Evaluation of time-dependent dimensional changes in dental casts fabricated from polylactic acid using fused filament fabrication additive manufacturing

Objectives: To evaluate the dimensional stability over time of full-arch dental casts fabricated using Fused Filament Fabrication (FFF) with three distinct polylactic acid (PLA)-based filaments intended for dental use. Methods: A maxillary typodont was digitized using a high-precision laboratory scanner, and the resulting standard tessellation language (STL) file was created using an FFF printer with three PLA-based materials: Filadental Tray PLA (FT), Filadental Plaster White PLA (FG), and Aligner Spezial Grey PLA (FA). Ten casts were fabricated per material. Each cast was stored at room temperature and scanned at 1 day (T0), 1 week (T1), 2 weeks (T2), 3 weeks (T3), and 4 weeks (T4). Dimensional deviations relative to the reference STL were assessed using root mean square (RMS) analysis in five anatomical regions. Data were analyzed with a generalized linear model at a significance level of p < 0.05. Results: All materials showed time-dependent dimensional changes, with statistically significant differences observed across materials, time points, and anatomical regions (p < 0.001). FA exhibited the highest dimensional stability at all time points, with overall mean RMS deviation values ranging from 23.4 ± 4.2 μm at T0 to 33.1 ± 5.1 μm at T4. FG showed intermediate performance (T0: 27.9 ± 5.0 μm; T4: 42.7 ± 7.3 μm), while FT demonstrated the greatest dimensional changes (T0: 30.2 ± 6.1 μm; T4: 57.8 ± 9.6 μm), particularly in anterior and posterior segments (p < 0.001). The soft tissue region was consistently the most stable across all materials, with minimal deviations over time (mean RMS: 18.2–28.9 μm). Conclusions: Considering the limitations of this study, FA showed superior dimensional stability, followed by FG and FT. Material composition and anatomical region significantly influence time-dependent deformation in FFF-printed dental casts. Clinical relevance: High-performance PLA materials such as FA may offer a dimensionally stable and cost-effective alternative for fabricating diagnostic or working dental casts, particularly in orthodontics and prosthodontics.