Three-dimensional printing of acrylic-based medical devices is projected to grow exponentially despite the limitations of photopolymerization and the lack of information on the…
Abstract
Purpose
Three-dimensional printing of acrylic-based medical devices is projected to grow exponentially despite the limitations of photopolymerization and the lack of information on the clinical performance of the materials. The purpose of this paper is to address an issue of critical importance in the translation of the three-dimensionally printed structures to the clinic, which is assessing the toxicity of the polymers and their precursors.
Design/methodology/approach
This review highlights the different manufacturing processes, challenges and novel experimental work including the zebrafish embryo model, which offers a potential method for toxicity profiling of biomedical photopolymers and their precursors due to its high genetic similarity to humans.
Findings
Materials information and experimental data available so far suggest that there is a need for regular and rigorous evaluation of new materials to establish their safety and protect users engaging in biomedically-related printing activities.
Originality/value
The review identifies stringent, contemporary and cost-effective analytical methods for assessing the safety of biomedical photopolymers and their precursors.
Details
Keywords
Frank Alifui-Segbaya, Jeffrey Lewis, Dominic Eggbeer and Robert John Williams
The purpose of this research paper is to compare corrosion data obtained from additive-manufactured heat-treated (HRx) and non-heat-treated (NHRx) cobalt-chromium (Co–Cr) alloys…
Abstract
Purpose
The purpose of this research paper is to compare corrosion data obtained from additive-manufactured heat-treated (HRx) and non-heat-treated (NHRx) cobalt-chromium (Co–Cr) alloys. Heat treatments are indicated as necessary in complex intra-oral framework production by additive manufacturing to remove accumulated thermal stresses. However, heat treatments have been linked to corrosion in cast dental alloys. Currently, there are few publications on this subject for laser-sintered dental alloys required for academic review.
Design/methodology/approach
Five rectangular specimens (n = 5), each with a total surface area of 10.27 cm2, were fabricated for the two groups. Specimens were immersed in an artificial saliva solution suspended by a nylon thread for 42 days at 37°C. Readings for Co, Cr and molybdenum ions released into the solution were obtained using an atomic absorption spectrometer at 1-, 4-, 7-, 14-, 21-, 28-, 35- and 42-day intervals at a detection limit of one part per million. Test methods are in accordance with ISO 10271.
Findings
Results showed a higher ion release in the HRx sample, statistically significant at 99 per cent confidence level (p < 0.01). A two-way ANOVA test conducted showed that there was a main effect of day and a main effect of finish, and there was also a significant interaction between these factors.
Originality/value
The study concludes that, although ion release in both samples was within the safe level recommended by ISO for the three major alloying elements, heat treatment, indeed, contributed extensively to the reduced corrosion resistance in the laser-sintered Co–Cr alloy. Further biocompatibility tests are recommended.
Details
Keywords
Frank Alifui‐Segbaya, Paul Foley and R.J. Williams
Rapid manufacture‐produced cobalt chromium alloys are beginning to be used in dentistry but there are few published results relating to their properties. The purpose of this paper…
Abstract
Purpose
Rapid manufacture‐produced cobalt chromium alloys are beginning to be used in dentistry but there are few published results relating to their properties. The purpose of this paper is to determine the corrosion resistance of a rapid manufacture‐produced dental alloy and compare it to a standard dental casting alloy.
Design/methodology/approach
In accordance with ISO 22674, ten samples of each alloy were fabricated in approximately 45 mm×10 mm×2 mm rectangular prisms, a sample number in excess of the standard requirements. The groups were further divided into those with highly polished surfaces and those with electrobrightened surfaces. Each sample was immersed in artificial saliva, suspended by a nylon thread for 42 days at 37°C. Readings for cobalt, chromium and molybdenum ions released into solutions were obtained using an atomic absorption spectrometer at 1, 4, 7, 14, 21, 28, 35, and 42 day intervals at a detection limit of one part per million.
Findings
Ion release of cobalt, chromium and molybdenum was well within the threshold prescribed by the standard. The alloys were safe for use as dental devices with respect to the above metals. The rapid manufacture alloy however performed better. In addition the data indicated that for both alloys, there was no discernable difference between a polished and an electrobrightened surface.
Originality/value
The rapid manufacture alloy studied shows a safe level of corrosion resistance with respect to cobalt, chromium and molybdenum according to ISO definitions. Further biocompatibility tests are recommended.