Bioactive liner materials are used to promote dentine bridge formation, reduce early pulp inflammation, and support remineralization. Ion release is a key factor in understanding their role in biomineralization processes. This study is the first to employ a single method to quantitatively and qualitatively analyze the simultaneous release of multiple ions from various liner materials. Ion chromatography was used to measure the release of 16 anions and cations into water, along with pH changes, on days 1, 4, 7, 14, and 30. The tested liner materials included an experimental liner/base from Solventum (EXP), TheraCal LC (TC), Dycal (DY), Lime-Lite Enhanced (LL), Fuji Lining LC Paste Pak (FL), and Medcem MTA (MC). Statistical analysis included the Shapiro-Wilk, Kruskal-Wallis, and Friedman-tests (α = 0.05). DY exhibited the highest pH (∼12) after 30 days, followed by MC (∼10), both significantly higher than FL. Of 16 tested ions, 9 were cumulatively released in quantifiable amounts. FL showed the highest F⁻ (279 µg/mL) and Sr²⁺ (128 µg/mL) release. LL released the most Cl⁻ (101 µg/mL) and PO₄³ ⁻ (31 µg/mL), while SO₄²⁻ peaked in TC (111 µg/mL). DY released the most Ca²⁺ (950 µg/mL). EXP showed the highest NH₄⁺ levels, MC the highest K⁺, and LL the highest Na⁺. The differences in ion release and pH values represent a mosaic stone in understanding the biomineralization effects of liner materials, particularly when considered alongside monomer release data in future studies addressing biological and clinical contexts.

Sustainable production in dental and orthodontic 3D printing has gained increasing attention due to environmental concerns and the need for cost-effective and resource-saving solutions. This study presents a proof of concept for using recycled polymers and fused granular fabrication (FGF) in a closed-loop 3D printing approach, omitting intermediate filament manufacturing. A desktop 3D printer served as the kinematic platform and was modified with a pellet-based extruder to directly process recycled polyethylene terephthalate glycol (PETG) flakes, obtained by shredding previously printed PETG parts, into dental models. Dimensional accuracy was evaluated using optical 3D scanning analysis. The results indicate that models produced from recycled PETG are, in principle, suitable for dental and orthodontic applications within the investigated scope. This technical note provides initial evidence supporting the integration of recycled thermoplastics into dental and orthodontic model fabrication as part of sustainable additive manufacturing workflows. Potential pathways for workflow integration in clinical and laboratory environments, as well as directions for future research, are outlined, including the optimization of printing parameters and process stability. The main technical challenges were unreliable feedstock flow, causing bridging and jamming, while thermal creep from insufficient inlet cooling promoted premature softening of the flakes, causing torque spikes and unstable feeding.