For the production of medical devices, which are in direct contact with human tissue, especially in the case of mucosa or blood, non-network bound components like photoinitiators or their cleavage products, but also residual monomers, stabilizers, degradation products or monomer impurities are of major concern. Many of these components state health risks when released to the human body by migration processes. This contribution deals with the investigation of photocurable thiol-yne resins covering several important aspects for the production of orthodontic clear aligners by UV based manufacturing processes. In this context, the performance of different low-toxic photoinitiators and stabilizers were evaluated in biocompatible thiol-yne formulations. In order to improve the stability of the investigated thiol-yne based formulations, hydroxybenzene based stabilizers were evaluated. In these experiments, lauryl gallate, which is approved as food additive, provided the most efficient stabilization. Notably, the thermo-mechanical properties of the investigated photopolymers are only slightly affected by water absorption. The 3D printability of these resins has been successfully demonstrated by fabricating test structures using a DLP printer. These results highlight the versatility of the present thiol-yne system for the production of orthodontic clear aligners by means of UV based 3D printing techniques.

Exploring photo-curable thiol-yne resins for the 3D printing of orthodontic clear aligners

2019 Spring National Meeting

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