Analyses of microplastic release and surface changes in materials used for intraoral devices subjected to sonication-induced aging

Abstract

Objective: To evaluate the release of microplastics (MPs) from different polymeric materials used in intraoral devices and to analyze their relationship with the surface degradation and roughness induced by an accelerated sonication-based aging method.

Methods: Three polymeric materials will be evaluated: milled acrylic resin, 3D-printed resin, and a thermoformed orthodontic aligner. Standardized specimens of each material will be fabricated and immersed in artificial saliva at 37°C, subjected to an accelerated aging protocol based on daily sonication sessions, with medium collection at 24 hours, 7 days, and 14 days. A control group will be included for each material, kept in artificial saliva at 37°C without sonication. The MPs released into the medium will be analyzed by Scanning Electron Microscopy (SEM) to determine particle size and morphology, and by fluorescence microscopy with Nile Red staining using a 3D holographic microscope (Nanolive) to confirm the presence of microplastics and analyze their morphology. Additionally, the surface roughness of the specimens will be evaluated before and after aging.

Expected Results: Preliminary evidence is expected on the usefulness of this novel sonication-based aging method, determining the release of MPs from the evaluated materials and its relationship with the associated surface changes. Differences in particle quantity, size, and morphology, as well as in surface roughness among the different materials, are anticipated following the sonication protocol.