Fabrication Technologies of the Sintered Materials Including Materials for Medical and Dental Application

This chapter of the book presents the basis of classical powder metallurgy technologies and discusses powder fabrication, preparation, preliminary moulding, sintering and finish treatment operations. A general description of the materials and products manufactured with the classical powder metallurgy methods is presented. New variants are characterised along with special and hybrid technologies finding their applications in powder metallurgy. Special attention was drawn to microporous titanium and to TiAl6V4 alloy fabricated using hybrid rapid manufacturing technologies with selective laser sintering/selective laser melting (SLS/SLM) used for innovative implant scaffolds in medicine and regenerative dentistry. Laser deposition, thermal spraying and detonation spraying of powders are also discussed as special methods in which powders of metals and other materials are used as raw materials

Porous Selective Laser Melted Ti and Ti6Al4V Materials for Medical Applications

This chapter characterises scaffolds manufactured in line with the make-to-order concept according to individual needs of each patient. The clinical data acquired from a patient during computer tomography, nuclear magnetic resonance or using traditional plaster casts is converted by a computer into a virtual solid model of a patient’s loss. The model, through the multiplication of a unit cell, is converted into a porous model on the basis of which an actual object is manufactured with the method of selective laser melting (SLM) from Ti/Ti6Al4V powders. The created scaffold is characterised by good mechanical properties, which is confirmed by the results of the performed tensile and compressive strength tests. The material is additionally subjected to surface treatment consisting of the deposition of atomic layers of titanium dioxide with nanometric thickness

Microporous Titanium-Based Materials Coated by Biocompatible Thin Films

This chapter presents the outcomes of numerous own works concerning constructional solutions and fabrication technologies of a new generation of custom, original, hybrid, microporous high-strength engineering and biological materials with microporous rigid titanium and Ti6Al4V alloy skeletons manufactured by Selective Laser Sintering (SLS), whose pores are filled with living cells. The so constructed and fabricated implants, in the connection zone with bone stumps, contain a porous zone, with surface treatment inside pores, enabling the living tissues to grow into. As the adhesion and growth of living cells are dependent on the type and characteristic of the substrate it is necessary to create the most advantageous proliferation conditions of living cells inside the pores of a microporous skeleton made of titanium and Ti6Al4V alloy. In order to improve the proliferation conditions of cells ensured by a fully compatible substrate, internal coatings with TiO2, Al2O3 oxides and Ca10(PO4)6(OH)2 hydroxyapatite of the surface of pores of a microporous skeleton made of titanium and Ti6Al4V alloy with SLS was used. Two technologies have been chosen for the deposition of thin coatings onto the internal surfaces of pores: Atomic Layer Deposition (ALD) and the sol-gel of deep coating from the liquid phase

Composite Materials Infiltrated by Aluminium Alloys Based on Porous Skeletons from Alumina, Mullite and Titanium Produced by Powder Metallurgy Techniques

The infiltration technology with reinforcement in the form of porous skeletons fabricated with powder metallurgy methods has been presented in relation to the general characteristics of metal alloy matrix composite materials. The results of our own investigations are presented pertaining to four alternative technologies of fabrication of porous, sintered skeletons, and their structure and their key technological properties are presented. Porous skeletons made of Al2O3 aluminium are sintered reactively using blowing agents or are manufactured by ceramic injection moulding (CIM) from powder. Porous skeletons made of 3Al2O3⋅2SiO2 mullite are achieved by sintering a mixture of halloysite nanotubes together with agents forming an open structure of pores. Titanium porous skeletons are achieved by selective laser sintering (SLS). The structure and properties of composite materials with an aluminium alloy matrix—mainly EN AC-AlSi12 and also EN AC-AlSi7Mg0.3 alloys—reinforced with the so manufactured skeletons are also described. A unique structure of the achieved composite materials, together with good mechanical properties and abrasive wear resistance at low density, ensured by an aluminium alloy matrix, are indicating broad application possibilities of such composites

Dacarbazine and interferon α with or without interleukin 2 in metastatic melanoma: a randomized phase III multicentre trial of the Dermatologic Cooperative Oncology Group (DeCOG)

In several phase II-trials encouraging tumour responses rates in advanced metastatic melanoma (stage IV; AJCC-classification) have been reported for the application of biochemotherapy containing interleukin 2. This study was designed to compare the efficacy of therapy with dacarbazine (DTIC) and interferon α (IFN-α) only to that of therapy with DTIC and IFN-α with the addition of interleukin 2 (IL-2) in terms of the overall survival time and rate of objective remissions and to provide an elaborated toxicity profile for both types of therapy. 290 patients were randomized to receive either DTIC (850 mg/m2every 28 days) plus IFN-α2a/b (3 MIU/m2, twice on day 1, once daily from days 2 to 5; 5 MIU/m23 times a week from week 2 to 4) with or without IL-2 (4.5 MIU/m2for 3 hours i.v. on day 3; 9.0 MIU/m2i.v. day 3/4; 4.5 MIU/m2s.c. days 4 to 7). The treatment plan required at least 2 treatment cycles (8 weeks of therapy) for every patient. Of 290 randomized patients 281 were eligible for an intention-to-treat analysis. There was no difference in terms of survival time from treatment onset between the two arms (median 11.0 months each). In 273 patients treated according to protocol tumour response was assessable. The response rates did not differ between both arms (P = 0.87) with 18.0% objective responses (9.7% PR; 8.3% CR) for DTIC plus IFN-α as compared to 16.1% (8.8% PR; 7.3% CR) for DTIC, IFN-α and IL-2. Treatment cessation due to adverse reactions was significantly more common in patients receiving IL-2 (13.9%) than in patients receiving DTIC/IFN-α only (5.6%). In conclusion, there was neither a difference in survival time nor in tumour response rates when IL-2, applied according to the combined intravenous and subcutaneous schedule used for this study, was added to DTIC and IFN-α. However, toxicity was increased in melanoma patients treated with IL-2. Further phase III trials with continuous infusion and higher dosages must be performed before any final conclusions can be drawn on the potential usefulness of IL-2 in biochemotherapy of advanced melanoma. © 2001 Cancer Research Campaign http://www.bjcancer.co

The digitisation for the immediate dental implantation of incisors with immediate individual prosthetic restoration

Purpose: The purpose of this study is to present the author's method of planning the procedure of immediate implant-prosthetic restoration in place of a tooth qualified for removal by performing a surgical template and implant-prosthetic restoration based on data obtained in the CBCT test and intraoral scanning 3D model. Design/methodology/approach: The method of planning the implant surgery through the design and manufacture of surgical templates and implant prostheses performed before the start of medical procedures was described on the basis of actual clinical data from patients with anterior segment teeth qualified for extraction for reasons of complications after endodontic treatment. The placement of the implant was planned using virtual reality, where the bone model and the virtual soft tissue model were combined, which made it possible to perform a surgical template and prosthetic implant restoration. For the manufacturing, 3D printing as stereolithography SLA and selective laser sintering SLS for the surgical template manufacturing and CNC milling in the case of the prosthetic implant were used for restoration. Findings: The method allows planning the implant position based on two connected bone and soft tissue models and allows to design and manufacture a surgical guide. In this way, it becomes possible to place implants in the patient's bone during surgery procedure in the planned position and to install the prosthetic implant restoration in the form of an individual abutment and a PMMA crown during the same procedure in the surgical part. Practical implications: Thanks to the method of computer-aided design/manufacturing CAD/CAM production of surgical templates and prosthetic restoration based only on digital models and the planned position of the implant, it is possible to carry out the procedure of immediate tooth extraction and replacement with permanent prosthetic restoration. The whole process is based on the CBCT test performed at the beginning. The presented method allows shortening the procedure time by four times and the rehabilitation time by 3-6 months when performing the procedure in a minimally invasive manner. Originality/value: This article presents the original design and production method of surgical guides. It allows for precise planning of the implant position and transfer of this data to the patient's mouth during the procedure, enabling permanent prosthetic restoration before starting medical procedures

Selektywne spiekanie i topienie laserowe proszków czystego tytanu i jego stopu Ti6Al4V oraz dobór środowiska chemicznego do trawienia tych materiałów

The aim of the investigations described in this article is to present a selective laser sintering and melting technology to fabricate metallic scaffolds made of pristine titanium and titanium Ti6Al4V alloy powders. Titanium scaffolds with different properties and structure were manufactured with this technique using appropriate conditions, notably laser power and laser beam size. The purpose of such elements is to replace the missing pieces of bones, mainly cranial and facial bones in the implantation treatment process. All the samples for the investigations were designed in CAD/CAM (3D MARCARM ENGINEERING AutoFab (Software for Manufacturing Applications) software suitably integrated with an SLS/SLM system. Cube-shaped test samples dimensioned 10×10×10 mm were designed for the investigations using a hexagon-shaped base cell. The so designed 3D models were transferred to the machine software and the actual rapid manufacturing process was commenced. The samples produced according to the laser sintering technology were subjected to chemical processing consisting of etching the scaffolds’ surface in different chemical mediums. Etching was carried out to remove the loosely bound powder from the surface of scaffolds, which might detach from their surface during implantation treatment and travel elsewhere in an organism. The scaffolds created were subjected to micro- and spectroscopic examinationsCelem badań, opisanych w niniejszym artykule jest zaprezentowanie technologii selektywnego spiekania i topienia laserowego w celu wytworzenia metalowych scaffoldów z proszków: czystego tytanu oraz jego stopu Ti6Al4V. Techniką tą przy zastosowaniu odpowiednich warunków wytwarzania między innymi mocy lasera i wielkości plamki lasera wytworzono tytanowe scaffoldy o różnych własnościach i strukturze. Tego typu elementy mają za zadanie zastąpić brakujące fragmenty kości głównie kości szczękowo-twarzowych w procesie leczenia implantacyjnego. Wszystkie próbki do badań zaprojektowano w odpowiednio zintegrowanym z systemem SLS/SLM oprogramowaniem CAD/CAM (3D MARCARM ENGINEERING AutoFab, Software for Manufacturing Applications). Przy wykorzystaniu komórki bazowej o kształcie heksagonalnym zaprojektowano próbki do badań w kształcie sześcianu o wymiarach 10×10×10 mm. Tak zaprojektowane trójwymiarowe modele przetransportowano do oprogramowania maszyny gdzie rozpoczęto właściwy proces wytwarzania przyrostowego. Wykonane w technologii spiekania laserowego próbki poddano obróbce chemicznej polegającej na trawieniu powierzchni scaffoldów, w różnych ośrodkach chemicznych. Trawienie wykonano w celu usunięcia z powierzchni scaffoldów luźno związanego proszku, który mógłby podczas leczenia implantacyjnego oderwać się od ich powierzchni i przedostać się w inne miejsce organizmu. Wytworzone scaffoldy poddano badaniom mikro- i spektroskopowym

Application of polymer impression masses for the obtaining of dental working models for the stereolithographic 3D printing

Purpose: The aim of the work is to execute measurements of digital dental models taken by scanning prosthetic impressions using the engineering CAD software and finding dimensional differences and scale factor for precise reproduction of patient tooth dimensions. Design/methodology/approach: Tests were carried out involving the execution of 3 series of impressions for selected impression materials, which were then scanned using two types of prosthetic scanners. Gypsum models based on mentioned impressions were scanned and dimensionally compared with impression-based digital models. Benchmark impressions were also performed in order to verify the obtained results and determine the correction factor for dimensions. The dimensional differences between impression groups were calculated by using Engineering CAD software. Findings: It was found, that compared to the base model, the digital model has a smaller volume than the object being mapped, the digital models based directly on the impression should be 0.09 - 0.12% rescaled to match the dimensions of the base model. Research limitations/implications: It is necessary to perform a practical verification of the results achieved and apply the determined coefficient in practice by creating working models using precise devices such as a 3D SLA printer and verify their results with intraoral scanner based models. Practical implications: This test will allow making precise working models using a 3D printer, allowing finally to perform, for example, implant-based bridges directly from the level of implants, using the masses described in the study. Originality/value: The comparative studies of polyvinyl siloxane and alignate impression materials were carried out in order to measure dimensional differences between working models made directly from the impression and gypsum models and compared with pattern, which allowed to determine the expansion coefficient, which will allow to work in 3D printing technology with close representation of real situation in the patient's oral cavity, which is particularly important when performing full arch bridges and extensive work on implants, including direct implants. The work has practical applications for both dental engineers and dentists performing advanced prosthetic work

Application Solid Laser-Sintered or Machined Ti6Al4V Alloy in Manufacturing of Dental Implants and Dental Prosthetic Restorations According to Dentistry 4.0 Concept

This paper presents a comparison of the impact of milling technology in the computer numerically controlled (CNC) machining centre and selective laser sintering (SLS) and on the structure and properties of solid Ti6Al4V alloy. It has been shown that even small changes in technological conditions in the SLS manufacturing variant significantly affect changes from two to nearly two and a half times in tensile and bending strengths. Both the tensile and bending strength obtained in the most favourable manufacturing variant by the SLS method is over 25% higher than in the case of cast materials subsequently processed by milling. Plug-and-play SLS conditions provide about 60% of the possibilities. Structural, tribological and electrochemical tests were carried out. In vitro biological tests using osteoblasts confirm the good tendency for the proliferation of live cells on the substrate manufactured under the most favourable SLS conditions. The use of SLS additive technology for the manufacturing of dental implants and abutments made of Ti6Al4V alloy in combination with the digitisation of dental diagnostics and computer-aided design and manufacture of computer-aided design/manufacturing (CAD/CAM) following the idea of Dentistry 4.0 is the best choice of technology for manufacturing of prosthetic and implant devices used in dentistry