the model and the biomaterial properties. The parameters chosen to be monitored are: Diameter of filament use, temperature in extrusion nozzle, ambient temperature in closed chamber, ambient humidity in closed chamber. The obtained results, after collected and analysing the data, present variations of up to 3% in the temperature of the nozzle of the extruder with respect to set temperature. In the case of the filament diameter the difference with respect to the value provided from the filament supplier is of 13,7%. In addition, the results show how the ambient humidity in closed chamber has changed by 2 percentage points and the ambient temperature in closed chamber has been increased 6,52 °C with respect to the set values.

Experimental Comparison on Dental BioTribological Pairs Zirconia/Zirconia and Zirconia/Natural Tooth by Using a Reciprocating Tribometer.

The application of tribology in dentistry is growing rapidly, intense research has been conducted to develop an understanding of dental tribology for better selection of artificial materials and dental implant design. Dental biotribology, has been one of the most important branches in biotribology in recent years. The aim of this research is to investigate the tribological performances in the tooth-to-tooth contact and material-to-natural tooth contact (zirconia vs. zirconia and natural tooth vs. zirconia). The presented research was carried out by testing the above mentioned tribological pairs with the use of a reciprocating tribometer under lubricated conditions (artificial saliva). The normal force used in the tests was 20 N the time for each test was of 60 min. The stroke length was 2 mm, according to the range of displacement used in scientific literature. The wear mass loss evaluation was evaluated by using a gravimetric method. In order to characterize the wear mechanisms, present in the worn surfaces after each of tribo-tests, a topographic analysis was carried with a 3D non-contact optical profiler. The results show that the minimum value of the COF is obtained in the case of Zirconia vs. Zirconia tribo-couple. The results on the wear mass loss show a very low wear rate when coupling in tribological condition natural tooth with a ceramic restoration (a mean value of 0.5 mg was found). This rate is even lower when the contact is between two artificial zirconia teeth.

Novel Technique Based on Fused Filament Fabrication (FFF) and Robocasting to Create Composite Medical Parts.

The purpose for this study is to obtain a new composite manufacturing system based on Additive Manufacturing techniques that allows the creation of parts for the medical industry. These pieces will be resistant, lightweight and may have geometries more complex than those created with traditional systems of composite material. The new system is based on the union of two heads on a 3D Rep-Rap printer. One of the heads is an extruder head of thermoplastic Fused Filament Fabrication (FFF) and the other is a dosing head, based on the Robocasting technique, designed to be assembled on the 3D printer. Thermoplastics material and epoxy resin will be used. The alternate printing of both materials generates a piece of composite material. This new technique will allow to increase the structural properties of the piece in the XY plane. The new additive manufacturing system allows to obtain mechanical improvements both in the modulus of elasticity and in the tensile strength. Increase the modulus of elasticity of a value between 50 and 80% depending on the thermoplastic filament used. In the same way the tensile strength has increased between 50 and 60%. The improvement in the strength / weight ratio allows to this new additive manufacturing system to create medical pieces in which the lightness and resistance are its main characteristic, such as orthopedic prostheses.The results show that the use of FFF together with Robocasting, as a manufacturing process for end-use parts, generates an additional advantage that had not been considered until now. The combination of a thermoplastic and an epoxy resin opens a new path in the additive manufacturing since it allows creating pieces with new qualities without being conditioned by the design.

3D Digitization and Prototyping of the Skull for Practical Use in the Teaching of Human Anatomy.

The creation of new rapid prototyping techniques, low cost 3D printers as well as the creation of new software for these techniques have allowed the creation of 3D models of bones making their application possible in the field of teaching anatomy in the faculties of Health Sciences. The 3D model of cranium created in the present work, at full scale, present accurate reliefs and anatomical details that are easily identifiable by undergraduate students in their use for the study of human anatomy. In this article, the process of scanning the skull and the subsequent treatment of these images with specific software until the generation of 3D model using 3D printer has been reported.