Three-dimensional printing versus conventional machining in the creation of a meatal urethral dilator: a cost and mechanical strength analysis

Abstract

Background Three-dimensional (3D) printing is a promising technology in medicine. Low-cost 3D printing options are accessible but the limitations are often poorly understood. We aim to compare fused deposition modelling (FDM), the most common and low cost 3D printing technique, with selective laser sintering (SLS) and conventional machining techniques in manufacturing meatal urethral dilators which were recently removed from the Australian market.Methods A meatal urethral dilator was designed using computer-aided design (CAD). The dilator was 3D printed vertically orientated on a low cost FDM 3D printer in polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS). It was also 3D printed horizontally orientated in ABS on a high-end FDM 3D printer with soluble support material, as well as on a SLS 3D printer in medical nylon. The dilator was also machined in medical stainless steel using a lathe. All dilators were tested mechanically in a custom rig by hanging calibrated weights from the handle until the dilator snapped.Results The horizontally printed ABS dilator experienced failure at a greater load than the vertically printed PLA and ABS dilators respectively (503g vs 283g vs 163g, p < 0.001). The SLS nylon dilator did not fail but began to bend and deformed at around 5,000g of pressure. The steel dilator did not bend even at 10,000g of pressure. The cost per dilator is highest for the steel dilator if assuming a low quantity of five at 98 USD, but this decreases to 30 USD for a quantity of 1000. In contrast, the cost for the SLS dilator is 33 USD for a quantity of five but relatively unchanged at 27 for a quantity of 1000.Conclusions SLS and conventional machining created clinically functional meatal dilators but low-cost FDM printing could not. We suggest that at the current time 3D printing is not a replacement for conventional manufacturing techniques which are still the most reliable way to produce large quantities of parts with a simple geometry such as the meatal dilator. 3D printing is best used for patient-specific parts, prototyping or manufacturing complex parts that have additional functionality that cannot be achieved with conventional machining methods.