Acrylic-based occlusal device materials - the influence of manufacturing techniques on material properties and the...

The material composition, manufacturing system, and post-processing steps used to fabricate acrylic-based occlusal devices may affect their clinical performance. This study aims to assess how manufacturing techniques and post-processing treatments influence the material properties of acrylic-based occlusal devices and the propensity of Streptococcus mutans to form biofilms on the surfaces.

Based on applied manufacturing technique and post-processing treatment, disc‑shaped specimens were manufactured using four 3D printing workflows (Splint 2.0‑Asiga Flash/Otoflash (OF), and LT Clear‑Form Cure/OF), one milling workflow (Therapon), and one autopolymerization workflow (PalaXtreme). Water sorption and solubility, surface free energy (SFE), average surface roughness, and Vickers hardness were tested across these workflows. The ATCC 700610 Streptococcus mutans strain served as a model for biofilm formation on the material surfaces. Two biofilm methods were employed: a 24-hour bioreactor approach and a 72-hour culture plate approach. Biofilm was quantified as colony-forming units per cm².

The Therapon and PalaXtreme workflows exhibited the lowest solubility, suggesting that these materials have the lowest release of material components in water. The Splint 2.0 workflows exhibited the lowest water sorption, indicating enhanced material integrity in humid conditions. Therapon showed the highest Vickers hardness, followed by PalaXtreme. The lower hardness of the print materials may make them susceptible to wear, which may not be optimal for treating patients with bruxism. No significant differences in SFE were observed between workflows. Low roughness values across all workflows indicate good polishability, which can enhance resistance to bacterial adhesion. In the 72-hour biofilm experiment, the Therapon workflow exhibited the most biofilm formation on material surfaces while PalaXtreme showed the least (p < 0.05). No significant differences between workflow groups were shown in the 24-hour biofilm experiment.In summary, material properties are influenced by material chemistry, manufacturing method, and associated post-processing treatment.