The additive manufacturing of parts made from close-to-production materials poses a great challenge. One example are highly viscous silicones, as used in injection moulding. For small production quantities, the manufacturing of injection moulds is uneconomical. This paper presents tensile specimens printed with an in-house developed dispensing system, which are analysed for air cavities (micro-CT scans) and mechanical properties. Based on the results, advice for the design and slicing parameters of parts using high-viscosity silicones in AM by means of material extrusion are developed.

Objectives: The authors present their experience of a new intralaryngeal silicone prosthesis used to manage laryngotracheal pathologies associated with severe deglutition and respiratory disorders.

Study design: This retrospective study, conducted in the head and neck surgery department of the Strasbourg University Hospital, France, included 10 patients (12 prostheses inserted) and was conducted from November 2000 to November 2003.

Methods: A pre-operative clinical examination and a computed tomography and/or magnetic resonance scan assessed patients' laryngeal function. Two different semirigid laryngotracheal prostheses were used, inserted under general anaesthetic into the region from the supraglottic area to the first tracheal cartilages including the vocal folds and the ventricles. In group one (n = 5), patients presented with laryngeal stenosis with preserved deglutition function, and patent prostheses were used to restore laryngeal patency. In group two (n = 5), patients suffered from severe deglutition disorders and were in poor general condition and so required a cuffed tracheostomy tube, therefore obstructed prostheses were inserted to stop aspirations and to suppress the cuff of the tracheostomy tube. The study was performed under the authorization of the Biomedical Research Patients' Protection Committee of Alsace I, France.

Results: The mean implantation duration was six months. The prosthesis used in the first group restored laryngeal patency without further complications such as aspiration or prosthesis (mucous) obstruction. The prosthesis used in group two prevented aspiration and allowed to change a cuff by an uncuffed tracheostomy tube.

Conclusions: The intralaryngeal prosthesis used in group one constituted a reversible and effective method of treating laryngotracheal stenoses. The intralaryngeal prosthesis used in group two constituted an alternative to classical larynx exclusion techniques. The insertion is performed in few minutes under general anaesthetic through an endoscopic procedure. This reversible technique aimed to treat patients rapidly to reduce complications and post-operative morbidity.

the idea underscoring our proposed development is to take advantage of the good properties of both polyurethanes (pu) and silicones (pdms). the attributes which make polyurethanes attractive as materials for biomedical applications are their excellent physical–chemical properties, and their relatively good biocompatibility. against their use is the phenomenon of biodegradation that occurs after long-term implantation. silicones, on the other end, are known to have long-term biostability and good haemocompatibility subsequent to their use in several biomedical settings.

Most patients have no response to injectable collagen or silicone, but some cases may have positive or ‘undersea’(= clinically negative but immunologically positive) response to collagen. From the results of the Macrophage migration inhibition test, the relative immunogenicity was augmented most when we used implants with the following combination. The firstimmunization was collagen and the second one was collagen with silicone.

The augmented antigenicity might be enough to cause an allergic reaction to the patients who had no response to each implant alone. The purpose of this article is to warn of the potential hazard of injection.